In June 1996, Tulane University researchers published a study claiming combinations of pesticides are as much as 1,600 times more potent as environmental estrogens than the individual pesticides tested alone.
At the time, I called the study junk science. But the media trumpeted it as the greatest thing since sliced bread. Science magazine not only published the study, but also ran a news item and an editorial about the study — a lot of fanfare for a science journal where most articles are low key.
And, unfortunately, the study was published just in time to "support" inclusion of a provision in the Food Quality Protection Act of 1996 mandating that EPA develop a screening program for pesticides that may have so-called "estrogenic properties."
Since the study was published, however, U.S. researchers tried, but failed, to reproduce the Tulane results. Then U.K. researchers tried, but failed, to reproduce the Tulane results. And earlier this year, the Tulane researchers were raked over the coals at the annual Society of Toxicology meeting because no one could reproduce the Tulane results.
Finally, the Tulane researchers have recanted their junk science. Here's their letter to Science:
Synergistic Effect of Environmental Estrogens: Report Withdrawn I write to formally withdraw the report "Synergistic activation of estrogen receptor with combinations of environmental chemicals" (7 June 1996, p. 1489) (1), for which I was corresponding author.
We have conducted experiments duplicating the conditions of our earlier work, but have not been able to replicate our initial results.
Also, since our publication in Science (1), others have been unable to reproduce the results we reported (2). Meanwhile, people in many walks of life have, on their own, put great weight on this report as the basis for much discussion, thought, and even public policy.
Whatever merit this publication contained, and despite the enthusiasm it generated, it is clear that any conclusions drawn from this paper must be suspended until such time, if ever, the data can be substantiated.
In our laboratory, for the last 6 months, we have conducted experiments to elucidate the mechanisms to explain the phenomenon of synergy between estrogenic chemicals. These studies have been directed toward understanding the roles that estrogen receptor levels (3), the difference between monomer and dimer conditions of the estrogen receptor (4), and chemical transport across the cell membrane (5) play in the action of weak estrogens. None have provided a satisfactory mechanism to explain our earlier findings. Taken together, it seems evident that there must have been a fundamental flaw in the design of our original experiment. As a consequence of our efforts and those of others, and considering the impact our report has had in so many quarters, we have decided to formally withdraw the paper and its finding. We take this step in recognition of the reliance so many have placed on our work.
Our laboratory will continue to aggressively conduct research on environmental endocrinology. We believe there are important and verifiable discoveries to be made.
The co-authors have concurred in writing with this decision.
John A. McLachlan Tulane-Xavier Center for Bioenvironmental Research, Tulane University,1430 Tulane Avenue, New Orleans, LA 70112, USA REFERENCES
1.S. F. Arnold, D. M. Klotz, B. M. Collins, P. M. Vonier, L. J. Guillette Jr., J. A. McLachlan, Science 272 1489 (1996). 2.K. Ramamoorthy, et al., ibid. 275, 405 (1997). 3.D. Q. Tran et al., Steroids, in press. 4.S. F. Arnold et al., in preparation; P. M. Vonier, J. A. McLachlan, in preparation. 5.S. F. Arnold et al., in preparation; D. Q. Tran , et al., Biochem. Biophys. Res. Comm. 235, 669 (1997) .Only one question: Where's all the publicity now?
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