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Benzene
Introduction

Benzene, also known as benzol, is a colorless liquid with a sweet odor. Benzene evaporates into air very quickly and dissolves slightly in water. Benzene is highly flammable. Most people can begin to smell benzene in air at 1.5-4.7 parts of benzene per million parts of air (ppm). Most people can begin to taste benzene in water at 0.5-4.5 ppm. Benzene is found is air, water, and soil.

Benzene found in the environment is from both human activities and natural processes. Benzene was first discovered and isolated from coal tar in the 19th century. Today, benzene is made mostly from petroleum sources. Because of its wide use, benzene ranks in the top 20 in production volume for chemicals produced in the United States. Various industries use benzene to make other chemicals, such as styrene, cumene (for various resins), and cyclohexane (for nylon and synthetic fibers). Benzene is also used for the manufacturing of some types of rubbers, lubricants, dyes, detergents, drugs, and pesticides. Natural sources of benzene, which include volcanoes and forest fires, also contribute to the presence of benzene in the environment. Benzene is also a natural part of crude oil and gasoline and cigarette smoke.

Fate & Transport

Benzene is commonly found in the environment. Industrial processes are the main sources of benzene in the environment. Benzene levels in the air can increase from emissions from burning coal and oil, benzene waste and storage operations, motor vehicle exhaust, evaporation from gasoline service stations, and use of industrial solvents. Since tobacco contains high levels of benzene, tobacco smoke is another source of benzene in air. Industrial discharge, disposal of products containing benzene, and gasoline leaks from underground storage tanks can release benzene into water and soil.

Benzene can pass into air from water and soil surfaces. Once in the air, benzene reacts with other chemicals and breaks down within a few days. Benzene in the air can attach to rain or snow and be carried back down to the ground.

Benzene in water and soil breaks down more slowly. Benzene is slightly soluble in water and can pass through the soil into underground water. Benzene in the environment does not build up in plants or animals.

Exposure Pathways

Most people are exposed to a small amount of benzene on a daily basis. You can be exposed to benzene in the outdoor environment and in the workplace. Exposure of the general population to benzene is mainly through breathing air that contains benzene. The major sources of benzene exposure are tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions. Vapors (or gases) from products that contain benzene, such as glues, paints, furniture wax, and detergents can also be a source of exposure. Auto exhaust and industrial emissions account for about 20 percent of the total nationwide exposure to benzene. About 50 percent of the entire nationwide exposure to benzene results from smoking tobacco or exposure to tobacco smoke. The average smoker (32 cigarettes per day) takes in about 1.8 milligrams (mg) of benzene per day. This is about 10 times the average daily intake of nonsmokers.

Background levels of benzene in air range from 2.8 to 20 parts of benzene per billion parts air (ppb) (1 ppb is 1,000 times less than 1 ppm and equals 3.26 micrograms of benzene in a cubic meter of air). People living in cities or industrial areas are generally exposed to higher levels of benzene in air than those living in rural areas. Benzene levels in the home are usually higher than outdoor levels. People living around hazardous waste sites, petroleum refining operations, petrochemical manufacturing sites, or gas stations may be exposed to higher levels of benzene in air.

For most people, the level of exposure to benzene through food, beverages, or drinking water is not as high as through air. Typical drinking water contains less than 0.1 ppb benzene. Benzene has been detected in some bottled water, liquor, and food. Leakage from underground gasoline storage tanks or from landfills and hazardous waste sites containing benzene can result in benzene contamination of well water. People with benzene-contaminated tap water can be exposed from drinking the water or eating foods prepared with the water. In addition, exposure can result from breathing in benzene while showering, bathing, or cooking with contaminated water.

Individuals employed in industries that make or use benzene may be exposed to the highest levels of benzene. As many as 238,000 people may be occupationally exposed to benzene in the United States. These industries include benzene production (petrochemicals, petroleum refining, and coke and coal chemical manufacturing), rubber tire manufacturing, and storage or transport of benzene and petroleum products containing benzene. Other workers who may be exposed to benzene because of their occupations include steel workers, printers, rubber workers, shoe makers, laboratory technicians, and gas station employees.

Metabolism

Benzene can enter your body through your lungs when breathing contaminated air. It can also enter through your stomach and intestines when eating food or drinking water that contains benzene. Benzene can enter your body through skin contact with benzene-containing products such as gasoline.

When you are exposed to high levels of benzene in air, about half of the benzene you breathe in leaves your body when you breathe out. The other half passes through the lining of your lungs and enters your bloodstream. Animal studies show that benzene taken in by eating or drinking contaminated foods behaves similarly in the body to benzene that enters through the lungs. A small amount of benzene will enter your body by passing through your skin and into your bloodstream during skin contact with benzene or benzene-containing products. Once in the bloodstream, benzene travels throughout your body and can be temporarily stored in the bone marrow and fat. Benzene is converted to products, called metabolites, in the liver and bone marrow. Some of the harmful effects of benzene exposure are believed to be caused by these metabolites. Most of the metabolites of benzene leave the body in the urine within 48 hours after exposure.

Health Effects

After exposure to benzene, several factors determine whether harmful health effects will occur and if they do what the type and severity of these health effects might be. These factors include the amount of benzene to which you are exposed and the length of time of the exposure. Most data involving effects of long-term exposure to benzene are from studies of workers employed in industries that make or use benzene. These workers were exposed to levels of benzene in air far greater than the levels normally encountered by the general population. Current levels of benzene in workplace air are much lower than in the past. Because of this reduction, and the availability of protective equipment such as respirators, fewer workers have symptoms of benzene poisoning.

Brief exposure (5-10 minutes) to very high levels of benzene in air (10,000-20,000 ppm) can result in death. Lower levels (700-3,000 ppm) can cause drowsiness, dizziness, rapid heart rate, headaches, tremors, confusion, and unconsciousness. In most cases, people will stop feeling these effects when they stop being exposed and begin to breathe fresh air.

Eating or drinking foods containing high levels of benzene can cause vomiting, irritation of the stomach, dizziness, sleepiness, convulsions, rapid heart rate, coma, and death. The health effects that may result from eating or drinking foods containing lower levels of benzene are not known. If you spill benzene on your skin, it may cause redness and sores. Benzene in your eyes may cause general irritation and damage to your cornea.

Benzene causes problems in the blood. People who breathe benzene for long periods may experience harmful effects in the tissues that form blood cells, especially the bone marrow. These effects can disrupt normal blood production and cause a decrease in important blood components. A decrease in red blood cells can lead to anemia. Reduction in other components in the blood can cause excessive bleeding. Blood production may return to normal after exposure to benzene stops. Excessive exposure to benzene can be harmful to the immune system, increasing the chance for infection and perhaps lowering the body's defense against cancer.

Benzene can cause cancer of the blood-forming organs. The Department of Health and Human Services (DHHS) has determined that benzene is a known human carcinogen. Long-term exposure to relatively high levels of benzene in the air can cause cancer of the blood-forming organs. This condition is called leukemia.

Exposure to benzene has also been linked with damage to chromosomes which are the parts of cells that are responsible for the development of hereditary characteristics. Exposure to benzene may also be harmful to the reproductive organs. Some women workers who breathed high levels of benzene for many months had irregular menstrual periods. When examined, these women showed a decrease in the size of their ovaries. However, exact exposure levels were unknown, and the studies of these women did not prove that benzene caused these effects. It is not known what effects exposure to benzene might have on the developing fetus in pregnant women or on fertility in men. Studies with pregnant animals show that breathing benzene has harmful effects on the developing fetus. These effects include low birth weight, delayed bone formation, and bone marrow damage.

The health effects that might occur in humans following long-term exposure to food and water contaminated with benzene are not known. In animals, exposure to food or water contaminated with benzene can damage the blood and the immune system and can even cause cancer.


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Dioxin
Introduction

The chlorinated dibenzo-p-dioxins are a class of compounds that are loosely referred to as dioxins. There are 75 possible dioxins. The one with four chlorine atoms at positions 2, 3, 7 and 8 of the dibenzo-p-dioxin chemical structure is called 2,3,7,8- tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). It is a colorless solid with no known odor. 2,3,7,8-TCDD does not occur occur naturally nor is it intentionally manufactured by any industry, except as a reference standard. It can be inadvertently produced in very small amounts as an impurity during the manufacture of certain herbicides and germicides and has been detected in products of incineration of municipal and industrial wastes. At the present time, 2,3,7,8-TCDD is not used for any purpose than scientific research.

Exposure Pathways

The main environmental sources of 2,3,7,8-TCDD are:

• Use of herbicides containing 2,4,5-Trichlorophenoxy acids (2,4,5-T)
• Production and use of 2,4,5-Trichlorophenol in wood preservatives
• Production and use of hexachlorophene as a germicide
• Pulp and paper manufacturing plants
• Incineration of municipal and certain industrial wastes
• Small amounts formed during the burning of wood in the presence of chlorine
• Accidental transformer/capacitor fires involving chlorinated benzenes and biphenyls
• Exhaust from automobiles powered with leaded gasoline
• Improper disposal of certain chlorinated chemical wastes

Although 2,4,5-T, 2,4,5-Trichlorophenol and hexachlorophene are no longer produced commercially (except for certain medical purposes), disposal sites of past production wastes are still sources of present exposure. 2,3,7,8-TCDD has been found in at least 28 of the 1,177 hazardous waste sites on the National Priorities List (NPL). Very low levels of 2,3,7,8-TCDD have been detected in ambient air. Detection of 2,3,7,8-TCDD in drinking water has not been reported. 2,3,7,8-TCDD has not been detected in most rural soils examined, but it can be present at trace levels in urban soils. The highest concentration of 2,3,7,8-TCDD was detected in a waste-oil-contaminated soil in Missouri that contained a 2,3,7,8-TCDD level more than one million times higher than soils from normal urban areas. 2,3,7,8-TCDD was detected in fish obtained from the contaminated sections of Lake Ontario, Saginaw Bay, the Michigan rivers, and several watersheds including those from Maine, Wisconsin, and Minnesota. In human milk, minute amounts of 2,3,7,8-TCDD have been detected in the United States and in several European countries.

