Organic Food Test Detects False Labels

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April 12, 2007 — A new test could help identify fraudulently labeled organic food, say British scientists.

It's based on testing the food for signs of synthetic nitrogen fertilizers, which are banned in organic farming methods.

Alison Bateman of the University of East Anglia in Norwich and colleagues reported their findings in a recent issue of the Journal of Agricultural and Food Chemistry.

There are a number of food tests designed to pick up residues of synthetic pesticides and herbicides that are not permitted in organic farming. But Bateman and her team are developing a test to see whether foods have been grown using synthetic nitrogen fertilizers, based on testing the foods' nitrogen isotope composition.

Conventionally grown lettuce and tomatoes, for instance, contain nitrogen isotope ratios of the kind found in synthetic fertilizers, their research found. The team says this isotope test could potentially be used to detect conventional produce grown using synthetic fertilizers that is fraudulently labeled as organic.

But the test can't say for certain whether synthetic fertilizers have been used. Rather, their test can determine whether it is "unlikely" or "highly unlikely" that a food with a particular nitrogen isotope composition would have been grown without synthetic nitrogen fertilizers. And the test is likely to be more useful for some crops than others, say the researchers.

For example, in their study carrots had the same nitrogen isotope composition whether grown organically or conventionally. Bateman and her team point out one possible explanation is that growing carrots generally requires less nitrogen and are thus conventionally grown carrots are likely to have less synthetic fertilizer applied.

The demand for organic produce is growing globally, not only in major markets such as Europe and North America but also in developing countries. In 2004, the worldwide market value of organic produce reached $27.8 billion.

But the higher prices obtained by producers provides an economic incentive for a few unscrupulous traders to pass off conventionally grown produce as organic.

The authenticity of organic produce currently relies on inspection and certification of the whole food production process, from "farm to fork." Bateman emphasized that chemical tests should not be a replacement for such auditing.

Lyn Austin of the National Association for Sustainable Agriculture Australia, one of Australia's certifiers of organic produce, agrees.

"A test for synthetic nitrogen would be a useful extra test option where there is suspicion," she said. "But the test on its own per se cannot be thought of as a replacement for organic certification and inspection."

Scott Kinnear of another certification body, Biological Farmers of Australia, says such a test would be very advantageous.

"Our organization is from time to time called upon to investigate allegations and this testing appears to be most promising," he said.

Kinnear said the appropriate government agencies should conduct some baseline research in Australia to see if the variations observed in Europe and the UK also appear in Australia.

"If the cost is feasible then we would look favorably on incorporating this testing in to our random sampling of organic produce grown by our certified clients."

There are about 100 standards schemes for organic produce around the world.