Pesticide’s Effect

A chart that accompanied your May 2 story on pesticide testing incorrectly implied that our herbicide product, alachlor, disrupts hormones. One could search records at the Environmental Protection Agency and find that rats exposed to high doses of alachlor had a thyroid effect. That explains how alachlor got on “hormone-disrupter” lists, but it doesn’t explain what caused the thyroid effect.

Here’s that explanation: Rats were fed a dose of alachlor 13 million times higher than expected human exposure. The dose was so high that the rats’ livers began to degrade hormones at an increased rate. The thyroid responded by overproducing hormones. After doing so for an extended period, the thyroid gland became damaged.

If one looks further into EPA records, one would learn that EPA agrees that there would be no thyroid or any other hormonal effect without the high dose.

WILLIAM F. HEYDENS, PhD

Manager, Toxicology

Monsanto

St. Louis