Not long after a New Zealand report damning the health claims associated with organic foods, a new study which compared pesticide residue data on fresh produce grown organically and conventionally has found significant difference between the two, and puts forward a strong case for organic foods.
A research team including scientists from the Organic Materials Review Institute (OMRI), an independent US-based organic-agriculture research,organisation and the American Consumers Union (CU), carried out the study which is published in the 8 May issue of Food Additives and Contaminants.
The researchers analysed test data on pesticide residues in more than 94,000 organic and non-organic food samples of some 20 different crops tested over nearly a decade. Data were obtained from three independent sources: tests undertaken by CU in 1997 on selected foods; surveys conducted by the Pesticide Data Program of the US Department of Agriculture on residues in a wide array of foods available on the US market; and California Department of Pesticide Regulation surveys of residues in foods sold in California.
"Our research confirms what organic farmers have known all along, but now we have the data to back it up," said Dr Brian Baker, OMRI research director and the study's lead researcher.
"Organic food clearly offers consumers the best choice to avoid pesticides in their diets," he said.
The USDA data showed that 73 per cent of conventionally grown produce had at least one pesticide residue, while only 23 per cent of organically grown samples of the same crops contained residues.
Also, more than 90 per cent of the USDA's samples of conventionally grown apples, peaches, pears, strawberries and celery had residues. Conventionally grown crops were also six times as likely to contain multiple pesticide residues.
In California state testing, residues were found in nearly a third of conventionally grown foods, but in only 6.5 per cent of organic samples. The researchers remarked that the California data were based on tests with less-sensitive analytical methods than those used to generate the USDA data, and hence, did not include many low-level residues detected by the USDA's testing methods.
California testing also revealed multiple pesticide residues nine times more often in conventional samples than in organic samples.
The Consumer Union's tests found residues in 79 per cent of conventionally grown samples and in 27 per cent of organically grown samples, with multiple residues six times as common in the former.
"Our team was struck by the consistency of the pesticide residues reported in three very different datasets. We now can say with confidence that organic farming systems help reduce exposure to pesticides in the human diet," one of the authors, Benbrook, explained.
The CU's Groth added: "Our findings are clear and compelling. These results are good news for consumers looking for ways to minimize pesticide exposures."
However the team did note that while fewer pesticide residues were found on all organic samples, some might question why there were any residues found at all. According to Baker, "organic" is not a pesticide-free claim, due to many factors beyond the control of the organic farmer. Most residues in organic samples appear because of pesticide spray drift from adjacent fields, or soil or irrigation-water contamination, he said.
"Mislabelling and occasional fraud also clearly account for some of the organic samples that tested positive for residues," Baker said. As an example, he referred to a Mexican sample of "organic" sweet bell peppers that contained six different pesticide residues.
The researchers noted that organic farming systems offer both organic and conventional farmers proven methods to lessen pest populations and pesticide use, and thus, also reduce the pesticide risks faced by farm workers and consumers.
They added that organic farmers and certifiers could benefit from routine access to information on pesticide residues found in organic food samples tested by government programmes. Early detection of residues would help certifiers, growers, and the organic food trade identify and deal with instances and locations where pesticide drift or soil contamination is leading to detectable residues in organic foods.
A summary of the study, as well as charts and tables that illustrate study results, can be found at http://www.omri.org/FAC.htmland at www.consumersunion.org