PRODUCTS LIABILITY GUIDE: Products Liability Law,
Mesothelioma Asbestos,
Benzene,
Food Poisoning,
Lead Poisoning, Manganese,
Silicosis,
SJS - Stevens Johnson Syndrome,
Teflon,
Toxic Birth Defects,
Toxic Mold,
Vinyl Chloride,
Guidant,
Medtronic,
Ortho Evra,
Antidepressants,
Paxil,
Prozac,
Remeron,
ADHD Drugs,
Adderall,
Accutane,
Trasylol,
Amiodarone,
Avandia,
Bextra,
Chantix,
Cox-2 Inhibitors,
Fen-Phen - PPH,
Fosamax,
Ketek,
Mirapex,
Tamiflu,
Thimerosal,
Vioxx,
Vytorin,
Zetia,
Zocor,
ZyprexaBENZENE
What is Benzene?
Benzene is a colorless liquid with a sweet odor. It evaporates into the air very quickly and dissolves slightly in water. It is highly flammable and is formed from both natural processes and human activities.
Benzene is widely used in the United States; it ranks in the top 20 chemicals for production volume. Some industries use benzene to make other chemicals which are used to make plastics, resins, and nylon and synthetic fibers. Benzene is also used to make some types of rubbers, lubricants, dyes, detergents, drugs, and pesticides. Natural sources of benzene include volcanoes and forest fires. Benzene is also a natural part of crude oil, gasoline, and cigarette smoke.
What happens to benzene when it enters the environment?
- Industrial processes are the main source of benzene in the environment.- Benzene can pass into the air from water and soil.- It reacts with other chemicals in the air 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.- It breaks down more slowly in water and soil, and can pass through the soil into underground water.- Benzene does not build up in plants or animals.
How might I be exposed to benzene?
- Outdoor air contains low levels of benzene from tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions.- Indoor air generally contains higher levels of benzene from products that contain it such as glues, paints, furniture wax, and detergents.- Air around hazardous waste sites or gas stations will contain higher levels of benzene.- Leakage from underground storage tanks or from hazardous waste sites containing benzene can result in benzene contamination of well water.- People working in industries that make or use benzene may be exposed to the highest levels of it.
How can benzene affect my health?
Breathing very high levels of benzene can result in death, while high levels can cause drowsiness, dizziness, rapid heart rate, headaches, tremors, confusion, and unconsciousness. Eating or drinking foods containing high levels of benzene can cause vomiting, irritation of the stomach, dizziness, sleepiness, convulsions, rapid heart rate, and death.
The major effect of benzene from long-term (365 days or longer) exposure is on the blood. Benzene causes harmful effects on the bone marrow and can cause a decrease in red blood cells leading to anemia. It can also cause excessive bleeding and can affect the immune system, increasing the chance for infection.
Some women who breathed high levels of benzene for many months had irregular menstrual periods and a decrease in the size of their ovaries. It is not known whether benzene exposure affects the developing fetus in pregnant women or fertility in men.
Animal studies have shown low birth weights, delayed bone formation, and bone marrow damage when pregnant animals breathed benzene.
How likely is benzene to cause cancer?
The Department of Health and Human Services (DHHS) has determined that benzene is a known human carcinogen. Long-term exposure to high levels of benzene in the air can cause leukemia, cancer of the blood-forming organs.
Workers exposed to benzene, the human carcinogen that has been responsible for instances of acute myelogenous leukemia, acute lymphocytic leukemia, chronic myelogenous leukemia, in addition to other forms of cancer and leukemia. While workers have the highest risk for becoming inflicted with adverse effects of benzene, benzene exists in the environment and in consumer products, putting everyone at risk to develop potentially deadly health conditions. The EPA estimates that half of the entire U.S. population has been exposed to the dangerous chemical.
Benzene Toxicity - Physiologic Effects
Hematopoietic System
Benzene exposure affects the CNS and hematopoietic system and may affect the immune system. Death due to acute benzene exposure has been attributed to asphyxiation, respiratory arrest, CNS depression, or cardiac dysrhythmia. Pathologic findings in fatal cases have included respiratory tract inflammation, lung hemorrhages, kidney congestion, and cerebral edema.