Consumer sources are:

• Skin contact with surfaces such as soil and vegetation contaminated by the chemical
• Skin contact and inhalation of wood dusts from use of pentachlorophenol-treated woods
• Inhalation of air near improperly maintained dump sites or municipal incinerators
• Consumption of fish and cow's milk from contaminated areas
• Consumption of breast milk containing 2,3,7,8-TCDD by babies
• Minute exposure from the use of paper towels, napkins, coffee filters, computer papers, and other contaminated paper products.

Workers at risk of contacting 2,3,7,8-TCDD are:

• Workers who have been involved in the production or use of trichlorophenol and salts, hexachlorophene, and 2,4,5-T or other herbicides containing this chemical. The production of 2,4,5-T and 2,4,5-Trichlorophenol, however, has been discontinued in the United States.
• Workers in the pulp and paper industry
• Workers at certain municipal and industrial incinerators
• Workers involved in the high-temperature/pressure treatment of woods with pentachlorophenol
• Workers at certain hazardous waste sites
• Workers involved in the cleanup of certain accidental capacitor/transformer fires and in the salvaging of transformers
• Workers who have been involved in spraying of phenoxy herbicides such as Agent Orange

2,3,7,8-TCDD can enter your body through:

• Absorption through skin from contaminated soils and other materials
• Ingestion of 2,3,7,8-TCDD through the consumption of contaminated fish, cow's milk, foodstuffs, and, in the case of small children, soil
• Breathing contaminated ambient air. This may contribute very small amounts to total body intake; however, particulates such as fly ash from municipal and industrial incineration may constitute a major source of exposure
• Intake of 2,3,7,8-TCDD from the consumption of drinking water should be negligible

According to one estimate of ambient exposure, breathing air constitutes 2 percent, drinking water less than 0.01 percent, and consuming foods 98 percent of the total human exposure to 2,3,7,8-TCDD. No estimate of relative intake of 2,3,7,8-TCDD due to skin absorption is available.

Health Effects

• In humans, 2,3,7,8-TCDD causes chloracne, a severe skin lesion that usually occurs on the head and upper body. Unlike common acne, chloracne is more disfiguring and often lasts for years after the initial exposure.
• There is suggestive evidence that 2,3,7,8-TCDD causes liver damage in humans, as indicated by an increase in levels of certain enzymes in the blood, although these effects might also have resulted from the concomitant exposure to the chemicals contaminated with 2,3,7,8-TCDD or to the solvents in which these chemicals are usually dissolved. Animal studies have demonstrated severe liver damage in some species.
• There is suggestive evidence that 2,3,7,8-TCDD causes loss of appetite, weight loss, and digestive disorders in humans, although these effects might also have resulted from the concomitant exposure to the chemicals contaminated with 2,3,7,8-TCDD or to the solvents in which these chemicals are usually dissolved. Animal exposure to 2,3,7,8-TCDD results in severe loss of body weight prior to death.
• Although not demonstrated in humans, in animal studies 2,3,7,8-TCDD produced toxicity to the immune system. This toxicity can result in greater susceptibility to infection.
• Although not demonstrated in humans, in some animal species exposure to 2,3,7,8-TCDD resulted in adverse reproductive effects including spontaneous abortions. The monkey is very sensitive to this toxic property of 2,3,7,8-TCDD.
• Although not demonstrated in humans, in some animal species exposure to 2,3,7,8-TCDD during pregnancy resulted in malformations in the offspring. Low levels of 2,3,7,8-TCDD have been detected in human milk, but the effects on infants and children are unknown.

The human evidence for 2,3,7,8-TCDD alone is inadequate to demonstrate or reflect a carcinogenic hazard, although certain herbicide mixtures containing a 2,3,7,8-TCDD as an impurity provide limited evidence of causing cancer in exposed humans. Based on the positive evidence in animal studies, 2,3,7,8-TCDD is probably carcinogenic in humans.


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Ethylbenzene
Introduction

Ethylbenzene is a colorless liquid that smells like gasoline. It evaporates at room temperature and burns easily. Ethylbenzene occurs naturally in coal tar and petroleum. It is also found in many man-made products, including paints, inks, and insecticides. Gasoline contains about 2 percent (by weight) ethylbenzene. It is most commonly found as a vapor in the air. This is because ethylbenzene moves easily into the air from water and soil. Once in the air, other chemicals help break down ethylbenzene into chemicals found in smog. This breakdown happens in about 3 days with the aid of sunlight. In surface water such as rivers and harbors, ethylbenzene breaks down by reacting with other compounds naturally present in the water. In soil, the major way ethylbenzene is broken down is by soil bacteria. It can also move very quickly into groundwater, since it does not readily bind to soil. Near hazardous waste sites, the levels of ethylbenzene in the air, water, and soil could be much higher than in other areas.

Exposure Pathways

There are a variety of ways you may be exposed to this chemical. If you live in a highly populated area or near many factories or heavily traveled highways, you may be exposed to ethylbenzene in the air. Releases of ethylbenzene into these areas occur from burning oil, gas, and coal and from discharges of ethylbenzene from some types of factories. The median level of ethylbenzene in city air is about 0.62 parts of ethylbenzene per billion parts (ppb) of air. The median level in suburban air is about 0.62 ppb. In contrast, the median level of ethylbenzene measured in air in country locations is about 0.01 ppb. Indoor air has a higher median concentration of ethylbenzene (about 1 ppb) than outdoor air. This is because ethylbenzene builds up after you use household products such as cleaning products or paints.

Ethylbenzene was found in only 1 out of 10 of the United States rivers and streams tested in 1982 and 1983. The average level measured was 5.0 ppb. Ethylbenzene gets into water from factory releases, boat fuel, and poor disposal of waste. Background levels in soils have not been reported. Ethylbenzene may get into the soil by gasoline or other fuel spills and poor disposal of industrial and household wastes.

Some people are exposed to ethylbenzene in the workplace. Gas and oil workers may come into contact with ethylbenzene either through the skin or by breathing ethylbenzene vapors. Varnish workers, spray painters and persons involved in gluing operations may also be exposed to high levels of ethylbenzene. Exposure may also occur in factories that use ethylbenzene to produce other chemicals. Families of these workers may be exposed to ethylbenzene through contact with contaminated clothing.

You may be exposed to ethylbenzene if you live near hazardous waste sites containing ethylbenzene or areas where ethylbenzene spills have occurred. Higher than background levels of ethylbenzene were detected in groundwater near a landfill and near an area where a fuel spill had occurred. No specific information on human exposure to ethylbenzene near hazardous waste sites is available.

You may also be exposed to ethylbenzene from the use of many consumer products. Gasoline is a common source of ethylbenzene exposure. Other sources of ethylbenzene exposure come from the use of this chemical as a solvent in pesticides, carpet glues, varnishes and paints, and from the use of tobacco products. Ethylbenzene does not generally build up in food. However, some vegetables may contain very small amounts of it.

Metabolism

When you breathe air containing ethylbenzene vapor, it enters your body rapidly and almost completely through your lungs. Ethylbenzene in food or water can also rapidly and almost completely enter your body through the digestive tract. It may enter through your skin when you come into contact with liquids containing ethylbenzene. Ethylbenzene vapors do not enter through your skin to any large degree. People living in urban areas or in areas near hazardous waste sites may be exposed by breathing air or by drinking water contaminated with ethylbenzene.

Once in your body, ethylbenzene is broken down into other chemicals. Most of it leaves in the urine within 2 days. Small amounts can also leave through the lungs and in feces. Liquid ethylbenzene also enters through your skin and is broken down. Ethylbenzene in high levels is broken down slower in your body than low levels of ethylbenzene. Similarly, ethylbenzene mixed with other solvents is also broken down more slowly than ethylbenzene alone. This slower breakdown may increase the time it takes for ethylbenzene to leave your body.

Health Effects

At certain levels, exposure to ethylbenzene can harm your health. People exposed to low levels of ethylbenzene in the air for short periods of time have complained of eye and throat irritation. Persons exposed to higher levels have shown signs of more severe effects such as decreased movement and dizziness. No studies have reported death in humans following exposure to ethylbenzene. However, evidence from animals suggests that it can cause death at very high concentrations. Whether or not long-term exposure to ethylbenzene affects human health is not known because little information is available. Short-term exposure of laboratory animals to high concentrations of ethylbenzene in air may cause liver and kidney damage, nervous system changes, and blood changes. The link between these health effects and exposure to ethylbenzene is not clear because of conflicting results and weaknesses in many of the studies.

