OCEAN 320 Chapter Unit 1C: Unit 1C PCB Threat to Whales, Dolphins & Porpoises
Unit 1C: Chemical Pollution in the Ocean
PCBs and the Threat They Pose to Marine Life
• PCB’s: group of chemical compounds that have been available commercially since
1930s; do not occur naturally, are created solely through industrial processes
o were incorporated into many different products, including flame-resistant
coatings, paints, some types of paper, drilling equipment and fluorescent lighting
• threaten marine life
o have entered and do enter oceans in large quantities and do not break down on
their own
o are toxic and potentially lethal if absorbed in high quanitites
• non-lethal but still dangerous threats
o cause many problems, and therefore less is acceptable to be consumed
o 1.5 mg/kg is acceptable in cow’s milk
o disruption of reproductive and immune systems
o disruption of hormones-causes MANY problems
▪ Decreased fertility in birds, fish, shellfish and mammals
▪ Decreased hatching success in birds, fish and turtles
▪ Deformities in birds, fish and turtles
▪ Abnormal behavior in birds
▪ Feminization of male fish, birds and mammals (and the reverse in female
birds and fish)
▪ Weakened immune systems in birds and mammals
• Threat to whales, dolphins, porpoises
o At the top of the food chains, so they absorb the highest concentrations of PCBs
through accumulative quantities; some contain levels so high that the whales
themselves could be considered toxic waste under US law
o store PCBs from their food in blubber, then release high levels of PCBs into the
body when blubber is broken down in times of stress/when food is scarce; floods
their bodies with chemicals and stresses their bodies even worse
o make few of the enzymes that many other species of animals use to break down
dangerous chemicals such as PCBs; they cannot metabolize these chemicals the
same way other organisms can try to
o females pass a large and potentially fatal amount of PCBs to their calves through
both womb and milk
▪ this releases many of the PCB’s from the mother, effectively lightening
the burden of the chemicals on her body, but transfers them in alarming
(and sometimes fatal) dosages to the calves
• belugas
o population of 500 belugas off the (highly contaminated) Gulf and estuary of St
Lawrence off eastern coast of Canada
▪ has declined dramatically over last century
▪ have much higher concentrations of PCBs than those in arctic
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