Central Nervous System Effects
Acute benzene exposure results in classic symptoms of CNS depression such as dizziness, ataxia, and confusion. These effects are believed to be caused by benzene itself rather than its metabolites, because the onset of CNS effects at extremely high doses is too rapid for metabolism to have occurred.
Hematologic Effects
* Pluripotential stem cells and lymphocytic cells are the probable targets of benzene toxicity.
Benzene can cause dangerous hematologic toxicity such as anemia, leukopenia, thrombocytopenia, or pancytopenia after chronic exposure. These effects are believed to be caused by the metabolites of benzene, which most likely damage the DNA of the pluripotential stem cells. All of the blood's components (i.e., erythrocytes, leukocytes, and thrombocytes [platelets]) may be affected to varying degrees. The accelerated destruction or reduction in the number of all three major types of blood cells is termed pancytopenia.
Potentially fatal infections can develop if granulocytopenia is present, and hemorrhage can occur as a result of thrombocytopenia. Paroxysmal nocturnal hemoglobinuria, a disorder in which the breakdown of the red blood cells is accelerated and results in bleeding into the urine during sleep when the condition is active, has been associated with benzene exposure. Cytogenetic abnormalities of bone marrow cells and circulating lymphocytes have been observed in workers exposed to benzene-abnormalities not unlike those observed after exposure to ionizing radiation. Myelodysplastic effects also can be seen in the bone marrow of persons chronically exposed to benzene.
Anemia
Aplastic anemia is caused by bone marrow failure, resulting in hypoplasia with an inadequate number of all cell lines. Severe aplastic anemia typically has a poor prognosis and can progress to leukemia, whereas pancytopenia may be reversible. Benzene-induced aplastic anemia is generally caused by chronic exposure at relatively high doses. Fatal aplastic anemia following benzene exposure was first reported in workers in the nineteenth century.
Leukemia
Several agencies (e.g., the U.S. Department of Health and Human Services, the U.S. Environmental Protection Agency [EPA], and the International Agency for Research on Cancer) classify benzene as a confirmed human carcinogen. EPA estimates that a lifetime exposure to 4 ppb benzene in air will result in, at most, 1 additional case of leukemia in 10,000 people exposed. EPA has also estimated that lifetime exposure to a benzene concentration of 100 ppb in drinking water would correspond to, at most, 1 additional cancer case in 10,000 people exposed.
Cohort studies of benzene-exposed workers in several industries (e.g., sheet-rubber manufacturing, shoe manufacturing, and rotogravure [a special printing process]) have demonstrated significantly elevated risk of leukemia-predominantly acute myelogenous leukemia, but also erythroleukemia and acute myelomonocytic leukemia. The latency period for benzene-induced leukemia is typically 5 to 15 years after first exposure. Patients with benzene-induced aplastic anemia progress to a preleukemic phase and develop acute myelogenous leukemia. However, a person exposed to benzene may develop leukemia without having aplastic anemia.
Studies addressing the risk of leukemia associated with occupational exposures to low levels of benzene (less than approximately 1 ppm) have been inconclusive. Death certificates do not reveal increased leukemia mortality among workers potentially exposed to low levels of hydrocarbons and other petroleum products.
However, in recent case-control studies, significantly more patients with acute nonlymphocytic leukemia were employed as truck drivers, filling station attendants, or in jobs involving exposure to low levels of petroleum products than were the controls.
Other Effects
* Benzene has not been shown to be teratogenic in humans.
Several reports relate benzene exposure to a variety of lymphatic tumors including non-Hodgkin lymphoma and multiple myeloma. Although this is plausible, there is no scientific proof of a causal relationship. The association between exposure to benzene and development of nonhematologic tumors remains inconclusive.
Information on the reproductive toxicity of benzene in humans is meager. Some effects on the testes have been noted in animals exposed via inhalation. Benzene has not been proven teratogenic in humans. In animals, high levels of benzene have resulted in decreased fetal weights and minor skeletal variants.
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