Our Stolen Futurea book by Theo Colborn, Dianne Dumanoski, and John Peterson Myers
 
 

 

 

Baker, BP, CM Benbrook, E Groth III and KL Benbrook. 2002. Pesticide residues in conventional, integrated pest management (IPM)-grown and organic foods: insights from three US data sets. Food Additives and Contaminants 19 (5): 427–446.


 
 

NYT press coverage

Industry 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]

Enter 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.

What 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 Agriculture’s Pesticide Data Program (PDP), the California Department of Pesticide Regulation (DPR’s) Marketplace Surveillance Program (California EPA 1999), and
data from private tests on four selected foods carried out
by Consumers Union.

Most 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.

None 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.

What 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.

Banned 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.

Multiple 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.

The frequency of encountering multiple residues, however, differed among the three produce types:

 

"In 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)."

 

Pooling 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.

What 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.

Current 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 procedures.

Some 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.

 

"Firm 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."

 

 

As 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.

  • Both conventional and organic growers use these natural pesticides.
  • Organic 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.
  • According 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.

This 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.

The good news:

 

"For 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 children’s 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."

 

 

 

 
 

 

 

Note, from above: This episode presaged the effort by ABC executives in Spring 2002 to replace Nightline newsman Ted Koppel with comedian David Letterman. A traditional news organization would have fired Stossel for his fabrication. ABC, in contrast, apparently places ratings above honesty and news value. Koppel should have seen the writing on the wall when Stossel was allowed to stay.

Stossel's transgressions linger on, continuing to sully his reputation. In Spring 2002 he was gently ridiculed on air by Daily Show (Comedy Central) host Jon Stewart, who asked whether Stossel's editors require review of everything he airs.

 

 

 

 

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