Environmental Engineering Reference
In-Depth Information
What effects do they have?
Dioxins, like chlorinated hydrocarbons, are persistent in sedi-
ments of marine systems, where their effects continue long
after they are banned. They also biomagnify through food
webs, and long-term effects are generally not well known.
Fish embryos are highly sensitive and develop a syndrome
that prevents their normal development. Ironically, pollution
can have some indirect positive effects on crabs. Blue crabs
in industrialized northern New Jersey accumulate such high
concentrations of dioxin that fishing for them is banned out
of concern for human safety. Consequently, their population
is growing and individuals grow larger than in clean areas
where they are still fished for.
Can PCBs or dioxins be a risk to people who eat seafood?
People who ingest fish or other seafood with high levels of
PCBs or dioxins, such as in Newark Bay may be exposed to high
concentrations. Toxic fish can be found in many other urban-
ized estuaries. Fish from the Columbia River near Portland,
Oregon have PCB levels thousands of times above what the
EPA considers safe for unrestricted consumption. Many riv-
ers in the Columbia Basin, including sections of the mainstem
Columbia River, have fish advisories that warn people not to
consume certain types of fish, but people do not always heed
the signs.
Maternal exposure to PCBs and dioxins was associated with
an increased risk of asthma and more frequent upper respira-
tory tract infections in babies. Furthermore, maternal expo-
sure to PCBs and dioxins was also associated with reduced
antibody response to a measles vaccine. Thus, prenatal dietary
exposure to PCBs and dioxins may increase the risk of asthma
and susceptibility to infectious diseases in early childhood.
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