Perchlorate, a hazardous chemical in rocket fuel, has been found at potentially dangerous levels in powdered infant formula, according to a study  by a group of Centers for Disease Control scientists. The study, published last month by The Journal of Exposure Science & Environmental Epidemiology, has intensified the years-long debate about whether or how the federal government should regulate perchlorate in the nation’s drinking water.

According to the CDC, perchlorate exposure can damage the thyroid, which can hinder brain development among infants. For nearly a decade, Democratic members of Congress, the Department of Defense, the White House and the Environmental Protection Agency have been fighting about how much perchlorate in water is too much.

In the new study, CDC scientists tested 15 brands of infant formula and found perchlorate in all of them.  The names of the brands weren’t revealed because the CDC says the study "was not designed to compare brands." But the study does say that the formulas with the highest perchlorate levels are the most popular. The most contaminated brands were lactose-based as opposed to soy-based and accounted for 87% of the infant formulas on the market in 2000, the latest data available from the U.S. Department of Agriculture.

The study points out that when perchlorate-contaminated powdered formula is mixed with water that also contains traces of the chemical, as many drinking water sources around the country do, the final concoction can become particularly harmful to babies.

"As this unprecedented study demonstrates, infants fed cow’s milk- based powdered formula could be exposed to perchlorate from two sources – tap water and formula. That suggests that millions of American babies are potentially at risk," said Anila Jacob, a physician and a senior scientist with Environmental Working Group, a Washington, D.C., nonprofit that posted the study on its Web site.

In December the EPA released an interim health advisory suggesting that water with a level of perchlorate limited to 15 parts per billion (ppb) is safe to drink.The level is not an enforceable standard, but is meant to provide guidance to states and local governments seeking to develop their own regulations.

Keeping perchlorate beneath that level would ensure that the amount of daily oral exposure would remain beneath a threshold called a reference dose, the EPA said. That is the amount of perchlorate humans could consistently consume over the course of a lifetime without increasing their risk of harm. Environmentalists argue that the EPA reference dose is too high.

The CDC study found that, hypothetically, 54% of infants consuming the perchlorate-contaminated formula would exceed EPA’s reference dose, if the formula were mixed with water containing perchlorate at 4 ppb.

Perchlorate has been found at that level in drinking water sources of at least 26 states and two territories, according to a study the CDC referenced in the report.

Perchlorate’s effect on individual infants will vary, the CDC scientists said, according to their weight and the amount of iodine in their diet.Iodine can counteract the harmful effects of perchlorate and is an ingredient in many brands of baby formula, the scientists said.

In a statement sent to reporters last night, Sen. Barbara Boxer, chair of the Environment and Public Works committee, said the study prompted her to ask the Food and Drug Administration to inform the public "how best to protect children from perchlorate." As she has done in the past, Boxer called on the EPA to "overrule the Bush Administration’s policy which was to walk away from setting a safe drinking water standard for perchlorate in our water supply."

In 2002 the EPA suggested limiting the amount of perchlorate in water to 1 ppb, but in December it changed that level to 15 ppb to the dismay of environmental advocates.

A March 2008 Government Accountability Office report criticized the Bush White House for injecting politics into the EPA’s chemical risk assessment of perchlorate and other toxins.The report suggested that the White House Office of Management and Budget was stalling the completion of risk assessments by forcing scientists to respond to comments from other federal agencies, including the Department of Defense. The report notes that tight restrictions on perchlorate and other toxins would greatly increase safety and cleanup costs incurred by the Defense Department and its contractors.The Perchlorate Information Bureau, an industry trade group supported by Lockheed Martin, Aerojet and other defense contractors, said the cost of an overly restrictive perchlorate standard would be "potentially staggering."

Perchlorate has been found leaching into public water wells from military bases and bomb-building facilities, especially in California.

Less than two weeks before the Bush administration left office, the EPA announced that it would delay its long-awaited decision on whether to set a drinking water standard for perchlorate until the National Academy of Sciences weighed in on the issue.That announcement effectively punted the decision to current EPA Administrator, Lisa Jackson, who promised to regulate perchlorate at her confirmation hearing.

As we reported previously, when Jackson headed the New Jersey Department of Environmental Protection, state scientists urged her to regulate perchlorate, which was found at 4 ppb in six of 123 public water wells (p. 41) in New Jersey in a 2005 survey.New Jersey still does not have a perchlorate standard.

Other states however, have stepped in to fill the regulatory void.California has set a perchlorate standard at 6 ppb and Massachusetts at 2 ppb.

As pressure to regulate perchlorate has mounted, so too has lobbying from the chemical manufacturing and defense industries. In February David Corn reported for Mother Jones that these industries have hired a former Democratic senator from Nevada to stymie efforts to regulate the chemical.   

An EPA spokesperson said in an email to ProPublica today that the agency is reviewing the Bush administration’s work and "hopes to announce our direction soon."

"Perchlorate exposure is a serious issue," the email said, "and it’s a top priority for Administrator Jackson, who is concerned about its health effects on children."