A toxic chemical in rocket fuel has been detected in California’s milk supply, although environmentalists and toxicologists disagree over whether the levels are high enough to pose a health threat to infants and young children.
Tests by the California Department of Food and Agriculture found perchlorate, a rocket fuel component widely used by the defense industry, in 32 samples of milk taken from Alameda, San Joaquin and Sacramento counties, according to a report released today by an environmental watchdog group.
The Environmental Working Group also analyzed 32 samples of milk from stores in Los Angeles and Orange counties and found that 31 of the samples contained minute amounts of perchlorate.
Perchlorate, which contaminates groundwater in parts of the state and the Southwest, has been linked to thyroid problems in humans, though research into specific levels of toxicity is inconclusive.
Bill Walker, the West Coast vice president for the Environmental Working Group, said the perchlorate levels found in milk pose a health risk, particularly to fetuses, infants and children. He said the state needs to move aggressively to reduce levels in the milk supply.
But some scientists say the findings are less worrisome because the amounts of perchlorate are minute.
“The important thing to remember is that these contaminant levels are infinitesimally small,” said Michael Payne, a veterinary toxicologist with the UC Davis. “They are on the same order of magnitude as a sugar cube in an oil tanker.”
The Environmental Working Group study found levels averaging 1.3 parts per billion and ranging up to 3.6 parts per billion, while the state tests found levels from 1.5 to 10.6 parts per billion.
The U.S. Environmental Protection Agency, the California Environmental Protection Agency and the Massachusetts Department of Environmental Protection — the only government agencies to directly address the chemical — recommend low exposure levels.
Perchlorate leaches into groundwater and rivers from rocket-fuel manufacturing plants and U.S. Department of Defense sites.
“A major source of perchlorate for California is the Colorado River,” Walker said. “There’s a defunct manufacturing site near Las Vegas that dumps perchlorate into Lake Mead. From there, about 500 pounds of perchlorate a day are released into the Colorado River.”
That water is used to irrigate the vast agricultural acreage of Southern California.
“Alfalfa is particularly good at accumulating perchlorate,” Walker said. “Two of the main growing areas for alfalfa in the state are in the Imperial Valley and the Chino Basin, both of which use Colorado River water. Alfalfa from those areas is used to feed dairy cows all over the state. We think that may be a big part of the problem.”
Walker criticized the state Food and Agriculture Department for failing to disclose the results of its tests at a time when another state agency state was developing a public health goal for perchlorate in drinking water. The results were obtained by Walker’s group through a state Public Records Act request.
“Food and Agriculture did not release the results of this study (conducted in April), and we find that troubling,” Walker said. “(Food and Agriculture) did not notify state public health agencies of the result. They’ve neglected a significant route of perchlorate exposure to the public.”
But Steve Lyle, a spokesman for the Food and Agriculture Department, said the tests were not released because “they were not comprehensive research. A new test was available, and we were trying it out. It was valid. There had already been preliminary indications last year that there may be perchlorate in state milk.”
Nancy Fletcher, a spokeswoman for the California Milk Advisory Board, said a lack of hard standards and data make the situation difficult to assess. “We have no standards for milk, we have no standards for drinking water,” Fletcher said. “We don’t know what’s safe. They (state and federal agencies) need to work on this.”
The state is expected to set drinking water standards for perchlorate later this year.
Payne, the UC Davis toxicologist, said it’s important not to confuse “the theoretical world with the real world.
“Perchlorate definitely blocks (thyroid function) at high levels. But at these minuscule levels, any damage is theoretical. In fact, two studies conducted with populations’ drinking water with much higher perchlorate levels than (those found in California milk) showed no adverse affects.”
Payne also cited a recent UC Irvine study that concludes perchlorate risk may be overestimated, particularly for adults.
There’s a bottom line to all this, Payne said. “I’m a toxicologist,” he said. “I’m more than passing familiar with these issues. I will not be making changes in my diet as a result of this, nor will my family.”
But Walker said there is evidence that even low levels can affect kids. “Perchlorate interferes with thyroid function. Low levels of thyroid hormones can lead to birth defects, and there’s evidence that we are talking very low levels of perchlorate.”
An Arizona study showed that women who drank Colorado River water with perchlorate levels of 1 to 2 parts per billion had infants with different thyroid hormone levels from infants from mothers who drank uncontaminated water, Walker said.
Lyle of the state Food and Agriculture Department said that “because (the perchlorate data) is inconclusive, there is no basis to recommend reducing (milk) consumption as part of a balanced diet.”
Walker said he did not recommend reducing milk consumption, “But I do think we need to reduce perchlorate in the state’s milk. It seems to me Food and Agriculture is more concerned with preserving the California dairy industry’s market share than it is in protecting the health of California’s citizens.”
06/22/2004 SF Chronicle, organicconsumers.org