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