Also, there is no clear evidence that the ability to get pregnant is affected by breathing air, drinking water containing ethylbenzene, or coming into direct contact with ethylbenzene through the skin. Birth defects have occurred in newborn animals whose mothers were exposed by breathing air contaminated with ethylbenzene. The seriousness of these effects seems to increase with higher exposure levels. One long-term study in animals suggests that ethylbenzene may cause tumors. However, this study had many weaknesses and no conclusions could be drawn about possible cancer effects in humans. EPA has determined that ethylbenzene is not classifiable as to human carcinogenicity.

Low levels of ethylbenzene in the air may cause harmful health effects. More serious effects to your health may occur at higher levels. You can smell ethylbenzene in the air at concentrations as low as 2 parts of ethylbenzene per million parts of air by volume (ppm).

There are no reliable data on the effects in humans after eating, drinking, or breathing ethylbenzene or following direct exposure to the skin. For this reason, levels of exposure that may affect your health are estimated from animal studies. Only two reports described the results of eye or skin exposure to ethylbenzene. In these studies, liquid ethylbenzene caused eye damage and skin irritation in rabbits. More animal studies are available that describe the effects of breathing air or drinking water containing ethylbenzene.


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Gasoline
Introduction

Gasoline as discussed here is automotive used as a fuel for engines in cars. Gasoline is a manufactured mixture that does not exist naturally in the environment. Gasoline is produced from petroleum in the refining process. Gasoline is a colorless, pale brown, or pink liquid, and is very flammable. Typically, gasoline contains more than 150 chemicals, including small amounts of benzene, toluene, xylene, and sometimes lead. How the gasoline is made determines which chemicals are present in the gasoline mixture and how much of each is present. The actual composition varies with the source of the crude petroleum, the manufacturer, and the time of year.

Fate & Transport

Small amounts of the chemicals present in gasoline evaporate into the air when you fill the gas tank in your car or when gasoline is accidentally spilled onto surfaces and soils or into surface waters. Other chemicals in gasoline dissolve in water after spills to surface waters or underground storage tank leaks into the groundwater. In surface releases, most chemicals in gasoline will probably evaporate; others may dissolve and be carried away by water; a few will probably stick to soil. The chemicals that evaporate are broken down by sunlight and other chemicals in the air. The chemicals that dissolve in water also break down quickly by natural processes.

Exposure Pathways

• Breathing vapors at a service station when filling the car's fuel tank is the most likely way to be exposed
• Working at a service station
• Using equipment that runs on gasoline, such as a lawn mower
• Drinking contaminated water
• Being close to a spot where gasoline has spilled or leaked into the soil

Health Effects

Many of the harmful effects seen after exposure to gasoline are due to the individual chemicals in the gasoline mixture, such as benzene and lead. Inhaling or swallowing large amounts of gasoline can cause death. Inhaling high concentrations of gasoline is irritating to the lungs when breathed in and irritating to the lining of the stomach when swallowed. Gasoline is also a skin irritant. Breathing in high levels of gasoline for short periods or swallowing large amounts of gasoline may also cause harmful effects on the nervous system. Serious nervous system effects include coma and the inability to breathe, while less serious effects include dizziness and headaches. There is not enough information available to determine if gasoline causes birth defects or affects reproduction.

The Department of Health and Human Services (DHHS) and the International Agency for Research on Cancer (IARC) have not classified automotive gasoline for carcinogenicity. Automotive gasoline is currently undergoing review by the EPA for cancer classification. Some laboratory animals that breathed high concentrations of unleaded gasoline vapors continuously for 2 years developed liver and kidney tumors. However, there is no evidence that exposure to gasoline causes cancer in humans.


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Lead
Introduction

Lead is a naturally occurring bluish-gray metal found in small amounts in the earth's crust. It has no characteristic taste or smell. Metallic lead does not dissolve in water and does not burn. Some natural and man-made substances contain lead, but do not look like lead in its metallic form. Some of these substances can burn.

Lead has many different uses. Its most important use is in the production of some types of batteries. Other uses include the production of ammunition, in some kinds of metal products (such as sheet lead, solder, and pipes) and in ceramic glasses. Some chemicals containing lead, such as tetraethyl lead and tetramethyl lead, are used as gasoline additives. However, the use of these lead-containing chemicals in gasoline is much less than it used to be because the last producer of these additives in the United States stopped making them in early 1991. Other chemicals containing lead are used in paint. The amount of lead added to paints and ceramic products, caulking, gasoline additives, and solder has also been reduced in recent years because of lead's harmful effects in humans and animals. However, the use of lead in ammunition and roofing has actually increased in recent years. Lead is also used for radiation shields for protection against X-rays and in a large variety of medical (electronic ceramic parts of ultrasound machines, intravenous pumps, fetal monitors, and other surgical equipment), scientific (circuit boards for computers and other electronic circuitry), and military equipment (jet turbine engine blades, military tracking systems).

Most lead used by industry comes from mined ores ("primary") or from recycled scrap metal or batteries ("secondary"). Human activities (such as use of "leaded" gasoline) have spread lead and substances that contain lead to all parts of the environment. For example, lead is in air, drinking water, rivers, lakes, oceans, dust, and soil. Lead is also in plants and animals that humans may eat.

Fate & Transport

Lead occurs naturally in the environment. However, most of the lead dispersed throughout the environment comes from human activities. Before the use of leaded gasoline was limited, most of the lead released into the U.S. environment came from car exhaust. Since the EPA has limited the use of leaded gasoline, the amount of lead released into the air has decreased. In 1979, cars released 94.6 million kilograms (kg) of lead into the air in the United States. In contrast, in 1989 cars released only 2.2 million kg to the air. Other sources of lead released to the air include burning fuel, such as coal or oil, industrial processes, and burning solid waste.

The release of lead to air is now less than the release of lead to soil. Most of the lead in inner city soils comes from landfills and leaded paint. Landfills contain waste from lead ore mining, ammunition manufacturing, and from other industrial activities such as battery production. Very little lead goes directly into water.

Higher levels of lead from car exhausts can be measured near roadways. Very low levels of lead from car exhausts are found at distances of 25 meters (about 80 feet) from the road edge. However, once lead goes into the atmosphere, it may travel thousands of miles if the lead particles are small or if the lead compounds are volatile. Lead is removed from the air by rain as well as by particles falling to the ground or into the surface water. Once lead deposits on soil, it usually sticks to soil particles. Small amounts of lead may enter rivers, lakes, and streams when soil particles are displaced by rainwater. Lead may remain stuck to soil particles in water for many years. Movement of lead from soil particles into underground water or drinking water is unlikely unless the water is acidic or "soft".

Some of the chemicals that contain lead are broken down by sunlight, air, and water to other forms of lead. Lead compounds in water may combine with different chemicals depending on the acidity and temperature of the water. The lead atom cannot be broken down.

The levels of lead may build up in plants and animals from areas where air, water, or soil are contaminated with lead. If animals eat contaminated plants or animals, most of the lead that they eat will pass through their bodies. It is the small amount absorbed that can cause harmful effects.

Exposure Pathways

People living near hazardous waste sites can be exposed to lead and chemicals that contain lead by breathing air, drinking water, eating foods, or swallowing or touching dust or dirt that contains lead. For people who do not live near hazardous waste sites, most exposure to lead occurs by eating foods that contain lead, occupationally in brass/bronze foundries, or in areas where leaded paints exist. Foods such as fruits, vegetables, meats, grains, seafood, soft drinks, and wine may have lead in them. Cigarettes also contain small amounts of lead. In general, very little lead is in drinking water. More than 99 percent of all drinking water contains less than 0.005 part of lead per million parts of water (ppm). However, the amount of lead taken into your body through drinking water can be higher in communities with acidic water supplies. Acidic water can make the lead found in lead pipes, solder, and brass faucets enter water. Eating lead-based paint chips or dust is another way you can be exposed to lead. These two latter routes are particularly relevant to children in lower-income urbanized populations. For occupationally exposed individuals, the predominant route of exposure is the inhalation of lead particles.

Exposure to gasoline additives that contain lead can happen while you are pumping leaded gasoline, from sniffing leaded gasoline, and possibly during the use of some do-it-yourself fuel additives. For people who are exposed to lead at work, the largest source of exposure comes from breathing air that contains lead. Breathing or swallowing dust and dirt that has lead in it is another way you can be exposed to lead. Children, especially those who are preschool age, can have a lot of lead exposure because they put many things into their mouths. Their hands, toys, and other items may have lead-containing dirt on them. In some cases, children swallow nonfood items such as paint and dirt ("pica"). These items may contain very large amounts of lead, particularly in and around older houses that were painted with lead-based paint. The paint in these houses often chips off and mixes with dust and dirt. Some old paint (when it is dry) is 5-40 percent lead. Skin contact with dust and dirt containing lead occurs every day. However, not much lead can get into your body through your skin. During normal use of lead-containing products, very little lead gets on your skin.

The burning of gasoline has been the single largest source (90 percent) of lead in the atmosphere since the 1920s. A lot less lead in the air comes from gasoline now because EPA reduced the amount of lead that can be used in gasoline. Less than 35 percent of the lead released to the air now comes from gasoline. Other sources of lead in the air include releases to the air from industries involved in iron and steel production, lead-acid-battery manufacturing, brass foundries, and manufacturing of tetraethyl and tetramethyl lead, the latter two being very volatile. Lead released into air may also come from burning of solid waste, windblown dust, volcanoes, exhaust from workroom air, burning or weathering of lead-painted surfaces, and cigarette smoke.

