Oranges to oranges

Going organic is an easy call for Wal-Mart and its competitors. For one thing, they can charge more for it. Organic food costs more to produce, but the profit margins are still higher than those in conventional food. And organic sales have exploded: While they only make up 2.5 percent of the US retail food market, sales have grown by an average of 20 percent a year since 1990.

Consumers, it seems, are increasingly willing to pay a premium for ``organic": food that has been produced under strict guidelines to minimize environmental impact and eliminate the use of synthetic chemicals, be they fertilizers, pesticides, or hormones. Organic farmers and purveyors tout a range of ethical and ecological benefits, from reduced soil erosion and cleaner rivers to happier livestock, but the majority of organic food shoppers, according to a recent Harris poll, are driven by concerns for their own health: They believe that organic food is either more nutritious or-being less laden with toxic chemicals-not as dangerous.

And yet, despite the $15 billion we spent on organic products last year, it's hard to find clear evidence that they're better for us. Some studies have been suggestive, others ambiguous, and interpreting the mix of data has occasioned a bitter debate. For the organic industry, as well as some botanists and public health experts, such results are simply a spur to further research. For the industry's critics-a small but vocal band of scientists and activists-they're further evidence that the organic movement may be little more than a confidence game.

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In 1939 the agronomist Eve Balfour, one of the early leaders of the organic movement, split her country estate into two plots, farming one organically and one conventionally. After nearly 40 years of study, she announced that, while her work had pointed out much of the waste and pollution inherent in conventional agriculture, she had found ``no consistent or significant differences between the sections" in terms of nutritional value.

Few organic proponents take this as the last word, however, and research on the nutritional content of organic versus conventional food continues. Donald Davis, a biochemist at the University of Texas, has found marked declines in the nutritional value of dozens of crops over the latter half of the 20th century, and he describes his work as supporting the notion that organic is healthier. ``The comparison was between conventional agriculture in 1950 and 1999," he says. ``But conventional agriculture in 1950 was more `organic' in that they were not using herbicides, pesticides, and fertilizers as intensively as they are now."

And some recent head-to-head studies comparing the nutrients in organic and conventional food have shown differences. Much of the current research focuses on levels of antioxidants, a class of compounds thought to help prevent cancer and strokes. Some botanists have theorized that plants grown with fewer pesticides create more antioxidants to defend themselves against parasites. Studies looking at Italian plums and French grapes have found higher antioxidant levels in the organic fruit. A team of food scientists at the University of California at Davis found similar results in corn and berries.

Organic skeptics, however, dismiss these results. Joseph Rosen, an emeritus professor of food toxicology at Rutgers University, charges that some of the antioxidant studies either misunderstood or fudged their results. He cites a 1999 Danish study showing that while some synthetic pesticides reduce antioxidant levels in crops, others actually increase it. And even if differences show up, Rosen believes the effect on the human body to be negligible: ``These antioxidants do not get absorbed very well by humans." Most of them, he says, are excreted.

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Many organic proponents admit that, in the words of Kathleen Merrigan, author of the USDA organic regulations and now an assistant professor at Tufts University's Friedman School of Nutrition Science and Policy, the science behind the nutrition claims ``is not ready for prime-time."

But it's a different story, they argue, on the issue of pesticides. Charles Benbrook is the lead scientist at the Organic Center, an organization set up by the organic industry to study and publicize the benefits of organic food. According to him, ``the most widely accepted benefit of organics is the absence of all synthetic pesticides," and the corresponding reduction in the risk of cancer and neurological disorders.

Organic farming is not pesticide-free. Even organic food contains trace amounts of long-lasting conventional pesticides, most of them now illegal, that were sprayed decades ago. In addition, organic farming allows for the use of certain pesticides, mostly (though not exclusively) compounds that are derived from natural substances and that quickly degrade after they're sprayed. Among them are pyrethrum, which is made from dried chrysanthemums and, according to the Environmental Protection Agency, is a likely human carcinogen. Rotenone, another organic pesticide, has been linked to Parkinson's disease in rat studies.

Still, as even organic skeptics concede, the stringency of organic regulations ensures that far less pesticide residue ends up on the food. ``There's reasonably good evidence that if it's a properly organic product, you're looking at less pesticide use," says Ewen Todd, a research scientist at the National Food Safety & Toxicology Center at Michigan State University. ``Whether that's a health issue is another question."

Todd and others don't argue that organic food is dangerous (though some claim that organic farming's higher reliance on manure rather than synthetic fertilizer increases the risk of e. coli and salmonella contamination). Instead, they insist that any difference in pesticide residue between organic and conventional food-and therefore any health benefit from organic-is trivial.

``The human risk," Todd argues, ``is very, very low. Any cooking process creates far more carcinogens than pesticides do."

According to Alex Avery, author of the forthcoming book ``The Truth About Organic Food" and a longtime organic food skeptic at the conservative think tank the Hudson Institute, even someone subsisting entirely on conventionally farmed fruit would ingest pesticide doses thousands of times lower than those regarded as dangerous by the EPA.

Not everyone shares Avery's trust in the EPA, however. Leo Trasande, a pediatrician and assistant director of the Mount Sinai Center for Children's Health and the Environment, believes that many EPA pesticide residue limits don't take into account children's unique vulnerability. While no studies have linked pesticides in food to health problems, a few have suggested that the residential spraying of some of the same pesticides used in agriculture leads to developmental problems in children and newborns. ``The little evidence that we have strongly suggests there is a danger from pesticides to brain development," says Trasande.

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The health question, then, remains an open one. But while health concerns may be the biggest part of the appeal of organic, they are still just a part. Some organic shoppers are driven by worries about the effects that pesticides and synthetic fertilizers have on the environment. Or they may just like the idea of supporting small farmers rather than the sprawling agribusiness plots associated with conventional farming.

Whole Foods, the country's leading organic retailer, emphasizes both of these benefits to its shoppers and shareholders. On its website, the company points to its own impeccable green credentials, and its stores are lined with photos of real-life local farmers, beaming amidst their produce.

But though real ideological differences separate the organic and conventional farming worlds, in certain ways the gap between the two may be closing. Many conventional farmers, while still relying much more heavily on pesticides than organic farmers, have reduced their spraying in recent years, partly through the use of plants genetically modified to produce their own pesticides (an organic no-no), and partly by adopting organic methods that take advantage of natural predators.

And organic is, perhaps in spite of itself, taking advantage of agribusiness-style economies of scale. Even before it acquired the Wal-Mart imprimatur of mass appeal, organic was big business. Whole Foods, a 180-store chain, posted $1.67 billion in revenue the first quarter of this year. And 70 percent of the organic lettuce sold in the United States comes from one company, Earthbound Farm, which grows over 100 types of fruits and vegetables on 28,000 acres spread through California, Colorado, Arizona, and Mexico.

All this without definitive proof of the health benefits of going organic. Should such evidence be found, there may be no telling how big an industry organic food could become.

Drake Bennett is the staff writer for Ideas. E-mail drbennett@globe.com.