November 14, 2005
Male fish with eggs in sewage off California coast
By Nichola Groom
LOS ANGELES (Reuters) - Researchers have found male fish
with eggs in their testes and female sex traits off the coast
of Southern California and believe that chemicals in sewage may
be the cause, an author of two studies said on Monday.
The two reports found the changes in fish such as English
sole and California halibut, both of which are bottom dwellers,
in water near where sewage is released, said Dan Schlenk, an
environmental scientist at the University of California,
High levels of estrogen, both natural and man-made
formulations used in birth control pills, are thought to cause
such abnormalities in fish. Estrogen makes its way into sewage
water and then the ocean through women's excretions.
Compounds that act like estrogen, found in certain
industrial chemicals, have also been blamed for such changes.
But in this instance, Schlenk said higher levels of the egg
protein were found in male fish in areas with lower levels of
estrogen and estrogen-like chemicals in the sediment. The cause
of the female characteristics, therefore, could be unknown
chemicals in the sediment, he said.
"We might have other players in this game," Schlenk said in
an interview on Monday. "We would guess they are primarily
coming from waste water."
He said the sewage contained natural and man-made chemicals
that was deposited in ocean sediment.
One of the culprits could be DDT, Schlenk said, a pesticide
banned in the United States in 1972 after it was shown to cause
reproductive damage to birds. DDT is no longer used but can
remain in the environment for a long time.
Los Angeles County's sewage outfall, Schlenk said, "has
probably one of the most contaminated DDT sites in North
America, and these responses are fairly consistent with that
kind of exposure."