Professional
FAQs - Hazardous Toxins
What are the top 12 hazardous toxins in our environment?
- Arsenic
- Lead
- Mercury
- Vinyl chloride
- PolyChlorinated Biphenyls (PCBs)
- Benzene
- Polycyclic aromatic hydrocarbons (PAHs)
- Cadmium
- Benzo[a]pyrene
- Benzo[b]fluoranthene
- Chloroform
- DDT
- Sources
- Origin of the CERCLA Priority List of Hazardous Substances:
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Federal law requires the Agency for Toxic Substances and Disease Registry (ATSDR) and the U.S. Environmental Protection Agency (EPA) to prepare a list, in order of priority, of substances that are most commonly found at facilities on the National Priorities List (NPL) and which are determined to pose the most significant potential threat to human health due to their known or suspected toxicity and potential for human exposure at these NPL sites. The CERCLA list is not a list of "most toxic" substances, but rather a prioritization of substances based on a combination of their frequency, toxicity, and potential for human exposure at NPL sites. Thus, it is possible for substances with low toxicity but high NPL frequency of occurrence and exposure to be on this priority list.
- Arsenic
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Arsenic is a naturally occurring element widely distributed in the earth's crust. In the environment, arsenic is combined with oxygen, chlorine, and sulfur to form inorganic arsenic compounds. Arsenic in animals and plants combines with carbon and hydrogen to form organic arsenic compounds. Inorganic arsenic compounds are mainly used to preserve wood. Copper chromated arsenic (CCA) is used to make "pressure-treated" lumber. CCA is no longer used in the U.S. for residential uses; it is still used in industrial applications. Organic arsenic compounds are used as pesticides, primarily on cotton plants.
Several studies have shown that ingestion of inorganic arsenic can increase the risk of skin cancer and cancer in the liver, bladder, and lungs. Inhalation of inorganic arsenic can cause increased risk of lung cancer. The U.S. Department of Health and Human Services (HHS), the International Agency for Research on Cancer (IARC), and the U.S. Environmental Protection Agency (EPA) have all declared inorganic arsenic to be carcinogenic to humans.
- Benzene
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Benzene is a widely used chemical formed from both natural processes and human activities. Breathing benzene can cause drowsiness, dizziness, and unconsciousness. Exposure to benzene, especially in the workplace, may cause cancer in animals and humans, including leukemia. In addition, benzene can pass from the mother's blood to a fetus. Animal studies have shown low birth weights, delayed bone formation, and bone marrow damage when pregnant animals breathed benzene.
You can reduce your exposure by limiting contact with gasoline and cigarette smoke. We encourage families not to smoke in their house, in enclosed environments, or near their children. Or better yet, quit smoking altogether!
- Benzo[a]pyrene and Benzo[b]fluoranthene
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Benzo[a]pyrene and Benzo[b]fluoranthene are two of the over 100 polycyclic aromatic hydrocarbons formed during the incomplete burning of organic matter.
Benzo[a]pyrene occurs ubiquitously in products of incomplete combustion of fossil fuels and has been identified in ambient air, surface water, drinking water, waste water, and char-broiled foods. Benzo[b]fluoranthene is found in fossil fuels and occurs ubiquitously in products of incomplete combustion; it has been detected in mainstream cigarette smoke; urban air; gasoline engine exhaust; emissions from burning coal and from oil-fired heating; broiled and smoked food; oils and margarine; and in soils, groundwater, and surface waters at hazardous waste sites.
Mixtures of PAHs containing benzo[a]pyrene have long been known to cause cancer---a 1775 report described scrotal cancer in chimney sweeps, and twentieth-century studies found skin cancer in workers exposed to shale oil and creosote. While the contribution of benzo[a]pyrene to the carcinogenicity of these PAH mixtures is uncertain, benzo[a]pyrene is known to be among the most potent and best documented skin carcinogens among non-human animals, and is commonly used as a positive control in skin application assays of other chemicals. Benzo[a]pyrene has been shown to cause skin tumors in mice, rats, rabbits, and guinea pigs. Based on the animal evidence, EPA has classed benzo[a]pyrene as a 'probable human carcinogen'.
