News Coverage
Cause for Concern
Published July 26, 2004
Since late June, dairy industry and health officials have been looking into reports that the state's milk supply is tainted with perchlorate - a substance used in rocket fuels, explosives, lubricating oils and a variety of manufacturing processes including leather tanning, electroplating, aluminum finishing and making rubber. The concern was kicked off by the release of a study conducted by the watchdog group the Environmental Working Group on June 24.
The study reported on samples of milk taken from retail outlets in Southern California as well as tests conducted by the California Department of Food and Agriculture of raw, bulk milk silos from throughout the state. The EWG study reported that perchlorate levels from 1.5 parts per billion to 11 ppb were found in the samples. The group called upon industry and health officials to move quickly to reduce the perchlorate levels in the state's milk, suggesting that the presence of the contaminant could pose a risk, especially to children and pregnant and nursing mothers. But state health officials are advising consumers to remain calm and avoid changing or restricting their diets to avoid milk and other dairy products. "We do not have sufficient scientific data available to say whether perchlorate, when found at these relatively low levels in the milk supply, poses any significant health risk to anyone," said Steve Lyle, a spokesman for the state department of food and agriculture. "There is just not enough known about perchlorate, how it affects human health and at what levels, to justify warning people to avoid milk and dairy products.
"In fact, at this point, there's every possibility that people could face more health risks from eliminating diary products from their diets than they would from drinking milk that contains low levels of perchlorates." Perchlorates have been the subject of intensive scientific scrutiny in recent years as they have turned up, first in the water supply and now in milk, at various spots throughout the nation. Though they are known to be associated with such products as rocket fuel and have sometimes been found in greater concentrations near sites such as military installations and rocket manufacturing operations, they are also present in locations not connected to such facilities.
Moreover, as pointed out by Rachel Kalder, a spokeswoman for the Dairy Institute of California, which represents milk processors and dairy product manufacturers, they can be found in the absence of any man-made sources. "Perchlorates are naturally occurring salts," Kalder said. "They are ubiquitous, and they tend to be found in the water supply everywhere across the country. We do not know for sure yet at what level their presence in the water or milk they become a risk."
Health authorities in California ruled earlier this year that perchlorates in water may be considered harmful when they reach a level exceeding 6 ppb. The risk perchlorates pose comes from their impact upon thyroid function. Research suggests that perchlorates inhibit the uptake of iodine by the thyroid, thereby causing adverse effects on the body's metabolic rate. In pregnant women, the impact can be especially crucial because of the added stresses that pregnancy itself puts on thyroid function, and researchers also suggest that elevated perchlorate exposure during pregnancy could affect the mental development of the unborn child by causing developmental delays related to the ability to learn.
While both health officials and dairy industry groups favor taking all possible steps necessary to reduce perchlorate levels in the water supply - and consequently cutting perchlorate levels in the crops grown to feed dairy cattle - they are advising consumers to take a wait-and-see approach to the reports about perchlorate levels in milk, rather than panicking and dropping milk and dairy products from their diets.
CDFA spokesman Lyle stresses that the presence of perchlorates in milk is such a new issue that there has been insufficient time to study and evaluate their risks. "We know that the body handles water and milk in different ways," he said. "It is quite possible that a level that would be risky in water, may not be a threat when measured in milk. Milk, for instance, contains iodine naturally, and that may mitigate the effects of perchlorates. "What we do know at this time is that we need a lot more research and scientific evidence before it can be determined if there is a risk involved with the perchlorate content levels that have been found in milk."