29 April 2003
Rocket Fuel Component in U.S. Lettuce: Study


LOS ANGELES (Reuters) -
California's winter crop of lettuce contains unhealthy levels of a rocket fuel component that can harm developing fetuses, according to a small study conducted for an environmental group by Texas Tech University.

The study, commissioned by the nonprofit Environmental Working Group, showed that lettuce produced in California's Central Valley farmland between October and March each year absorbs four times as much perchlorate from the Colorado River as is considered safe by federal environmental authorities.

Although just 22 samples of lettuce were examined for traces of the solid rocket fuel component, the study's organizers hoped it would spur a more comprehensive look at the situation.

"We are a small non-profit organization and we are hoping that the results from our admittedly small sample will spur the federal government to do a more definitive study," Environmental Working Group spokesman Bill Walker said on Monday. "This question has been around since 1997 yet the federal government has failed to clear it up."

Perchlorate is the explosive component of rocket and missile fuel and is highly soluble in water. Exposure to perchlorate can cause mental retardation, loss of hearing and speech, and motor skill deficits in developing fetuses.

Perchlorate contaminates the drinking water of 20 million people in 20 states, and the Colorado River, which irrigates 70 percent of the nation's winter lettuce, the study said.

The U.S. Environmental Protection Agency has tentatively set the standards for safe perchlorate levels in water at one microgram per liter but there are now no enforceable standards or widespread testing for the substance, the study found.

In January and February, the scientists bought 22 commercial lettuce samples for analysis, including prepackaged and head lettuces, adult and baby greens, both organically and conventionally grown from several different distributors.

Four of the samples contained an average of four micrograms per liter, the study said. Although the rest did not have measurable levels, researchers cautioned that the detection level for perchlorate in foods is relatively high.


29 April 2003
High Levels of Toxic Rocket Fuel Found in Lettuce
Environmental Working Group Report


Eating lettuce or other vegetables grown in fields irrigated by the Colorado River may expose consumers to a larger dose of toxic rocket fuel than is considered safe by the U.S. Environmental Protection Agency, according to test data and documents obtained by Environmental Working Group (EWG).

Test results never before made public show that leafy vegetables grown with contaminated irrigation water take up, store and concentrate potentially harmful levels of perchlorate, a thyroid toxin that is the explosive main ingredient of rocket and missile fuel.

Sworn depositions and other courtroom documents show that the giant aerospace and defense contractor Lockheed Martin — a major user of perchlorate responsible for widespread contamination of Southern California water supplies — knew as early as 1997 that vegetables stored high concentrations of the chemical, but said nothing to the EPA or state health officials. [PDF documents: Lockheed letter | Test results ] Since most perchlorate-related work by defense contractors is done for the U.S. military, the Department of Defense may also have known, but said nothing to warn other agencies, consumers — or farmers whose crops, through no fault of their own, may be tainted by contaminated irrigation water.

If the perchlorate levels reported here are confirmed by further testing, immediate government action will be needed to reduce perchlorate in lettuce and other vegetables. In the interim, we strongly recommend that the Food and Drug Administration immediately begin testing lettuce and selected other vegetables grown with Colorado River water for perchlorate, and that the results of this testing be made public as soon as they are confirmed.

In addition, any grower who is adversely affected by perchlorate contamination of their crops should be fully compensated for any and all economic losses to their farming operations and property values.

Perchlorate in food could threaten human health

In a front-page story on Dec. 16, 2002, The Wall Street Journal reported that “tests on several vegetable samples from a perchlorate-contaminated farm in Redlands found the plants concentrated perchlorate from local irrigation water by an average factor of 65, according to calculations by Renee Sharp of the Environmental Working Group in Oakland, Calif., one of the few nonprofit groups focused on perchlorate contamination. That means the perchlorate dose in the vegetables was 65 times the amount in the water.” Sharp told the Journal: “If people are eating it, on top of drinking it, the EPA will have to lower its proposed drinking-water standard substantially.” [ Read the story ]

Perchlorate, which impairs the thyroid’s ability to take up iodide and produce hormones critical to proper fetal and infant brain development, has contaminated almost 300 drinking water sources and farm wells in California and an unknown number of sources in at least fifteen other states. Sources known to be contaminated include the Colorado River from near Las Vegas to the Mexican border — the primary or sole source of irrigation water for farms in California, Arizona and Nevada that grow the great majority of the lettuce sold in the U.S. during winter months.