Similarly, although there are no human data that specifically link exposure to benzo[b]fluoranthene to human cancers, benzo[b]fluoranthene is a component of mixtures that have been associated with human cancer, including coal tar, soots, coke oven emissions, and cigarette smoke, and benzo[b]fluoranthene itself produced tumors in mice in studies using a variety of methods of exposure. Based on the animal evidence, EPA has classed benzo[b]fluoranthene as a 'probable human carcinogen'.
Oak Ridge National Laboratory, Risk Assessment Information System. Toxicity Summaries for BENZO[A]PYRENE and BENZO[B]FLUORANTHENE.
- Cadmium
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Cadmium is used in batteries and plastics and is released in cigarette smoke and in the burning of fossil fuels. Long-term exposure to cadmium can result in kidney diseases, lung damage, and fragile bones.
In the home, store substances that contain cadmium safely, and keep nickel-cadmium batteries out of reach of young children. If you work with cadmium, use all safety precautions to avoid carrying cadmium-containing dust home from work on your clothing, skin, hair, or tools. A balanced diet can reduce the amount of cadmium taken into the body from food and drink.
- Chloroform
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This substance can be found in contaminated air and water. Chloroform is considered by several agencies, including the U.S. Department of Health and Human Services (HHS), the U.S. Environmental Protection Agency (EPA), and the International Agency for Research on Cancer (IARC), as a probable carcinogen in humans. This is largely based on evidence that exposure to chloroform has caused liver and kidney cancer in laboratory animals.
- DDT
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DDT (dichlorodiphenyltrichloroethane) is a pesticide once widely used to control insects in agriculture and insects that carry diseases such as malaria. DDT is a white, crystalline solid with no odor or taste. Its use in the U.S. was banned in 1972 because of damage to wildlife, but is still used in some countries.
You can be exposed to DDT by eating contaminated foods imported from countries that still allow the use of DDT to control pests, or by breathing contaminated air, drinking contaminated water, or swallowing contaminated soil particles near waste sites and landfills that contain these chemicals. Children of mothers who have been exposed can also be exposed through their mother's breast milk.
Studies in DDT-exposed workers did not show increases in cancer, but animals given DDT with their food did show an increased rate of liver cancer.
- Lead
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Lead can leak into drinking water through old pipes and can be found also in the air near areas with deteriorating lead based paints.
Exposure to lead can damage the nervous system and can cause an increase in blood pressure in middle-aged adults. In pregnant women, high levels of exposure to lead may cause miscarriage. High-level exposure in men can damage the organs responsible for sperm production. According to several health agencies, lead may have the potential to cause cancer in humans, although a conclusive link has not been established.
Do not allow children to chew or mouth painted surfaces that may have been painted with lead-based paint. If you have a water lead problem, run or flush water that has been standing overnight before drinking or cooking with it. Some types of paints and pigments that are used as make-up or hair coloring contain lead. Read the labels carefully to avoid using those products.
- Mercury
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Contact with mercury can occur during dental and medical treatments and from contaminated water, air, and seafood. Inorganic mercury compounds are sometimes used in skin lightening creams and as antiseptic creams and ointments.
The different forms of mercury have distinct patterns of adverse health effects. Exposure to high levels of mercury may cause brain or kidney damage and harm a developing fetus. The U.S. Environmental Protection Agency (EPA) has determined that two types of mercury, mercuric chloride and methylmercury, are possible human carcinogens.
Carefully handle and dispose of products that contain mercury, such as thermometers or fluorescent light bulbs. Do not vacuum up spilled mercury, because it will vaporize and increase your exposure.
- Polychlorinated Biphenyls (PCBs)
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Polychlorinated biphenyls are mixtures of up to 209 individual chlorinated compounds; there are no known natural sources. PCBs have been used as coolants and lubricants in electrical equipment because they don't burn easily and are good insulators. The manufacture of PCBs was stopped in the U.S. in 1977 because of evidence they build up in the environment and can cause harmful health effects.
