A laboratory test of 22 types of lettuce bought at Northern California supermarkets found that four were contaminated with perchlorate, a toxic rocket-fuel ingredient that has polluted the Colorado River, the source of the water used to grow most of the nation's winter vegetables.
The environmental group that paid for the testing by Texas Tech University conceded that the sample was far too small to draw any definite conclusions about how much perchlorate is in the lettuce Americans eat. But the organization, the Environmental Working Group, said the results were alarming enough to warrant a broad examination by the Food and Drug Administration.
"It appears perchlorate in produce is reaching consumers, which should be a wake-up call for the FDA," said Bill Walker, a western representative in the group's office in Oakland, Calif. "A lot of people might look at this and say it was only four out of 22 -- what is the problem? Well, when nearly one in five samples of a common produce item are contaminated with a chemical component of rocket fuel, that's significant."
In response, FDA officials said they had been planning to begin testing foods for perchlorate at a number of sites around the United States but were still developing the methods to do it.
"We do understand that there is a potential for perchlorate from irrigation water to end up in food," said Terry Troxell, the director of the FDA's office of plant and dairy foods and beverages. "We have already been moving in this area. We will certainly take their results into account."
The four lettuce samples all contained substantial quantities of perchlorate. One, a prepackaged variety of organic mixed baby greens, had a level of perchlorate contamination at least 20 times as high as the amount California now considers safe for drinking water. The other three were packaged butter lettuce and radicchio, romaine lettuce and radicchio and a plain head of iceberg lettuce. All were at least five times as high as California considers safe for water.
State and federal environmental officials believe that perchlorate, a salt widely used by the U.S. government to help power missiles and the space shuttle, may cause health problems, even in trace amounts. Because it is known to affect the production of thyroid hormones, which are critical to early brain development, researchers believe perchlorate exposure may be especially dangerous for pregnant women and young children.
