A Toxic Chemical Polluting The Colorado River. A toxic rocket fuel ingredient that is polluting the Colorado River the main water source for millions of Californians and most of the nation’s winter lettuce may be dangerous to public health even at extremely low levels, state and federal environmental officials now believe.
The U.S. Environmental Protection Agency and the California Office of Environmental Health Assessment, which are independently working to set the nation’s first enforceable regulations on ammonium perchlorate, are concluding from a number of new studies that the substance could lead to health problems, even in trace amounts.
Those findings present a serious environmental problem for the Southwestern United States, because the entire lower Colorado River is polluted with small amounts of perchlorate from a now-closed Nevada rocket fuel factory.
California officials first discovered the contamination five years ago, and an effort has been underway since then to stem the pollutant’s flow from a desert wash near the factory into Lake Mead. But more than 500 pounds of perchlorate still enters the river system every day, and it will be years before it is fully flushed out.
No one is saying a few glasses of tap water pose an immediate danger.
Environmental health scientists say there is an outside risk of developing health problems from perchlorate, basing their estimates on the assumption that a person would drink about two liters of the slightly tainted water each day of a lifetime.
Nonetheless, environmental groups say perchlorate’s presence in the Colorado River raises questions about the safety of drinking the river’s water and of eating foods, such as lettuce, that are grown with it.
Questions are thought to be particularly significant for pregnant women and babies. Perchlorate is known to affect the production of thyroid hormones, which are considered critical to brain development, so fetuses and newborn children may face a greater risk.
“The more we know about perchlorate, the more concerned we get, because the science is pointing to low doses affecting brain functions,” said Gina Solomon, a health expert with the Natural Resources Defense Council, an environmental group.
“The kind of things that low to moderate doses of perchlorate might do include delays in things like language acquisition, motor coordination,” Solomon said.
In all, more than 15 million people, including those in the urban expanses of Las Vegas and much of Southern California, depend on drinking water from the lower Colorado River. Roughly 15% of California’s water supply comes from the river.
Water siphoned off to the casinos of Las Vegas contains 10 to 12 parts per billion of perchlorate, according to officials with the Southern Nevada Water Authority. Water diverted downstream by the Metropolitan Water District of Southern California is less polluted, usually somewhere between 5 and 8 parts per billion. It is subsequently blended with Northern California water before being piped to Southern California consumers, reducing its contamination to below detectable levels.
One part per billion is roughly equivalent to a grain of sand in an Olympic-size swimming pool, according to the Metropolitan Water District.
Perchlorate pollution is an unexpected byproduct of the race to put a man in space and build bigger and better rockets during the Cold War.
Defense contractors and the Pentagon do not dispute that it can be harmful, but their interpretation of the data differs from that of environmental officials. The contractors and military authorities conclude that the contaminant is dangerous only in higher concentrations.
“Let me make this perfectly clear. We think the concentration in the Las Vegas Wash is not a health concern for those drinking it,” said Pat Corbett, director of environmental affairs for Kerr-McGee Corp., which owns the former perchlorate factory near Henderson, Nev. The Las Vegas Wash is the desert streambed where the perchlorate pollution enters Lake Mead in greatest concentration.
Using the defense industry’s own data, however, the federal EPA and California are arriving at far different conclusions.
The EPA has issued a preliminary public health goal of 1 part per billion for perchlorate a number one-seventh the average contamination now in the lower Colorado River. The number is also one 200th of what the defense industry says is scientifically sound.
California health officials have issued a draft public health goal of 2 to 6 parts per billion for perchlorate. The state expects to establish new regulations next year; the EPA estimates it will take several more years to put federal standards in place.
Most of the studies reviewed by the state and federal environmental officials were paid for by the military and its contractors, which have been cooperating for the last five years with the government regulators in the effort to arrive at new safety standards. But now the two sides find themselves at odds.
Perchlorate Pollution Problem
“We didn’t really care” what the number considered safe by regulators was, “as long as it was based on good science,” said Air Force Lt. Col. Dan Rogers, who has helped lead the military’s response to the perchlorate pollution problem since 1997, and estimates that the Pentagon, NASA and defense contractors have invested $22 million in studies.
“Unfortunately, some scientists disagree with EPA’s interpretation of the data,” Rogers said.
