In 2005, Mike Skinner’s group at Washington State University published a disturbing observation: pregnant rats exposed to high levels of a commonly used fungicide had sons with low sperm counts as adults.
To see if other environmental chemicals could have the same effect, Skinner and colleagues screened a host of potentially toxic chemicals: jet fuel, plastics ingredients, and more pesticides. Again, exposed animals had offspring with reproductive problems, which were passed down for generations. The researchers also saw another phenotype pop up again and again: obesity.