Chemical Residues in Food: The Debate Goes On
The debate over the threat posed by chemical residues in food was underscored recently by two separate but related developments that demonstrate again why consensus on the issue is elusive and the discussions are heated.
The first episode was driven by economics. Namely, the California Legislature passed a bill last month that would further delay the ban on methyl bromide--a fumigant believed to deplete the Earth’s ozone layer--for two years or until 2001.
Gov. Pete Wilson and agriculture interests, led by such groups as the Western Growers Assn. in Newport Beach, lobbied heavily for the postponement because there are no suitable replacements for methyl bromide. The chemical is used on strawberries, grains, nuts and other export crops to control insects, bacteria, nematodes and weeds.
A ban before another chemical substitute could be found would pose severe financial hardship on several leading sectors of the state’s agriculture industry. A recent study by the state’s Department of Food and Agriculture estimates the loss from damaged crops in the absence of methyl bromide at $346 million annually in California.
In the current political climate, economics takes precedence over suspected damage to the environment.
California’s rescheduled methyl bromide ban will now coincide with a similar Environmental Protection Agency-ordered phase-out of the chemical for the entire country on Jan. 1, 2001.
Nevertheless, big agriculture’s continued use of methyl bromide here has prompted criticism by environmentalists. State Sen. Tom Hayden (D-Santa Monica) even suggested a boycott of produce sprayed with the chemical, most notably strawberries.
Hayden’s comments, according to his spokesman, were made in the context of the ozone debate, and there is no organized effort to orchestrate a boycott of California strawberries, currently entering their peak harvest season of April, May and June.
The criticism is a continuing concern for the industry because the fruit was also targeted recently by the Washington-based Environmental Working Group as being among the “10 worst” produce items in terms of farm chemical residues. An estimated 70% of strawberries analyzed by the Food and Drug Administration were positive for pesticides, although the levels are within federal guidelines for the crop and are considered safe.
Teresa Thorne, communications director for the California Strawberry Commission in Watsonville, says that her member growers have never made a secret of their need for methyl bromide. However, she points out, the state’s $608 million strawberry crop accounts for only 10% of California’s total methyl bromide usage.
Thorne speculates that Hayden, the Environmental Working Group and others have singled out California strawberries because they are a popular food that, according to commission surveys, is purchased by 94% of all consumer households.
“We are very popular and very recognizable. That is a big reason why we get a lot of attention,” she said.
At virtually the same time as California’s methyl bromide controversy, there was the release in Washington of a little-noticed National Research Council report on the relative cancer risk presented by chemical residues in food.
The council convened a distinguished panel of scientists to review the scientific literature and determine whether synthetic chemicals--such as pesticides and additives--pose a greater risk of causing cancer in humans than do naturally occurring chemicals--such as mycotoxins and alkaloids--found in food.
The group’s 407-page report, Carcinogens and Anticarcinogens in the Human Diet, concludes, “Data are insufficient to determine whether the dietary cancer risks from naturally occurring substances exceed that for synthetic substances.”
The popular perception is that man-made compounds are much more toxic and carcinogenic than those that naturally occur in foods or are created during routine processing or cooking. The opposing school of thought, led by UC Berkeley biochemist Bruce Ames, maintains that naturally occurring chemicals are more of a cancer risk than synthetic chemicals because they are present in far greater numbers throughout the food chain. Based on the NRC report, neither side can claim victory and, in a sense, state-of-the-art science was again unable to resolve the long-running dispute.
The dilemma did not prevent some involved in the residue debate from spinning the report to their benefit.
The International Food Information Council, a nonprofit group funded by the food and beverage industries, was quick to issue a statement essentially dismissing the residue question.
“By enjoying a wide selection of foods in moderate amounts from our safe and abundant food supply, adequate physical activity and moderate intake of alcohol, we can strive for cancer prevention every day,” the council stated. “The [NRC] report acknowledges that some compounds found in minute amounts in the food supply are known to be carcinogenic, but the dietary risk to humans is small.”
There are more than 500,000 cancer deaths annually in this country, with an estimated 35% of these attributable to diet-related causes. How many are the result of life-long consumption of a particular chemical is unknown, according to the NRC report.
More likely causes of cancer, the group concluded, was excess calorie intake, high-fat diets and alcohol abuse. But again, the panel hedged, saying that the evidence has not shown, for instance, over what aspect of fat (high calories, the saturated fat content, or the byproducts produced by cooking) may trigger the disease.
The NRC report added that the entire process for determining which ingredients or chemicals in foods are carcinogenic, including rodent-feeding studies, is flawed and inadequate.
Ronald W. Estabrook, chair of the group which prepared the report, stated, “The ability to relate results obtained using rodent [feeding tests] to the [cancer] risk for humans--who are exposed to low levels of a chemical in a complex mixture (of other chemicals in the diet)--is a weakness that puts into question how the results of such evaluations are applied. . . . We need to know much more than we know today.”
In fact, the whole field in which chemicals act as anticarcinogens in the diet has been generally overlooked and also needs closer examination.
“[Anticarcinogens] have been so inadequately studied that their effect is uncertain,” the NRC report concluded.
To further cloud the pesticide residue question a report was released Friday by the World Resources Institute, a Washington-based environmental group, that claims the real risk from pesticides is to the immune system of children and adults.
“The most widespread public health threat from pesticides is immunosuppression that weakens the body’s resistance to infectious diseases and to cancers,” the institute stated.
The group is calling for more research by the World Health Organization into the link between pesticide exposure and immune systems damage. It is a conclusion shared by every commission or agency that has ever studied the question of chemical residues in food.
