Friday, June 03, 2005

Chemical generations

'Toxins may pass down generations', says BBC News, reporting on research from Washington State University. Pregnant rats were exposed to two agricultural chemicals during the period of gestation where sex is determined. Where male rats were born, they had low sperm counts and poor fertility. However, where it was possible for these rats to mate with female rats who were not exposed to the chemicals, the offspring were again affected by the same fertility problems. This pattern was repeated in a total of four generations. The researchers believe there could be a link between this process and the rising rates of breast and prostate cancer in humans.

It is always wise to take research findings found only in animals as preliminary. In this case, the old adage 'the dose makes the poison' seems to apply. As Professor Alan Boobis told BBC News, 'This effect is likely to be concentration dependent, and these animals were exposed to very high levels of chemicals. We need to find out whether this trans-generational effect is translated to much lower doses.'

What this particular alarm illustrates is the fascination with finding something hazardous about artificial chemicals. In fact, there are plenty of chemicals ordinarily produced naturally which mimic reproductive hormones. Fruit and soya, for example, can increase exposure to oestogen mimics. As Bruce Ames and Lois Swirsky Gold demonstrate elsewhere on spiked, 'Human exposure to naturally occurring rodent carcinogens is ubiquitous and dwarfs the exposure of the general public to synthetic rodent carcinogens.' In other words, most of the hazardous chemicals we encounter are natural, not man-made. Yet such effects tend to be ignored because of the widely-held prejudice that man-made is bad, but natural is good.

The existence of these natural nasties is entirely logical - plants produce them to protect themselves from pests and predators. For the most part, they're harmless in the small quantities we are exposed to - but we still face much higher levels of exposure to these substances than to the artificial chemicals that get such a bad press.

Publicising research like this new study on rats can only alarm people unnecessarily. The only thing that's being polluted here is the public's attitude to very useful, man-made substances.

First published on spiked's Don't Panic page.