Washington, Aug 26 (IANS): In a significant revelation that may have a bearing on studying human mental disorders, researchers found that male and female rats are affected differently by ancestral exposure to a common fungicide called vinclozolin or endocrine disrupting chemicals (EDCs).

Vinclozolin is a fungicide commonly used by farmers to treat fruits and vegetables.

The study by researchers from University of Texas at Austin and Washington State University showed that female rats whose great grandparents were exposed to vinclozolin became much more vulnerable to stress and anxiety.

But males with same combination of ancestral exposure and stress do not have the same adverse effects.

"These results should concern us all because we have been exposed to endocrine disrupting chemicals for decades and we all go through natural challenges in life," explained lead researcher David Crews from University of Texas at Austin.

Those challenges are now being perceived differently because of this ancestral exposure to environmental contamination, he added.

For the study, they confined some rats to soft, warm cylinders for six hours a day for three weeks.

They found that for female rats, ancestral exposure to vinclozolin alone or stress during the animal's adolescence alone had negligible effects on the rats' hormonal balance and behaviour.

However, the combination of ancestral exposure and stress caused female rats to have dramatically higher levels of corticosterone -a stress hormone similar to cortisol in humans- leading to anxiety and more anxious behaviour.

The study appeared in the journal Endocrinology.