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#545 - Fish Sex Hormones, 07-May-1997

In the early 1990s, British researchers at Brunel University in
Uxbridge noticed that male fish living downstream from a sewage
treatment plant near London had testes laden with eggs. The male fish
had become hermaphrodites (also known as intersex --having the sexual
characteristics of both males and females).[1]

Subsequently, when caged trout were placed downstream from sewage
treatment plants in several British rivers, the males were discovered
to have elevated levels of a protein called vitellogenin in their
blood.[2] Vitellogenin is the protein responsible for making egg yolks
in female fish. Ordinarily, little, if any, vitellogenin is found in
the blood of male fish.[3] Male fish have a gene which, if triggered by
estrogen (female sex hormone) can produce vitellogenin, but male fish
ordinarily lack sufficient estrogen to trigger the vitellogenin-making

British researchers John Sumpter and Susan Jobling then reported that
male trout caged downstream from sewage treatment plants throughout
England showed the telltale vitellogenin in their blood, indicating
that something coming out of sewage treatment plants was having an
estrogenic effect on the fish.[3] Every sewage treatment plant in
England caused the estrogenic effect. It took only 2 to 3 weeks for the
vitellogenin to begin to appear in the blood of caged trout.

The British researchers tested a few common industrial chemicals to see
if they could stimulate the production of vitellogenin in male trout
under laboratory conditions. They found that several common industrial
chemicals could do the trick, and could do it in a dose-dependent way:
the more chemical the male trout were exposed to, the more vitellogenin
they produced.

Chemicals found to induce vitellogenin in males included octylphenol
and nonylphenol (both alkyl phenols, which are commonly used in
detergents, toiletries, lubricants and spermicides); bisphenol-A (the
building block of polycarbonate plastics); o,p'-DDT (the common
pesticide, banned in the U.S. but still widely used in some
industrializing parts of the world); and Arachlor 1221 (one of the 209
varieties of PCBs, or polychlorinated biphenyls --common industrial
chemicals now banned in the U.S. but still widely found in the

These same researchers then tested mixtures of these chemicals. They
showed that mixtures were more powerful at producing vitellogenin than
any of the individual chemicals alone. They thus demonstrated
conclusively under laboratory conditions that these chemicals, at
levels commonly found in British rivers, could induce vitellogenin in
male fish.[3]

They found that the chemicals tended to bioconcentrate in the flesh of
the fish; in other words, as time passed, the concentration of the
chemicals increased. Thus even low concentration of a weakly estrogenic
chemical could eventually build up to a level that induced vitellogenin
production in male fish.

Sumpter and Jobling then asked themselves whether the estrogen effects
of these chemicals would be limited to one species. After reviewing
available literature and conducting a limited number of experiments
themselves, they concluded that, "Most evidence supports the idea that
if a chemical is estrogenic in one species, it will be in all others."

Sumpter and Jobling then asked themselves what are the consequences for
aquatic organisms (such as fish) living in a "sea of estrogen." The
answer, they said, is easy: we do not know. The possible effects are
"almost endless," they said, because of the large number of roles
played by natural estrogens. They did pinpoint reproduction as the
process mostly likely to be disrupted and they said it is "probable
that these changes [production of vitellogenin in males] from the
normal pattern will adversely affect reproduction."

In late 1996, U.S. researchers published studies confirming that up-to-
date sewage treatment plants in the U.S. can cause the same effects in
fish living downstream.[4] Scientists with U.S. Environmental
Protection Agency, Tulane University, the University of Florida, and
the Minnesota Department of Natural Resources examined male carp from
five locations in the Mississippi River downstream from the Minneapolis
sewage treatment plant, and from a tributary, the Minnesota River,
which receives heavy agricultural runoff. For comparison, they captured
male carp from the St. Croix River, which is classified as a National
Wild and Scenic River and is not heavily contaminated.

