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

 

   

background on bisphenol A

In 1998 industry scientists began publicizing a study funded by the Society of the Plastics Industy and the European Chemical Industry Council purporting to show that vom Saal's work on low-level bisphenol A impacts could not be replicated.

Their study was first released in an industry press conference, in which the conclusions were made available to the press but data sufficient to allow independent confirmation of the results were not.

They also promoted the study aggressively at the first international meeting of the Japanese Society for Endocrine Disruption Research (December 1998; see below).

Months later it was published in the journal Toxicological Sciences .

Industry made a great deal of this non-replication, and continues to do so as of August 2000. Unfortunately, not only was their effort flawed (see below), but independent scientists have now replicated vom Saal's work. Thus this episode teaches more about industry tactics than science.

The initial release touted several parts of industry's work:

  • They followed vom Saal's procedure as closely as possible.
  • The sample size was significantly larger.
  • In addition to a control group and an experimental group, they also included a positive control group in which they exposed fetal mice to a single low level of diethylstilbestrol.
  • The found no impact of bisphenol A treatment and no impact of exposure to diethylstilbestrol.

They concluded that their failure to replicate vom Saal exonerated bisphenol A, and prominently promoted this conclusion to the press. Industry lawyer Jim Lamb was even quoted in the British science journal, Nature, to this effect.

Unfortunately, the press release unwittingly damned their effort, at least for the informed reader, revealing that their failure to replicate was more likely due to an incompetent laboratory. This is because of the failure of their positive control with DES. By acknowledging that their positive control had failed, they acknowledged that their experiments were invalid.

Scientists use positive controls to demonstrate they can perform the experimental procedure. Positive controls should yield positive results. The fact that they found no positive impact of DES casts doubt on their competency.

Interestingly, the Toxicological Sciences publication of the result no longer refers to the DES work as a positive control. And industry scientist John Ashby (Zeneca) has since published on the industry's bisphenol A web page arguing (a PDF file) that DES was an inappropriate positive control. These appear more like damage control than substance.

The debate over vom Saal's work became especially heated at the Japanese meeting in Kyoto in 1998. Industry held daily press conferences to influence press coverage. They excluded from these conferences knowledgeable, independent scientists. In fact, when a contingent of independent scientists attempted to attend one of the industry press conferences, the industry rep, Jim Lamb, quickly adjourned the meeting only a few minutes after it had started.

Someone within the industry delegation also is reported to have made a highly questionable telephone call from Kyoto to a senior scientist/administrator at the National Institute of Environmental Health Sciences (USA), in an effort to suppress data from NIEHS that would have shown that using DES as a positive control was proper. Industry knew these data existed and it would have completely undermined their case. The call had its impact; the data were not released.

In 2002, data began to emerge indicating that the industry's failure to replicate arose because of inadvertent estrogenization of the study's control group of mice. The prostates of the control group were already enlarged above normal, making further enlargement by additional estrogen signaling (i.e., by the addition of bisphenol A) impossible. A 2003 publication by Welshons et al. explores in depth the potential for false negatives when background estrogen contamination causes positive controls to fail.

 

 

 
     

 

 

 

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