If the perchlorate concentrations shown in the test results obtained by EWG and cited by the Journal affect the entire Colorado River winter vegetable crop, it would have huge implications for current efforts to set safety standards for exposure to perchlorate. It would signal that decades of negligence by chemical manufacturers, the aerospace industry and the U.S. military have contaminated not only the drinking water of millions of Americans, but their food supplies as well.

Both the EPA and the state of California are working toward establishing standards for perchlorate in drinking water. Under state law, California is supposed to set a standard by January 2004, although progress has been delayed by a lawsuit filed by St. Louis-based Lockheed Martin and Kerr-McGee Corp. of Oklahoma City, which until 1998 manufactured the chemical at a now-closed plant near Las Vegas that is a main source of contamination of the Colorado River. (The sole remaining U.S. producer of perchlorate is American Pacific Corp. of Las Vegas; until 1988 its plant, now in Cedar City, Utah, was near Kerr-McGee’s in Nevada.) EPA says it doesn’t plan to adopt national standards for perchlorate in drinking water until at least 2006, although both local and state elected officials in California — where more contaminated sources are discovered almost weekly — are calling for faster federal action.

But the newly revealed test data suggest that vegetables from the Imperial Valley region of California and Arizona, which produces most of the nation’s lettuce sold nationwide from November to March, may be a more significant source of perchlorate exposure than drinking water.

In a 1999 study, the EPA’s National Environmental Research Lab grew lettuce seedlings in perchlorate-contaminated water and found that “perchlorate was accumulated in the leaves to significant levels” — by factors of 100 times or more. ( Susarla et al. 1999. ) The tests showed that lettuce was able to take up and store 95 percent of the perchlorate in the water. This extraordinarily high rate of bioaccumulation would mean that lettuce grown in water with even low levels of perchlorate could deliver large doses of the toxin to consumers — doses far higher than the EPA’s provisional drinking water standard.

But EPA discounted the results of the 1999 tests because the water used was contaminated with concentrations of perchlorate much higher than are typically found in water supplies, and because the lettuce seedlings were grown in greenhouses and harvested before maturity. Another 1999 lab study found that a variety of native (non-crop) plants took up perchlorate from water, a potential biological aid to remediating s oil and water contaminated by the chemical. ( Bacchus et al. 1999 .) Despite the troubling results of these studies and the absence of data on perchlorate in U.S. or imported produce, the EPA concluded that “the available information ... suggests that foods do not contribute to” perchlorate accumulation in the human body. (EPA 2002.)

To close the data gaps, in April 1999 the EPA convened an “eco-summit” whose attendees included the Air Force; a coalition of perchlorate manufacturers and users, including Lockheed Martin, called the Perchlorate Study Group; and five Indian tribes who are major producers of winter vegetables irrigated by the Colorado River. The year before, at a perchlorate forum in Henderson, Nev., the environmental manager for the Yuma, Ariz., Quechan tribe stated:


“Irrigation is a way of life for our people. We have 13,000 acres dedicated to the production of lettuce. We produce annually eight heads of lettuce for every man, woman and child [in the United States]. That food is produced from Colorado River water and 23 million people derive their water supply from the lower Colorado River in three states and two countries. That’s how big this problem is.” (Rogers 1998.)

At the “eco-summit,” top priority was given to a “real-world” study that would test a variety of crops through the Department of Agriculture, and the Department of Defense provided $650,000 to fund it and other studies. EPA, USDA and the Food and Drug Administration developed an extensive protocol for the study — before deciding it was too expensive and postponing it indefinitely.

Instead, the Air Force decided it would pay for a second study of greenhouse-grown lettuce. The findings of this second study have never been made public. In 2000, responding to a Freedom of Information Act request by a California public-interest law firm for “All materials related to any investigation or research conducted by, or for, any U.S. Government Agency, regarding the health effects of perchlorate on humans beings and the environment,” the Air Force provided some material, but nothing on either of the lettuce studies. The Air Force stated that those and other records "are fully exempt from disclosure until the formally sponsored EPA peer review is complete. They contain information that is exempt under the deliberative process privilege.” The EPA-sponsored peer review of proposed perchlorate standards is now complete, but the lettuce studies remain unreleased.

