Polychlorinated Biphenyls
(PCBs)
WHAT ARE PCBs
same properties that made PCBs so useful in industrial applications such as their stability and non-flammability, is also the reason they stay in environment for a very long time
colorless and odorless chemicals that were once widely used in electrical equipment such as transformers and capacitors before their production was banned in 1976
STRUCTURE OF PCBs
a synthetic organic chemical compound of chlorine attached to biphenyl, which is a molecule composed of two benzene rings.
FACTS
PCBs enter the food chain and become progressively concentrated from small organisms to larger fish and mammals
Most PCBs that have entered the environment end up in rivers, lakes, and ultimately the ocean
Many large, fatty fish like lake trout, carp, and Chinook salmon have been found to contain very high concentrations of PCBs.
products that contain PCBs are still often being disposed of improperly.
some fish may contain high enough levels that they are considered unsafe for human consumption, or with concentration levels where consumption should be restricted.
About half has entered the environment through discharges to the air, land, and water.
APPLICATIONS
stabilizing additives in flexible PVC coatings of electrical wiring & electronic components
~pesticide extenders
~cutting oils
plasticizers in paints & cements
reactive flame retardants, lubricating oils, hydraulic fluids, & sealants
coolants & insulating fluids for the transformers & capacitors, such as those used in old fluorescent light ballasts
wood floor finishes (such as Fabulon & other products of Halowax in the U.S.) paints
~waterproofing compounds, casting agents, vacuum pump fluids,
~fixatives in microscopy, surgical implants
EFFECTS OF PCBs
PCBs can contribute to a variety of human health problems, including :
~developmental problems in children
~liver damage
~various forms of cancer
Women of childbearing age, especially those pregnant or nursing, are advised to minimize risk of exposure by avoiding eating fish from waters known to contain PCB contaminants
health risks are highest in the fetus or nursing infant, especially if the mother is or has been exposed to PCBs.
How is the public protected from consuming contaminated fish?
Currently, the EPA's Office of Water health screening level for all PCBs in fish tissue is 0.01 ppm.
At this level in fish tissue, we would expect one additional cancer due to PCBs in a population of 100,000, assuming an adult (70 kg) eats 1 meal/month (6.5 g/day) over a lifetime
The EPA sets standards based exclusively on protection of public health, whereas the FDA has to consider many factors including economics.
The FDA periodically tests fish typically sold in markets to determine the levels of PCBs and other contaminants and when necessary, confiscates contaminated products.
In 1984, the FDA lowered the allowable level of PCBs from
5.0 ppm for edible fish
2.0 ppm for fish and shellfish
FDA is responsible for setting the standards for tolerable levels of PCBs in fish sold via interstate commerce.
Guidelines to reduce PCBs in fish
Slice off fat belly meat along the bottom of fish.
Cut away the dark, V-shaped wedge of fat located along the lateral line on each side of the fish.
Cut away the dark fat on top of fish along its backbone.
Do not eat raw fish.
Remove all skin.
Bake or broil skinned, trim fish on a rack or grill so fat drips off and discard drippings.
Throw away internal organs, skin, head and tail.
Thoroughly clean and trim fish when making stew or soup