We already know that exposures to toxic substances can have immediate consequences for our offspring. But what about the next generation, and the next generation after that? Without genetic mutations? The field of epigenetics studies how we can have intergenerational consequences for public health hazards without the genes themselves being mutated. Researchers look at, for example, how molecules can attach themselves to the DNA molecule without changing the genetic sequences themselves, but then ride along from generation to generation. The latest issue of Rachel's Environment & Health News reports on the latest epigenetic discovery: The latest information appears in a new study by Michael Skinner and colleagues at Washington State University, published in the June 3 issue of Science magazine. Skinner found that mother rats exposed to hormone-mimicking chemicals during pregnancy gave birth to four successive generations of male offspring with significantly reduced fertility. Only the first generation of mothers was exposed to a toxin, yet four generations later the toxic effect could still be detected. Prior to this study, scientists had only been able to document epigenetic effects on the first generation of offspring. These new findings suggest that harm from toxins in the environment can be much longer lasting and pervasive than previously known because they can impact several generations. And therefore a precautionary approach to toxics is even more important that previously believed.