News Coverage
Studies find disturbing amounts of chemical contamination in lettuce
Published April 28, 2003
For six months of the year, 70% of the nation's lettuce comes from a few Western counties irrigated by the Colorado river.
Now, two studies have found that some of this winter lettuce is contaminated with perchlorate, a pollutant that has found its way into the groundwater in as many as 20 states, from the manufacture of rocket fuel, flares and munitions and is known to contaminate the Colorado.
A study by the Environmental Working Group found perchlorate in four of 22 lettuce samples purchased in January and February in the San Francisco Bay Area.
The four positive samples had more than 30 parts per billion of the pollutant. The U.S. Environmental Protection Agency has set a preliminary safety level of one part per billion of perchlorate in water.
And recent tests by The Press-Enterprise newspaper of Riverside, Calif., found perchlorate in 18 of 18 lettuce samples, at an average of eight parts per billion.
Perchlorate affects the thyroid gland and can disrupt hormone production. This is of particular concern to pregnant women because proper thyroid function is crucial to the development of a baby's brain and nervous system.
It's believed that the Colorado's contamination comes from two now-closed perchlorate plants near Las Vegas. The plants' water is known to contain perchlorate levels from three to 10 parts per billion.
Lettuce was tested because it is mainly composed of water. Jeff Farrar of the California Department of Health Services noted that the environmental group's study was very small, "so no major scientific conclusions can be drawn from it."
But it does raise important questions. "There's just not a lot of information out there on perchlorate, both in crops and in animals used for foods," he says.
In fact, there's no consensus on what a safe level for perchlorate in water would be. The EPA has asked the National Academy of Sciences to review its preliminary level of one part per billion.
The state of California has set a water level of four parts per billion, but no level for food has been set.
But the Environmental Working Group's Bill Walker says recent research shows that to protect infants in utero, it should be set at 0.1 part per billion.
This is truly a national issue, says Farrar, and California is looking for federal agencies to take the lead. A Food and Drug Administration official said people shouldn't start avoiding lettuce or changing their diets. Agency scientists are developing ways to test for perchlorate in foods before taking a nationwide look at the problem.
Perchlorate pollution is highly politicized because almost all production can be either directly or indirectly traced back to the military. The Pentagon has argued that perchlorate is safe in drinking water at levels much higher than the EPA has set.
The Bush administration has backed a bill before Congress that would exempt the Pentagon and defense contractors from environmental regulations requiring the cleanup of toxic waste, saying that compliance would hinder military readiness. Hearings are to begin next week.