Commercially marketed "produce washes" that claim great efficiency in removing pesticide residue from vegetables are in fact not much more effective than plain tap water, according to a new study by UC Riverside researchers.
Robert Krieger, a toxicologist with the university's extension office, was intrigued reading advertising that such washes are as much as 10 times more effective than water -- claims he determined are a mathematical impossibility because water itself is so efficient.
The research comes amid increased consumer concern over pesticides left on produce.
TGI Friday's Inc., operator of a chain of popular restaurants, used to advertise on its menus that its vegetables were washed with Procter & Gamble Co.'s Fit Fruit and Vegetable Wash. Proctor & Gamble marketed not only the wash but a Fit Soak Bottle and a Fit Washing Kit containing a colander and bowl in which to wash the produce.
Yet "clearly this study shows that there is no reason to spend extra money on these washes when water is just as effective," Krieger determined.
The research is to be formally published in February's Bulletin of Environmental Contamination and Toxicology.
The study focused on one of the lesser claims, that Procter & Gamble's Fit wash was "98% more effective than water at removing pesticides most commonly found on produce."
"When you make a statement that it's [nearly] 100% better than water, put your money on the table -- you're wrong," Krieger said. "As soon as they did that, they created unrealistic expectations" on the part of consumers.
The research triggered questions but no action from the Federal Trade Commission.
Procter & Gamble spokeswoman Melissa Johnson said the company discontinued Fit wash last year as "strictly a business decision" to concentrate on more popular products. In a summary of its research, the company said its claims were confirmed by independent laboratories in 1995 and 1999, using California produce.
Other companies, meanwhile, claim that their vegetable washes are three, four, five or even 10 times more effective than water.
That's mathematically impossible, because water alone removes much of the pesticide residue, Krieger said.
"Water is a pretty effective solvent," he said. "If water takes off 50%, you can't take off 10 times more than that because that's 500%."
Researchers conducted their study with samples of California fruit that had been routinely sprayed with pesticides in the field.
They found that water removed 39% of pesticide from one group of fruit, and that Fit removed 45%. In a second study, water removed 81% and Fit removed 90% of one type of residue. The split was 18% and 39% for a different pesticide remnant, respectively.
In addition, researchers had 10 households run the water-versus-wash tests over several days.
"We wanted to really see if it made a significant difference" under real life and laboratory conditions, Krieger said. "The results were exactly the same."
All the pesticide residue levels -- even on the unwashed produce -- were well below federal environmental and health guidelines, Krieger said.
The study tracks a 2000 World Health Organization summary finding that water alone substantially reduced pesticide residue on fruits and vegetables.