In October 2002, at a water industry-sponsored perchlorate conference in Ontario, Calif., Air Force spokesman Dave Mattie was asked about the second greenhouse lettuce study before a group that included regional EPA officials. Mattie replied that the study had been completed, but “someone walked away with the data.” When asked why the the “real world” study of vegetables grown with Colorado River water had been cancelled, Mattie again said it was for lack of funds.

But unknown to the EPA, there had in fact been a “real world” study of lettuce grown with perchlorate-contaminated water in 1997 — two years before the "eco-summit" at which such a study had been made a priority. And Lockheed Martin, a key member of the Perchlorate Study Group, was intimately aware of its results. Since the Air Force has worked closely with Lockheed Martin and other members of the Perchlorate Study Group on a number of perchlorate research projects — including unethical tests on human subjects — the U.S. military may have known of these earlier lettuce tests as well.

Lockheed Martin is responsible for polluting dozens of water supplies in the Redlands area of San Bernardino County, Calif., with high levels of perchlorate and other chemicals. A class action lawsuit has been brought against the company by more than 800 residents of the area, who blame contaminated drinking water for a variety of health problems including cancer. Farms in the area are not irrigated by the Colorado River, but draw from wells that have been contaminated by perchlorate plumes from now-abandoned Lockheed facilities.

Lawyers at Engstrom, Lipscomb and Lack in Los Angeles, who represent the Redlands residents suing Lockheed Martin, learned that the company had earlier been in negotiation with Lucky Farms, a San Bernardino grower of lettuce and other vegetables, over contamination of the farm’s water supply. The lawyers subpoenaed all materials from the negotiations, and have discovered that Lockheed was sitting on startling evidence of vegetables’ uptake and concentration of perchlorate.

The subpoenaed documents, obtained by EWG from the lawyers, showed that in late 1997 and early 1998, Lucky Farms conducted a series of tests on its produce to see if they were contaminated with perchlorate. [PDF documents: Lockheed letter | Test results ] These tests were conducted on four samples of “leafy vegetables” and four samples of some kind of “vegetable matter” which was not identified.

The results of the testing were dramatic: The four "leafy vegetable" samples averaged 4,490 micrograms of perchlorate per kilogram (ug/kg), with a maximum concentration of 6,900 ug/kg. Perchlorate levels in the “vegetable matter” were lower, averaging 213 ug/kg with a high of 420 ug/kg. Overall, the vegetables were found to have an average of more than 2,600 micrograms of perchlorate per kilogram — thousands of times higher than what the EPA considers to be a safe amount in a liter of water. Although there is currently no federal drinking water standard for perchlorate, the EPA’s proposed “reference dose,” which is what the agency considers the level that is safe to consume each day, is just one microgram per liter of water or two micrograms per day for an adult.

Despite the startling results, Lucky Farms was somehow persuaded not to bring legal action against Lockheed Martin. However, there was one significant result. Since at least 1995, farm workers living and working on Lucky Farms property were required to sign a form stating that they had been warned of the dangers of drinking irrigation water. [ View document ] But after perchlorate was found in the water (and vegetables) in 1997, the forms were amended to include a more specific warning: "This water may cause cancer or birth defects.”

According to EWG’s analysis, if a pregnant woman were to eat a typical serving of vegetables with the contamination level found at Lucky Farms, she would get a dose of rocket fuel more than 100 times higher than the EPA considers safe in a liter of drinking water. ( Figure 1. ) One sample of “leafy vegetables” contained 386 micrograms of perchlorate per one-cup serving, and the average amount of perchlorate in the vegetable samples was 146 micrograms per two-ounce serving.

figure 1 According to other documents acquired by Engstrom, Lipscomb and Lack, the perchlorate concentration found in the five wells on Lucky Farms’ property ranged from 10 to 130 parts per billion (ppb) and averaged 40.1 ppb. Because it is not known which wells were used to irrigate which samples it is difficult to calculate exactly how much each of the tested vegetables concentrated perchlorate, but using average figures for the amount of perchlorate found in the wells and the vegetables, EWG analysis shows that the vegetables concentrated perchlorate by a factor of 65. This means that perchlorate levels in the vegetables were on average 65 times higher than the levels in the water.

