Published
in the Waterloo-Cedar Falls Courier, Sunday, May 13, 2001
Iowans
losing battle against chemical dependency in common household items
By Jeffrey Weld, Dept. of Biology
Iowa's biggest gamble has nothing to do with casinos or the
Lottery. We're all players in a bet that chemical technology at work
in our homes, offices, and farm fields, is doing us no harm. The industry-sponsored
mantra "Better Living Through Chemistry" that ushered in a synthetics
revolution is turning out, thanks to recent advances in biological risk
assessment, to be naive and short sighted. Widely used chemicals in
plastics and pesticides are affecting living things in a most subtle
yet profound way--disfiguring the sex organs of animals and interfering
with reproduction. What had been a safe wager is growing far riskier
as the science matures, so that we face the classic addict's predicament--chemical
dependency despite accumulating signs that it is damaging our health.
Synthetic compounds that make plastic bendable and pesticides sticky
also behave like animal hormones--estrogen, testosterone, and others.
Lately this list of "pseudohormones", pollutants that interfere with
our endocrine systems, has exploded to include a broad menu of the most
common materials in our environment--candy wrappers to dish soap, teething
toys to nail polish. What's new is not that synthetics can mimic hormones--DDT
and PCB were identified as endocrine disruptors decades ago--but at
what tiny amounts these apparently benign chemicals are having potent
effects. In the early 1990's, all hormone mimics appeared to be "feminizers" acting as pseudoestrogens. The short list included chemical plasticizers,
pesticide surfactants, and the ever-present PCB, and they were linked
to such broad effects as breast cancer in men and women, reproductive
tract malformation, and sterility in male animals. But with each year
comes news of other, more pervasive compounds that are both masculinizers
and feminizers. They include diesel exhaust, the adhesive component
in dental sealants, mosquito repellants, dishwashing detergents, and
pine sterols from paper mills.
The same "andro" that St. Louis Cardinals slugger Mark McGuire admitted
to using during his record-breaking 1999 home run streak has been identified
as the culprit in masculinizing fish and slugs in rivers and creeks
downstream from paper mills in Alabama. Both males and females have
grossly exaggerated male sex organs, rendering many of the female fish
sterile and uncharacteristically aggressive. The detective work of researchers
at Samford University pinpointed waste pine sterols, converted to andro
by creek bottom bacteria, as the cause.
Something in diesel exhaust--even with soot particles filtered out,
causes masculinization of newborn rats. Researchers in Tokyo found last
February that the fetuses of mother rats that breathed significant amounts
of filtered diesel exhaust possessed delayed or abnormal testes and
ovaries. The mother's blood had ten times the normal level of testosterone.
Their study preceding this one had found young adult males sperm production
to be diminished by one-third when exposed to diesel exhaust. Florida,
downstream recipient of just about everyone's effluent, has a panther
population decline crisis where more than half of the panthers born
between 1985 and 1990 had undescended testes and unbalanced hormone
levels leading to sterility.
Pesticides acting as environmental estrogens are believed to be the
cause. And Florida's Alligator population, particularly at sites adjacent
to pesticide manufacturing, have a ten-fold increase in hatchling mortality.
Adult males in one Florida lake have ovaries instead of testes, and
the females produce far too many eggs.
Hitting closer to home are the surfactants that give detergents their
dirt-binding capacity, and pesticides or herbicides their cling to target
weeds or bugs. This ubiquitous class of chemicals, alkylphenols, have
been found to decrease the size of testes and lower sperm count in males
rats. Related compounds, pthalates, used in making ubiquitous flexible
polyvinyl products, caused dramatic decline in testosterone and missing
or blood-filled testes in rats, according to a recent EPA study. The
Center for Disease Control recently found pthalate residues occurring
at an alarming rate in the urine of randomly tested children and adults.
Technology addicts rationalize these sorts of studies as bad news for
rats, slugs, fish, alligators, and panthers, but we're humans. The thing
is, hormone physiology is widely shared (biologically, conserved) in
the animal kingdom--we all use estrogen, testosterone, and the cell
receptors that bring the effects to life. And we do have indirect evidence
of something afoot in the human condition, namely inexplicable increases
in prostate abnormality, breast and ovarian cancers, declining sperm
counts, and precocious onset of puberty--all of these events closely
intertwined with blood hormone levels. Baby-boomers are the first generation
ever to be exposed to these agents from cradle to grave and there's
plenty of evidence that our addiction is harming wildlife if not ourselves.
We need to rein in our technology habits by adopting more long-term
views when making purchasing and political choices, and through cleaner,
simpler ways of living.
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