CHARLESTON, W.Va. -- Two weeks ago, when the state and the water company told West Virginia residents to begin flushing their home plumbing systems, they said not to worry if the water still smelled like black licorice after they were done.
"Any lingering smell, which is expected, is not a health issue," said the "How to Flush Your Plumbing System" pamphlet posted online by West Virginia American Water on the morning of Jan. 13.
Water company officials and state government representatives repeatedly told the public that Crude MCHM from the Elk River chemical leak had a "low odor threshold." People would smell it in their water at levels far below what was dangerous, those company and government officials said.
The problem was the "material safety data sheet" from Eastman Chemical, which made the chemical that leaked from Freedom Industries, said there was "no data available" on Crude MCHM's odor threshold.
State officials have offered varying figures for what they believe an odor threshold for the chemical might be. In some cases, they haven't made clear where they got their numbers, and the best estimate the state seems to have was apparently provided after the water company's flushing guidance was issued.
Now, though, a new National Science Foundation-funded study announced earlier this week has as one of its central goals to figure out exactly how small a concentration of Crude MCHM humans can smell, and how that number compares to levels that could pose public health risks.
"I do have a sense that we have a lot of numbers out there for an odor threshold," said the study's lead researcher, Andrea Dietrich, a Virginia Tech environmental scientist and engineer.
Experts seem to agree that, while they don't know a specific number, the odor threshold for MCHM is low. But Dietrich said that doesn't mean West Virginia officials should have ignored the potential for lingering odors in the region's drinking water.
"It's part of water quality," Dietrich said Thursday. "Just because there's not a health effect, annoying odors are still annoying and aren't supposed to be in the water."
Dietrich's study is one of three new emergency projects that the NSF is funding to help West Virginia residents get answers about the chemical leak that a foundation official called "one of the largest human-made environmental disasters in this century."
The studies focus on a variety of unknowns: How much of the chemicals from the leak might remain inside home plumbing systems; what the potential human health effects are; and exactly what sorts of steps could be taken to prevent future incidents.
In her study, Dietrich plans to learn more about the chemical and physical properties of Crude MCHM. Among other things, this work will include trying to establish an accurate odor threshold, according to information made public by the NSF.
A summary of Dietrich's study plan indicates that the chemical is believed to have "a low aqueous odor threshold," which means that "consumers can potentially become important monitoring sentinels for exposure to low levels" of the chemical.
"The main location in the house to detect off-odors is the shower because of high water temperatures and water flows in a confined area," the summary said. Dietrich plans to develop models of chemical air concentrations for typical showering conditions.
"This will confirm if consumer sensory detection can aid in detecting locations of residual MCHM," the summary said. "It will also aid in the utility's understanding of consumer complaints, and in the longer term will aid in exposure assessment through inhalation."
On Jan. 13, four days after the Freedom Industries leak, water company officials and the state government began a weeklong process of lifting broad "do not use" orders for sections of the nine-county area impacted by the MCHM leak. After the order was lifted, residents were advised to run their hot water for 15 minutes, their cold water for 5 minutes and their outside faucets for 5 minutes, to flush the chemical from their homes.
However, since then, residents have continued to complain that the black-licorice smell of the chemical is lingering, especially in their hot water.
State officials, in announcing their guidance for flushing, rejected an earlier recommendation from the federal Agency for Toxic Substances and Disease Registry that residents be advised to flush their plumbing systems until the chemical odor is gone.
In a Jan. 10 email message to the state's Department of Health and Human Resources, the ATDSR said it did not "anticipate any adverse health effects" if levels of MCHM were below 1 part per million in drinking water.
"That said, because of the odor and not knowing an odor threshold, we would also recommend that the system or residents be told to flush their systems until it was no longer observed," wrote Larry F. Cseh, emergency response coordinator for ATSDR's U.S. Public Health Service.
Also, early in the incident, the federal Environmental Protection Agency had said in internal documents that flushing the chemicals out of the system "may require a fairly prolonged time to complete," perhaps two to three weeks.
After most residents had completed the flushing process and the do-not-use order was lifted, the Gov. Earl Ray Tomblin's administration issued a news release that said MCHM could "temporarily adhere to plastic pipelines . . . resulting in a lingering licorice odor for some time." The release, issued Jan. 18, said the chemical could be smelled at concentrations far below the level where adverse health effects might occur.