Environmental Engineering Reference
In-Depth Information
concern are chemicals with the ability to cause embryonic
malformations (teratogenesis), genetic alterations (mutagen-
esis), endocrine disruption, or cancer (carcinogenesis).
Chlorinated hydrocarbons such as DDT, which bio-
magnify and take a long time to break down, can prevent
marine larvae from developing normally, reduce respiration
and metabolism, impair growth, and impair salt and water
balance. Organophosphate and carbamate pesticides, the
“second-generation” pesticides, still have harmful effects. The
insecticide Sevin® (carbaryl), used to control ghost shrimp in
Pacific oyster beds, is also very toxic to commercially impor-
tant Dungeness crabs. Their larvae are highly sensitive to other
insecticides and fungicides as well, as reviewed by Feldman
and colleagues. Malathion slows down larval development by
delaying molting; Abate® affects behavior, making animals
more susceptible to predators.
What is endocrine disruption?
There is particular concern about chemicals that, even at very
low concentrations, alter the development and functioning of
the endocrine system and affect development. These chemi-
cals are called endocrine disruptors, a term coined by Theo
Colborn. Known endocrine disruptors include DDT and other
chlorinated hydrocarbon pesticides, certain PCBs and dioxins,
some metals, plastics, detergents, and flame retardants. These
chemicals have different mechanisms of action, depending on
the life stage at which the animal is exposed, and they may
have effects that are not seen for years after exposure. The most
commonly studied chemicals are those affecting reproduc-
tion, and they may mimic natural hormones or inhibit them
so that reproduction may be disrupted, intersex offspring may
be produced, and metamorphosis may be delayed, accelerated,
or prevented.
The first documented examples of endocrine disruption in
the estuarine environment were in dog whelks and mud snails
Search WWH ::
Custom Search