PCBs

Polychlorinated biphenyls (PCBs) are a class of industrial chemicals
manufactured from 1930 to 1977 for use in electrical and hydraulic products.
PCBs are still present in the environment because of their persistence and
accumulation at higher concentrations up the food chain (bioaccumulation), but
have been showing a trend of decreasing concentrations (<a href="http://
www.epa.gov/opptintr/pbt/pcbs.htm">EPA Persistent
Bioaccumulative and Toxic (PBT) Chemical Program</a> ). PCBs are a concern
to human and ecological health,
because they can affect neurodevelopment and reproduction and are classified
by the U. S. Environmental Protection Agency (EPA) as probable human
carcinogens. In Minnesota, PCBs are assessed in fish and in some surface
waters. Information on Fish Consumption Advice can be found at the
<a href="http://www.health.state.mn.us/divs/eh/fish/index.html">Minnesota
Department of Health site</a>. Minnesota’s Water Quality Standards for PCBs
are based
on the total concentration of PCBs and are measured in nanograms (one
billionth of a gram) per liter (ng/L) to picograms (one trillionth of a gram) per
liter (pg/L) in water. In fish, PCBs are measured in units of nanogram (one
billionth of a gram) per gram (ng/g).