PCBs

<B>P</B>oly<B>C</B>hlorinated <B>B</B>iphenyls, a mixture of up to 209 chlorinated chemicals.

Although PCBs are no longer produced in the US where they were once known under the trade name Aroclor, PCBs are still found in the environment.

A number of adverse health effects have associated with exposure to PCBs.

PCBs have been used as coolants and lubricants in transformers, capacitors, and other electrical equipment because they don't burn easily and are good insulators.

Products made before 1977 that may contain PCBs include old fluorescent lighting fixtures and electrical devices containing PCB capacitors, and old microscope and hydraulic oils.

The manufacture of PCBs was stopped in the US in 1977 because of evidence they build up in the environment and can cause harmful health effects.

PCBs enter the air, water, and soil during their manufacture, use, and disposal; from accidental spills and leaks during their transport; and from leaks or fires in products containing PCBs.

PCBs can still be released to the environment from hazardous waste sites; illegal or improper disposal of industrial wastes and consumer products; leaks from old electrical transformers containing PCBs; and burning of some wastes in incinerators.

PCBs bind strongly to soil.

They do not readily break down and may persist in the environment for long periods of time.

PCBs can also travel long distances in the air and be deposited in areas far away from where they were released.

In water, a small amount of PCBs may remain dissolved, but most stick to organic particles and bottom sediments.

PCBs are taken up by small organisms and fish in water.

They are also taken up by other animals that eat these aquatic animals as food.

PCBs accumulate in fish and marine mammals, reaching levels that may be many thousands of times higher than in water.

Farmed salmon contain higher levels of PCBs than wild ones.

This reflects the fact that farmed salmon may be fed ground-up smaller fish that have themselves been contaminated in polluted ocean waters.

The most commonly observed health effects in people exposed to large amounts of PCBs are skin conditions such as acne and rashes.

Studies in exposed workers have shown changes in blood indicating liver damage.

Some studies of workers indicate that PCBs are associated with certain kinds of cancer in humans, such as cancer of the liver and biliary tract.

There is transplacental transfer of PCBs.

Women exposed to relatively high levels of PCBs during pregnancy had babies who tended to weigh less than normal.

Babies born to women who ate PCB-contaminated fish also showed abnormal responses in tests of infant behavior.

Some of these behaviors, such as problems with motor skills and a decrease in short-term memory, lasted for several years.

Other studies suggest that the immune system was affected in children born to and nursed by mothers exposed to increased levels of PCBs.

Men who had been exposed before age 20 to PCB-laced cooking oil in Taiwan were found to be 35% less likely to have a male child.

The deficit in male children indicates that PCBs have an important effect omn male reproduction.

There are no reports of structural birth defects caused by parental exposure to PCBs.

The Department of Health and Human Services (HHS) has concluded that PCBs may 'reasonably be anticipated' to be carcinogens (to be agents that cause cancer).

The Environmental Protection Agency (EPA) and the International Agency for Research on Cancer have also determined that PCBs are probably carcinogenic to humans.

The EPA has set a limit of 0.0005 milligrams of PCBs per liter of drinking water (0.0005 mg/L).

Discharges, spills or accidental releases of 1 pound or more of PCBs into the environment must be reported to the EPA.

The FDA requires that infant foods, eggs, milk and other dairy products, fish and shellfish, poultry and red meat contain no more than 0.2-3 parts of PCBs per million parts (0.2-3 ppm) of food.