Toxic rocket fuel found in milk samples from Texas supermarkets.

• Position: Thinking Ecologically

A toxic component of rocket fuel has been found in supermarket milk at levels exceeding the federal government's currently recommended safe dose for drinking water, according to a peer-reviewed scientific study. A team of five researchers from the Institute of Environmental and Human Health at Texas Tech University report in the journal Environmental Science and Technology that perchlorate was "unambiguously detected" in seven of seven cow's milk samples from Lubbock grocery stores.

Perchlorate levels in the milk ranged from 1.7 to 6.4 parts per billion--all higher than the US Environmental Protection Agency's most recent proposed safety standard of one ppb. Enforceable federal standards are not expected for at least five years, but the State of California has set four ppb of perchlorate as the "action level" at which a public water supply should be shut down.

Perchlorate, the explosive main ingredient of solid rocket and missile fuel, can disrupt the thyroid gland's ability to make essential hormones. For fetuses, infants and children, disruptions in thyroid hormone levels can cause lowered IQ, mental retardation, loss of hearing and speech, and motor skill deficits.

Perchlorate, most of it leaking from military bases or defense plants, contaminates more than 500 drinking water supplies in at least 20 states, serving well over 20 million people. Among major perchlorate-polluted sources is the Colorado River, which is used to irrigate 1.4 million acres of cropland in California and Arizona.

Early in 2003, a study for the Environmental Working Group, conducted by the same team from Texas Tech, reported that about 1 in 5 samples tested of winter lettuce irrigated by the Colorado had perchlorate levels averaging four times the EPA's draft safety standard.

"These troubling results are the first indication that perchlorate is not only contaminating drinking water and irrigation water, but that livestock can pass it on to humans," said EWG Senior Analyst Renee Sharp. "How much more evidence do we need before the government takes action to protect our water, our food and our selves from this toxic chemical?"

The milk samples represented six different brands, four packaged locally at the same plant and two at separate plants outside Texas. Researchers also found perchlorate in one sample of...