Dioxins
are highly toxic chemicals that are formed during the combustion
(burning) of materials and the manufacture of certain
chlorinated chemicals. Dioxins can be emitted from a variety
of sources including cars and trucks, waste incineration,
chemical manufacturing plants and other industrial sources
that burn fuel. Dioxins can also be emitted from
other sources such as forest fires and residential wood
burning. These toxic chemicals are inhaled directly or can
contaminate vegetation and be eaten by animals and humans.
Dioxins then accumulate in the body. The Air Resources Board (ARB)
has identified dioxins as a toxic air contaminant (TAC)
and they are listed as hazardous air pollutants by the
United States Environmental Protection Agency (U.S. EPA).
Many studies, including U.S. EPA's
Reassessment of Dioxins, have shown that dioxins can
cause cancer and other health problems including birth defects and liver damage.