Leafy green vegetables grown with contaminated water store and concentrate potentially harmful levels of perchlorate, a thyroid toxin that is a main ingredient of rocket and missile fuel, according to tests.

Further, aerospace and defense contractor Lockheed Martin, a major user of perchlorate, reportedly knew as early as 1997 that vegetables stored high concentrations of the chemical, but did not release the information to health officials. There is also speculation that the Department of Defense may also have known, but did not warn other agencies, farmers or consumers.

Analysts recommend that the Food and Drug Administration (FDA) begin testing on vegetables grown with water from the Colorado River, and, if harmful perchlorate levels are confirmed, take immediate action to reduce contamination and keep the food off the market.

Additionally, farmers who are adversely affected by perchlorate contamination of their crops should be fully compensated for all economic losses.

Perchlorate has contaminated close to 300 drinking water sources and farm wells in California and an unknown number of sources in at least 15 other states. The chemical impairs the thyroid’s ability to take up iodide and produce hormones that are critical to proper fetal and infant brain development.

The EPA doesn’t plan to adopt national standards for perchlorate in drinking water until at least 2006, although elected officials in California are calling for faster federal action.

However, it appears that vegetables grown with perchlorate-contaminated water may pose more of a threat than drinking water.

According to a 1999 study of lettuce seedlings grown in perchlorate-contaminated water, perchlorate was accumulated in the leaves by factors of 100 times or more. The lettuce was able to take up and store 95 percent of the perchlorate in the water, which means that lettuce grown in water with even low levels of perchlorate could deliver doses far higher than the EPA’s provisional drinking water standard.

Despite preliminary research that suggests food is likely to be an equal or greater source for perchlorate exposure than drinking water, this hasn’t been reflected in the proposed drinking water standards, which would need to be substantially lower to account for the exposure coming from food.

Environmental Working Group June, 2003