News Coverage
More tainted lettuce found
PERCHLORATE: Another study shows the chemical in store-bought heads of the leafy vegetable.
Published April 27, 2003
An environmental group is calling for widespread testing of the nation's food supply after a rocket-fuel chemical was found in lettuce purchased at Bay area grocery stores.
The Environmental Working Group's lettuce study, to be made public today, found perchlorate contamination. A test of Inland lettuce samples commissioned by The Press-Enterprise and reported Sunday also found perchlorate.
About 90 percent of the nation's winter lettuce is grown in California and Arizona, irrigated with Colorado River water. The lower reaches of the river have been polluted with perchlorate from a plant near Las Vegas that manufactured the chemical until 1998.
"They ship this stuff (lettuce) all over the nation, so we just might as well have bought this stuff in Maine," said Renee Sharp, an Oakland-based analyst with the group who wrote the report. The nonprofit organization, based in Washington, D.C., does research focusing on pollution of air, water and food.
Perchlorate has been linked to impaired thyroid function and has been shown in laboratory animals to cause cancer and to harm brain development. But it's not clear whether long-term consumption of small amounts can affect people's health.
Based on its lettuce findings and other research, the Environmental Working Group is demanding:
* Cleanup of perchlorate pollution in the Colorado River.
* Widespread testing of the nation's food supply and testing of irrigation water.
* That the U.S Department of Defense remain responsible for perchlorate pollution at military sites.
* That future drinking water standards for perchlorate adequately reflect exposure through food.
Crop testing
Officials with the U.S. Department of Agriculture and the U.S. Food and Drug Administration said Friday that they plan to move forward with testing of crops irrigated with perchlorate-tainted water. They want to determine whether various fruits and vegetables contain perchlorate, a chemical used in rocket fuels and fireworks.
The environmental group's report said that a one-cup serving of lettuce could contain four times more perchlorate than a "reference dose" proposed by the U.S. Environmental Protection Agency. A reference dose, currently 1 part per billion, is the amount in drinking water considered safe for everyone, even the most vulnerable people.
Defense industry officials and some water agencies have criticized the EPA for proposing an overly conservative reference dose.
The environmental group purchased 22 samples of lettuce in January and February and had them tested by scientists at Texas Tech University in Lubbock.
Perchlorate averaging 70 parts per billion was detected in four samples, the group's report said. Perchlorate in the Colorado River has been measured between 4 and 9 parts per billion.
The Press-Enterprise tests found less perchlorate in the Inland lettuce but found the chemical in each of the 19 samples tested. The lettuce collected at Inland grocery stores, an Imperial Valley farm and a Riverside back yard averaged about 8 parts per billion.
Complementary tests
Shridar Susarla, a University of Georgia research engineer who tested the lettuce for The Press-Enterprise, said the two sets of test results complement each other. He said the lower concentrations he found could be attributable to differences in the weather when the samples were harvested from fields.
Perchlorate pollution in the Colorado River has been traced to a factory near Las Vegas owned by the Oklahoma-based Kerr-McGee Corp.
The company's medical director, Dr. John Gibbs, said perchlorate in food crops would be unlikely to harm humans.
"Even if some perchlorate is taken up (from Colorado River water), it's such a low level compared to what we've seen in our employees and in other studies, it wouldn't be a health effect," Gibbs said.
He said he would have difficulty commenting on any study of perchlorate in lettuce until he could see the results and examine how the tests were conducted. But he suggested that chemical tests in food are difficult to conduct and that results could be skewed by such things as use of certain fertilizers. He said certain Chilean fertilizers have been found to contain 1 to 3 percent perchlorate.
"The more people are looking, the more they're finding it," Gibbs said.
Sharp said she's concerned that much of the nation's food supply also may be contaminated.
"There are so many unanswered questions," she said. "This may be the tip of the iceberg."