Environmental Engineering Reference
In-Depth Information
advise the public to check for local advisories on fish caught
from local waters that may be more greatly affected by pollu-
tion sources. These guidelines are not meant for adult men or
for woman past childbearing age, but individuals concerned
with exposure to Hg should follow them as well. The best solu-
tion may be to refrain from eating the large fish species often
and to focus on eating smaller fish that do not have high lev-
els of Hg. Cod, salmon, haddock, herring, and sardines, for
example, do not have high levels.
Can metal pollution be found in calcium supplements derived
from oyster shells?
Calcium is needed for prevention or treatment of osteoporo-
sis, but some calcium supplements have been found to have
elevated metals. Lead (Pb) has been found in some calcium
carbonate supplements labeled as oyster shell. Pb is a neuro-
toxin that affects the brain and nervous system. The level of
contamination has decreased recently, but still may present a
health risk. Calcium supplements rarely list their Pb content,
which should be less than 2 parts per million. California scien-
tists analyzed the Pb in a variety of calcium supplements and
found that two-thirds of them failed to meet the California's
criteria for acceptable Pb levels in consumer products, which
are stricter than the national criteria. Alternatives to so-called
natural calcium supplements are plain calcium carbonate pills
or calcium citrate.
What problems can result from eating seafood containing
organic contaminants?
Persistant PCBs and related chemicals may remain a problem
for quite some time. Because they become attached to par-
ticles in the water, they settle out in the sediments. When
bottom dwelling animals feed, they ingest the contaminated
sediments and pass them up the food chain, where they
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