CAS Number: 1336-36-3. Any of several compounds that are produced
by replacing hydrogen atoms in biphenyl with chlorine. They have
various industrial applications, and are poisonous environmental
pollutants which tend to accumulate in animal tissues. Molecular
weight = 291.98 - 360.86 g/mol.
Glossary Term Acronym
PCBs
Glossary Term Category
Glossary Term Show In Main
Yes
Glossary Term Ext Def
Polychlorinated biphenyls (PCBs) are a group of chemicals that
contain 209 individual compounds (known as congeners) with
varying harmful effects. Information on specific congener
toxicity is very limited. Most toxicity testing has been done
on specific commercial mixtures; however, PCB mixtures found in
the environment will differ in composition from the commercial
mixtures because of partitioning, biotransformation, and
bioaccumulation. The U.S. Environmental Protection Agency (EPA)
treats all PCBs as being potentially hazardous based on results
from some formulations. However, this can have large
uncertainty for any given mixture situation.
PCBs are no longer produced or used in the United States today;
the major source of exposure to PCBs today is the redistribution
of PCBs already present in soil and water. Chronic (long-term)
exposure to some PCB formulations by inhalation in humans
results in respiratory tract symptoms, gastrointestinal effects,
mild liver effects, and effects on the skin and eyes such as
chloracne, skin rashes, and eye irritation. Epidemiological
studies indicate an association between dietary PCB exposures
and developmental effects. Human studies provide inconclusive,
yet suggestive, evidence of an association between PCBs exposure
and cancer. Animal studies have reported an increase in liver
tumors in rats and mice exposed orally to all tested PCB
formulations. EPA has classified PCBs as a Group B2, probable
human carcinogen.