They found that carp living near the Minneapolis sewage treatment plant
showed "a pronounced estrogenic effect," namely the production of
vitellogenin and reduced levels of testosterone (male sex hormone).
Carp from the pesticide-contaminated Minnesota River had sharply-
reduced testosterone levels but showed no vitellogenin effect. Carp
from the St. Croix River were normal.[4]

The U.S. Geological Survey (USGS) reported in April that industrial
contaminants in many U.S. rivers and lakes seem to be affecting the
levels of sex hormones in fish throughout the U.S.[5] "The finding of a
correlation between hormone levels and contaminant levels in fish from
such diverse locations is both a cause for concern and a call for
further investigation," said Dr. Gordon Eaton, director of USGS,
releasing the study.

The study was conducted by USGS in collaboration with the National
Biological Service (now the Biological Resources Division within USGS)
and the University of Florida.

The study analyzed 647 carp collected from 25 streams (including 11
major rivers, such as the Mississippi, the Columbia, and the Hudson) in
13 states and the District of Columbia. The streams were selected based
on the kind of area they drain; the goal was to select streams that
represented environmental settings that are typical of major regions of
the nation.

The fish were tested for estrogen and testosterone (female and male sex
hormones) in their blood. All fish have both estrogen and testosterone
in their blood; however, the ratio of the two hormones varies between
females and males. The ratio is important. As Bette Hileman has said,
"In the developing fetus of both humans and animals, a specific ratio
of estrogen to androgens (male hormones [such as testosterone]) is
necessary for sexual differentiation [the process of developing into a
male or a female]. If the ratio is perturbed, the offspring may be born
with two sets of partially developed sexual organs (intersex) or with a
single set that is incomplete or improperly developed."[6]

In addition to testing for the estrogen/testosterone ratio, USGS also
tested carp for organochlorine pesticides and PCBs [polychlorinated
biphenyls] in their blood. Organochlorine pesticides (such as DDT,
aldrin, and dieldrin) and PCBs are known to affect hormone levels in

Furthermore, at sites where fish were captured, USGS took samples of
sediments and analyzed them for total phenols, phthalates, and
polycyclic aromatic hydrocarbons (PAHs); all three of these classes of
chemicals are known to affect hormones in wildlife. (Phenols, as we saw
above, have many uses; phthalates are widely used in plastics; PAHs are
produced by combustion of gasoline, oil, coal, garbage, medical and
hazardous wastes, and by metal smelters.)

USGS concluded that its most significant findings included these:

** At half the locations tested, one or more male carp were producing
vitellogenin at low levels.

** In both male and female carp, the estrogen/testosterone ratio was
most disturbed by dissolved pesticides in water. The site with the
highest level of dissolved pesticides (the Platte River at Louisville,
Nebraska) had the lowest estrogen/testosterone ratio.

** For both male and female carp, the presence of phenols was
associated with reduced levels of both estrogen and testosterone.

USGS researchers said their study was too crude to actually determine
that specific contaminants were causing specific changes in the sex
hormones of fish. However, as noted above, the agency said the findings
were "cause for concern."

It is apparent that many waters of the U.S. contain substances that can
alter the sex hormones of fish. The implications are clear: whatever is
altering the sex hormones of fish originates on the land, and is caused
by human activities. Because estrogen and testosterone perform many of
the same functions in fish, birds, amphibians, reptiles, and mammals
(including humans), mans), there is no reason to believe (or even hope)
that humans are exempt from the chemicals that are altering the fish.

One might think --based on common sense and simple prudence --that it
would be appropriate to begin controlling hormone-disrupting chemicals.
Unfortunately, U.S. EPA has adopted the position of the Chemical
Manufacturers Association (CMA), which is this: merely altering the sex
hormones of fish OR EVEN HUMANS is not sufficient reason to initiate
controls on known hormone-disrupting chemicals. It is up to us (the
public) to prove that altering our sex hormones is bad for us (causing
"adverse effects" is how EPA expresses it).[7] It will take many
decades, perhaps centuries, to gather the necessary evidence to
convince the likes of the CMA (the permanent government[8]) that an
"adverse effect" has occurred. Think of the history of tobacco. In the
meantime, with EPA's blessing, the chemical industry will continue to
do its business in our water.

