[Pharmwaste] UCR scientist finds key to sex alterations in fish
Laurie.Tenace at dep.state.fl.us
Tue Nov 15 13:39:40 EST 2005
UCR scientist finds key to sex alterations in fish
07:07 AM PST on Tuesday, November 15, 2005
By JENNIFER BOWLES / The Press-Enterprise
Sunscreen may be good for people, but bad for male fish off the Southern
Sunscreen washed off in the shower or flushed down the sink appears to
sexually alter male fish, a UC Riverside scientist has found, raising
concerns that sewage contains chemicals that can affect an animal's
Dan Schlenk, in some of the first studies examining how ocean species react
to hormone-disrupting compounds, found that a chemical in the widely used
skin product is partly to blame for some male fish developing ovary tissue
and female egg protein.
Illustration: Click to enlarge
Oxybenzone -- which protects skin from ultraviolet light and mimics the
chemical makeup of the female hormone estrogen -- survives the
sewage-treatment process and settles onto the ocean floor at sewage outfalls,
where bottom-dwelling fish like sole and turbot consume it.
So far, Schlenk said, the presence of the mixed-gender fish isn't affecting
the species' ability to reproduce. The fish ratio is about 60 percent male
and 40 percent female, which is about normal. Previous studies by other
scientists have shown that mixed-gender fish were infertile.
"It doesn't appear to be that big of a deal here," Schlenk, a professor of
aquatic eco-toxicology, said Monday in a telephone interview. He is in
Baltimore this week presenting his studies at the Society of Environmental
Toxicology and Chemistry.
Oxybenzone, Schlenk said, is similar in chemical structure to estrogen, the
female sex hormone. Women send estrogen -- naturally occurring and from
birth-control pills -- into the sewage through their urine. But Schlenk said
natural estrogen for unknown reasons doesn't appear to feminize male fish.
"The only compound we can exclusively identify is oxybenzone," Schlenk said.
Schlenk said that while oxybenzone most likely plays a contributing role, it
might not be a primary player. Off the Palos Verdes Peninsula, experts
believe the pesticide DDT dumped long ago appears to be feminizing fish in
that area, he said.
Estrogenic substances such as oxybenzone discharge into the ocean two to
seven miles offshore and aren't considered a threat to beachgoers. State
officials, however, have long advised against eating bottom-feeding fish
caught between Malibu and Newport Beach because of health risks from chemical
At the Huntington Beach outfall more than three miles off the coast, Mary Ann
Irwin, a UCR graduate working with Schlenk, found that 47 of 72 male turbot
and sole produced a female egg protein, much higher than fish a few miles to
"Obviously, it's not supposed to be there," Schlenk said.
And in a similar study conducted by the Southern California Coastal Water
Research Project, 11 of 64 fish caught between Santa Monica and Huntington
Beach had ovary tissue in their testes.
The group's director, Steve Weisberg, said the research is in its early
stages and more studies need to be conducted on more fish species to
determine the significance of the findings.
In Schlenk's UCR lab, he exposed halibut for one week to sediment from
outfalls off Huntington Beach, the Palos Verdes Peninsula and San Diego. All
the males grew small amounts of female egg protein, he said.
Schlenk said his studies were funded primarily through the University of
California Marine Council and its coastal environmental quality initiative.
Orange County Sanitation District allowed Schlenk and Irwin on its boats so
they could collect fish specimens. More studies are planned, he said.
The studies looked at sewage outfall from Los Angeles and Orange counties,
which is about one billion gallons a day. While most sewage from the Inland
area flows into the Santa Ana River, most of it is collected by the Orange
County Water District, which filters it into groundwater basins and pumps it
back out for drinking water.
Shlenk said that while he found similar estrogenic compounds in the Santa Ana
River by Prado Dam near Corona, they haven't shown up in the well water that
is sent to Orange County residents.
Laurie J. Tenace
Florida Department of Environmental Protection
2600 Blair Stone Road, MS 4555
Tallahassee, Florida 32399-2400
PH: (850) 245-8759
FAX: (850) 245-8811
Laurie.Tenace at dep.state.fl.us
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