Two new findings from the federal government's examination of the January 2014 chemical leak at Freedom Industries raise new questions about the toxicity of MCHM and other materials involved in the incident.
The study updates from the National Toxicology Program at the U.S. Department of Health and Human Services found evidence that some of the leaked chemicals could affect neurological function or be related to genetic mutations, according to materials recently posted on the program's website.
Agency officials said in those materials that the findings, based on studies involving a type of minnow and several strains of bacteria, did not prove that the leaked chemicals caused such effects in humans, especially at the levels Kanawha Valley residents might have been exposed to when Freedom's leak into the Elk River in Charleston contaminated the drinking water supply for hundreds of thousands of residents across the region.
One study update, dated August 2015 and posted Monday, evaluated the movements of zebrafish, a type of minnow, in response to light in the presence of one of the leaked chemicals, 4-MCHM. The study found that both 4-MCHM and a similar chemical that was not involved in the leak "altered" the zebrafish response at doses as low as 4.5 parts per million.
The update said, "the finding that MCHM exposure caused neurotoxic effects in zebrafish is consistent with clinical signs of neurotoxicity" found in rat studies conducted by Eastman Chemical, the maker of MCHM.
"In the rat studies, the dose levels where these effects were observed are more than 1,000-fold higher than the estimated human exposure levels during the spill," the study update said. "Notably, outward signs of neurotoxicity were not observed in rats exposed to doses that are in the range of human exposure during the spill."
In another study update, dated July 2015 and posted online Friday, federal scientists used bacteria to test for the potential for two additional chemicals that were "minor constituents" from the leak to cause genetic mutations. They found that one of those chemicals, dimethyl 1,4-cyclohexanedicarboxylate, "caused mutations in two of the bacterial strains that were used in the test."
The update said that finding "does not establish" that the chemical's presence in the leak "would result in DNA mutations in humans."
"Factors such as the amount of exposure and differences in how the human body handles the chemical compared with bacteria would determine whether similar effects might occur in humans," the update said.
Previously, federal officials had reported that they found no mutagenic effects when they conducted similar tests on eight other chemicals from the leak, including 4-MCHM, the primary leaked material. The two new chemicals included in the July update accounted for less than 2 percent of the leaked material, officials said.
A third new study update, also dated July 2015 and posted Friday, found no developmental effects in zebrafish related to exposure to six chemicals from the leak.
West Virginia public health officials said Wednesday that they had not yet reviewed the findings, which were quietly posted on the Internet without a news release or any of the public fanfare that accompanied the mid-June publication of earlier study results that were touted as proof the state responded appropriately during the water crisis that followed the Freedom leak.
In those earlier results, federal scientists said their testing thus far had found evidence of potential long-term health effects from the leaked chemicals only at exposures greater than the government's 1-part-per-million health advisory, but they also conceded that their work didn't consider inhalation of Crude MCHM or fully account for health impacts during the "flushing" of home plumbing systems.
Federal officials abandoned a plan in the immediate aftermath of the leak to come up with a limit for how much MCHM was safe in the air. No air sampling was done in homes or public buildings. Additionally, follow-up research has warned that residents could have been exposed to dangerous levels of chemicals during flushing procedures.
The most common health problems reported after the leak were rashes, nausea, vomiting and diarrhea, and the most common way affected residents were exposed to the chemical was through skin contact while bathing, showering or washing hands - routes not considered in the government's screening level during the crisis or studied by federal officials since the incident.
During a meeting Wednesday of the West Virginia Public Water Supply System Study Commission, Barbara Taylor, a deputy commissioner at the state Bureau for Public Health, summarized previous National Toxicology Program studies for the commission members, but she indicated that the most recent results were those made public in mid-June. Taylor and Bureau for Public Health Commissioner Dr. Rahul Gupta said after the meeting they did not know that the July and August updates had been posted online. Gupta said his agency would review the results and discuss them with federal officials.
Robin Mackar, communications officer for the National Toxicology Program, said a notice announcing that the reports had been posted was distributed via a mass emailing on Monday.
Reach Ken Ward Jr. at kward@wvgazette.com, 304-348-1702 or follow @kenwardjr on Twitter.