--Peter Montague (National Writers Union, UAW Local 1981/AFL-CIO)


[1] Jocelyn Kaiser, "Scientists Angle for Answers," SCIENCE Vol. 274
(December 13, 1996), pgs. 1837-1838.

[2] John P. Sumpter, "Feminized responses in fish to environmental
estrogens," TOXICOLOGY LETTERS Vol. 82-83 (Dec., 1995), pgs. 737-742.
See also: C. Purdom and others, "Estrogenic Effects of Effluents From
Sewage Treatment Works" CHEMISTRY AND ECOLOGY Vol. 8 (1994), pgs. 275-
285. And see: S. Jobling and J. Sumpter "Detergent components in sewage
effluent are weakly oestrogenic to fish: an IN VITRO study using
Vol. 27 (1993), pgs. 361-372.

[3] John P. Sumpter and Susan Jobling, "Vitellogenesis as a Biomarker
for Estrogenic Contamination of the Aquatic Environment," ENVIRONMENTAL
HEALTH PERSPECTIVES Vol. 103, Supplement 7 (October, 1995), pgs. 173-

[4] Leroy C. Folmar and others, "Vitellogenin Induction and Reduced
Serum Testosterone Concentrations in Feral Male Carp (CYPRINUS CARPIO)
Captured Near a Major Metropolitan Sewage Treatment Plant,"
ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 104, No. 10 (October 1996), pgs.

[5] Steven L. Goodbred and others, RECONNAISSANCE OF 17BETA-ESTRADIOL,
ENDOCRINE DISRUPTION [U.S. Geological Survey Open-File Report 96-627]
(Denver, Colorado: U.S. Geological Survey, 1997). Available for $7.75
(prepaid) from: U.S. Geological Survey, Branch of Information Services,
Box 25286, Denver federal center, Denver, CO 80225. The report is also
available on the world wide web at: http://water.wr.usgs.gov.

[6] Bette Hileman, "Environmental Estrogens Linked to Reproductive
Abnormalities, Cancer," C&EN [CHEMICAL & ENGINEERING NEWS] January 31,
1994, pgs. 19-23.

[7] EPA's position is clearly stated in Thomas M. Crisp and others,
ASSESSMENT AND ANALYSIS [EPA/630/R-96/012] (Washington, D.C.:
Environmental Protection Agency, Risk Assessment Forum, February,
1997). Available via the internet:
http://www.epa.gov/ORD/WebPubs/endocrine/ .

[8] See REHW #517.


To celebrate Barry Commoner's 80th birthday, a group of his friends and
colleagues have organized a day-long symposium in New York City May
30th, titled "Barry Commoner's Contribution to the Environmmental
Movement: Science and Social Action." The purpose is to draw lessons
from the past and create momentum for a strong future for the
environmental movement. The public is invited. It is free. Speakers
will include Ralph Nader, Tony Mazzocchi, John O'Connor, Peter Bahouth
(invited), Judi Enck, Dan Kohl, Virginia Brodine, Eric Goldstein,
Vernice Miller, Taghi Farver, Giovanni Berliguer, Chicco Testa. David
Cleverly, Peter Montague, and others. Barry himself will end the day
with a talk titled, "What Is Yet To Be Done." The symposium starts at 9
am May 30th in the Great Hall at Cooper Union (7 East 7th Street
between 3rd and 4th Avenues). Contact: Sharon Clark Peyser, CBNS,
Queens College, Flushing, NY 11367; telephone (718) 670-4180; fax (718)
670-4189. Hope to see you there! --P.M.

Descriptor terms: endocrine disruptors; fish; wildlife; trout; carp;
studies; usgs; epa; mississippi river; water pollution; hudson river;
columbia river; great britain; sexual development; hermaphroditism;
sewage treatment; vitellogenin; estrogen; testosterone; androgens;
alkyl phenols; nonylphenol; octylphenol; ddt; bisphenol-a; pcbs; barry