CHARLESTON, W.Va. -- Federal health officials on Thursday defended their recommended 1-part-per-million threshold for acceptable levels of "Crude MCHM" in West Virginia drinking water, but also said they continue to gather data on the chemical's potential health impacts."This is a dynamic and evolving event," said Dr. Vikas Kapil, chief medical officer for the U.S. Centers for Disease Control and Prevention's National Center for Environmental Health.Kapil said the CDC stands by its initial recommendation -- made in the absence of any regulatory standards or established public-health guidance -- but that the agency is searching for additional information that might help scientists refine their work."As we get additional information, we will be able to use that information as it becomes available," Kapil said. "However, we stand by the 1-part-per-million screening level that we have recommended."Kapil made his statements during a conference call with local and national reporters, as the CDC faced increasing pressure to explain how it came up with the figure being used by state and local health officials in West Virginia.However, agency officials also conceded that it's "almost as if we're learning as we go" in dealing with a chemical spill last Thursday that fouled the drinking water supply that serves nearly a third of a million West Virginians.Other toxic-chemical experts continued to question the CDC's figures, to advise West Virginians that the number might not be as conservative as the agency would have residents believe and that the lack of data reflects a far broader problem."As much as this stinks, this is the way it works for almost all chemicals," said Laura Vandenberg, an assistant professor of environmental health at the University of Massachusetts at Amherst.In Charleston and across a nine-county region, state officials and West Virginia American Water have been clearing residents since Monday night to resume drinking, bathing and cooking in water from their taps. Water company officials have given residents a zone-by-zone go-ahead to flush out their home plumbing systems based on water samples showing less than 1 part per million of MCHM, a coal-cleaning chemical also known as 4-methylcyclohexanemethanol.Officials with the administration of Gov. Earl Ray Tomblin have backed the move, saying they trust the CDC recommendation, which Bureau for Public Health Commissioner Letitia Tearney said is based on one study result, called an LD50, that determined at what level of the chemical half of the exposed experimental rats would die.Late Wednesday evening, though, the state Department of Health and Human Resources, acting on the CDC's advice, recommended that pregnant women not drink tap water until there is no MCHM, the chemical that leaked into the Elk River last week, detectable in the water.Thursday morning -- after refusing repeated interview requests since last week -- the CDC made Kapil available for an interview with The Charleston Gazette. In that interview, Kapil stressed that the new recommendation to the state was made out of an "abundance of caution" and said pregnant women who have been drinking the water since "do not use" orders began to be lifted on Monday should not expect adverse effects."We would not expect that, at the levels we're talking about, that we would expect any adverse health effects, either for the mom or their baby or their unborn babies," Kapil said.Kapil told the Gazette that the new advisory was not made because of newly discovered information."It's really just out of an abundance of caution. Exposure during pregnancy and reproductive toxicology is a challenge," Kapil said. "We often don't have a lot of reproductive toxicology information available on those exposures."
In a letter Wednesday to DHHR Secretary Karen Bowling, though, CDC Director Dr. Thomas Frieden specifically noted, "since making the initial calculation, scientists have obtained additional animal studies about MCHM. These are currently being reviewed."At this time, the scientists continue to recommend 1 ppm as a protective level to prevent adverse health effects," Frieden wrote. "However, due to limited availability of data, and out of an abundance of caution, you may wish to consider [an] alternative drinking water source for pregnant women until the chemical is at non-detectable levels in the water distribution system."
Richard Denison, a biochemist with the Environmental Defense Fund, has been following the West Virginia situation and writing about the CDC's risk-assessment efforts on his organization's blog.Writing late Wednesday, Denison noted that the CDC letter made it appear that the newly obtained studies played some role in the federal agency's recommendation and the state's action. That, Denison said, "raises the question as to whether the new animal studies suggest a potential for developmental toxicity or a related effect."Clearly something prompted the issuance of the advisory," Denison wrote. "This new development, I believe, lends even greater weight to the need for immediate public release of available studies and the methodology."Denison and some other critics had focused on the fact that initial reports from the state were that the CDC had used only the LD50 study, a move that would have, among other things, considered what level would be lethal, but did not examine other adverse health effects.
On Thursday, though, Kapil disclosed the existence of another study used by the CDC. He said that it resulted in a figure called the No Observable Adverse Effects Level, or NOAEL. That figure shows the maximum amount of chemical in which there are no biological or health effects visible in the test animals, which Kapil thought were either rats or guinea pigs.The NOAEL for Crude MCHM is 100 milligrams per kilogram of body weight, Kapil said.To that number, toxicologists at the CDC applied three safety factors, to try to account for uncertainty. The first safety factor accounts for the variation between animals and humans.The second accounts for variation within humans, as some populations -- the elderly, children, those with pre-existing conditions -- could be more vulnerable.
