Health effects of styrene
Contents
Introduction
Pure styrene is a colorless liquid that evaporates easily and has a sweet smell. However, styrene often contains other chemicals that give it a sharp, unpleasant smell. Styrene dissolves in some liquids, but dissolves only slightly in water. Styrene is used mostly to make rubber and plastics. Billions of pounds of styrene are produced for this purpose each year in the United States. Products produced from styrene include packaging, insulation (electrical and thermal), fiberglass, pipes, automobile parts, drinking cups and other "food-use" items, and carpet backing. These products mainly contain styrene linked together in long chains, polystyrene. However, most of these products also contain a residue of unlinked styrene. Styrene is also present in combustion products such as cigarette smoke and automobile exhaust. Low levels of styrene occur naturally in a variety of foods, such as fruits, vegetables, nuts, beverages, and meats. Styrene can be found in air, soil (Health effects of styrene) , and water after release from the manufacture, use, and disposal of styrene-based products.
Styrene is quickly broken down in the air, usually within 1-2 days. Styrene evaporates from shallow soils and surface water. Styrene that remains in soil or water may be broken down by bacteria.
Exposure
The major way you can be exposed to styrene is by breathing air containing it. Styrene is found in city air and indoor air. Styrene is released into the air from industries that make and use styrene. It is also released from automobile exhaust, cigarette smoke, building materials, and consumer products (polystyrene products such as packaging materials, toys, housewares and appliances that may contain residual amounts of unlinked styrene). Accidental spills and hazardous waste disposal sites are also sources of styrene in air. Usually indoor air that has less movement contains higher levels of styrene than does outdoor air. Rural or suburban air generally contains lower concentrations of styrene than city air.
Styrene is not usually found in drinking water. When it is found in water, the main source is usually industrial waste discharge from factories and coal gasification plants. Also styrene may leach into groundwater around hazardous waste sites. Soil may become contaminated with styrene by spills, landfilling with wastes, and industrial discharges. Styrene can be a natural part of some foods, or can be transferred to food from polystyrene packaging material.
Pathways in the enviroment
Styrene can enter your body through your lungs if you breathe contaminated air or through your stomach and intestines if you eat or drink contaminated food or water. Styrene can also pass through the skin into your body. Studies on humans show that styrene enters the body tissues quickly after it is breathed in or taken in by mouth. Because styrene is not usually found in drinking water, the most common way it will enter your body is if you breathe air containing it. Ingestion of styrene contaminated foods is another way styrene can enter the body. Once styrene is in the body, it changes quickly to other chemical forms and leaves the body through the urine and exhaled air within a few days to a few weeks.
Health effects
Illness or injury has been reported in people, especially workers, who breathe large amounts of styrene for short periods of time. The most common health problems involve the nervous system. These health effects include depression, concentration problems, muscle weakness, tiredness, and nausea. People exposed to styrene may also have irritation of the eyes, nose, and throat. There have been no reports of death as a result of styrene exposure. Recovery from the ill effects of short-term exposure is rapid after styrene exposure ends. The health effects for people exposed to styrene for longer periods of time are not known except for limited information on the harmful effects on the nervous system in occupationally exposed workers.
Some studies of female workers exposed to elevated air concentrations of styrene have suggested that styrene may cause lower birth weights and produce an increased risk of spontaneous abortions. However, these studies are not completely reliable because the studies often involved exposure to chemicals other than styrene.
Styrene vapor affects the lungs of animals that breathe it. Animal studies have shown that inhalation of styrene can result in changes in the lining of the nose that can last up to 12 weeks after exposure ceases. Long-term animal exposure to high levels of styrene results in damage to the liver but this effect has not been seen in people.
There is little or no information regarding adverse effects in humans following oral or dermal exposure to styrene. However, animal studies indicate that ingestion of styrene can produce effects on the liver, kidney, blood, immune system and nervous system. Dermal exposure has resulted in irritation to the skin and eyes of rabbits. The International Agency for Research on Cancer has determined that styrene is possibly carcinogenic to humans.
Medical tests
Styrene and its breakdown products can be found in your blood, urine, and body tissues for a short time following exposure to moderate-to-high levels. Because urine samples are easily obtained, urine is often analyzed for the common breakdown products to determine whether a person has been exposed to styrene. However, the breakdown products can also be found in the urine of persons who have been exposed to chemicals other than styrene. The tests for styrene and its breakdown products in urine require specific methods and equipment and are not usually available at a doctor's office. Because styrene is cleared quickly from the body, the above methods are useful only for detecting exposures that have occurred within 1 day. Testing within 1 day after moderate-to-high exposures allows us to estimate the actual exposure level. Testing urine for styrene and its breakdown products usually does not help predict how severe the resulting health effects may be.
Further Reading
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