Such results are consistent with the high concentrations of perchlorate that have been found in non-crop plants growing in contaminated areas. (EPA 2002.) But the data has profound implications for future perchlorate drinking water standards — as well as for anyone who eats Imperial Valley lettuce.

The lower Colorado River is used to irrigate an estimated 1.46 million acres of farmland in California and Arizona. Water is distributed from the Colorado River to the nearby Imperial Valley of California and southwestern Arizona via extensive irrigation canals. It is used to grow a variety of crops including cotton, alfalfa, lettuce, wheat, citrus, barley, melons, dates, grapes, avocados, tomatoes, onions, carrots and cauliflower. (CRWUA 2002.)

Of particular concern for perchlorate accumulation is a high water content crop like lettuce (which requires three acre-feet of water per acre). In Imperial County, CA, 20,000 acres of iceberg lettuce and 10,500 acres of leaf lettuce were harvested in 1999. (Imperial County 2002.) That year, 45,000 acres of wintertime head lettuce, 5,300 acres of leaf lettuce and 9,300 acres of Romaine lettuce were harvested in Yuma County, AZ. (UA Extension 2002.)

EPA and the state of California are in the process of developing drinking water standards for perchlorate, and both are required to consider sources of exposure other than drinking water. The preliminary research on vegetable uptake of perchlorate strongly suggests that food is likely to be an equal or greater source for perchlorate, but so far this hasn’t been reflected in the proposed drinking water standards of either agency.

California’s latest draft public health goal (PHG) of 2 to 6 parts per billion (ppb) assumes that 80 percent of a person’s exposure to perchlorate comes through drinking water. (OEHHA 2002.) EPA has calculated a “drinking water equivalent level“ of 1 ppb for their most recent proposed reference dose (RfD), but has not yet considered the issue of relative source contribution in calculations of a proposed drinking water standard. (EPA 2002.) If vegetables irrigated with Colorado River water are in fact concentrating perchlorate, the drinking water standards will have to be substantially lower to account for the considerable exposure coming from food.

If Lockheed-Martin’s perchlorate is indeed contaminating crops to unsafe levels, FDA will have to take emergency action to keep the food off the market. And the growers will have to be compensated for damage to their farming operations and property values.


If the perchlorate levels reported here are confirmed by further testing, immediate government action will be needed to reduce perchlorate in lettuce and other vegetables. In the interim, we recommend that the Food and Drug Administration begin immediately testing lettuce and selected other vegetables grown with Colorado River water for perchlorate, and that the results of this testing be made public as soon as they are confirmed.

In addition, any grower who is adversely effected by perchlorate contamination of their crops should be fully compensated for any and all economic losses to their farming operations and property values.


  1. Bacchus, S.T., S. Susarla, L. Wolfe, G. Harvey, and S.C. McCutcheon. Predicting field performance of herbaceous species for phytoremediation of perchlorate. Paper presented at the August 22-26, 1999 meeting of the American Chemical Society.
  2. CRWUA 2002. Colorado River Water Users Association. www.crwua.org .
  3. Environmental Protection Agency. 2002. Perchlorate Environmental Contamination: Toxicological Review and Risk Characterization. External Review Draft. January 16, 2002.
  4. Imperial County 2002. Agricultural Commissioners Report for 1999.
  5. Office of Environmental Health Hazard Assessment. 2002. Draft Public Health Goal for Perchlorate in Drinking Water. California Environmental Protection Agency. December, 2002.
  6. Rogers, Keith, 1998. Chemical’s effect on crops worries tribes. Las Vegas Review-Journal. May 20, 1998.
  7. Susarla, A., N.L. Wolfe and S.C. McCutcheon. Perchlorate uptake in lettuce seedlings. Paper presented at the August 22-26, 1999 meeting of the American Chemical Society.
  8. UA Extension 2002. University of Arizona Cooperative Extension. http://ag.arizona.edu/crops/counties/yuma


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