New U.S. research is suggesting that chemicals can change the way genes work and that toxic chemicals that poisoned your great-grandparents may also damage your health.
A team from Washington State University has produced worrying evidence that some inherited diseases may be caused by poisons polluting the womb.
The researchers found in their work on rats,an indicatation that man-made environmental toxins may alter genetic activity, giving rise to diseases that pass down at least four generations.
Lead researcher Dr Michael Skinner says it is a new way to think about disease.
The scientists exposed pregnant rats to two agricultural chemicals during the period that the sex of their offspring was being determined.
The compounds used were vinclozolin, a fungicide commonly used in vineyards, and the pesticide methoxychlor, both are known as endocrine disruptors, chemicals that interfere with the normal functioning of reproductive hormones.
The team found that the rats exposed to the compounds produced male offspring with low sperm counts and poor fertility, and when these rats were then mated with females that had not been exposed to the toxins, they were still able to produce young, but their male offspring had the same problems.
This effect persisted through at least four generations, impairing the fertility of more than 90% of male offspring in each generation.
The researchers found the damage was not caused by alterations in the DNA code, but changes in the way the genes work. They say these epigenetic changes, are caused by small chemicals that become attached to the DNA, modifying its activity.
Epigenetic changes have been observed before, but were not previously known to pass onto later generations.