Winter lettuce crops in California are contaminated with perchlorate, a component of rocket fuel, which can harm humans, especially infants and developing fetuses, according to a study.

Exposure to perchlorate, which is highly water-soluble, can cause mental retardation, loss of hearing and speech, and motor skill deficits in developing fetuses. The compound is a known contaminate of drinking water in 20 states and also contaminates the Colorado River, which irrigates 70 percent of the United States’ winter lettuce supply, according to the study.

In the study, researchers analyzed 22 commercial lettuce samples, including prepackaged and head lettuces, adult and baby greens, and organic and conventionally grown.

Four of the 22 samples tested contained perchlorate in excess of 30 parts per billion (ppb). The highest sample, mixed organic baby greens, had 121 ppb. In 2002, the Environmental Protection Agency found that perchlorate in drinking water poses health risks in concentrations above one part per billion.

Based on those results, the study researchers concluded that 1.6 million U.S. women of childbearing age are exposed each day to levels of perchlorate above the EPA's recommended safe dose from winter crops of lettuce alone.

According to the study, lettuce, which is being sold in U.S. supermarkets, absorbs and concentrates significant amounts of perchlorate from polluted irrigation water.

Moreover, close to 90 percent of the U.S. winter lettuce supply is grown in Southern California and Arizona with irrigation water from the Colorado River, which is contaminated with perchlorate.

However, several groups have come out against the EPA’s recommendation, including the Pentagon and several defense contractors, who could be responsible for billions of dollars in potential cleanup liability for perchlorate pollution, arguing that perchlorate is safe in drinking water in quantities 70 to 200 times greater than the EPA’s recommended safe dose.

Definitive data on the levels of perchlorate in U.S. produce was supposed to have been available years ago, however, the Defense Department reportedly would not fund the estimated $215,000 needed to collect samples of vegetables, leading some environmentalists to question whether the Defense Department really wanted to know if perchlorate was contaminating food.

According to one environmental scientist, "If they can spend $1 million on a cruise missile, it seems kind of ridiculous they won't spend $200,000 to see if our food is contaminated with rocket fuel."

Researchers of the current study say that their results are not conclusive due to their small sample size. However, they hope that their results will spur the federal government to conduct a more definitive study that will take a comprehensive look at the potentially widespread perchlorate contamination.

Wall Street Journal April 28, 2003