Pregnant female lab mice received the brew in their drinking water at four concentrations, from 400 parts per million (ppm) down to less than 0.04 ppm — equivalent to one drop of pesticide in 500 bathtubs of water, Porter says.
Diamond's lab circumvented this problem by creating female mice that had a key interferon gene knocked out; in a second experiment, they treated pregnant animals with an anti-interferon antibody.