Sources of lead in drinking water include lead that can come out of lead pipes, faucets, and solder used in plumbing. Lead-containing plumbing may be found in public drinking water systems, in houses, apartment buildings, and public buildings. Sources of lead in surface water or sediment include deposits of lead-containing dust from the atmosphere, waste water from industries that handle lead (primarily iron and steel industries and lead producers), and urban runoff.

Sources of lead in food and beverages include deposition of lead-containing dust from the atmosphere on crops and during food processing and uptake of lead from soil by plants. Lead may also enter foods when foods are put into improperly glazed pottery and ceramic dishes and leaded-crystal glassware. Illegal whiskey made using stills that contain lead-soldered parts (such as truck radiators) may also contain lead. The potential for exposure to lead in canned food from lead-soldered containers is greatly reduced because the content of lead in canned foods has decreased 87 percent from 1980 to 1988. Lead may also be released from soldered joints in kettles used to boil water for beverages.

Sources of lead in dust and soil include deposition of atmospheric lead and weathering and deterioration of lead-based paint. Lead in dust may also come from windblown soil. Disposal of lead in municipal and hazardous waste dump sites also adds lead to soil.

Exposure to lead occurs in many jobs. People employed in lead smelting and refining industries, brass/bronze foundries, rubber products and plastics industries, soldering, steel welding and cutting operations, battery manufacturing plants, and alkyl lead manufacturing industries may be exposed to lead. People who work at gasoline stations, in construction work, and at do-it-yourself renovations, or who work at municipal waste incinerators, pottery and ceramics industries, radiator repair shops, and other industries that use lead solder may also be exposed. Between 0.5 and 1.5 million workers are exposed to lead in the workplace; in California alone over 200,000 workers are exposed to lead. Families of workers may be exposed to elevated levels of lead when workers bring home lead dust on their work clothes. You may also be exposed to lead in the home if you work with stained glass as a hobby, or if you are involved in home renovation that involves the removal of old lead-based paint.

Metabolism

Some of the lead that enters your body comes from breathing in lead dust or chemicals that contain lead. Once this lead gets into your lungs, it goes quickly to other parts of the body in your blood.

You may swallow a lot of lead by eating food and drinking liquids that contain it. Most of the lead that enters your body comes through swallowing, even though very little of the amount you swallow actually enters your blood and other parts of your body. The amount that gets into your body from your stomach partially depends on when you ate your last meal. It also depends on how old you are and how well the lead particles you ate dissolved in your stomach juices. Experiments in adult volunteers showed that the amount of lead that got into the body from the stomach was only about six percent in adults who had just eaten. In adults who had not eaten for a day, about sixty to eighty percent of the lead from the stomach got into their blood. On the other hand, fifty percent of the lead swallowed by children enters the blood and other body parts even if their stomachs are full.

Frequent skin contact with lead in the form of lead-containing dusts and soils can result in children swallowing lead through hand-to-mouth behavior. In adults, only a small portion of the lead will pass through your skin and enter your body if it is not washed off after skin contact. More lead can pass through your skin if it is damaged. Certain types of lead compounds, however, may penetrate your skin.

Shortly after lead gets into your body, lead travels in the blood to the soft tissues, (such as the liver, kidneys, lungs, brain, spleen, muscles, and heart). After several weeks most of the lead then moves into your bones and teeth. In adults, about 94 percent of the total amount of lead in the body is contained in their bones and teeth. Children, on the other hand, have only about 73 percent of the lead in their bodies stored in their bones. The rest is in their soft tissues and blood. Part of the lead can stay in your bones for decades. Part of the lead can leave your bones and may reenter your blood and organs at a later time.

Your body does not change lead atoms into any other form. Once it is taken in and distributed to your organs, the lead that is not stored in your bones leaves your body in your urine or your feces. About 99 percent of the amount of lead that you take into your body will leave in your waste within a couple of weeks, but only about 32 percent of the lead taken into the body of children will leave in the waste.

Health Effects

Exposure to lead can be particularly dangerous for unborn children because of their great sensitivity during development. Exposure to lead can also be dangerous for young children because they swallow more lead through normal mouthing activity, take more of the lead that they swallow into their bodies, and are more sensitive to its effects. Unborn children can be exposed to lead through their mothers. This may cause premature births, smaller babies, and decreased mental ability in the infant. Lead exposures may also decrease intelligence quotient (IQ) scores and reduce the growth of young children. These effects have been seen more often following exposure to high levels of lead, than following exposure to low levels of lead.

In adults, lead exposure may decrease reaction time and possibly affect the memory. Lead exposure may also cause weakness in your fingers, wrists, or ankles. Lead exposure may increase blood pressure in middle-aged men. It is not known whether lead has an effect on blood pressure in women. Lead exposure may also cause anemia, a disorder of the blood. The connection between the occurrence of these effects and low lead exposures is not certain. At high levels of exposure, lead can severely damage the brain and kidneys in adults and children. In addition, high levels of exposure to lead may cause abortion and damage the male reproductive system (the organs responsible for sperm production). The effects of lead are the same regardless of whether it enters the body through breathing or swallowing.

Kidney tumors have developed in rats and mice given large doses of lead. We have no proof that lead causes cancer in humans. Furthermore, the animal studies have been criticized by a panel of EPA scientists because of the very high doses used, among other things, and should not be used to predict what may happen in humans. The Department of Health and Human Services has determined that lead acetate and lead phosphate may reasonably be anticipated to be carcinogens based on these studies in animals, but that there is inadequate evidence for the carcinogenicity of these lead compounds in humans.nformation excerpted from

Toxicological Profile for Lead April 1993 Update
Agency for Toxic Substances and Disease Registry
United States Public Health Service


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Motor Oil
Introduction

Used mineral-based crankcase oil is the brown-to-black, oily liquid removed from the engine of a motor vehicle when the oil is changed. It is similar to unused oil except it contains additional chemicals from it's use as an engine lubricant.

The chemicals in oil include hydrocarbons, which are distilled from crude oil, and various additives that improve the oil's performance. Used oil also contains chemicals formed when the oil is exposed to high temperatures and pressures inside an engine. It also contains some metals from engine parts and small amounts of gasoline, antifreeze, and chemicals that come from gasoline when it burns inside the engine.

The chemicals found in used mineral-based crankcase oil vary depending on the brand and type of oil, whether gasoline or diesel fuel was used, the mechanical condition of the engine that the oil came from, and the amount of use between oil changes. Used oil is not naturally found in the environment.

Fate & Transport

Used mineral-based crankcase oil enters the air through the exhaust system during engine use. It may enter water or soil when disposed of improperly. The hydrocarbon components of the oil generally stick to the soil surface. Some hydrocarbons evaporate into the air very quickly, and others evaporate more slowly. Hydrocarbon components of the oil that enter surface water bind to small particles in the water and eventually settle to the bottom. Hydrocarbons from used mineral-based crankcase oil may build up in shellfish or other organisms. Some metals in used mineral-based crankcase oil dissolve in water and move through the soil easily and may be found in surface water and groundwater.

Exposure Pathways

• When you change the engine oil in your car
• Breathing a small amount of the chemicals from the oil in exhaust fumes or from burning the oil as heating fuel
• Touching contaminated soil or drinking contaminated water

Health Effects

The health effects of used mineral-based crankcase oil vary depending on the brand and type of oil used and the characteristics of the engine it came from. Mechanics and other auto workers who are exposed to used mineral-based crankcase oil from a large number of cars have experienced skin rashes, blood effects (anemia), and headaches and tremors. However, these workers are also exposed to other chemicals, which may have caused these health effects.

Volunteers who breathed mists of used mineral-based crankcase oil for a few minutes had slightly irritated noses, throats, and eyes. Animals that ate large amounts of this oil developed diarrhea. Thus, people who swallow used mineral-based crankcase oil may also have diarrhea. Some cows that ate used oil containing metals such as molybdenum and lead in contaminated pastures experienced anemia and tremors. Some of the cows died. We do not know if exposure to used mineral-based crankcase oil affects the reproductive ability of men or women or whether it causes birth defects.

Long-term exposure (365 days or longer) of the skin to used mineral-based crankcase oil causes skin cancer in mice. PAHs in the oil have been identified as the cancer-causing agents because some PAHs are known to cause cancer and because the carcinogenicity of various batches of the used oil increased with increasing amounts of PAHs in the oil. The Department of Health and Human Services (DHHS), the International Agency for Research on Cancer (IARC), and the EPA have not classified used mineral-based crankcase oil with regard to its carcinogenicity in people.


