Consumer's Union pesticide alarm is bogus: Study confuses safety and regulation

By Steven Milloy
Copyright 1999 Junkscience.com
February 20, 1999

They're at it again -- timed perfectly for the 10th anniversary of the alar scare. And like that scare, this one is rotten to the core, too.

Consumer's Union has a new report claiming that children are exposed to unsafe levels of pesticides. The study is flawed because its safety determinations were based on measurements that have little, if anything, to do with safety.

The study relies on three analytic constructs: (1) an Acute Toxicity Index (ATI); (2) a Chronic Toxicity Index (CTI); and (3) a Toxicity Index, a combination of the ATI and CTI.

The ATI is calculated by dividing 100 by the LD50 -- the dose of a chemical that kills half of the exposed group of test animals. There is an LD50 for every substance, including water, table sugar and table salt.

The regulatory levels of exposure to pesticide residues are obviously set well below the LD50 levels. They are also set well below "safe" exposure levels. In any event, the ATI has nothing to do with safety.

The CTI is calculated from a regulatory construct called the "reference dose" or "RfD," which also has nothing to do with safety.

To calculate an RfD, you first determine the dose level in an animal experiment at which no adverse effect was observed or the lowest dose level at which an adverse effect was observed. This dose level is then arbitrarily -- i.e., based on political, not scientific consideration -- divided by a number anywhere from 10 to as much as 3,000. That's the RfD.

Clearly the CTI has nothing to do with safety either.

And since neither the ATI not CTI involve safety, it follows that the TI doesn't either. That means the Consumers Union study has nothing to with safety -- a point completely lost upon the media.