Mercury and Fish
how does mercury get into fish in rivers. what is the
ecological process involved which could produce toxic levels of mercury in fish
and eventually get into humans?
Nowadays mercury or its compounds are used at a high
scale in many industries as the manufacture of chemicals,
paints, household itens, pesticides and fungicides. These
products can contaminate humans (and mamals) by direct
contact, ingestion or inhalation. Besides the air can become
contaminated also, and since mercury compounds produce
harmful effects in body tissues and functions, that pollution
is very dangerous.
Now for your question: Efluent wastes containing mercury
in various forms sometimes are dropped in sea water or in
rivers or lakes. There the mercury may be converted by
bacteria, that are in the muddy sediments, into organic
mercurial compounds particularly the highly toxic alkyl
mercurials ( methyl and di-methyl mercury), which may
in turn be concentrated by the fishes and other aquatic
forms of life that are used as food by men.
The fishes dont seem to be affected but they are able to
concentrate mercury in high poisoning levels, and if
human beings, mamals or birds eat these containing
mercury fishes, algae, crabs or oysters they will be
contaminated and poisoned.
By the middle of last century that danger was not
quite known and some mass disaster killed many
people poisoned by that way.
Hopefully now ecology has its turn and laws or
recommendations all over the world prevents
(or try to prevent) the careless disposition of these
Thanks for asking NEWTON!
(Dr. Mabel Rodrigues)
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Update: June 2012