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PCB's
Introduction

PCBs are a group of synthetic organic chemicals that contain 209 individual compounds (known as congeners) with varying harmful effects. There are no known natural sources of PCBs in the environment. PCBs are either oily liquids or solids and are colorless to light yellow in color. They have no known smell or taste. PCBs enter the environment as mixtures containing a variety of individual components and mixtures. Seven types of PCB mixtures include 35% of all the PCBs commercially produced and 98% of PCBs sold in the United States since 1970. Some commercial PCB mixtures are known in the United States by their industrial trade name, Arochlor. The name, Arochlor 1254, for example, means that the molecule contains 12 carbon atoms (the first two digits) and approximately 54% chlorine by weight (second two digits). Because they don't burn easily and are good insulating materials, PCBs have been widely used as coolants and lubricants in transformers, capacitors, and other electrical equipment. The manufacture of PCBs stopped in the United States in October 1977 because of evidence that PCBs build up in the environment and cause harmful effects. Consumer products that may contain PCBs are old fluorescent lighting fixtures, electrical devices or appliances containing PCB capacitors made before PCB use was stopped, old microscope oil, and hydraulic fluids.

Fate & Transport

Before 1977, PCBs entered the air, water, and soil during their manufacture and use. Wastes that contained PCBs were generated during manufacture and use of PCBs, and these wastes were placed in dump sites. PCBs also entered the environment from accidental spills and leaks during the transport of the chemicals, or from leaks or fires in transformers, capacitors, or other products containing PCBs. Today, PCBs can be released into the environment from poorly maintained hazardous waste sites that contain PCBs; illegal or improper dumping of PCB wastes; such as transformer fluids; leaks or releases from electrical transformers containing PCBs; and disposal of PCB-containing consumer products into municipal or other landfills not designed to handle hazardous waste. PCBs are also currently released into the environment by municipal and industrial incinerators from the burning of organic wastes.

PCBs in air can be present in both solid and liquid aerosols, and as vapors that eventually return to the land and water by settling or washout by snow and rain. PCBs may remain in the air for an average of more than 10 days depending on the type of PCB. Once in the air, PCBs can be carried long distances. They have been found in snow and sea water in areas far away from where they were released into the environment. In water, a small amount of PCBs may remain dissolved but most tend to stick to particles and sediments. The more volatile PCBs in water partially evaporate and then return to earth by rainfall, snow, or settling of dust particles. This cycle can be repeated many times. PCBs in water concentrate (build up) in fish and can reach levels hundreds or thousands of times higher than the levels in water. Extremely small amounts of PCBs can remain in water for years. PCBs bind strongly to soil and sediments and may remain there for several years. PCBs will not typically travel deep into the soil with rainwater. However, PCBs from some waste landfills have been found in groundwater. PCBs partially evaporate from soil surfaces to air. In general, the breakdown of PCBs in the water and soil occurs over several years, or even decades. Sediments containing PCBs at the bottom of a large body of water such as a lake, river, or ocean generally act as a reservoir from which PCBs may be released in small amounts to the water. PCBs have been found in a very limited number of drinking water supplies.

Exposure Pathways

Although PCBs are no longer made in the United States, people can still be exposed to them. Many older transformers and capacitors still contain PCBs. These transformers can be used for 30 years or more. Old fluorescent lighting fixtures and electrical devices and appliances, such as television sets and refrigerators, made before PCB use was stopped may contain PCBs. When these electric devices get hot during operation, small amounts of PCBs may leak into the air and raise the level of PCBs in indoor air.

The two main sources of exposure to PCBs are from the environment and from the workplace. PCBs are found throughout the environment and remain there a very long time. Small amounts of PCBs can be found in almost all outdoor air, in indoor air, on soil surfaces, and in surface water. PCBs enter the bodies of fish from water, sediment, particulates in water, and from eating prey that have PCBs in their bodies. PCBs also enter bodies of birds of prey from eating contaminated fish. Measurements made in the late 1970s and 1980s indicate that the typical concentrations (1 to 10 thousandths of a millionth of a gram in a cubic meter of air [ng/m3]) in urban areas and 0.6 ng/m3 in rural areas. The PCB concentrations in indoor air of seven public buildings (schools and offices) ranged from 230 to 460 ng/m3. The mean concentration of PCBs in waters of the Great Lakes is 0.5 to 17 nanograms per liter (0.5 to 17 thousandths of a millionth of a gram in a liter of water [ng/L]). Typical concentrations of PCBs in soil are less than 10 to 40 micrograms per kilogram (less than 10 to 40 millionths of a gram in one kilogram of soil [ug/kg]). Average PCB concentrations as high as 4.3 g/kg have been found in soil from a hazardous waste site. The mean concentration of PCBs in whole fresh water fish is 0.5 ug/g (0.5 millionths of a gram in 1 gram of fish). The concentrations of PCBs in air, water, soil, and food have generally decreased since PCB production stopped in 1977. Although PCBs are usually found in the parts of fish that most people do not eat, the amount of PCBs found in the parts of fish that are typically eaten is high enough to make eating fish an important source of exposure. PCBs are also found in meat and milk and their by-products. Breathing indoor air in buildings that have electrical parts that contain PCBs may also be a major source of human exposure. Persons may be exposed to several micrograms of PCBs per day from air, water, and food.

People who live near hazardous waste sites that contain PCBs may be exposed primarily by breathing air that contains PCBs. Children playing at or near these sites may be exposed by touching and eating soil that contains PCBs. The most likely way infants will be exposed is from drinking breast milk that contains PCBs or from the exposed mother when in the womb.

Workplace exposure to PCBs can occur during repair and maintenance of PCB transformers; accidents, fires, or spills involving PCB transformers; and disposal of PCB materials. Contact with PCBs at hazardous waste sites can happen when workers breathe air and touch soil containing PCBs. Exposure in the workplace occurs mostly by breathing air containing PCBs and by touching substances that contain PCBs. Fewer than 2,500 people were thought to be exposed to excess levels of PCBs in the workplace during 1981 to 1983.

Metabolism

I f you breathe air that contains PCBs, they can enter your body through your lungs and pass into the bloodstream. We do not know how fast or how much of the PCBs will pass into the bloodstream. If you swallow food, water, or soil contaminated with PCBs, most of the PCBs will probably enter your body and pass from the stomach into the bloodstream quickly (in minutes). If you touch soil containing PCBs (for example, at a hazardous waste site) some of the PCBs will pass through the skin and then into the bloodstream. A common way for PCBs to enter your body is through eating meat or fish products or other foods that contain PCBs. PCBs can also enter your body if you breathe indoor air in buildings that have electrical parts containing PCBs. Exposure from drinking water is less than from food.

Once PCBs are in your body, some may change into other related chemicals called metabolites. Some metabolites of PCBs may have the potential to be as harmful as unchanged PCBs, but there is no conclusive experimental evidence to support this assumption. Some of the metabolites may leave your body in the feces in a few days, but others may stay in your body fat for months. Unchanged PCBs may also stay in your body and be stored for years in your body fat and liver. PCBs build up in milk fat and can enter the bodies of infants through breastfeeding.

Health Effects

Skin irritations, such as acne and rashes, can occur in people exposed to PCBs. Studies in the workplace suggest that exposure to PCBs may also cause irritation of the nose and lungs. The concentrations of PCBs in the workplace are usually much higher than concentrations in other places such as in air in buildings that have electrical parts that contain PCBs or in outdoor air, including air at hazardous waste sites. We do not know the possible effects in persons who are exposed to high levels of PCBs for a short period.

Rats that ate food containing large amounts of PCBs for a short period had mild liver damage, and some died. Animals that ate smaller amounts of PCBs in their food over several weeks or months had many serious health effects, including liver, stomach, and thyroid gland injuries. They also had anemia, acne, and damaged reproduction. These effects have been seen in many different kinds of animals, including monkeys, as well as in the offspring of animals that ate PCBs. No birth defects have been found. Only a small amount of information exists on the health effects in animals exposed to PCBs by skin contact or breathing. This information indicates that liver, kidney, and skin damage occurred in rabbits following repeated skin exposure, and that a single exposure to a large amount of PCBs on the skin caused death in rabbits and mice. Breathing PCBs over several months also caused liver and kidney damage in rats and other animals, but the levels necessary to produce these effects were very high. It is not known if the same effects would happen in people if they were exposed in the same way.

Studies of workers do not provide enough information to determine if PCBs cause cancer in humans. Rats that ate certain PCB mixtures throughout their lives developed cancer in their livers. Based on the cancer in animals, the Department of Health and Human Services has determined that PCBs may reasonably be anticipated to be carcinogens. The International Agency for Research of Cancer has determined that PCBs are probably carcinogenic to humans. The EPA has determined that PCBs are probable human carcinogens.


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Toluene
Introduction

Toluene is a clear, colorless liquid with a distinctive smell. It is added to gasoline along with benzene and xylene. Toluene occurs naturally in crude oil and in the tolu tree. It is produced in the process of making gasoline and other fuels from crude oil, in making coke from coal, and as a by-product in the manufacture of styrene. Toluene is used in making paints, paint thinners, fingernail polish, lacquers, adhesives, and rubber and in some printing and leather tanning processes. It is disposed of at hazardous waste sites as used solvent (a substance that can dissolve other substances) or at landfills where it is present in discarded paints, paint thinners, and fingernail polish. You can begin to smell toluene in the air at a concentration of 8 parts of toluene per million parts of air (ppm), and taste it in your water at a concentration of 0.04-1 ppm.

Fate & Transport

Toluene enters the environment when you use materials that contain it, such as paints, paint thinners, adhesives, fingernail polish, and gasoline. As you work with these materials, the toluene evaporates and becomes mixed with the air you breathe. Toluene enters surface water and groundwater (wells) from spills of solvents and petroleum products as well as from leaking underground storage tanks at gasoline stations and other facilities. Leaking underground storage tanks also contaminate the soil with toluene and other petroleum-product components.

