Pregnant rats exposed to an industrial pollutant passed on a variety of diseases to their unexposed great-grandkids, according to a study published Wednesday. Washington State University scientists found that third-generation offspring of pregnant rats exposed to dioxin had high rates of kidney and ovarian diseases as well as early onset of puberty. They also found changes in the great-grandsons' sperm. The great-grandkids – the first generation not directly exposed to dioxin – inherited their health conditions through cellular changes controlling how their genes were turned on and off, the researchers reported. The dioxin doses used in the study were low for lab rats, but are higher than most people’s exposures from the environment. The study raises questions that won’t be easy to answer about people’s exposure to dioxins from food and industrial sources.