The third safety factor accounts for how little information is available on Crude MCHM.Each safety factor was given a weight of 10. They were multiplied by each other to produce a total safety factor of 1,000. CDC officials then divided the 100 milligram per kilogram of body weight NOAEL by 1,000, and came up with a figure of 0.1 milligrams per kilogram.CDC officials then assumed a child who weighs 10 kilograms (22 pounds) and drinks 1 liter (slightly more than a quart) per day of water, ending up with a recommended screening level of 1 part per million.Kapil said that at every step, scientists used the most conservative estimates."Some people apply smaller factors, sometimes three, sometimes four, depending on what it is you're talking about, but we applied the highest, so we feel pretty comfortable that the 1-part-per-million number is a number that would not be associated with any adverse effects for humans, based on this methodology," he said.Denison, though, said that what the CDC refers to as "safety factors" -- and tells the public add conservatism to the agency's risk assessment -- actually are more like "reality factors," which simply help translate animal studies of a limited range of health effects to the real world."They do not impose this super safety standard," Denison said. "That's a standard claim of industry."If the CDC wanted to include additional levels of safety to be conservative toward protecting public health, Denison said, the agency would have divided the 0.1-milligram per kilogram number by 10 again, or by 100, to add more protections.Denison said residents should remember the uncertainties involved, and make their own decisions about using the water. And they should know that, especially for children, how much water they consume is important."These numbers are certainly far from precise," Denison said. "What it does mean is that, if your child is drinking more than a liter a day, they are getting a larger dose."When asked if he would drink the water in Charleston if it was at a level of 0.9 parts per million, CDC's Kapil responded, "Absolutely. I would have no hesitation whatsoever."However, Kapil and Tom Skinner, a CDC senior press officer, stressed that they did not have as much information as they would like."Ideally, we would like to have a whole host of studies -- like human epidemiology studies, human toxicology studies -- all of that information available to us," Kapil said. "We do have limited animal data and, from that animal data, we have to somehow figure out a way to extrapolate for decision-making related to these types of human exposure."Skinner said the CDC did not have much experience dealing with a fast-moving situation of this magnitude."This whole situation is very fluid, so it's almost as if we're learning as we go," he said. "This experience that we're involved with now is actually going to provide us with a lot of information to base future decisions on."The studies the CDC has been using were produced by the Eastman Chemical Co., whose plant in Kingsport, Tenn., manufactured the MCHM.Eastman officials, responding to email questions, initially refused to provide copies of any of their studies or data about the potential impacts of MCHM."Eastman's toxicological studies for crude MCHM are not published in scientific journals and therefore are not what are commonly referred to as peer-reviewed studies," wrote Maranda Demuth, an Eastman spokeswoman. "The studies, however, were conducted under Good Laboratory Practices, and according to OECD guidelines, at a reputable laboratory where rigorous internal review processes were performed."On Thursday, though, the company announced that it would post the studies on its website, perhaps that night or early Friday.That move came after Rep. Henry A. Waxman, ranking Democrat on the House Committee on Energy and Commerce, wrote to Eastman to request that the company release its MCHM studies.Also, on Thursday afternoon, Sen. Joe Manchin, D-W.Va., and Rep. Shelley Moore Capito, R-W.Va., wrote to Frieden requesting the detailed methodology behind their calculations, the information that led them to change the advisory for pregnant women, the date when the CDC became concerned about lower-level exposure in pregnant women and the CDC's level of confidence in the 1-part-per-million standard going forward."It is particularly concerning that as many as 150,000 people who had been under a 'do-not-use' water order were told that their water supply was safe for use before the CDC's recommendation that pregnant women should consider an alternate drinking water source," they wrote. "We are deeply disappointed in the CDC for recommending a screening level before receiving all relevant studies and information, which has resulted in confusion, fear and mistrust among Kanawha Valley residents."In a Facebook posting after the DHHR's advisory to pregnant women, West Virginia American Water commented that the company "does not set water quality standards.""Our responsibility is to follow the rules and guidelines established by federal and state regulatory agencies, such as the CDC, EPA, West Virginia Department of Health and Human Resources' Bureau for Public Health and the West Virginia Department of Environmental Protection," the company posted. "West Virginia American Water has followed the regulatory guidelines and testing protocols required to lift the Do Not Use order ban, and we are fully confident that we are providing customers with drinking water that meets all regulatory standards."Reach David Gutman at email@example.com or 304-348-5119. Reach Ken Ward Jr. at firstname.lastname@example.org or 304-348-1702.