An Expert Witness for the Other Side Helps Our Case
In my previous few posts, I’ve been recounting the testimony, and my cross-examination, of expert witness Dr. Robert Brent, who said that while every genetic test done on the Castillos came back negative, he still personally believed genetics was the most likely cause.
What Dr. Robert Brent did say was that every proven chemical or drug teratogen results in multiple malformations, and benomyl was a proven teratogen in rats. But he also believed that the rats had multiple malformations along with microphthalmia in the studies that had been done.
In fact, he believed that all the fetuses born with abnormal eyes in the Staples studies also had growth retardation.
In reality, it was clear from the studies’ underlying data that multiple malformations occurred only with very high doses of benomyl, and single malformations occurred with lower doses. Yet while Dr. Brent believed that humans could experience a teratogenic effect from benomyl, he also believed that effect would only come at doses higher than humans have the capability of being exposed to.
When I asked Dr. Brent if he knew what those doses would be, he said he couldn’t calculate a dose of benomyl that would result in a teratogenic effect in a human fetus because he would need response curves and blood levels.
He did say all chemicals in the blood supply would circulate through both the fetal blood supply and the entire blood supply of a pregnant woman. On cross-examination, Dr. Brent admitted, after having reviewed DuPont’s papers on dermal and inhalation exposure based on the company’s own data and data from the World Health Organization (WHO), that he believed that 10% to 15% of the amount of the chemical applied to the skin would get into the human bloodstream. This testimony was great for the Castillos.
I asked, “Do you believe that, based on Donna Castillo’s exposure, benomyl could have gotten into her bloodstream?”
“Yes, Dr. Brent said. “Some would have gotten into her bloodstream; however, a very small proportion. Her absorption rate was probably less than 10 to 15%, because it was a windy day and it dried on her skin.” His estimation was up to five times higher than the 3% rate we were using. That fact fit perfectly with Johnny’s low-dose exposure and his having only a single malformation to make the ideal picture we were hoping to create for the case.
When I pushed Dr. Brent about how he could possibly know this, he admitted that he wasn’t in a position to testify about the rate of benomyl absorption into Donna’s bloodstream, but he still believed humans have lower absorption rates than rats, because humans have thicker skin.
As it turned out, Dr. Brent had to admit he was not an expert on dermal exposure. In fact, he had never written a published work or given a seminar or presentation on benomyl or its potential teratogenic effects. He had never conducted a study looking for reproductive toxicity in humans or rats with benomyl, either.
Though Dr. Brent was tough, I did my best to challenge his expertise and authority. It wasn’t easy, and in fact it got a bit ugly at times, but in the end I had a good feeling that I had managed to do more than just rattle his cage—I clearly established that at least 3% of the Benlate that Donna had been exposed to got into her bloodstream.
That was big.
In my next post, I recount how our victories were handled by the DuPont defense, as its lawyers used questionable tactics to sway the jury.
You’ll find a full narrative of the trial, the science behind the chemicals in question, the people involved and my own background, in my book, Blindsided, from which this blog post is adapted.