News Coverage
Pollutant found in state's milk
Published June 21, 2004
In a report to be released today, the Environmental Working Group said its samples of supermarket milk generally confirm unpublished tests done by the California Department of Food and Agriculture, which in April sampled milk at a few dozen processors statewide.
Both the state and the Environmental Working Group said adults and children should keep drinking milk - which offers calcium and important vitamins - because little is known about risks of perchlorate in milk.
"This is not an issue of alarm," said Bill Walker, the Oakland-based vice president of the Environmental Working Group. "This is an issue of concern."
Of the 64 milk samples in the two studies, 63 had detectable perchlorate, a contaminant that is showing up at low levels in a wide range of foods. Half of the state's milk samples were above the level recently established by the state as posing "no significant health risk" for drinking water, though there's no agreement about what's safe in milk.
Perchlorate can hamper the thyroid gland's ability to take up the essential nutrient iodide and make thyroid hormones.
For healthy adults, the levels of perchlorate found in California milk would not be expected to create problems. However, long-term perchlorate exposure could be dangerous for nursing infants and children because thyroid hormone disruption is known to retard development, state and university scientists said.
At Western United Dairymen, an industry group in Modesto, CEO Michael Marsh emphasized the scientific uncertainty about perchlorate dangers but said the new findings have his attention.
"We need to work to find the (perchlorate) source and rid whatever very low levels there may be from any milk supply," he said.
Studies across the country in recent years have found perchlorate in everything from tomatoes and cucumbers to wheat and alfalfa - a staple in cow diets and a likely source of the chemical in milk.
The culprit in many cases is contaminated water. The Colorado River,polluted for decades by a shuttered perchlorate factory near Las Vegas, supplies farm and drinking water to Arizona and huge swaths of Southern California - including the intensely farmed Imperial Valley.
In all, perchlorate contaminates more than 350 water sources in California, along with wells and rivers in 22 states. In the Rancho Cordova area,perchlorate pollution from rocket builder Aerojet has forced abandonment of several wells.
Perchlorate accumulates in the food chain, but the processing of milk is not known to concentrate the chemical. Contamination affects both organic and conventional crops, which use the same water sources.
"There are two things of concern," said thyroid expert Thomas Zoeller, a biology professor at the University of Massachusetts, who reviewed the environmental group's report. "People don't know that they have been exposed or they are being exposed, and the cumulative exposure may be a lot bigger than anybody was thinking."
Zoeller was on Massachusetts' review panel when that state advised in January that one part per billion of perchlorate was the goal for drinking water. The U.S. Environmental Protection Agency has issued a similar advisory, which is under review by the National Academy of Sciences.
In March, California's Office of Environmental Health Hazard Assessment released its public-health goal of six parts per billion. That's the level at which the state says perchlorate would not be expected to pose significant health risks to the most sensitive person drinking water for a lifetime. The agency does not set percentages for how likely someone is to become ill from perchlorate-tainted water.
An enforceable California drinking water standard is expected by early next year. Eventually, those standards will force cleanup or closure of contaminated water sources.
The environmental group said the milk samples suggest the state may not have been conservative enough in its March advisory on drinking water because it didn't specifically account for the newly released milk data.
"It's not a fictional or make-believe situation," said Jonathan Parfrey,executive director of the California chapter of Physicians for Social Responsibility in Los Angeles, which gathered milk samples for the environmental group's study. "Children are drinking this contamination."
At the state health hazards office, however, spokesman Allan Hirsch said scientists recognized the possibility of non-water pollution, and he didn't anticipate revising the public health goal. Neither the state nor the environmental group had completed milk tests when Hirsch's office set its health goal.
"We probably want to take a closer look at those numbers just to be sure," Hirsch said.
Neither test was designed as a comprehensive assessment of the state's milk supply.
Half of the state's 32 milk samples came in above the public health goal, with a range of 1.5 parts per billion to 10.6 parts per billion.
CDFA spokesman Steve Lyle said the samples were taken to test a new chemical-sensing tool and did not constitute a public health study. He said the agency did not attempt to determine whether the perchlorate came from rocket fuel.
Lyle said CDFA has no plans for follow-up studies, and he warned against making any connection between perchlorate in milk and water.
"There isn't any scientific data on milk at this time," he said. "To link the two is like comparing apples and oranges."
The environmental group's own tests - 32 samples taken from grocery store cartons in Orange and Los Angeles counties - showed lower levels of perchlorate, an average of 1.3 parts per billion. The chemical didn't show up in one of its samples.