Organic Lettuce Passes the PDP Test with Complete Success

July 31, 2011

Close-up of an iceberg lettuce field in Northe...

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In 2009, the Pesticide Data Program (PDP) of USDA tested a total of 386 organic lettuce samples, by far the most extensive sampling of organic food crop for pesticide residues that is carried out ever in the world.

The results are very encouraging and remarkable. Only four samples were found to have pesticide residues that are not authorized for use in organic production. Three samples contained organophosphate insecticide phosmet and one sample contained synthetic pyrethroid insecticide cypermethrin.

Accordingly, just over 1% out of 386 samples of organic lettuce contained a residue that should supposedly not present. On average over the past decade, around 25% of organic produce samples has contained a pesticide residue that is not approved for use on organic farms.

Two pesticides were also found to have a total of 78 residues approved for use on organic lettuce such as spinosad and neem (azadirachtin). Consequently, taking into account all pesticides found on organic lettuce, the average organic sample contained 0.2 residues.

In the last year 2005, PDP tested conventional lettuce contained an average of 3.9 residues per sample. Consequently, conventional lettuce contains an average of about 19-times more residues compared to organic lettuce.

In terms of risk levels, based on the percentage of each pesticide’s toxicity, samples testing positive and mean of positives, the Organic Center uses a “Dietary Risk Index” (DRI) to translate residues that were found in a given food into quantitative measure of relative pesticide risk.

Both organic lettuce and conventional pose relatively low pesticide risks per serving. The conventional lettuce DRI in 2005 was 0.118, while the organic lettuce DRI in 2009 was 0.001, about 120-fold lower.

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