advocate/"reporter" John Stossel claimed in a now infamous
(and retracted) edition of ABC's 20/20 (4 February 2000, "The
Food You Eat") that organic produce was just as contaminated
by pesticides as conventionally-grown food, and indeed that not
only was more expensive but also less safe because of the likelihood
of dangerous bacteria. Stossel's allegations were shown not just
to be false, but knowingly fabricated: he made up the data and
was subsequently forced by his editors to apologize for the story
on air. [Note]
Baker et al. with real data on pesticide residues, summarized
in this publication. They find precisely what you would anticipate,
that organic produce contains fewer pesticide residues than either
conventionally-grown produce or produce grown using integrated pest
management techiques to lower, but not avoid, pesticide use.
IPM produce ranks between organic and conventional.
did they do? Baker et al. analyzed three different data
sets, comparing the frequency of encountering pesticides on produce
of different types. The data sets were: the US Department of Agricultures
Pesticide Data Program (PDP), the California Department of Pesticide
Regulation (DPRs) Marketplace Surveillance Program (California
EPA 1999), and
data from private tests on four selected foods carried out
by Consumers Union.
of the data were from measurements made from samples of food in
which the distributor made no claim about organic growing or IPM.
It was assumed that these samples were grown conventionally. Most
samples were from fresh fruits and vegetables. While the samples
cannot be regarded to be rigorously representative of market conditions
as a whole, the sampling (in all over 90,000 measurements of a broad
range of products) is sufficient to support general comparisons
of residue patterns across a wide range of different foods.
of the data sets included information about the use of pesticides
permitted in organic growing, such as botanical pesticides like
rotenone and pyrethrum, or metallic fungicides.
did they find? Organically-grown produce was less likely to
contain pesticide residues overall. For example, from the USDA dataset
they calculated that 23%, 47% and 73% of samples contained pesticide
residues for organic, IPM and conventional samples, respectively.
organochlorine compounds which are residual in soils accounted for
40% of pesticide detections on organic produce. These were also
present in the other produce types, which also had pesticides in
modern use. Excluding banned OC compounds from the organic calculation
reduces the percentage of positive detections from 23% to 13%. Excluding
banned OCs from the other two produce types had little effect: the
percent positive for IPM dropped from 47% to 46% whereas that for
conventional produce dropped only from 73% to 71%. With the California
data set, excluding banned compounds reduced organic detections
more than it reduced conventional detections.
pesticide types were found in many samples. Samples with 2-4 different
residues were common. Up to 14 residue types were found on green
pepper and spinach. Peaches, spinach, strawberries, pears, cucumbers
and celery also routinely carried multiple residue types.
frequency of encountering multiple residues, however, differed among
the three produce types:
the PDP (USDA) tests, 46% of conventional samples, 24% of
IPM/NDR samples and just 7% of organic samples had multiple
residues. DPR (California) found multiple residues in 12%
of conventional samples and about 1% of organic samples. CU
found multiple residues in 62% of conventional, 44% of IPM/NDR
and only 6% of its organic samples. These differences are
all highly statistically significant (p < 0.001)."
data from all three datasets, Baker et al. determined that
not only were residues less frequent on organic produce, but that
residue levels, when present, were also lower.
does it mean? Buying organic food will lessen consumers' intake
of pesticide residues. IPM (marketed as "no detectable residue"
produce) will reduce intake also, although not as much. People eating
conventionally-grown produce will regularly ingest pesticide residues
at higher levels and of more diverse types. Thus while there
is considerable scientific uncertainty about the health risks of
ingesting these residues, consumers can take precautionary steps
to lower current risks by choosing organic food.
growing conditions do not allow organic produce consumers to avoid
pesticide residues altogether. Residual soil contamination of banned
organochlorine pesticides continue to be picked up by produce, and
drift and volatilization of currently used pesticides continue to
create unavoidable contamination even for growers following organic
of the residual measurements on produce labelled organic, however,
were too high to interpret as drift or volitalization. They could
have resulted from mistakes in labelling, data entry error by the
surveys, or fraudulent misrepresentation of the product.
conclusions could not be reached in any given case [of high
residues on organic produce], but fraud, chain-of-custody
errors bythe grower or shipper, or laboratory error may explain
some relatively high positive samples. In about half the cases,
however, residues were very low and consistent with unavoidable
environmental contamination because of drift, persistent residues
in the soil, or contaminated irrigation water supplies."
noted above, the data sets contain one significant gap: a failure
to measure for the presence of natural pesticides. It thus might
be the case that organic produce contains much more of these, and
if they are dangerous, the benefits of lower conventional pesticide
residues could be negated. Baker et al. offer several comments
on this possibility.
conventional and organic growers use these natural pesticides.
growers, however, use any pesticide as a last resort. A survey
cited by Baker et al. indicates that 52% of organic farmers
never use even botanical pesticides, with fewer still using sulpher-
or copper-based compounds.
to Baker et al. available data on toxicity of "natural"
pesticides, when available, suggest lower toxicity compared to
conventional pesticides, as does farming experience. On the other
hand, available data are not plentiful and there may still be
unidentified hazards. Some synthetic pyrethroids (modified from
the plant extract) are estrogenic.
data gap warrants further study, both to determine the level of
natural pesticide residues and to increase understanding of their
toxicological profiles. Ultimately, what matters is not whether
they are synthetic
or natural, but rather whether they cause harm.
conventional farmers in both the USA and in countries that
export fruits and vegetables to the USA, continued implementation
of the FQPA [Food Quality Protection Act] will increase pressures
to eliminate or to markedly reduce residues of high-risk pesticides
in foods, especially foods that are prominent in childrens
diets. If the FQPA goal of an increased safety margin is met,
residues in conventionally grown foods will trend downward
toward levels currently found in some IPM/NDR foods. Tighter
residue limits and reduced pesticide use by conventional growers
should also reduce drift incidents and other sources of unavoidable
environmental contamination. These factors may prompt organic
producers to make even greater efforts to avoid residues,
so that the organic label can maintain its distinctive promise
of relatively lower pesticide exposure and risk."