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  • Jim Ferraro

Calculating Exposure

Once the judge cleared my line of questioning, I began slowly and meticulously walking DuPont’s expert toxicologist Dr. Judith C. Stadler through each of my 10 mathematical calculations, which I had created to simplify some of the math regarding dosage and exposure. Some of these calculations were as simple as clarifying how many ounces there are in a pound.

“Doctor,” I began, “these calculations will all relate to a simulated gavage exposure based on the Staples study.

Would you agree that the 1982 Staples study came up with a low effect level of 62.5 milligrams per kilogram per day of exposure to benomyl?”

“That’s right,” she said.

“Would you also agree the 1980 Staples study came up with up with a low effect level of 10 milligrams per kilogram per day of exposure to benomyl?”

“That’s right, but it’s disputed.”

I continued, “And the milligrams are the amount of the chemical, and the kilogram measurement is the amount of the body weight, right?”

“That’s right.”

“Would you convert kilos to kilograms (1,000 grams per kilo) and compare milligrams (1,000 milligrams per gram) to kilograms? Doctor,” I said, “if you need my chart or a calculator at any point, please let me know, because I am aware this is confusing, because a kilogram is one thousand grams, and a milligram is one-thousandth of a gram. So basically, in Staples 1982, we are talking about 62.5 millionths of a kilo? Does that sound correct? I still have a calculator if you need to calculate it.”

When I asked whether Dr. Stadler wanted to use my calculator, and then held it out for her to see if it would make things easier, the jury chuckled, which was unintentional on my part. After all, wasn’t she one of the three top experts in the world?

Dr. Stadler didn’t like my methodology, but she didn’t disagree with my math. I asked, “Would you agree that an ounce is 28.35 grams?”

As she tried to anticipate where I was going with this, she began to appear uncomfortable and was unable to answer even the simplest questions.

“I’m not sure about that,” she said. “I don’t have anything right now to say that’s true.”

“Do you know anyone in the toxicology department at DuPont who knows how many grams are in an ounce?”

“There are probably people who know it. Offhand, I always look it up if I try to do a conversion.”

“Does 28.35 grams sound familiar to you?”

“I honestly do not know.”

“Let’s operate under the assumption that’s correct,” I said. “What I’m doing is converting this .625 to grams so we can start to make our conversion to ounces, because we want to get to a bottom line that is in ounces. In other words, what we’re doing here is taking .000625 kilograms and making it into grams. To do that, we’re knocking off three decimal places.”

“I’m sorry. I’m not used to doing this.”

“Doctor, just take your time. Again, I have a calculator if you need it,” I said. Clearly, Dr. Stadler was getting flustered.

“And to make kilograms into grams,” I continued, knowing there was nothing simple about this, “you would simply make one thousand grams, correct?”

“That’s right,” she agreed.

At this point, the judge could also see that Dr. Stadler was uneasy and offered to have the bailiff bring her a calculator that converted ounces to grams and so on.

While Dr. Stadler wouldn’t take the calculator from me, she gladly accepted it from the bailiff. Once she did, she was able to follow along with the rest of my calculations, including the assumption that at the time of her exposure, Donna Castillo weighed 170 pounds.

“I assume you know how many ounces are in a pound?”


“Correct. So that would make 170 pounds how many ounces?”

“I don’t think she weighed that much.”

“She doesn’t today, but unfortunately, during her pregnancy, I think that’s what she weighed.”

“Objection to counsel’s comment as to fortunate or unfortunate,” said the DuPont attorney Clem Glynn.


“If Mrs. Castillo weighed 170 pounds,” I said, “which equals 2,720 ounces, therefore, she would weigh 77.11 kilograms, right?”

“That sounds about right.”

“You recall that there are 28.35 grams in an ounce, correct?”


I continued, “According to my calculations doctor, 2720 oz. times 28.35 g. equals 77,112 g. Then you divide that by 1000 to get 77.11 kg. Now, you come up with the total ounces of active ingredient for her body weight, which equals 0.1619, approximately one-sixth of an ounce over the course of an entire day of exposure, if you converted the Staples 1982 study number of 62.5 to an adult the size of Mrs. Castillo, correct?”

“One-sixth of an ounce taken by gavage, that is correct.”

“Then if you went to the 1980 Staples study and you accepted his methodology and the written statement in his summary that the low-level effect level was 10 milligrams per kilogram per day, you would simply divide the 62.5 by 10, and now the number becomes one­fortieth of an ounce by gavage exposure for Mrs. Castillo.”

Although Dr. Stadler fought against answering each calculation, especially the last one, and Glynn objected to my mischaracterization of the study, the judge overruled the objection and Dr. Stadler was forced to answer, essentially agreeing with each of my calculations.

Once I got her to admit to each number on the list of 10, she was left extremely flustered and confused.

I will continue recounting the doctor’s testimony in my next post.

In the meantime, I’d love to hear from you about your experiences with experts of any sort, who know one thing and stick to it, despite conflicting evidence that might prove them wrong. Thank you for sharing!


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