You can be exposed to PCBs by using old fluorescent lighting fixtures and electrical devices and appliances, such as television sets and refrigerators, that were made 30 or more years ago (these items may leak small amounts of PCBs into the air when they get hot during operation, and could be a source of skin exposure), but the most likely way is by eating contaminated food, including fish (especially sportfish caught in contaminated lakes or rivers), meat, and dairy products. It's also possible to be exposed by breathing air near hazardous waste sites and drinking contaminated well water, or through work-related exposures (such as during PCB disposal operations, maintenance on PCB-containing equipment, or due to accidents involving such equipment).
Known PCB-related health effects include acne-like skin conditions in adults, neurobehavioral and immunological changes in children, and a variety of injuries and disorders in animals, including anemia; acne-like skin conditions; liver, stomach, and thyroid gland injuries; immune system changes; behavioral alterations; impaired reproduction; and cancer. The U.S. Department of Health and Human Services (HHS), the International Agency for Research on Cancer (IARC), and the U.S. Environmental Protection Agency (EPA) have all determined that PCBs are likely to cause cancer in humans.
- Polycyclic aromatic hydrocarbons (PAHs)
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Polycyclic aromatic hydrocarbons are formed by the incomplete combustion of coal, oil, petrol, wood, tobacco, charbroiled meats, garbage, or other organic materials. There are more than 100 different compounds which fall into the PAH familyl; most have no known use, though a few are used in medicines, and to make dyes, plastics, and pesticides. Naphthalene, also known as mothballs, is used in making dyes, explosives, plastics, lubricants, and moth repellent. Anthracene is used in dyes, insecticides and wood preservatives.
In the home, polycyclic aromatic hydrocarbons are present in tobacco smoke, smoke from home heating (burning wood or oil), char-grilled food and cresote treated wood products. Some workplaces can give exposures to polycyclic aromatic hydrocarbons. High concentrations of polycyclic aromatic hydrocarbons have been found in coal-tar production plants, coking plants, bitumen and asphalt production plants, smoke houses, aluminium production plants, and trash incinerators. They are found in facilities that manufacture or use petroleum, petroleum products or coal, or where wood, or other plant materials are burned. People may also be exposed to polycyclic aromatic hydrocarbons in the soil where coal, wood, petrol or other products have ben burned. Food produced from these soils may also contain polycyclic aromatic hydrocarbons.
Exposure can irritate the eyes, nose, throat and bronchial tubes. Skin contact can cause irritation or a skin allergy. Very high levels may cause headaches, nausea, damage the red blood cells, damage the liver and kidneys, and may even cause death. The International Agency for Research on Cancer has cited a number of polycyclic aromatic hydrocarbons as 'probably carcinogenic to humans', a number of others are cited as being 'possibly carcinogenic to humans'.
ATSDR: PAHs
Australia National Pollutant Inventory Substance Profile: PAHs - Vinyl chloride
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Vinyl chloride is used in plastic industries and also can be found in hazardous waste sites and landfills.
Exposure to vinyl chloride can cause dizziness, sleepiness, unconsciousness, and at extremely high levels can cause death. Exposure over a long period of time (factory workers) can cause nerve damage, permanent liver damage, immune reactions, and liver cancer. The U.S. Department of Health and Human Services (HHS), the International Agency for Research on Cancer (IARC), and the U.S. Environmental Protection Agency (EPA) have all declared vinyl chloride to be carcinogenic.
Aside from reducing occupational exposures, one way to limit your family's contact with vinyl chloride is to limit their exposure to cigarette and cigar smoke.
- Sources:
- Agency for Toxic Substances and Disease Registry (ATSDR) Toxic Substances Portal.
- See also links under each section.
To inquire about Center for Environmental Oncology activities, please send an e-mail to envonc@upmc.edu or call 412-623-3375.
