CU Research Team Shows: Organic Foods Really DO Have Less Pesticides
WEDNESDAY, MAY 8, 2002
Amy Barr (OMRI)
Consumers Union Research Team Shows:
Organic Foods Really DO Have Less Pesticides
WASHINGTON – Do organically-grown
foods contain fewer residues of toxic crop pesticides than conventionally-grown
foods do? The answer is an emphatic yes, according to a scientific study published
today in the peer-reviewed journal Food Additives and Contaminants. The study
team included analysts from Consumers Union (CU), the Yonkers, NY-based publisher
of Consumer Reports magazine, and from the Organic Materials Research
Institute (OMRI), an independent research, education and evaluation organization
in Eugene, OR.
Organic foods are grown
without most synthetic chemical inputs used in conventional farming, and many
consumers who buy organic do so to avoid dietary pesticides. But the issue has
been surprisingly controversial, with some conservative and media commentators
claiming organic foods have just as many residues as foods grown conventionally.
"We have shown
that consumers who buy organic fruits and vegetables are exposed to just one-third
as many residues as they’d eat in conventionally-grown foods, and the residues
are usually lower as well," said Edward Groth III, Senior Scientist at
CU and one of the paper’s co-authors.
The paper published
today is the first detailed analysis of pesticide residue data in foods grown
organically and conventionally. "Until now, the scientific community had
few empirical data to answer this question," explains Charles Benbrook,
a consultant to CU and co-author of the paper. "But in the last few years,
enough good data have become available to do a rigorous analysis."
The authors obtained
and analyzed test data on pesticide residues in organic and non-organic foods
from three independent sources: Tests done on selected foods by CU in 1997;
surveys of residues in a wide array of foods on the US market conducted by the
Pesticide Data Program of the US Department of Agriculture in 1994 through ’99;
and surveys of residues in foods sold in California, tested by the California
Department of Pesticide Regulation in 1989 through ’98. The combined residue
data sets covered more than 94,000 food samples from more than 20 different
crops; 1,291 of those samples were organically grown. "We’ve pulled together
the best available data on residues in organic produce to generate a clear picture
of the category as a whole," says co-author Karen Benbrook, who carried
out much of the data analysis for CU.
The USDA data showed
that 73 percent of conventionally grown foods had at least one pesticide residue,
while only 23 percent of organically grown samples of the same crops had any
residues. More than 90 percent of the USDA’s samples of conventionally-grown
apples, peaches, pears, strawberries and celery had residues, and conventionally-grown
crops were six times as likely as organic to contain multiple pesticide residues.
The California data (based on tests with less sensitive detection limits) found
residues in 31 percent of conventionally grown foods and only 6.5 percent of
organic samples, and found multiple residues nine times as often in conventional
samples. CU tests found residues in 79 percent of conventionally grown samples
and 27 percent of organically grown samples,
with multiple residues ten times as common in the former. The levels of residues
found in organic samples were also consistently lower than levels of the same
pesticides found in conventional samples, in all three sets of residue data.
"The results are
remarkably consistent across all three data sets," says Brian Baker of
OMRI, a co-author of the study. "If we take the results as a whole, the
evidence is very convincing that-as you’d expect-there are fewer residues by
far in organically grown foods."
The USDA and CU tests
also included some samples of "green labeled" foods-foods that are
not organically grown, but are marketed with claims based on reduced pesticide
use, or "no detectable residues." Foods in this category had residues
in 47 percent of USDA samples and 51 percent of CU samples-intermediate between
results for organic and conventional crops.
The authors explored
reasons why organic foods contain any pesticide residues at all. When they excluded
residues of persistent, long-banned organochlorine insecticides such as DDT
from their analysis of the USDA data, the fraction of organic samples with residues
dropped from 23 to 13 percent. Most residues in organic foods (and some of the
residues in conventional foods) can readily be explained as unavoidable results
of environmental contamination by past pesticide use, or by "drift"
(sprays blown in from adjacent non-organic farms). Some tested samples may also
have been mislabeled as organic, either because of fraud or because of lapses
in maintaining the identity of foods as they moved from the farm to point of
purchase. Such problems represent opportunities for producers to improve their
performance, says Baker.
What about residues
of natural pesticides, used by some organic (and non-organic) farmers? Critics
of organic agriculture have suggested that residues of natural pesticides in
organic foods pose risks comparable to those of residues of conventional crop
chemicals in non-organic foods. The paper concludes there is no current evidence
to support that assertion, although the authors see this as an interesting question
that should be pursued with better data.
"At present there
are no good residue data on the botanicals and other natural pesticides, and
some of those substances definitely should be more fully evaluated for potential
toxic effects," says Groth. But he emphasized that "There is now no
objective evidence of a problem with residues of natural pesticides, whereas
health risks associated with residues of conventional pesticides in foods are
well-established and the focus of substantial regulatory efforts."
While the analysis for
this study was conducted with no funding from outside sources, the CU database
that made that portion of the analysis possible was developed with partial support
in recent years by since-completed grants from the Pew Charitable Trusts, the
Joyce Foundation, and the W. Alton Jones Foundation.
Union, publisher of Consumer Reports magazine, is an independent nonprofit testing,
educational and information organization serving only the consumer. We are a
comprehensive source of unbiased advice about products and services, personal
finance, health, nutrition and other consumer concerns. Since 1936, our mission
has been to test products, inform the public and protect consumers.