Illustration by Carol Burkhart
Hormone Disruptors:
Cause for Precautionary ActionBy Peter Montague, Ph. D.
RACHEL's Health and Environmental Weekly
#665 - August 26, 1999After four years of study, the National Research Council
(NRC) of the National Academy of Sciences on August 4
published its report on hormone-disrupting chemicals in the
environment.[1] The report represents a consensus statement
by the NRC's Committee on Hormonally Active Agents in the
Environment, a committee made up of 16 scientists,[2]
including some who are closely aligned with the chemical
industry.The Committee had been asked by Congress and by U.S.
Environmental Protection Agency (EPA) to evaluate the
hazards posed by hormone-disrupting chemicals in the
environment. Dozens, perhaps hundreds, of common
industrial chemicals are known to interfere with hormones
under some conditions, so the stakes are high.Hormones are naturally-occurring chemicals that circulate at
very low levels in the blood stream of all vertebrate animals
including reptiles, amphibians, fish, birds and mammals.
(Vertebrates are animals with a backbone.) In all vertebrate
species, hormones act as chemical messengers and as
switches, turning on and off bodily systems that control
growth, development, learning and behavior. Hormones start
affecting every animal shortly after it begins life as a fertilized
egg. Hormones control growth and development prior to birth
or hatching, and hormones continue to influence behavior
throughout life. Hormones tell bears when to hibernate, tell
salmon when to return to their spawning grounds, and cause
women to menstruate every 28 days or so. Hormones
profoundly affect the nervous system, the reproductive system,
and the immune system. Naturally-occurring hormones are
also implicated in some forms of cancer, such as female breast
cancer which is widely believed to be linked to a woman's
lifetime exposure to estradiol (estrogen), the main female sex
hormone.[1,pg.197]Because of the importance of hormones in the life of all
vertebrates, industrial chemicals that can interfere with
hormones are exceedingly important from a public health
perspective. They also represent major embarrassments and
liabilities for the corporations that put such chemicals into
common use without adequate safety tests. The presence of
synthetic [human-created] hormone-disrupting chemicals in air,
water, sediments, soil and food also represents a major failure
of the U.S. Public Health Service and the U.S. Environmental
Protection Agency.Furthermore, if hormone-disrupting chemicals in the
environment are identified as an important problem, then
someone may be held responsible (at least in the court of public
opinion) and confidence in government and in the chemical
industry may drop below their present subterranean levels.
Therefore, there is powerful pressure from many parts of "the
Establishment" to deny the existence of this problem. NEW
YORK TIMES writer Gina Kolata has distinguished herself as
the main spokesperson for the deniers.[3]Despite the highly-charged nature of the subject, and despite
the presence of chemical industry representatives on the
committee, the NRC's consensus report is rather strong, as
indicated by these verbatim quotations:"Adverse reproductive and developmental effects have been
observed in human populations, wildlife, and laboratory
animals as a consequence of exposure to HAAs [hormonally
active agents]."[1,pg.3]"Most notable are the adverse reproductive and developmental
effects that have been observed in birds such as cormorants,
herrings gulls, Caspian terns, and bald eagles that feed on
contaminated fish, which have led to drastically lowered
reproductive success and population declines."[1,pg.9]"Laboratory studies using male and female rats, mice, and
guinea pigs, and female rhesus monkeys have shown that
exposure of these animals during development to a variety of
concentrations of certain HAAs (e.g., DDT, methoxychlor,
PCBs, dioxin, bisphenol A, octylphenol, butyl benzyl
phthalate (BBP), dibutyl phthalate (DBP), chlordecone, and
vinclozolin) can produce structural and functional abnormalities
of the reproductive tract."[1,pg.3]"There is evidence of suppression of the immune system by
exposure to organochlorines (predominantly PCBs) in birds in
the Great Lakes region. There is also evidence of suppression
of innate and acquired immune responses in seals fed fish from
the PCB-contaminated Baltic Sea. Such immunosuppression is
believed to be the reason for the increased incidences of
bacterial and viral infections in seals in similarly contaminated
waters."[1,pg.5]"Environmental HAAs [hormonally active agents] probably
have contributed to declines in some wildlife populations,
including fish and birds of the Great Lakes and juvenile
alligators of Lake Apopka [in Florida], and possibly to
diseases and deformities in mink in the United States, river
otters in Europe, and marine mammals in European
waters."[1,pg.6]"Synthetic HAAs [i.e., HAAs released by chemical
corporations] have been detected in all environmental media
[air, water, sediments, and soil], although concentrations of
some compounds, such as PCBs and DDT, have declined in
some regions, because their use has been discontinued in those
countries. However, those HAAs and others can persist in
some media, such as sediments, for years and can contaminate
areas far removed from the original site of contamination (e.g.,
via atmospheric transport)."[1,pg.7]"Human dietary intake of synthetic HAAs remains substantial,
even intake of HAAs that have not been used commercially for
many years. For example, a recent survey of the U.S. diet
found detectable residues of DDT in 16% of the food samples.
