Differences in how male and female mammals respond to toxins at the cellular level appear to extend beyond differences already observed in reproductive cells. A group of UC Davis researchers has shown for the first time that male and female fat cells respond differently to toxins, specifically the chemical dioxin. They differ not only in the degree to which the cells respond, but in the actual mechanics as well. "We've shown that looking at one gender is not necessarily the way to show the effects of a toxin," says Bill Lasley, a professor of veterinary medicine at UC Davis. Working with guinea pigs and monkeys, the researchers found that males were more susceptible than females to dioxins. Similar gender differences are likely to be found in people, the researchers say. The discovery of the mechanistic differences of toxicity between males and females may have implications for chemical exposure guidelines, depending on what is learned in the future about the mechanisms of gender-specific toxicity. The researchers' findings will be published this fall in the journal Reproductive Toxicology.