Research
Glossary of Current Research Toxins

Arsenic (As)
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.
Uses - Inorganic arsenic compounds are mainly used to preserve wood. Organic arsenic compounds are used as pesticides, primarily on cotton plants
Health Effects - Breathing arsenic can cause sore throats or irritated lungs. Ingesting can cause death; low level ingestion may result in corns or warts on palms, soles, and torso.

CERCLA Priority List of Hazardous Substances
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) section 104 (i), as amended by the Superfund Amendments and Reauthorization Act (SARA), requires ATSDR and the 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. CERCLA also requires this list to be revised periodically to reflect additional information on hazardous substances.

Chlorpyrifos
Chlorpyrifos is an insecticide that is a white crystal-like solid with a strong odor. It does not mix well with water, so it is usually mixed with oily liquids before it is applied to crops or animals. It may also be applied to crops in a capsule form.

Uses - In the home, it is used to control cockroaches, fleas, and termites; it is also used in some pet flea and tick collars. On the farm, it is used to control ticks on cattle and as a spray to control crop pests.
Health Effects - Breathing the air in an area in which Chlorpyrifos has recently been sprayed or ingestion through food, food containers or objects that have been contaminated with Chlorpyrifos may produce a variety of effects on the nervous system including headaches, blurred vision, watering of the eyes (called lacrimation), excessive salivation, runny nose, dizziness, confusion, muscle weakness or tremors, nausea, diarrhea, and sudden changes in heart rate. Exposure to high levels may cause severe sweating, loss of bowel control, severe muscle tremors, seizures, loss of consciousness (coma), or death.

Dieldrin (DED) (Aldrin)
Aldrin and Dieldrin are insecticides with similar chemical structures. They are discussed together in this because Aldrin quickly breaks down to Dieldrin in the body and in the environment. Pure Aldrin and Dieldrin are white powders with a mild chemical odor. The less pure commercial powders have a tan color. Neither substance occurs naturally in the environment

Uses - From the 1950s until 1970, Aldrin and Dieldrin were widely used pesticides for crops like corn and cotton. Because of concerns about damage to the environment and potentially to human health, EPA banned all uses of Aldrin and Dieldrin in 1974, except to control termites. In 1987, EPA banned all uses.
Health Effects – Ingestion of large amounts of Aldrin or Dieldrin can cause convulsions and death. Workers exposed to moderate levels in the air for a long time experience headaches, dizziness, irritability, vomiting, and uncontrolled muscle movements. Workers removed from the source of exposure rapidly recover from most of these effects. Animals exposed to high amounts of Aldrin or Dieldrin also have nervous system effects. In animals, oral exposure to lower levels for a long period also affected the liver and decreased their ability to fight infections.

Lead
Lead is a naturally occurring bluish-gray metal found in small amounts in the earth's crust. Lead can be found in all parts of our environment. Much of it comes from human activities including burning fossil fuels, mining, and manufacturing.

Uses - It is used in the production of batteries, ammunition, metal products (solder and pipes), and devices to shield X-rays. Because of health concerns, lead from gasoline, paints and ceramic products, caulking, and pipe solder has been dramatically reduced in recent years.
Health Effects - Lead can affect almost every organ and system in your body. The main target for lead toxicity is the nervous system, both in adults and children. Long-term exposure of adults can result in decreased performance in some tests that measure functions of the nervous system. It may also cause weakness in fingers, wrists or ankles. Lead exposure also causes small increases in blood pressure, particularly in middle-aged and older people and can cause anemia. Exposure to high lead levels can severely damage the brain and kidneys in adults or children and ultimately cause death. 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.

Maganese (Mn)
Manganese is a naturally occurring metal that is found in many types of rocks.

Uses - Manganese can also be combined with carbon to make organic manganese compounds. Common organic manganese compounds include pesticides, such as maneb or mancozeb, and methylcyclopentadienyl manganese tricarbonyl (MMT), a fuel additive in some gasolines. Manganese is an essential trace element and is necessary for good health. Manganese can be found in several food items, including grains and cereals, and is found in high amounts in other foods, such as tea.
Health Effects - Exposure to high levels of airborne manganese, such as in a manganese foundry or battery plant, can affect motor skills such as holding one's hand steady, performing fast hand movements, and maintaining balance. Exposure to high levels of the metal may also cause respiratory problems and sexual dysfunction. Some individuals exposed to very high levels of manganese for long periods of time in their work can develop mental and emotional disturbances and slow and clumsy body movements.

