The Fine Details of Chemical Exposure
The following morning, the day after his in-depth testimony on the many different ways an embryo or fetus can be impacted by environmental factors, Dr. Howard took the stand once again.
The dialogue that ensued focused on the rate at which benomyl penetrated the skin. Employing a micropipette—a scientifically calibrated instrument frequently used in labs to measure out specific amounts of liquid—Dr. Howard showed the jury the small amount of benomyl (20 microliters) that was used in the ICI study.
Drawing from the pipette, he proceeded to drop the 20 microliters into my hand. It was instantly clear that a droplet that small wouldn’t even cover the fingernail on Donna’s pinky. Dr. Howard then went on to explain at length the chemistry of the breaking down of chemicals—specifically benomyl—in the liver. The body takes benomyl and converts it into hydroxyl-5MBC and carbendazim. All three are toxic to the body, and the effects they have on the developing eye are the same.
Eventually the body wants to get rid of this stuff, which means it has to make it more water-soluble to get it through the kidneys and to release it. It’s quite a fast process, and we have lots of microsomes in our cells that help make it happen. Unfortunately, the embryo or fetus cannot do this on its own, so it relies on the mother to take the hydroxyl-5MBC out.
Next, Dr. Howard laid out his chemical exposure calculation, which was based on the amount of the surface area of Donna Castillo’s skin that was exposed to the chemical on the day she was doused. Donna’s total body surface area came to 18,800 square centimeters. Because she was wearing shorts and a sleeveless top that day, leaving her face, neck, arms, and legs uncovered, Dr. Howard estimated that half of that total surface—9,400 square centimeters of skin—was exposed directly to benomyl that day. That was equal to 9,400 times the fingernail-sized amount we had demonstrated moments earlier in the courtroom.
At the given dermal transmission rate, 49 micrograms of benomyl per square centimeter was transmitted through Donna’s skin during each hour that passed until she showered. If you multiply that by the total number of square centimeters of Donna’s skin that was exposed, it would create an amount of benomyl in her bloodstream in the hundreds of parts per billion.
With exposure to doses this high, we knew benomyl was the cause. We just had to prove it.
Dr. Howard then systematically went through each of the studies to back up his findings, including DuPont’s, ICI’s, and Dr. Van Velzen’s in-vitro tests, which showed cell death, otherwise known or “apoptosis,” occurring at amounts as low as 22 parts per billion (PPB). Even worse, we had the evidence of neurite retraction at 3 PPB.
By the end of day two, I thought we had made a very strong case. Dr. Howard had done an excellent job stating the facts and had been a terrific witness on direct exam for the Castillos. But we weren’t completely out of the woods yet, as the DuPont lawyer Clement “Clem” Glynn still had to cross-examine him.
I will write about that cross-examination in my next post.
You’ll find much more about the Castillo-DuPont trial, as well as information on my background and my thoughts on aspects of the judicial process, in my book, Blindsided.