Tainted milk may have reached valley

Stephen Curran

Friday, June 25, 2004 | 10:57 a.m.

Shipments of milk found this week in California laced with minute traces of a chemical used to produce rocket fuel may have reached Southern Nevada grocery stores, the state's top dairyman said Thursday.

Meanwhile Nevada dairy commissioners have no plans to remove the milk from circulation in Nevada, saying the amounts found in California -- between 1.3 and 3.6 parts per billion of rocket fuel additive ammonium perchlorate -- were far below the federal safety standards that limit the chemical to 32 parts per billion in food supplies, said Mike Compston, executive director of the Nevada State Dairy Commission.

Compston estimated that Southern Nevada brings in about 40 percent of its milk from California, the largest out-of-state producer.

"If it came in from California, it could have contained the same parts per billion," Compston said.

About a third of milk for sale in Nevada is produced in the state and the rest comes from other neighboring states, he said.

Compston said Nevada milk is tested for perchlorate among hundreds of other tests run on the purity of the milk. There are no indications of high perchlorate levels in Nevada milk, he said, but he said he did not have immediately available the specific levels that have been found.

"It's impossible to test for every compound, absolutely impossible," he said. "There are literally thousands of compounds out there."

The findings may even have been a mistake, as highly sensitive machines used to check for chemical and biological contaminants including E. coli often pick up on non-harmful amounts of various compounds, he said.

Perchlorate is a naturally occurring chemical often used as an oxygen source in rocket fuel. In high doses it can interfere with the body's ability to regulate thyroid, a hormone that controls metabolism. It has been found in ground and surface waters in 17 states.

Traces of the substance were found this week in milk in Los Angeles and Orange counties, and where Colorado River water is a key source of drinking water, as well as in parts of the San Francisco Bay Area and San Joaquin Valley, where the water is not used.

Some of the chemical is believed to have originated from two Henderson plants that used to manufacture the substance, said Pat Corbett, the former Henderson plant manager for Oklahoma City-based chemical manufacturer Kerr-McGee Corp., one of those companies.

After seeping into the Lake Mead through the Las Vegas Wash, the water may have then been ingested by milk-producing cows in Nevada and Southern California, said Corbett, now Kerr-McGee's director of environmental affairs.

Both Kerr-McGee and American Pacific Corp. now are cleaning up perchlorate from the ground water in Henderson.

Water recently tested at Lake Mead contained between 5 and 7 parts per billion of perchlorate, said Peggy Roefer, regional water quality supervisor for the Southern Nevada Water Authority.

Even if the chemical is found in Nevada's milk, its effects on humans who drink it is a subject of debate among scientists.

Dr. John Gibbs, a physician working for Kerr-McGee, said claims that the traces found in California were harmful don't "hold water."

Studies in Chile that documented pregnant women and children living near a water source with naturally occurring perchlorate have found that humans can safely consume upward of 100 parts per billion, Gibbs, Kerr-McGee's corporate medical director, said.

"Quite frankly we have not found any effect on levels significantly higher than 100 parts per billion," he said. "When we took a common sense approach it (claims the perchlorate is harmful) doesn't hold water."

But Tom Zoeller, a biology professor at the University of Massachusetts, Amherst, who worked with the federal Environmental Protection Agency in 1999 when it conducted its first review of the substance, said not enough is known about perchlorate's effects to say it's not harmful. Zoeller began laboratory studies on animals in 2002.

While scientists continue to debate the human threshold for the chemical, a widely used formula finds that the average 150-pound adult can tolerate up to 200 parts per billion, a number that varies based on weight, Zoeller said.

Using the same formula, a 7-pound baby can only tolerate between 15 and 20 parts per billion. The difficulty, Zoeller added, is speculating on whether infants are more or less sensitive to perchlorate.

"There's a source of uncertainty that requires some caution," he said. "We don't know if newborn babies are more sensitive to perchlorate."

Researchers at Loma Linda University in California began human studies of the chemical's effects in 2001. The study, funded by Defense Department contractor Lockheed Martin, examined the effects on 100 volunteers who took pills containing 83 times more perchlorate than the traces typically found in drinking water.

The study came after Lockheed Martin was sued by residents of Redlands, Calif., who claimed the company exposed them to perchlorate through their drinking water. The results have not been published.

Perchlorate was used in the 1950s and '60s to treat Graves Disease, a chronic overproduction of thyroid, Gibbs said.

In those cases, perchloride was prescribed in doses of 1,000 milligrams, almost a million times the amount found in California's milk supplies.

But a high level of uncertainty is why policy-makers should be cautious in setting standards, Zoeller said, as new findings are continually forcing scientists to alter their perceptions about the chemical.

"It's not simply a quantitative issue," he said. "There doesn't seem to be a single perspective on what the problem is. That's what people respond to, and I can't say I blame them."