When toluene-containing products are placed in landfills or waste disposal sites, the toluene can enter the soil and water near the waste site. Toluene does not usually stay in the environment; it is readily broken down to other chemicals by microorganisms in soil and evaporates from surface water and surface soils. Toluene dissolved in well water does not break down quickly while the water is under the ground because there are few microorganisms in underground water. Once the water is brought to the surface, the toluene will evaporate into the air. Windows and doors in rooms where toluene-containing products are used should be opened to allow the toluene gas to escape. The toluene in the air will combine with oxygen and form benzaldehyde and cresol. These compounds can be harmful to humans.

Toluene can be taken up into fish and shellfish, plants, and animals living in water containing toluene, but it does not concentrate or build up to high levels because most animal species can make the toluene into other compounds that are excreted.

Exposure Pathways

You may be exposed to toluene from many sources, including drinking water, food, air, and consumer products. You may also be exposed to toluene through breathing the chemical in the workplace or during deliberate glue sniffing or solvent abuse. Automobile exhaust can also put toluene into the air. People who work with gasoline, kerosene, heating oil, paints, and lacquers are at the greatest risk of exposure. Printers are also exposed to toluene in the workplace. Because toluene is a common solvent and is found in many consumer products, you can be exposed to toluene at home and outdoors while using gasoline, nail polish, cosmetics, rubber cement, paints, paintbrush cleaners, stain removers, fabric dyes, inks, and adhesives. Smokers are exposed to small amounts of toluene from cigarette smoke.

You can be exposed to toluene at some hazardous waste sites. EPA reported in 1991 that toluene was found in well water, surface water, or soil at 63% of the hazardous waste sites surveyed. If you live near a waste site and get your drinking water from a well, you might find toluene in the water. Toluene vapors might also be present in the air.

Federal and state surveys do not show toluene to be a common impurity in drinking water supplies. Toluene was found in about 1% of the groundwater sources (wells) at amounts lower than 2 parts per billion (ppb). It was found more frequently in surface water samples at similar concentrations. If toluene is in your drinking water you can be exposed by drinking the water or by eating cold foods prepared with the water. Evaporation during cooking tends to decrease the amount of toluene found in hot foods or water. Additional exposure will occur when you breathe in the toluene that evaporates from water while you shower, bathe, clean, or cook with the water.

The toluene level in the air outside your home is usually less than 1 ppm in cities and suburbs that are not close to industry. The toluene inside your house is also likely to be less than 1 ppm. The amount of toluene in food has not been reported, but is likely to be low. Traces of toluene were found in eggs that were stored in polystyrene containers containing toluene.

Unless you smoke cigarettes or work with toluene-containing products, you are probably only exposed to about 300 micrograms (ug) of toluene a day. A microgram is one one-millionth of a gram. If you smoke a pack of cigarettes a day, you add another 1,000 ug to your exposure. People who work in places where toluene-containing products are used can be exposed to 1,000 milligrams of toluene a day when the average air concentration is 50 ppm and they breathe at a normal rate and volume. A milligram is one one-thousandth of a gram.

Metabolism

Toluene can enter your body when you breathe its vapors or eat or drink contaminated food or water. When you work with toluene-containing paints or paint thinners, the toluene can also pass through your skin into your bloodstream. You are exposed to toluene when you breathe air containing toluene. When this occurs the toluene is taken directly into your blood from your lungs. Where you live, work, and travel and what you eat affects your daily exposure to toluene. Factors such as your age, sex, body composition, and health status affect what happens to toluene once it is in your body. After being taken into your body, more than 75% of the toluene is removed within 12 hours. It may leave your body unchanged in the air you breathe out or in your urine after some of it has been chemically changed to make it more water soluble. Generally, your body turns toluene into less harmful chemicals such as hippuric acid.

Health Effects

A serious health concern is that toluene may have an effect on your brain. Toluene can cause headaches, confusion, and memory loss. Whether or not toluene does this to you depends on the amount you take in and how long you are exposed. Low to moderate, day-after-day exposure in your workplace can cause tiredness, confusion, weakness, drunken-type actions, memory loss, nausea, and loss of appetite. These symptoms usually disappear when exposure is stopped. Researchers do not know if the low levels of toluene you breathe at work will cause any permanent effects on your brain or body after many years. You may experience some hearing loss after long-term daily exposure to toluene in the workplace.

If you are exposed to a large amount of toluene in a short time because you deliberately sniff paint or glue, you will first feel light-headed. If exposure continues, you can become dizzy, sleepy, or unconscious. You might even die. Toluene causes death by interfering with the way you breathe and the way your heart beats. When exposure is stopped, the sleepiness and dizziness will go away and you will feel normal again.

If you choose to repeatedly breathe in toluene from glue or paint thinners, you may permanently damage your brain. You may also experience problems with your speech, vision, or hearing, have loss of muscle control, loss of memory, poor balance, and decreased mental ability. Some of these changes may be permanent.

Toluene may change the way your kidneys work, but in most cases, the kidneys will return to normal after exposure stops. If you drink alcohol and are exposed to toluene, the combination can affect your liver more than either compound alone. This phenomenon is called synergism. Combinations of toluene and some common medicines like aspirin and acetaminophen may increase the effects of toluene on your hearing.

In animals, the main effect of toluene is on the nervous system. Animals exposed to moderate or high levels of toluene may also show slightly adverse effects in their liver, kidneys, and lungs.

Several studies have shown that unborn animals were harmed when high levels of toluene were breathed in by their mothers. When the mothers were fed high levels of toluene, the unborn animals did not show any structural birth defects, although some effects on behavior were noted. We do not know if toluene would harm your unborn child if you drink water or breathe air containing low levels of toluene, because studies in people are not comprehensive enough to measure this effect. However, if you deliberately breathe in large amounts of toluene during your pregnancy, your baby can have neurological problems and retarded growth and development.

Studies in workers and in animals exposed to toluene indicate that toluene does not cause cancer. The International Agency for Research on Cancer (IARC) and the Department of Health and Human Services (DHHS) have not classified toluene for carcinogenic effects. The EPA has determined that toluene is not classifiable as to its human carcinogenicity.


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Trichloroethene
Introduction

Trichloroethene is also known as Triclene and Vitran and by other trade names in industry. It is a nonflammable, colorless liquid at room temperature with a somewhat sweet odor and a sweet, burning taste. This manmade chemical does not occur naturally in the environment. Trichloroethene is now mainly used as a solvent to remove grease from metal parts. It is also used as a solvent in other ways and is used to make other chemicals. Trichloroethene can also be found in some household products, including typewriter correction fluid, paint removers, adhesives, and spot removers. Most people begin to smell trichloroethene in air when there are around 100 parts of trichloroethene per a million parts of air (ppm).

Fate & Transport

By far, the biggest source of trichloroethene in the environment is evaporation from factories that use it to remove grease from metals. It can also enter the air and water when it is disposed of at chemical waste sites. It evaporates easily but can stay in the soil and in groundwater. Once it is in the air, about half will be broken down within a week. When trichloroethene is broken down in the air, phosgene, a lung irritant, can be formed. Under certain conditions found in the workplace, trichloroethene can break down into chemicals such as dichloroacetylene and phosgene. In the body, trichloroethene may break down into dichloroacetic acid (DCA), trichloroacetic acid (TCA), chloral hydrate, and 2-chloroacetaldehyde. These chemical products have been shown to be toxic to animals and are probably toxic to humans. Once trichloroethene is in water, much will evaporate into the air; again, about half will break down within a week. It will take days to weeks to break down in surface water; in groundwater the breakdown is much slower because of the much slower evaporation rate. Very little trichloroethene breaks down in the soil, and it can pass through the soil into underground water. It is found in some foods; the trichloroethene found in foods is believed to come from contamination of the water used in food processing, or from the food processing equipment cleaned with trichloroethene. It does not build up in fish, but it has been found at low levels in them. It is not likely to build up in your body.

Exposure Pathways

Trichloroethene is found in the outdoor air at levels far less than 1 ppm. When measured several years ago, some of the water supplies in the United States were found to have trichloroethene. The most recent monitoring study found mean levels in surface water ranging from 0.0001 to 0.001 parts of trichloroethene per million parts (ppm) of water and a mean level of 0.007 ppm in groundwater. About 400,000 workers are exposed to trichloroethene in the United States on a full-time (i.e., a 40-hour workweek) basis. The chemical can also get into the air or water in many ways, for example, at waste treatment facilities; by evaporation from paints, glues, and other products; or by release from factories where it is made. Another way you may be exposed is by breathing the air around factories that use the chemical. People living near hazardous waste sites may be exposed to it in the air or in their drinking water, or in the water used for bathing or cooking. Products that may contain trichloroethene are some types of typewriter correction fluids, paints and paint removers, glues, spot removers, rug cleaning fluids, and metal cleaners.

Metabolism

Trichloroethene enters your body when you breathe air or drink water containing it. It can also enter your body if you get it on your skin. You could be exposed to contaminated water or air if you live near or work in a factory that uses trichloroethene or if you live near a waste disposal site that contains trichloroethene. If you breathe the chemical, about half the amount you breathe in will get into your bloodstream and organs; you will exhale the rest. If you drink trichloroethene, most of it will be absorbed into your blood. If trichloroethene comes in contact with your skin, some of it can enter your body, although not as easily as when you breathe or swallow it.