Strict new state and federal perchlorate rules could cost defense contractors and water agencies tens of millions of dollars, spent to cleanse waters of pollution. Many of those involved predict that taxpayers will ultimately foot the bill for a massive cleanup.
One central question bearing on the cost is how much risk may come from eating vegetables irrigated with perchlorate-contaminated water. More than 1.4 million acres of farmland are irrigated with Colorado River water, mostly in California’s Imperial Valley and the Yuma, Ariz., area. Together, these areas grow more than 90% of the country’s fresh lettuce during winter months.
Though data remain limited, some recent studies have suggested that perchlorate may collect in lettuce at higher concentrations than it does in the water used to grow the plants, adding to the concern about perchlorate in the river.
“We know perchlorate can attain high concentrations in plants we know that,” said Phil Smith, a toxicologist at Texas Tech University who is conducting a study on perchlorate in plants for the U.S. Department of Agriculture. What remains unclear, Smith said, is whether perchlorate consumed by eating vegetables has the same effect on people and animals as perchlorate in drinking water.
Defense industry officials contend it is scientifically premature to conclude that perchlorate concentrates in plants. They say other research has even shown that some plants can naturally break down perchlorate over time. They argue that a 1999 EPA test of lettuce seedlings that found high concentrations of perchlorate in the seedlings had been discounted by some scientists because of the testing methods. The EPA is conducting a second lettuce study and expects to release its findings within weeks.
If perchlorate is shown to collect in vegetables and affect people who eat them, the finding would have significant consequences.
“It would mean that the problem of perchlorate is not confined to people in the West who rely on this drinking water, but the entire nation, which is eating this lettuce in the winter months,” said Bill Walker of the Environmental Working Group, an organization that has sounded an alarm about perchlorate for several years and is now doing its own lettuce tests.
In addition to the Colorado River, the EPA has identified roughly 75 perchlorate pollution sites around the country.
In California, the San Gabriel Valley, the Inland Empire and the Rancho Cordova area near Sacramento are all struggling to address perchlorate pollution. In all three places, dozens of residents near the polluted sites have alleged they developed health ailments including thyroid problems and cancer from exposure to perchlorate. The state Department of Health Services is studying whether there is an increase in thyroid problems near those areas.
Though perchlorate had been a public concern for years, it was not until 1997 that the magnitude of the problem became clear. That year, California health officials developed a new method to detect the pollutant at levels far lower than previously possible, and water officials discovered to their surprise that contamination was far more widespread than first believed.
The Metropolitan Water District of Southern California, the area’s primary urban wholesaler, soon detected perchlorate deep in its massive Colorado River Aqueduct, which pipes water 240 miles into Riverside County. It performed further tests and found that pollution levels increased as testing moved upstream. The sleuthing eventually pinned down the source of the contamination as the Las Vegas Wash, a formerly seasonal stream that now flows year-round with the treated waste water of Las Vegas. Tests further up the stream found no perchlorate.
The discovery quickly triggered a response from the EPA, the Nevada Division of Environmental Protection and Kerr-McGee, which owned a nearby perchlorate plant that for years dumped tons of the rocket fuel oxidizer directly into unlined lagoons.
The plant, which Kerr-McGee acquired through a merger in the late 1960s, was first converted to perchlorate manufacturing by the Navy after World War II. It was closed in 1998, when Kerr-McGee got out of the perchlorate business.
The current cleanup, overseen by Nevada and funded by the company, started in 1998 and is showing signs of success, according to state, EPA officials and the defense contractor.
Officials isolated an underground stream that was carrying perchlorate pollution, and are now running 34 wells to pump out the ground water before it reaches the Las Vegas Wash.
As a result, the contamination spilling into the wash has dropped from an average of 900 to 1,000 pounds per day to 500 to 550 pounds, and recent gains suggest the numbers could go down dramatically in coming months, said Todd Croft, the Nevada official in charge of the cleanup.
Purging Lake Mead of perchlorate, however, is a far more complicated matter. EPA officials speculate it could take decades to fully wash out, even after the stream polluting it is cleaned up.
“Lake Mead is a complex reservoir,” said Kevin Mayer, the EPA’s point man on perchlorate. “It is not going to flush like a bathtub.”
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