Polychlorinated Biphenyl (PCB) belongs to a broad family of man-made organic chemicals known as chlorinated hydrocarbons. PCBs were domestically manufactured from 1929 until their manufacture was banned in 1979. They have a range of toxicity and vary in consistency from thin, light-colored liquids to yellow or black waxy solids. Due to their non-flammability, chemical stability, high boiling point, and electrical insulating properties, PCBs were used in hundreds of industrial and commercial applications. These include: electrical, heat transfer, and hydraulic equipment; plasticizers in paints, plastics, and rubber products; in pigments, dyes, and carbonless copy paper; and many other industrial applications.
Fish consumption appears to be the major pathway of exposure. PCBs do not easily break down and can bioaccumulate in the fatty tissues of fish and mammals. A significant trend of increasing body burden is associated with increased fish consumption.
People who live near hazardous waste sites may be exposed to PCBs by consuming PCB contaminated sport fish and game animals, by breathing PCBs in air, or by drinking PCB contaminated well water. PCBs generally biomagnify along the food-chain, which leads to greater PCB concentrations in organisms that are higher up in the food chain.
Although PCBs are no longer made in the United States, people can still be exposed to them. Many older transformers and capacitors may still contain PCBs, and this equipment can be used for 30 years or more. Old fluorescent lighting fixtures and old electrical devices and appliances, such as television sets and refrigerators, may contain PCBs if they were made before PCB use was stopped. When these electric devices get hot during operation, small amounts of PCBs may get into the air and raise the level of PCBs in indoor air. Because devices that contain PCBs can leak with age, they could also be a source of skin exposure to PCBs.
Workplace exposure to PCBs can occur during the repair and maintenance of PCB transformers, accidents, fires, or spills involving PCB transformers and older computers and instruments, and disposal of PCB materials. In addition to older electrical instruments and fluorescent lights that contain PCB-filled capacitors, caulking materials, elastic sealants, and heat insulation have also been known to contain PCBs. Contact with PCBs at hazardous waste sites can happen when workers breathe air and touch soil containing PCBs. Exposure in the contaminated workplace occurs mostly by breathing air containing PCBs and by touching substances that contain PCBs.
Thousands of medical PCB studies have shown that polychlorinated biphenyls (PCBs) cause a wide variety of health effects, often at very low exposure levels. The average American already carries enough PCB in his or her body to meet or exceed the minimum threshold for beginning health problems due to PCBs. Not all of the 209 kinds of PCB have the same effects. Some have properties like dioxin (one of the world's most toxic man-made compounds), some PCBs act like hormones, and other PCBs are nerve poisons. PCBs alter major systems in the body (immune, hormone, nervous, and enzyme systems); and affect a wide variety of body organs and functions.

Polybrominated Diphenyl Ethers (PBDEs) are flame retardant chemicals added to products so they won't catch fire or burn so easily if they are exposed to flame or high heat. PBDEs have been used for over 30 years in products such as mattresses, upholstered furniture, foam carpet pads, draperies, television sets, computers, stereos and other electronics, cable insulation, adhesives, and textile coating.
The primary commercial source of nicotine is by extraction from the dried leaves of the tobacco plant. Since nicotine is the drug in tobacco leaves, whether someone smokes, chews, or sniffs tobacco, he or she is delivering nicotine to the brain. Each cigarette contains about 10 milligrams of nicotine. Because the smoker inhales only some of the smoke from a cigarette and not all of each puff is absorbed in the lungs, a smoker gets about 1 to 2 milligrams of the drug from each cigarette. A drop of pure nicotine would kill a person. It is unlikely that a person would overdose on nicotine through smoking alone, although overdose can occur through combined use of nicotine patches or nicotine gum and cigarettes at the same time. Spilling a high concentration of nicotine onto the skin can cause intoxication or even death, since nicotine readily passes into the bloodstream following dermal contact.
Chemically speaking, MSG is approximately 78 percent free glutamic acid, 21 percent sodium, and up to 1 percent contaminants. It's a misconception that MSG is a flavor or "meat tenderizer." In reality, MSG has very little taste at all, yet when you eat MSG, you think the food you're eating has more protein and tastes better. It does this by tricking your tongue, using a little-known fifth basic taste called umami.
Lindane is an organochlorine insecticide and fumigant which has been used on a wide range of soil-dwelling and plant-eating insects. It is commonly used on a wide variety of crops, in warehouses, in public health to control insect-borne diseases, and (with fungicides) as a seed treatment. Despite a recent global ban on its agricultural use, the pesticide, a potent neurotoxin, is still used in shampoos and lotions in the U.S. to control head lice and scabies.
An insecticide is a pesticide used to kill insects. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind the increase in agricultural productivity in the 20th century. This is great for production, but those of us that eat the food have now ingested these toxic insecticides.
Hexane (n-Hexane) is a chemical made from crude oil. Most of the hexane used in the industry is mixed with similar chemicals in products known as solvents. The major use for solvents containing hexane is to extract vegetable oils from crops such as soybeans. Because cooking oils are processed with solvents containing hexane, very small amounts may be present in these products. They are also used as cleaning agents in the printing, textile, furniture and shoemaking industries. Certain kinds of special glues used in the roofing and the shoe and leather industries also contain hexane. Gasoline contains about 1-3% hexane, so it is released into the air at service stations and in automobile exhaust. Hexane is also present in rubber cement.
Herbicides, also commonly known as weed killers, are used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant hormones. Herbicides that are used to clear waste ground, industrial sites, railways and railway embankments are non-selective and kill all plant material that they come into contact with. Smaller quantities are used in forestry, pasture systems, and management of areas set aside as wildlife habitat.
Fungicides are extensively used in industry, agriculture, and the home and garden for a number of purposes. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. At the end of the season, profit is the greatest concern for farmers, so companies will use fungicides to protect seeds during shipment and storage. Fungicides are chemicals used to cure fungal, mold and slime diseases in gardens, lawns, and crops. They are also used in protection of carpet and fabrics in the home.
Formaldehyde is naturally produced in very small amounts in our bodies as a part of our normal, everyday metabolism and causes us no harm. It can also be found in the air that we breathe at home and at work, in the food we eat, and in some products that we put on our skin. A major source of formaldehyde that we breathe everyday is found in smog in the lower atmosphere. Automobile exhaust from cars without catalytic converters or those using oxygenated gasoline also contain formaldehyde.