News Coverage
Federal tests find perchlorate in food
Lettuce growers, state officials say the levels do not pose a health threat
Published November 22, 2003
Federal tests released this week provide mounting evidence that a rocket-fuel chemical is finding its way into winter lettuce irrigated with tainted Colorado River water.
The tests are the first acknowledgement by the federal government that perchlorate, a chemical used in NASA rockets, fireworks and military missiles and ammunition is turning up in the nation's food supply. The Colorado River contamination is from a former perchlorate manufacturing plant near Las Vegas.
Canada is worried about the contamination and is preparing to test lettuce and other crops imported from the rich agricultural region straddling the California-Arizona border, a Canadian food-safety official said.
In the United States, health experts said the levels of perchlorate found in lettuce grown in California and Arizona are so low that they are unlikely to have any significant effect on human health. In high doses, perchlorate is known to disrupt the thyroid's ability to produce hormones necessary for metabolism and fetal development.
Discoveries of perchlorate in food could lead to stricter limits in drinking water to reduce overall exposure. California is expected to develop a health standard for perchlorate in drinking water within the next year. A federal counterpart could be years away.
The U.S. Department of Agriculture released test results this week that showed measurable levels of perchlorate in six of 10 samples of Romaine and leaf lettuce gathered last spring from the lower Colorado River valley.
Perchlorate was not found in samples of carrots, corn and onions that were tested, said Allen Jennings, director of the USDA's Office of Pest Management Policy. The chemical tends to concentrate in leaves, making leafy vegetables more susceptible, he said.
"We don't see the accumulation in other crops," Jennings said by telephone from his office in Washington, D.C. "We take comfort in that."
An earlier study by Texas Tech University found perchlorate in cow's milk purchased in grocery stores.
Hank Giclas, vice president of strategic planning, science and technology for the Western Growers Association, said the doses found in lettuce are small and don't pose a health threat.
"We have confidence in the safety of what we are shipping and continuing to ship," Giclas said by telephone from Irvine.
Still, he added, "We don't like to have a compound like this in the water."
More tests
For now, food regulators aren't expected to do much more than conduct additional tests until a human health standard is set for the chemical, which is currently unregulated, Jennings said.
"We are trying to get a better idea of what food is contaminated with perchlorate and at what level, but until there is a health standard there is not much we can do, other than collect the data and be prepared," he said.
He said Food and Drug Administration will be doing more comprehensive studies. Food and Drug officials did not return phone calls seeking comment Friday.
Rene Cardinal, chief of fresh produce safety for the Canadian Food Inspection Agency, said the government will test for perchlorate in samples of lettuce and other crops grown in Southern California and Arizona.
"If the water is contaminated and the produce is contaminated, it is my responsibility and my concern," Cardinal said by phone from Montreal.
In the United States, the health effects of perchlorate have been fiercely debated. Military and industry officials have argued that levels as high 200 parts per billion are safe for humans.
The federal Environmental Protection Agency's current draft drinking-water guideline, a level at which regulators believe the chemical would not harm even the most vulnerable people, ranges between 4 and 18 parts per billion.
The health standard could have a huge impact on the military, the nation's biggest consumer of perchlorate, because of potential liability for existing water contamination.
A National Academies of Science committee is examining whether an EPA report released nearly two years ago provides an accurate estimate of perchlorate's risks to human health. That EPA report was intended to provide the scientific foundation for standards governing how much perchlorate is allowable in drinking water.
Bill Kearney, a National Academies spokesman, said the committee expects to conclude its work by late summer or early fall next year.
California also is trying to develop health guidelines for perchlorate in drinking water. A proposed public health goal, which could eventually form the foundation for a state drinking-water standard, is undergoing scientific peer review.
In that recommendation, food was considered a minor contributor to the total amount of perchlorate a person might consume, said George Alexeeff, deputy director of the state's Office of Environmental Health Hazards Assessment, which developed the draft public health goal. Contaminated drinking water was considered the main source.
But as more tests turn up perchlorate in lettuce, milk and other foodstuffs, scientists may have to reassess, he said. The result may be a stricter standard for drinking water.
Still, Alexeeff said he does not consider the small amounts of perchlorate found in lettuce to pose a major health risk.
"At that level, it would be an insignificant risk level," Alexeeff said. "I don't have any concerns on an individual basis. I eat a lot of lettuce myself."
The USDA began having food crops tested after studies of winter lettuce commissioned separately by The Press-Enterprise and the Environmental Working Group last spring detected perchlorate in lettuce samples. Charles Sanchez, a University of Arizona researcher who led the USDA study, sampled leaf and Romaine lettuce gathered from farms on the Arizona side of the Colorado River. He found perchlorate in all 10 samples, although he could quantify the amounts in only six of the samples. The concentrations in those heads ranged from 54 to 85 parts per billion; Colorado River water carries 4 to 9 parts per billion.
Perchlorate was found in the river in the late 1990s and was traced to a plant where perchlorate was manufactured for the U.S. military for more than 40 years beginning in the early 1950s.system from the defunct plant. Nevada officials have said a cleanup should reduce the pollution to about 50 pounds a day.
The Western Growers Association supports efforts to determine the extent of crop contamination and clean up the river, Giclas said.