Pollutants Long Gone, But Disease Carries On

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Exposure to certain pollutants early in a rat’s pregnancy can foster disease in her offspring during their adulthood as well as in subsequent generations, a new study shows. A wide range of pollutants elicited such lasting effects, despite future generations never encountering the triggering pollutant.

Some chemicals tested led to premature puberty among great-granddaughters, with an increased risk of disease in reproductive tissues. In some tests, the chemicals disrupted ovarian function, something that in humans could lead to infertility or premature menopause. And another chemical exposure caused premature death of sperm-forming cells in the great-grandsons, researchers report online February 28 in PLoS ONE.

Rather than altering genes, the tested pollutants altered chemical switches that regulate genes, reports Michael Skinner and his colleagues at Washington State University in Pullman. These epigenetic switches can lock a gene on or off.

These master switches for DNA are fairly easy to modify throughout life. Early in development, a fetus erases any epigenetic changes acquired during its parents’ lifetimes, resetting those switches back to healthy, default programming.