Azara Blog: Toxic chemicals can have effects down the generations

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Date published: 2005/06/04

The BBC says:

Toxic chemicals that poisoned your great-grandparents may also damage your health, US research suggests.

A team from Washington State University has produced evidence that some inherited diseases may be caused by poisons polluting the womb.

Research on rats indicates man-made environmental toxins may alter genetic activity, giving rise to diseases that pass down at least four generations.

The research is published in the journal Science.

The scientists exposed pregnant rats to two agricultural chemicals during the period that the sex of their offspring was being determined.

The compounds 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.

Rats exposed to the compounds produced male offspring with low sperm counts and poor fertility.

They were still able to produce young, however. When these rats were then mated with females that had not been exposed to the toxins, their male offspring had the same problems.

The 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.

These epigenetic changes, as they are known, 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.
...
The levels of chemicals the rats were exposed to were very high - much higher than people normally ever encounter.

Professor Alan Boobis, a toxicologist at Imperial College London, UK, told the BBC News website the findings were interesting, but he said there was no need for people to be alarmed.

"This effect is likely to be concentration dependent, and these animals were exposed to very high levels of chemicals," he said.

"We need to find out whether this trans-generational effect is translated to much lower doses."

Interesting as far as it goes, but the main problem with the research is as noted at the end, the concentrations used were extremely high (not unusual in research on chemicals).

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