Once in your blood, your liver changes much of the trichloroethene into other chemicals. The majority of these breakdown products leave your body in the urine within a day. You will also quickly breathe out much of the trichloroethene that is in your bloodstream. Some of the trichloroethene or its breakdown products can be stored in body fat for a brief period, and thus may build up in your body if exposure continues.

Health Effects

Trichloroethene was once used as an anesthetic for surgery. People who are exposed to large amounts of trichloroethene can become dizzy or sleepy and may become unconscious when exposed to very high levels. Death may occur from inhalation of large amounts. Many people have jobs where they work with trichloroethene and can breathe it or get it on their skin. Some people who get concentrated solutions of trichloroethene on their skin develop rashes. People who breathe moderate levels of trichloroethene may have headaches or dizziness. Some people who breathe high levels of trichloroethene may develop damage to some of the nerves in the face. Humans have reported health effects when exposed to the level of trichloroethene at which its odor is noticeable. Effects have also occurred at much higher levels. Animals that were exposed to moderate levels of trichloroethene had enlarged livers, and high-level exposure caused liver and kidney damage. However, we do not know if these changes would occur in humans.

It is uncertain whether people who breathe air or drink water containing trichloroethene are at higher risk of cancer or if their children have more birth defects. People who used water for several years from two wells that had high levels of trichloroethene may have had a higher incidence of childhood leukemia than other people. Increased numbers of children were reported to be born with cardiac abnormalities, a finding which is supported by data from some animal studies showing developmental effects of trichloroethene on the heart. However, other chemicals were also in the water from this well. We do not have any clear evidence that trichloroethene alone can cause leukemia or any other type of cancer in humans. As part of the National Exposure Registry, the Agency for Toxic Substances and Disease Registry (ATSDR) compiled data on 4,280 residents of three states (Michigan, Illinois, and Indiana) who had environmental exposure to trichloroethene. It found no definitive evidence for an excess of cancers from trichloroethene exposure. In studies using high doses of trichloroethene in rats and mice, tumors in the lung, liver, and testes were found, providing some evidence that high doses of trichloroethene can cause cancer in experimental animals. We do not know if trichloroethene affects human reproduction.


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Vinyl Chloride
Introduction

Vinyl chloride is a colorless gas as normal temperatures. It is also known as chloroethene, chloroethylene, ethylene monochloride, or monochloroethylene. It is flammable (easily capable of burning) as a gas and is not stable at high temperatures or pressure. Vinyl chloride will exist in liquid form if it is kept under high pressure. Vinyl chloride has a mild, sweet odor. Most people begin to smell vinyl chloride in the air at 3,000 parts vinyl chloride per million parts (ppm) of air. Most people begin to taste vinyl chloride in water at 3.4 ppm.

All vinyl chloride is man-made or results from the breakdown of other manmade substances, such as trichloroethene, trichloroethane, and tetrachloroethene. Production of vinyl chloride in the United States has grown an average of 7 percent from the early 1980s to the early 1990s, with an additional increase of approximately 22 percent between the years of 1992 and 1993. Most of the vinyl chloride produced in the United States is used to make polyvinyl chloride (PVC). PVC is used to make a variety of plastic products including pipes, wire and cable coatings, and packaging materials. Other uses include furniture and automobile upholstery, wall coverings, housewares, and automotive parts. At one time, vinyl chloride was also used as a coolant, as a propellant in spray cans, and in some cosmetics. Since the mid 1970s, it has not been used for these purposes.

Fate & Transport

Most of the vinyl chloride that enters the environment comes from the plastics industries, which release it into the air or into waste water. EPA limits the amount that industries may release. Vinyl chloride is a breakdown product of other manmade chemicals in the environment. Vinyl chloride has entered the environment at hazardous waste sites as a result of its improper disposal or leakage from storage containers or from spills. Vinyl chloride has been found in tobacco smoke, perhaps as a result of the manufacturing process.

Liquid vinyl chloride evaporates easily into the air. Vinyl chloride in water or soil evaporates rapidly if it is near the surface. Vinyl chloride in the air breaks down in a few days. When vinyl chloride breaks down in air, it can form other harmful chemicals.

A limited amount of vinyl chloride can dissolve in water. It can enter groundwater and can also be found in groundwater from the breakdown of other chemicals. It is unlikely that vinyl chloride will build up in plants or animals that you might eat.

Exposure Pathways

Since vinyl chloride commonly exists in a gaseous state, you are most likely to be exposed to it by breathing it in. Vinyl chloride is not normally found in urban, suburban, or rural air in amounts that are detectable by the usual methods of analysis. However, vinyl chloride has been found in the air near plastics industries, hazardous waste sites, and landfills. The amount of vinyl chloride in the air near these places ranges from trace amounts to 0.041 ppm of air, but may exceed 1 ppm. Levels as high as 44 ppm have been found at some landfills. One can also be exposed to vinyl chloride in the air through tobacco smoke from cigarettes or cigars.

You may also be exposed to vinyl chloride by drinking water from contaminated wells but how often this occurs is not known. Most drinking water supplies do not contain vinyl chloride. In a 1982 survey, vinyl chloride was found in less than 1 percent of the 945 groundwater supplies tested in the United States. The concentrations found in groundwater were up to 0.008 ppm, with a detection limit of 0.001 ppm. Other studies have reported groundwater vinyl chloride concentrations at or below 0.38 ppm. At one time, the flow of water through PVC pipes added very low amounts of vinyl chloride to water. For example, in one study of newly installed pipes, the drinking water had 0.001 ppm of vinyl chloride. No current information on the amount of vinyl chloride released from PVC pipes into water is available. In the past, vinyl chloride could get into food that was stored in materials that contained PVC. Now the U.S. government regulates the amount of vinyl chloride in food packaging materials. A model of food systems shows that when levels less than 1 ppm of vinyl chloride monomer are used in PVC packaging, "essentially zero" vinyl chloride enters food by contact with these products.

Exposure to vinyl chloride can also occur in the workplace by breathing in any vapors in the air or if it comes into contact with your skin or eyes. Almost 80,000 people work with vinyl chloride at their jobs. This number includes workers who make vinyl chloride and PVC and workers who use PVC to make other objects such as pipes.

Metabolism

If vinyl chloride comes into contact with your skin, negligible amounts may pass through the skin and enter your body. Vinyl chloride is more likely to enter your body when you breathe air or drink water containing it. This could occur near certain factories or hazardous waste sites or in the workplace.

Most of the vinyl chloride that you breathe in or swallow enters your blood rapidly. The vinyl chloride in your blood travels through your body. When some portion of it reaches your liver, it is changed into several different substances. Most of these new substances also travel in your blood. Once they reach the kidneys, they leave your body in your urine. Most of the vinyl chloride is gone from your body a day after you breathe it in or swallow it. The liver, however, makes some new substances that do not leave your body as rapidly. A few of these substances are more harmful than vinyl chloride because they react with chemicals inside your body and interfere with the way your body uses or responds to these chemicals. Some of these substances react in the liver and cause damage there. It takes more time for your body to get rid of these changed chemicals, but eventually your body will remove them as well. If you breathe in or swallow more vinyl chloride than your liver can chemically change, you will breathe out excess vinyl chloride.

Health Effects

If you breathe high levels of vinyl chloride, you will feel dizzy or sleepy. These effects occur within 5 minutes at about 10,000 ppm of vinyl chloride. You can easily smell vinyl chloride at this concentration. If you breathe very high levels, you may pass out. You can rapidly recover from these effects if you breathe fresh air. Some people get a headache when they breathe fresh air immediately after breathing very high levels of vinyl chloride. People may die if they breathe extremely high levels of vinyl chloride. These levels are much higher than the levels that cause you to pass out.

Studies in animals show that extremely high levels of vinyl chloride can damage the liver, lungs, and kidneys. These levels can also damage the heart and prevent blood clotting. The effects of drinking high levels of vinyl chloride are unknown. If you spill liquid vinyl chloride on your skin, it will numb the skin and cause redness and blisters.

Some people who have breathed vinyl chloride over several years have developed changes in the structure of their livers. People are more likely to develop these changes if they breathe high levels of vinyl chloride. Some people who have worked with vinyl chloride have developed nerve damage, and others have developed an immune reaction. The lowest levels that cause liver changes, nerve damage, and the immune reaction in humans are not known. Certain jobs related to polyvinyl chloride production expose workers to very high levels of vinyl chloride. Some of these workers have problems with the blood flow in their hands. Their fingers turn white and hurt when they go into the cold. It may take a long time to recover when they go into a warm place. In some of these people, changes have appeared on the skin of their hands and forearms. Also, bones at the tips of their fingers have broken down. Studies suggest that some people may be more sensitive to these effects than others.

Some men who work with vinyl chloride have complained of a lack of sex drive. Results of studies in animals show that long-term exposure may damage the sperm and testes. Some women who work with vinyl chloride have had irregular menstrual periods. Some have developed high blood pressure during pregnancy. Studies of women who live near vinyl chloride manufacturing plants could not prove that vinyl chloride causes birth defects. Studies using pregnant animals show that breathing vinyl chloride may harm their unborn offspring. Animal studies also show that vinyl chloride may cause increased numbers of miscarriages early in pregnancy. It may also cause decreased weight and delayed skeletal development in fetuses. The same very high levels of vinyl chloride that caused these fetal effects also caused adverse effects in the pregnant animals.