Mercury (Hg)
Mercury is a naturally occurring metal which has several forms. The metallic mercury is a shiny, silver-white, odorless liquid. If heated, it is a colorless, odorless gas.

Uses - Metallic mercury is used to produce chlorine gas and caustic soda, and is also used in thermometers, dental fillings, and batteries. Mercury salts are sometimes used in skin lightening creams and as antiseptic creams and ointments.
Health Effects - Exposure to high levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetus. Effects on brain functioning may result in irritability, shyness, tremors, changes in vision or hearing, and memory problems. Short-term exposure to high levels of metallic mercury vapors may cause effects including lung damage, nausea, vomiting, diarrhea, increases in blood pressure or heart rate, skin rashes, and eye irritation

Molybdenum
Molybdenum is a metallic element which is most frequently used as an alloying addition in alloy and stainless steels.

Uses - Molybdenum is primarily used in steels,
Health Effects - Acute molybdenum poisoning in human beings is extremely unlikely because of the massive dose required. The effect of repeated exposure to small concentrations of molybdenum compounds is more difficult to assess. In animals and human beings Molybdenum is adsorbed and excreted rapidly and is not likely to be a cumulative poison. In checking for possible Molybdenum toxicity it is important to know where and in what form toxic effects may occur. In experimental animals, Molybdenum toxicity causes loss of weight, harmful changes in the liver, kidneys, and bones and diminution of the strength of conditioned reflexes.

Polychlorinated Biphenyls (PCB’s)
PCBs are mixtures of man-made chemicals with similar chemical structures. PCBs can range from oily liquids to waxy solids.

Uses - Due to their non-flammability, chemical stability, high boiling point and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications including electrical, heat transfer, and hydraulic equipment; as plasticizers in paints, plastics and rubber products; in pigments, dyes and carbonless copy paper and many other applications.
Health Effects - PCBs have been shown to cause cancer in animals. PCBs have also been shown to cause a number of serious non-cancerous health effects in animals, including effects on the immune system, reproductive system, nervous system, endocrine system and other health effects. Studies in humans provide supportive evidence for potential carcinogenic and non-carcinogenic effects of PCBs.

Polycyclic Aromatic Hydrocarbons (PAHs)
Polycyclic aromatic hydrocarbons (PAHs) are a group of over 100 different chemicals that are formed during the incomplete burning of coal, oil, gas, garbage, or other organic substances like tobacco or charbroiled meat. PAHs are usually found as a mixture containing two or more of these compounds, such as soot.

Uses - Some PAHs are manufactured. These pure PAHs usually exist as colorless, white, or pale yellow-green solids. PAHs are found in coal tar, crude oil, creosote, and roofing tar, but a few are used in medicines or to make dyes, plastics, and pesticides.
Health Effects - Mice that were fed high levels of one PAH during pregnancy had difficulty reproducing and so did their offspring. These offspring also had higher rates of birth defects and lower body weights. It is not known whether these effects occur in humans. Animal studies have also shown that PAHs can cause harmful effects on the skin, body fluids, and ability to fight disease after both short- and long-term exposure. However, these effects have not been seen in humans.

REFERENCES
A-Z Index ToxFAQ’s. Retrieved May 18, 2006, from http://www.atsdr.cdc.gov/toxfaq.html
International Molybdenum Association Overview of Molybdendum. Retrieved May 18, 2006 from http://www.hse.imoa.info/ Default.asp?page=110
Polychlorinated Biphenyls(PCBs). Retrieived May 18, 2006 from http://www.epa.gov/pcb
United States. Agency for Toxic Substances and Disease Registry. Division of Toxicology. Cooperative Program with the Minority Health Professions Foundation. January 2004. Atlanta: GPO,2004.
What is the CERCLA List? Retrieived May 18, 2006 from http://www.atsdr.cdc.gov/cercla