Our Stolen Futurea book by Theo Colborn, Dianne Dumanoski, and John Peterson Myers
 
 

 

 

Steven Safe's op-ed in the Wall Street Journal ("Another enviro-scare debunked," August 20, 1997) concludes that concerns about the health risks of endocrine disruptors are unwarranted and that sections of the 1996 Food Quality Protection Act about endocrine disruption should be revamped.

Those might seem odd conclusions for a scientist who was involved midstream (at the time of writing the op-ed) in a National Academy of Sciences panel that decided, when the its report was finally released, that the crucial studies to refute or prove human health effects simply had not been done, and recommends broad-based screening of chemicals, similar to the approach established by the FQPA.

Safe takes a shotgun approach in his attack, stringing together an unconnected series of points in an effort, seemingly, to create a shot pattern discrediting concerns about endocrine disruption even while lacking a cohesive, compelling argument.

Unfortunately, Safe's pattern is full of holes.

He begins by citing several examples out of the body of evidence that raised concern about endocrine disruption initially. The examples he use include possible declines in sperm count, breast cancer, and a study suggesting very high synergistic interactions among different pesticides. He then attempts to discount each of these examples and in the process dismiss endocrine disruption as a health concern.

The overall logic of this argument is severely flawed. Even if he were able definitively to disprove each of the cases he cites, many health concerns about endocrine disruptors would remain. This was apparent when he wrote the article; it is even more so now given the wealth of research that continues to be published.

Moreover, he errs in his presentation of the cases cited.

On sperm count, he cites several studies indicating that in some areas there has been no change in sperm count, including a study from Denmark. This seems superficially telling, particularly to critics of sperm count declines, because the study that drew widespread attention to this issue was carried out by Danish scientists. How ironic, Safe seems to be arguing, that in the very backyard of the scientists who did the original work is refutation of their hypothesis! Safe's argument errs logically because it is possible to have an overall average decline even as some places holding steady. That's how averages work. Many places are showing declines. Some places appear to be holding steady (although several of the most prominent of the cases showing no decline are based upon biased data—e.g., Fisch et al. 1996 or Acacio et al. 2000). In contrast to the many places with large declines and a smaller number holding steady, virtually none show large increases—in otherwords, an overall average decline.

Safe acknowledges that declines have occurred, and states correctly that the cause of the declines is unknown, but then goes on to state erroneously "it is unlikely that they are related to environmental estrogens and related contaminants, since levels of these compounds in humans, wildlife and foods are similar in most regions, and some have been declining." This is wrong for two reasons:

  • First, there is wide geographic variation in exposure to environmental estrogens. Safe is simply choosing to ignore data to bolster his point.
  • Second, Safe completely ignores here the fact that large time lags should be expected between exposure and impact. Afterall, the sperm count argument is not about fetal sperm count, it is about adult sperm count as affected by fetal exposure. While exposures to some of the suspected chemicals have declined, that decline only began (slowly) in the late 1970s. Men entering their peak reproductive years in 1997 (when Safe wrote the op-ed) were in the womb just at the time that compounds like DDT and PCBs were beginning to be banned. The time lag is even longer: Women born during the years when these compounds were being banned received from their mothers (via maternal transfer) unprecedented levels of contamination, which where then compounded by their own exposure as they grew up before the full impact of the bans entered into force. These women then transferred contamination to their own babies in the womb.

On breast cancer, Safe argues "Two recent studies also cast doubt on the hypothesis that xenoestrogens are a cause of breast cancer." The studies he cites fail to support his claim. They (and a more recent study) do indicate that adult exposure does not elevate breast cancer risk. But they do nothing to refute the hypothesis that developmental (fetal or pubertal) exposure to xenoestrogens might elevate breast cancer risk. And these two studies (indeed almost all breast cancer - xenoestrogen studies) examine a very small number of compounds. Safe then commits the logical error of concluding from experiments with these small number of compounds that all xenoestrogens are innocent.

The fallacy of this logic—obvious even when he wrote it—became irrefutable in 1999 with studies showing significant increases in breast cancer risk from exposure to another xenoestrogen, dieldrin. Not only does dieldrin increase risk of breast cancer, women with higher levels of dieldrin are more likely to die once they contract breast cancer than women with breast cancer but with low levels of exposure.

Finally, Safe points to controversial work on synergistic interactions among pesticides as another death knell for endocrine disruption. This work seemed to indicate that pesticides in mixtures would have impacts vastly greater than the impacts of each pesticide by itself. Subsequent attempts to confirm the work failed, and ultimately the laboratory that performed the work originally withdrew the study.

While Safe is correct to report that this study was withdrawn, his inference that this invalidates concerns about endocrine disruption is wrong. First, endocrine disruption clearly takes place even without large synergistic interactions among chemicals. Indeed, we wrote Our Stolen Future before the withdrawn study was planned, much less performed or reported. The phenomenon of endocrine disruption does not rest on this one study. Moreover, many other studies report additive and synergistic interactions among chemicals.

 

 

 

 

 

 

 

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