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June 7, 2000


Accuracy; Roush on % Positives


AgBioView - http://www.agbioworld.org, http://agbioview.listbot.com

Subj: Accuracy; Roush on % Positives
Date: Wed, 7 Jun 2000 5:30:35 PM Eastern Daylight Time
From: Charles Benbrook

Ag BioView List --

In the interests of keeping the discussion factually based, I offer
the following data in contrast to Rick Roush's statement in a June 7
message that "tests routinely fail to find any detectable residues in more
than 95% of foods sampled, at least in the US and Australia." I have seen
similar statements on this list. This is one issue and assertion that
there is an enormous database to draw upon in assessing accuracy.

USDA's Pesticide Data Program has become the most widely used and
highly regarded/accurate source of pesticide residues in domestic and
imported foods. It is the source EPA relies on most heavily when carrying
out a dietary exposure/risk assessment. With colleagues in Consumers
Union, we have analyzed this database extensively, as part of our work on
the implementation of the Food Quality Protection Act.

Across all foods tested by PDP in recent years about half of the
samples were found to contain one or more residues; about one-third have 2
or more. The exact percent in 1998 was 45% (see the 1998 PDP summary
report, page xii.

Nearly all samples of fruits and vegetables have one or residue; very
low percentages of many processed foods, oils, and grain are found to have
residues. Herbicide residues are rare; insecticide residues are the most
common, with fungicides somewhat less common (except for post-harvest
uses, which lead to residues in high % of cases).

I looked at our database across 1994-1998 PDP testing. There were
about 1,825 cases of a food-residue found across all countries of origin
(i.e., chlorpyrifos found on tomatoes from the U.S., and from Mexico; or,
dicofol found on pears from Chile). Of these 1,825 cases --

* 1,070 had one or more residues in 2% or more of samples tested;
* 770 had 5% positives or more
* 525 had 10% or more
* 240 had 30% positive or more
* 118 had 50% positives or more.

These data cover all food-pesticide-country or origin combinations with
10 or more samples.

For CU's detailed analysis of residues in foods, see the just released
report on the USDA's 1998 PDP testing, accessible at --


The tables are posted one at a time, since some are very long. Find
these at --

Also, I might note that EPA Administrator Browner will make a major
announcement tomorrow, I believe at 11:00 am EST, on the Agency's
long-awaited actions on ag and home/urban uses of chlorpyrifos. This is
likely to be the most important decision reached on an OP insecticide
under the FQPA, and will have major implications for use of higher-risk
OPs on fruit and vegetable crops. It should be noted that it is not
likely that the corn and cotton uses of Lorsban will be significantly
impacted, since they very rarely lead to residues in food.

Chuck Benbrook

Charles Benbrook CU FQPA site
Benbrook Consulting Services Ag BioTech InfoNet www.biotech-info.net
5085 Upper Pack River Road IPM site www.pmac.net
Sandpoint, Idaho 83864
208-263-5236 (Voice) 208-263-7342 (Fax)