Human exposure is further demonstrated by concentrations of
DDT in the adipose (fatty) tissue. Over 95% of adipose tissue
samples taken from the U.S. population contained detectable
concentrations of some HAA. Although the concentrations
were found to be greatest in older individuals, even children
were not immune from exposure."[1,pg.76]"Concentrations of HAAs and other xenobiotics [chemicals
foreign to the body] have been measured in milk from humans
around the globe."[1,pg.82]"In the Michigan/Maternal Infant Cohort Study, Fein et al.
(1984) evaluated the birth size and gestational age of 242
infants and found that maternal consumption of fish and
concentrations of PCBs in cord serum [in blood in the
umbilical cord] were correlated with lowered birth weight,
shortened gestation [time in the womb], and smaller head
circumference. Lower weight was also observed in children
from this cohort at 4 yr [years] in a dose-dependent fashion
(Jacobson et al. 1990). Children with cord serum PCB levels
of 5.0 ng/mL [nanograms per milliliter] or more weighed 1.8
kg [4 pounds] less on average than the lowest exposed
children. Prenatal exposure was also associated with deficits in
neurologic development in followup studies of these children at
up to 11 yr [years]."[1,pg.125]"Elevated levels of the herbicide atrazine found in municipal
water supplies in Iowa were associated with excess rates of
cardiovascular, urogenital, and limb-reduction deficits [birth
defects]."[1,pg.130]"Studies with laboratory animals have shown that prenatal
exposure to some HAAs, such as methoxychlor, TCDD
[dioxin], and octylphenol and bisphenol A can reduce sperm
production."[1,pg.131]"A neurologic assessment of an aging population of Great
Lakes fisheaters is currently being conducted by Schantz et al.
(1996). In all, 104 fisheaters and 84 nonfisheaters, age 50 or
older, were enrolled in the study.... the fisheaters performed
more poorly on tests requiring cognitive flexibility, word
naming, auditory recall, and more complex motor task [sic]
compared with individuals who do not eat fish."[1,pg.173]"Long-term epidemiologic studies of cognitive and
neurobehavioral development have been conducted in
Michigan, New York, North Carolina, and the Netherlands on
children exposed pre- and postnatally to PCBs from maternal
consumption of contaminated fish or other food products.
