Riverside Press-Enterprise, David Danelski
Published January 25, 2006
A rocket-fuel chemical that has contaminated Inland water supplies could be much more prevalent in food than previously believed, according to data gathered by the federal Centers for Disease Control and Prevention.
Agency scientists made the discovery unexpectedly, while evaluating a new method of testing for perchlorate in the human body.
The researchers asked CDC employees in Atlanta to donate urine samples in order to screen a technique that the agency is now using in a major health study of perchlorate in thousands of Americans. The chemical, in sufficient amounts, interferes with thyroid function that regulates metabolism and, in fetuses and babies, brain and nerve development.
The chemical is barely detectable in Atlanta's drinking water, but all 62 urine samples contained perchlorate in higher concentrations than those found in the water. One of the employees had more than 100 times the concentration in the city water. The researchers determined that the person's body contained a level slightly higher than the amount deemed safe by the U. S. Environmental Protection Agency.
One of the goals of the current CDC study is to determine if such levels are affecting people.
The researchers believe the source could be food.
"The thing that surprised me the most was the prevalence of perchlorate in all urine samples when none was expected," said Ben Blount, a research chemist for the agency. He is scheduled to present his findings today at a water conference in Santa Clara.
Milk and Lettuce
Perchlorate can accumulate in certain plants eaten by people and livestock. It has been discovered in lettuce, grains and milk. The lower Colorado River, which provides irrigation water for one of the nation's most productive agricultural regions, is contaminated with the chemical leaching from a former perchlorate factory near Las Vegas.
Regulators need to know how much perchlorate people are consuming in food so they can determine what concentration can safely be allowed in water, EPA officials have said.
Using a National Academy of Sciences analysis of perchlorate research, the EPA set a safe dose for human consumption last year and is now weighing whether it should set a legal limit for the nation's drinking-water supplies. Knowing how much perchlorate comes from food is necessary to make that decision.
If food is found to be a major source, regulators could call for tougher limits, forcing costly cleanups of water supplies.
California and Massachusetts are developing state limits for the chemical in drinking water.
California, which is more than two years behind a legislative deadline, was expected to propose a legal limit last year. State health officials are working on it, said Lea Brooks, a state Department of Health Services spokeswoman.
Regulators and health officials are worried that the chemical, consumed in water and food, might be interfering with brain and nerve development of fetuses, babies and small children. In sufficient doses, it blocks the thyroid's ability to absorb iodide, which the gland needs to make the hormones that guide nerve development.
The chemical is used in rocket fuel, bombs, munitions and fireworks, as well as matches and road flares. And it occurs naturally in some fertilizers. A salt, perchlorate mixes easily with water and has leached from defense industry factories and military facilities, contaminating some Inland groundwater supplies.
Contamination Testing
Widespread testing of the nation's food supplies has been moving slowly.
In 1999, the U.S. Air Force agreed to test crops irrigated with Colorado River water, but it never followed through on the research, according to federal records.
In 2003, separate tests commissioned by The Press-Enterprise and the Environmental Working Group, an advocacy organization, found perchlorate in lettuce purchased in California grocery stores that winter. Roughly 90 percent of the nation's winter lettuce is grown in the Coachella and Imperial valleys, using water from the Colorado River.
The results were confirmed in tests done later by the federal Food and Drug Administration and Department of Agriculture.
Testing CDC Employees
All these efforts, however, have failed to draw a complete of picture of the chemical's presence in the American diet.
Blount, working in collaboration with the FDA, hopes to fill that knowledge gap.
He developed a urine test that gives researchers the ability to monitor how much perchlorate a person consumes in water, food and other potential sources such as cigarettes.
To evaluate Blount's test, volunteers were asked to leave samples in restrooms at CDC offices in Atlanta, Blount said in a telephone interview.
Atlanta's water has about one-fifth of one part perchlorate per billion parts of water.
The lowest reading in the urine samples was three times that amount, and the mean was 17 times the level in the drinking water.
Blount said few conclusions can be drawn from the preliminary results.
He expects to get answers in the far more comprehensive study expected to be published later this year.
Blount and his colleagues are testing 2,280 people chosen as representative of the U.S. population. Each was thoroughly interviewed and given a physical examine. Blood tests will show how their thyroid glands are functioning.
SIDEBAR:
Perchlorate in food
2000: U.S. Environmental Protection Agency greenhouse experiments show that lettuce can absorb perchlorate.
April 2003: The Press-Enterprise and the Environmental Working Group independently test winter lettuce purchased in California grocery stores. Perchlorate is found in most samples.
September 2003: Texas Tech University scientists find the chemical in cow's milk.
November 2003: U.S. Department of Agriculture funds
a study of perchlorate in lettuce grown with tainted Colorado River water.
November 2004: U.S. Food and Drug Administration finds perchlorate in lettuce and milk samples taken from around the nation.
February 2005: Texas Tech researchers find perchlorate in human breast milk.