Results from several studies suggest that breathing air or drinking water containing low levels of vinyl chloride may increase the risk of getting cancer. Studies of workers who have breathed vinyl chloride over many years showed cancer of the liver. Brain cancer, lung cancer, and some cancers of the blood also may be connected with breathing it daily for several years. Studies of long-term exposure in animals show that increases in cancers of the liver and mammary glands may occur at very low levels of vinyl chloride in the air. Studies show that animals fed low levels of vinyl chloride each day during their lifetime had an increased risk of getting liver cancer.

The Department of Health and Human Services has determined that vinyl chloride is a known carcinogen. The International Agency for Research on Cancer has determined that vinyl chloride is carcinogenic to humans, and EPA has determined that vinyl chloride is a human carcinogen.



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Xylene
Introduction

In what follows, the terms xylene, xylenes, and total xylene are used interchangeably. There are three forms of xylene in which the methyl groups vary on the benzene ring: meta-xylene, ortho-xylene, and para-xylene (m-, o-, and p-xylene). These different forms are referred to as isomers. The term total xylenes refers to all three isomers of xylene. Mixed xylene is a mixture of the three isomers and usually also contains 6-15 percent ethylbenzene. Xylene is also known as xylol or dimethylbenzene. Xylene is primarily a synthetic chemical. Chemical industries produce xylene from petroleum. Xylene also occurs naturally in petroleum and coal tar and is formed during forest fires. It is a colorless, flammable liquid with a sweet odor.

Xylene is one of the top 30 chemicals produced in the United States in terms of volume. It is used as a solvent (a liquid that can dissolve other substances) in the printing, rubber, and leather industries. Along with other solvents, xylene is also used as a cleaning agent, a thinner for paint, and in varnishes. It is found in small amounts in airplane fuel and gasoline. Xylene is used as a material in the chemical, plastics, and synthetic fiber industries and as an ingredient in the coating of fabrics and papers. Isomers of xylene are used in the manufacture of certain polymers, such as plastics.

Xylene evaporates and burns quickly. Xylene does not mix well with water; however, it does mix with alcohol and many other chemicals. Most people begin to smell xylene in air at 0.08-3.7 parts per million parts of air (ppm) and begin to taste it in water at 0.53-1.8 ppm.

Fate & Transport

Xylene is a liquid, and it can leak into soil, surface water (creeks, streams, rivers), or groundwater, where it may remain for months or more before it breaks down into other chemicals. However, because it evaporates easily, most xylene (if not trapped deep underground) goes into the air, where it stays for several days. In the air, the xylene is broken down by sunlight into other less harmful chemicals.

Xylene can enter the environment when it is made, packaged, shipped, or used. Most xylene that is accidently released evaporates into the air, although some is released into rivers or lakes. Xylene can also enter soil, water, or air in large amounts after an accidental spill or as a result of an environmental leak during storage or burial at a waste site.

Xylene very quickly evaporates into the air from surface soil and water. Xylene stays in the air for several days until it is broken down by sunlight into other less harmful chemicals.

Most xylene in surface water evaporates into the air in less than a day. The rest of it is slowly broken down into other chemicals by small living organisms in the water. Only very small amounts are taken up by plants, fish, and birds. We do not know exactly how long xylene stays in water, but we do know that it stays longer in underground water than in lakes and rivers, probably because it can evaporate from the latter.

Xylene evaporates from soil surfaces. Xylene below the soil surface stays there for several days and may travel down through the soil and enter underground water (groundwater). Small living organisms in soil and groundwater may transform it into other less harmful compounds, although this happens slowly. It is not clear how long xylene remains trapped deep underground in soil or groundwater, but it may be months or years. Xylene stays longer in wet soil than in dry soil. If a large amount of xylene enters soil from an accidental spill, a hazardous waste site, or a landfill, it may travel through the soil and contaminate drinking water wells. Only a small amount of xylene is absorbed by animals that live in water contaminated with xylene.

Exposure Pathways

You may be exposed to xylene because of its distribution in the environment. Xylene is primarily released from industrial sources, in automobile exhaust, and during its use as a solvent. Hazardous waste disposal sites and spills of xylene into the environment are also possible sources of exposure. You are most likely to be exposed to xylene by breathing it in contaminated air. Levels of xylene measured in the air of industrial areas and cities of the United States range from 1 to 88 parts of xylene per billion parts of air (a part per billion [ppb] is one thousandth of a part per million [ppm]; one ppm equals 1,000 ppb). Xylene is sometimes released into water and soil as a result of the use, storage, and transport of petroleum products. Surface water generally contains less than 1 ppb, although the level may be higher in industrial areas. You can also be exposed to xylene by drinking or eating xylene-contaminated water or food. Levels of xylene in public drinking water supplies have been reported to range from 0 to 750 ppb. Little information exists about the amount of xylene in food. Xylene levels ranging from 50 to 120 ppb have been found in some fish samples. Xylene has been found in chicken eggs and in the polystyrene packaging in which they are sold.

You may also come in contact with xylene from a variety of consumer products, including cigarette smoke, gasoline, paint, varnish, shellac, and rust preventives. Breathing vapors from these types of products can expose you to xylene. Indoor levels of xylene can be higher than outdoor levels, especially in buildings with poor ventilation. Skin contact with products containing xylene, such as solvents, lacquers, paint thinners and removers, and pesticides may also expose you to xylene.

Besides painters and paint industry workers, others who may be exposed to xylene include biomedical laboratory workers, distillers of xylene, wood processing plant workers, automobile garage workers, metal workers, and furniture refinishers also may be exposed to xylene. Workers who routinely come in contact with xylene-contaminated solvents in the workplace are most likely to be exposed to high levels of xylene.

Metabolism

Xylene is most likely to enter your body when you breathe xylene vapors. Less often, xylene enters the body through the skin following direct contact. It is rapidly absorbed by your lungs after you breathe air containing it. Exposure to xylene may also take place if you eat or drink xylene-contaminated food or water. The amount of xylene retained ranges from 50% to 75% of the amount of xylene that you inhale. Physical exercise increases the amount of xylene absorbed by the lungs. Absorption of xylene after eating food or drinking water containing is both rapid and complete. Absorption of xylene through the skin also occurs rapidly following direct contact with xylene. Absorption of xylene vapor through the skin is lower than absorption of xylene vapor by the lungs. However, it is not known how much of the xylene is absorbed through the skin. At hazardous waste sites, breathing xylene vapors, drinking well water contaminated with xylene, and direct contact of the skin with xylene are the most likely ways you can be exposed. Xylene passes into the blood soon after entering the body.

In people and laboratory animals, xylene is broken down into other chemicals especially in the liver. This process changes most of the xylene that is breathed in or swallowed into a different form. Once xylene breaks down, the breakdown products rapidly leave the body, mainly in urine, but some unchanged xylene also leaves in the breath from the lungs. One of the breakdown products of xylene, methylbenzaldehyde, is harmful to the lungs of some animals. This chemical has not been found in people exposed to xylene. Small amounts of breakdown products of xylene have appeared in the urine of people as soon as 2 hours after breathing air containing xylene. Usually, most of the xylene that is taken in leaves the body within 18 hours after exposure ends. Storage of xylene in fat or muscle may prolong the time needed for xylene to leave the body.

Health Effects

Short-term exposure of people to high levels of xylene can cause irritation of the skin, eyes, nose, and throat; difficulty in breathing; impaired function of the lungs; delayed response to a visual stimulus; impaired memory; stomach discomfort; and possible changes in the liver and kidneys. Both short- and long-term exposure to high concentrations of xylene can also cause a number of effects on the nervous system, such as headaches, lack of muscle coordination, dizziness, confusion, and changes in one's sense of balance. People exposed to very high levels of xylene for a short period of time have died. Most of the information on long-term exposure to xylene is from studies of workers employed in industries that make or use xylene. Those workers were exposed to levels of xylene in air far greater than the levels normally encountered by the general population. Many of the effects seen after their exposure to xylene could have been caused by exposure to other chemicals that were in the air with xylene.

Results of studies of animals indicate that large amounts of xylene can cause changes in the liver and harmful effects on the kidneys, lungs, heart, and nervous system. Short-term exposure to very high concentrations of xylene causes death in animals, as well as muscular spasms, incoordination, hearing loss, changes in behavior, changes in organ weights, and changes in enzyme activity. Long-term exposure of animals to low concentrations of xylene has not been well studied.

Information from animal studies is not adequate to determine whether or not xylene causes cancer in humans. Both the International Agency for Research on Cancer (IARC) and EPA have found that there is insufficient information to determine whether or not xylene is carcinogenic and consider xylene not classifiable as to its human carcinogenicity.

Exposure of pregnant women to high levels of xylene may cause harmful effects to the fetus. Studies of unborn animals indicate that high concentrations of xylene may cause increased numbers of deaths, decreased weight, skeletal changes, and delayed skeletal development. In many instances, these same concentrations also cause damage to the mothers. The higher the exposure and the longer the exposure to xylene, the greater the chance of harmful health effects. Lower concentrations of xylene are not so harmful.

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Reference