Studies of cognitive development (i.e., short-term memory,
visual discrimination, and IQ scores) in Michigan show
consistent correlations between prenatal exposure to PCBs and
deficits at up to 11 yr [years]. Similarly, in the Netherlands,
lower cognitive scores were associated with prenatal exposure
when tested in 3.5-yr-old children."[1,pg.174]"Taken together, the results of animal and human studies
indicate that prenatal exposure to PCBs can affect neurologic
development."[1,pg.175]"It has been well documented that HAHs [halogenated aromatic
hydrocarbons] such as TCDD [dioxin], polychlorinated
dibenzofurans (PCDFs), and PCBs, affect immune response,
and they appear to affect all functional arms of the immune
system (innate immunity and host resistance, cell-mediated
immunity, and humoral immunity)."[1,pg.178]"There have only been a few studies of the effects of HAAs
[hormonally active agents] in humans, but the results of
laboratory and wildlife studies suggest that HAAs have the
potential to affect human immune functions."[1,pg.194]The NRC report concludes that, at present, the 70,000
industrial chemicals already in use cannot be tested to see if
they are hormone-disrupters or not, because the necessary tests
do not exist.[1,pg.414] Meanwhile between 1000 and 2000
new chemicals are being put into commercial use each year,
inadequately tested.Therefore, adequate knowledge of hormone-disrupting
chemicals lies many decades in the future, a kind of scientific
holy grail. What is not known about hormone-disrupting
chemicals is considerably larger than what is known and will
remain so for a long time to come.Yet the NRC report has amply documented, from studies of
wildlife, laboratory animals, and humans, that many industrial
chemicals, at levels already present in the environment, are
currently interfering with hormones, causing problems in
reproduction and development, the nervous system (including
diminished IQ and learning ability), and the immune system
(which protects us all from bacteria, viruses and cancers).
Harm is happening now.Thus hormone-disrupting chemicals meet the two tests
established by the precautionary principle: scientific
uncertainty, and a reasonable suspicion of harm. (See REHW
#657.)Therefore, while scientific study continues, decision-makers
have a duty to take precautionary action to prevent further harm
even though scientific certainty has not been established. As a
signatory to the Rio Declaration of 1992, the U.S. is legally
obligated to take precautionary action. But of course our
government will not act spontaneously merely to comply with
the law or do the right thing. To put it bluntly, our government
will only respond if popular pressure is sufficient to offset
inertia, the forces of denial, and election-time bribery from the
chemical industry. Building that pressure is up to us.++=====
--Peter Montague(National Writers Union, UAW Local
1981/AFL-CIO)=====
[1] Ernst Knobil and others, HORMONALLY ACTIVE
AGENTS IN THE ENVIRONMENT (Washington, D.C.:
National Academy Press, July 1999). ISBN 0-309-06419-8.[2] Members of the NRC Committee on Hormonally Active
Agents in the Environment included: Ernst Knobil (chair), The
University of Texas-Houston Medical School, Houston, Tex.;
Howard A. Bern, University of California, Berkeley, Cal.;
Joanna Burger, Rutgers University, Piscataway, N.J.; D.
Michael Fry, University of California, Davis, Calif.; John P.
Giesy, Michigan State University, East Lansing, Mich.; Jack
Gorski, University of Wisconsin, Madison, Wis.; Charles J.
Grossman, Department of Veterans Affairs Medical Center,
Cincinnati, Ohio and Xavier University, Cincinnati, Ohio;
Louis J. Guillette, Jr., University of Florida, Gainesville, Fla.;
Barbara S. Hulka, University of North Carolina, Chapel Hill,
N.C.; James C. Lamb IV, Jellinek, Schwartz & Connolly,
Arlington, Va.; Leslie A. Real, Emory University, Atlanta,
Ga.; Stephen M. Safe, Texas A&M University, College
Station, Tex.; Ana M. Soto, Tufts University, Boston, Mass.;
John J. Stegeman, Woods Hole Oceanographic Institution,
Woods Hole, Mass.; Shanna Helen Swann, University of
Missouri, Columbia, Mo.; Frederick S. vom Saal, University
of Missouri, Columbia, Mo.[3] See REHW #486, #487. And see Gina Kolata, "Study
Inconclusive on Chemicals' Effects," NEW YORK TIMES
August 4, 1999, pg. 16. For less biased coverage of the NRC
report, see J. Fialka, "More Clinical Tests of Humans Exposed
to Chemicals are Urged in a US Study," WALL STREET
JOURNAL August 4, 1999, pg. unknown, and Marla Cone,
"Hormone Study Finds No Firm Answers," LOS ANGELES
TIMES August 4, 1999, pg. 3.Descriptor terms: hormone disrupters; endocrine disrupters;
wildlife; fish; birds; chemicals and health; national research
council;
