New study conducted at Washington State University and published in the journal Science suggest that toxin exposure during pregnancy might have damaging effects that are inherited by at least four generations.

In the study, Dr Skinner, who led the research team, exposed pregnant rats to high levels of endocrine disruptors — chemicals that mimic or interfere with reproductive hormones.

The pregnant rats exposed to the toxins produced male offspring that had low sperm counts and low fertility. The offspring fathered rats with similar problems, and the effects persisted through the four generations.

If this is the case it could mean that certain diseases that afflict people today may be influenced by toxins to which their great-grandparents were exposed.

Michael Skinner, who led the research, said: “We believe this phenomenon will be widespread and be a major factor in understanding how disease develops.”

Dr Skinner said that such changes might be involved in several human diseases, such as breast and prostate cancer, because the incidence of these conditions is increasing more quickly than expected.