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Pesticide fears and bad diets

Posted 12/09/2011 by KatieJ

Bruce Ames is a world authority on cancer. His Ames test for the disease – which uses bacteria to assess whether substances damage the genetic material DNA and thus may be potential carcinogens – has become a hallmark for carcinogenicity testing since it was invented in the 1970s. Thirty years on, however, Ames is more concerned about human nutrition – and particularly the paucity of essential vitamins and minerals even in developed world diets, he told delegates attending last month’s ACS meeting in Denver, Colorado.

A significant proportion of the typical American diet offers no nutritional benefit at all, other than as an energy source, Bruce lamented. And fears about the potential carcinogenicity risks of pesticides aren’t helping to encourage consumers to eat more fruits and vegetables since organic varieties are considerably more expensive – despite the absence of scientific evidence that they are any safer. Indeed, food poisonings such as E. coli and Salmonella are just as if not more likely with organic produce, he continued – pointing for example to incidences such as the E. coli outbreak in bagged organic spinach.

In a paper in Science in 1990, Ames and colleague Lois Swirsky Gold reported research indicating that almost all pesticides – more than 99% – in the human diet are substances present naturally in plants to protect them from insects. While animal cancer tests are done at the ‘maximum tolerated dose’ (MTD) of synthetic chemicals such as pesticides, the results are being ‘misinterpreted’ to mean that miniscule doses in the diet are relevant to human cancer, Ames believes. ‘Over half of all chemicals tested, whether natural or synthetic, are carcinogenic in rodent tests,’ Ames said – a finding that has more to the high doses tested than the real risk that this poses.

Unfounded worries over the risks of pesticides are not only bad science but they also have more serious consequences, Ames continued. Today’s obesity epidemic is largely the result of bad diets that lack healthy foods containing vitamins, minerals and fibre –ingredients that are all to be found in fruits and vegetables. Yet fears about the dangers of pesticides – and concerns over the high prices of organic foods – may stop consumers from buying them. With the obesity crisis set to grow even larger in coming years, at the same time that consumers’ budgets become more straitened and food productivity more strained, maybe this is a message that governments in developed nations should do more to get across.

Cath O’Driscoll- Deputy editor

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