News Coverage
Yuma scientist continues study of perchlorate in water, crops
Texas
Published September 25, 2003
First detected in the drinking water sources for millions of people, then in a handful of samples of lettuce grown in the desert Southwest, now a component of rocket fuel has been found in milk sold in Texas supermarkets.
Seven bottles of milk and one can of evaporated milk taken randomly from store shelves in grocery stores in Lubbock, Texas, contained perchlorate, according to a recently published report of a study by the Institute of Environmental and Human Health at Texas Tech University.
The study was published last week on the online version of the Environmental and Technology Journal. Researchers cautioned that the sample was too small to determine a public health hazard.
The report, however, is the latest volley in a campaign by the Environmental Working Group to call attention to the contaminant and pressure the U.S. government to set a safe standard for the presence of perchlorate in food and water.
Perchlorate is an oxidizer in solid propellants for rockets, fireworks and other explosives. A recent study in Tucson also has determined that some fertilizers are sources.
To date, the contaminant has been found in groundwater and surface water in more than 20 states. That includes the Colorado River, with perchlorate from rocket fuel production in the Las Vegas area 50 years ago still entering the river.
Perchlorate can disrupt thyroid function, particularly in developing fetuses and newborns.
With the latest finding of perchlorate in milk, research by University of Arizona scientist Charles Sanchez has been expanded to alfalfa hay used to feed dairy cattle. Last winter, Sanchez, a soil and water scientist based at the Yuma Agricultural Center, began a study of head lettuce grown here. The study, funded by the Arizona Iceberg Lettuce Research Council, was later expanded to leaf and romaine lettuces and other vegetables through a grant from the U.S. Department of Agriculture.
Sanchez said he has detected perchlorate in iceberg lettuce, but mostly in the outer leaves that are discarded. He explained that's likely because perchlorate builds up in those leaves as they transpire moisture. But he detected much lower or no levels at all in the edible portions of the lettuce heads.
As for other vegetables, Sanchez said he is still in the process of reanalyzing his samples with a machine he recently was able to purchase with special funding. In the past, he had to send his samples to the Sandia National Laboratory in New Mexico. The new state-of-the-art machine can detect much lower levels of perchlorate.
"We've been running day and night for two weeks," he said, adding that he hopes to have more data by next month.
He also will continue his sampling program this winter for the Research Council and USDA, including lemons, broccoli, cauliflower and cabbage.
In addition, he will be studying factors that impact the uptake of perchlorate by lettuce with another grant from the Research Council.
And he's been analyzing Colorado River water on a regular basis, finding levels of perchlorate ranging from 3 to 7 parts per billion.
Meanwhile, a debate continues over what the safe standard should be for perchlorate. The U.S. Department of Defense wants it set at 200 parts per billion, the U.S. Environmental Protection Agency wants 1 ppb and the Environmental Working Groups says it should be 0.1 ppb.
The Bush administration has turned the challenge of determining the most reasonable standard over to the National Academy of Sciences.
But it will probably be at least a year before the standard is determined, Sanchez said.