Opinion ID: 1890564
Heading Depth: 1
Heading Rank: 7

Heading: Rat Gavage Studies

Text: DuPont and Pine Island argue the Castillos' expert exposed rats to benomyl through the gavage method, not dermal exposure, that rats were exposed to far greater quantities than the 20 ppb which Dr. Howard concludes is the low effect level for benomyl to become a human teratogen, and rats are different species than humans so there can be no analogy from the rat gavage data to humans. The Castillos respond that rats are used for in-vivo testing because, as in humans, the placenta in rats has no barrier system between the mother's blood and the fetal blood. Animal testing is done because a known or suspected toxic substance cannot ethically be administered to humans. Gavage studies, in which the substance is delivered to the rat through a tube as opposed to lacing its food, are done because the quantity of the dose is more accurately measured and rats do not have a vomit reflex. Because animals are resistant to chemicals, the doses have to be high in rats, but then the scientist statistically compares dose response relations. The Castillos' experts calculate that, compared to the amounts given to the rats, the human would have to ingest, or the skin would have to absorb, about 1/35th or 1/38th of an ounce of benomyl to see the same effects. As for various species of mammals being tested, Dr. Howard testified that he relied upon the basic principle of toxicology and pharmacology that in qualitative extrapolation, one can usually rely on the fact that a compound causing an effect in one mammalian species will cause it in another species. DuPont and Pine Island's dispute is not that rat gavage studies are inappropriate scientific studies per se, but that the dosages given to the rats were far greater than any amount a human would be exposed to, and thus the study in this case was invalid. The underlying scientific methodology in general is undisputedly accepted in the scientific community. DuPont and Pine Island do not argue that rat gavage studies are per se junk science. What DuPont and Pine Island dispute is the result that the Castillos' experts reached. That is not what Frye considers, and DuPont and Pine Island had the opportunity to attack the findings and conclusions at trial.