Where's the beef? Consumer Reports' studies of pesticides and irradiated meat have come under fire. Credit: R. B. LEVINE/NEWSCOM

A food chemist has accused a leading consumer publication of using flawed science in its food safety surveys.

The researcher says that Consumer Reports, which has four million subscribers, ignored published research that contradicted its tests on food irradiation, and used an unscientific toxicity scale to measure pesticide residues.

Joseph Rosen, who works at Rutgers University in New Brunswick, New Jersey, made the claims at a session on organic food at the American Chemical Society's annual meeting in Philadelphia on 23 August. The magazine rejects the allegations, saying its surveys are based on rigorous science developed by professional toxicologists and statisticians.

Rosen says he first looked into Consumer Reports' methods after reading an article on irradiated meat, which it published in August 2003. This examined US food producers' claims that treating meat with beams of electrons or γ-rays kills harmful bacteria. It concluded that treated meat had a “slight off-taste” and offered no safety benefit to the “careful cook”.

The magazine regularly examines industry claims, and its defenders say that it is a counterweight to the food industry's marketing. The magazine is “highly effective” in its approach, says Caroline Smith-Dewaal, food safety director at the Center for Science in the Public Interest, a Washington-based group that campaigns on food science issues.

But Rosen says that Consumer Reports based its irradiation article on reports from just two trained taste testers, and ignored a 2003 test involving more than 100 subjects conducted by researchers at Kansas State University. That study found that consumers could not tell irradiated from non-irradiated meat.

Consumers Union, the New York-based advocacy group that publishes Consumer Reports, says that it knew of the Kansas research, but that the magazine does not typically run consumer panels. “We evaluate attributes and not preferences,” says Urvashi Rangan, a toxicology and environmental health expert with the union. She adds that the article stated that the off-taste was subtle and might be missed by untrained tasters.

Rosen also says it is alarmist for the magazine to state that the energy in irradiation is “150 times the dose capable of killing an adult”, as consumers are not exposed to the beams. Rangan counters that the measure was needed to correct food industry promotional material, which portrays the beams as no more powerful than sunlight.

The magazine's work on pesticides also aroused Rosen's ire. A March 1999 article used a specially designed toxicity scale to compare residues on fruits and vegetables. Consumer Reports concluded that parents should avoid giving children large amounts of some produce.

Rosen says the evaluations used arbitrary factors, and that the scale confuses the maximum safe amount of a residue that can be consumed at once with that which can be consumed over a lifetime. Rangan concedes there is an arbitrary element to the weightings, but says that they were needed to allow comparison of residues in different foods.

“I was struck by the shoddiness of their work,” says Rosen, who advises the American Council on Science and Health, a lobby group generally supportive of the food industry. He says he gets no research money from the organization.