By Peter Montague
The American Chemical Society [ACS] recently affirmed (Chemical & Engineering News, January 31, 1994) the following phenomena:
- Sperm count in men worldwide has dropped to 50% of what it was 50 years ago.
- The incidence of testicular cancer has tripled in some countries in the last 50 years, and prostate cancer has doubled.
- Endometriosis — the growth outside the uterus of cells that normally line the uterus — -which was "formerly a rare condition, now afflicts 5 million American women", the ACS said.
- In 1960, a woman's chance of developing breast cancer during her lifetime was one in 20. Today the chances are one in nine.
- Female common terns are sharing nests near a PCB-contaminated site in Massachusetts, an unnatural female-female pairing.
- Male alligators in pesticide-contaminated lakes in Florida are growing up with penises so small that they are "sexually incompetent".
In January, the US National Institute of Environmental Health Sciences [NIEHS] convened a meeting of 300 scientists who presented papers on oestrogens and oestrogen mimickers in the environment.
Many of those scientists think there's probably a connection between diminished sperm counts, increasing endometriosis, female-to-female pairing in birds, sexually incompetent alligators and breast cancer in women. The connection is poorly understood, they say, but the common link is probably chemicals dumped into the environment that mimic, or interfere with, hormones.
Mainstream scientific thinking has been coming to grips with this accumulating bad news. First the American Chemical Society began to write about it. Then the NIEHS started writing about it.] And in February the Journal of the American Medical Association broke the story for its readers: "Oestrogen and [chemical] agents that mimic it appear to be more pervasive and problematic then ever suspected".
Oestrogen is usually considered a female hormone, but males produce oestrogen too, in small amounts. In the developing foetus, in both humans and animals, a specific ratio of oestrogen to androgens (male hormones) must be maintained for proper sexual differentiation to occur. For a male to become a male and a female to become a female, a certain balance of male and female hormones must be present in the mother between the time of fertilisation and the time of birth or hatching.
If the hormone balance is disturbed, the offspring will be born with two sets of partially developed sex organs, or with a single set that is incompletely or improperly developed. Diminished sperm count, or future cancer, may be set at this early stage.
Hormones are chemical messengers, essential to the body's healthy cooperation and internal communication. Hormones are present at very low levels (parts per billion or even parts per trillion), and often for only short periods of time, yet they have very powerful, long-lasting effects on growth, development and metabolism.
Oestrogen, and chemicals that mimic oestrogen, operate inside cells by fitting themselves into "oestrogen receptors" (proteins) the way a key fits into a lock. Once the key is in the lock, the key-and-lock together can move into the nucleus of a cell and attach to the DNA, releasing messenger RNA which then causes a cascade of changes in cells, tissues and organs throughout the body.
Some oestrogen mimics fit into the lock wrong, filling up the space that the "correct" key would have used, thus interfering with natural oestrogens; these are called oestrogen antagonists. Some oestrogen mimickers fit into locks that weren't ever intended to have an oestrogen fitted into them.
Most natural oestrogens are bound up by sex-hormone-binding proteins in the bloodstream, which are not able to bind oestrogen mimickers. This increases the effective dose of the mimickers. The many ways oestrogen mimickers can cause problems are just now beginning to be appreciated.
"The structural diversity of oestrogenic chemicals is enormous", says John A. McLachlan, chief of the reproductive and developmental toxicology laboratory at NIEHS.
In other words, you cannot simply observe a molecule and tell, by its chemical structure, whether it will act as an oestrogen mimic or not.
"Compounds with widely different structure bind to oestrogen receptors even though they bear no obvious structural resemblance" to oestrogen, says John A. Katzenellenbogen, professor of chemistry at the University of Illinois.
Examples of oestrogen mimickers are DDT and its breakdown by-product DDE; Kepone; dieldrin; dicofol; methoxychlor; some PCBs; 3,9-dihydrooxybenz[a]anthracene; and alkyl phenols from penta- to nonylphenol, as well as bisphenol-A (the building block of polycarbonate plastics), which is used in many common detergents, toiletries, lubricants and spermicides.
Many oestrogen mimickers are persistent (they resist breaking down in the environment) and highly soluble in fat, causing them to accumulate in fish, birds and mammals, including humans. Many of them pass from the mother to the developing foetus.
Finally, the Journal of the AMA reported that oestrogenic chemicals have a cumulative effect. David Feldman, professor of medicine and endocrinology at Stanford University, says, "The cumulative effect may be much greater than any individual molecule". Ana M. Soto at Tufts University combined 10 oestrogen mimickers, each at one-tenth of the dose required to produce a minimal response; she found that the combination produced an oestrogenic response.
This last information has far-reaching implications for the regulation of chemicals. For 50 years the US has regulated chemicals one by one, by conducting laboratory experiments on animals, and by experimenting on workers. If rats or workers get sick, then a particular chemical may be regulated to a level 10 times (or 100 times) lower than the lowest amount that caused an observable effect.
If chemicals at low ("safe") levels combine to produce an effect, this means that chemicals will have to be regulated in combination. "Testing mixtures is right on the mark" says George M. Stancel, at University of Texas Medical School.
Kenneth Olden, head of NIEHS, agrees. "[W]e cannot ignore this milieu we live in that has all these oestrogens. We have polluted our environment. It is polluted. Now we have to allocate resources to sort out the different effects of agents and learn whether they are synergistic, additive, inhibitory or antagonistic. We don't know."
But these are scientists pretending that science can do something it cannot actually do. There is not sufficient money to study the full effects of individual chemicals, much less combinations of chemicals.
Scientists can pretend, but in so doing they perform a great disservice, preventing decision-makers from seeing what really needs to be done: we need to abandon the practice of chemical-by-chemical regulation. We need to regulate whole classes of chemicals. The dangerous classes need to be phased out and banned. Zero discharge. Pollution prevention. These are the keys to sustainability and survival.
[Abridged from Rachel's Hazardous Waste News (US).]