Study Examines MCHM Odors in Water
31 January 2014
By Ken Ward Jr.
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
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
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
"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
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.
Lawrence Messina, a spokesman for the West Virginia Department of
Military Affairs and Public Safety, said those statements were
based on consultations with the Louisville Water Co., which he
said developed its own odor threshold for MCHM. Messina said he
was told those consultations took place in a Jan. 14 conference
Kelley Dearing Smith, communications director for Louisville
Water, said the company uses a panel of specially trained staffers
for daily odor testing of its water supply.
"Louisville Water has a long history of dealing with and managing
taste and odor issues," Smith said. "Many times, the compounds are
not necessarily a health concern, but aesthetics plays a large
role in our quality control and, of course, public perception. The
taste of tap water is a big deal in Louisville. We're known for
Louisville Water officials began their work when the MCHM plume in
the Ohio River was above Cincinnati, which was around Jan. 13 or
14, Smith said. By the middle of the week, Louisville Water
officials had settled on a figure they were comfortable with --
about 1 part per billion -- as an odor threshold for the chemical.
"In this instance, we had the luxury of planning time -- but we
also believe our expertise played a role, too," Smith said. "We
were using an odor threshold of 5 parts per billion. Turns out, it
was 1 to 3 parts per billion, much more sensitive to the nose.
"We learned throughout the week that extremely sensitive people
could detect the sweet odor of MCHM at 1 part per billion,
although, for most people, it was 3 parts per billion."
Dietrich, the Virginia Tech scientist, said the Louisville figure
is the lowest she's seen as a possible odor threshold for MCHM.
"I'm hoping that they're right and that the odor threshold is
below the health threshold," Dietrich told the Gazette-Mail, "but
that doesn't make the odor any less annoying. Odors in drinking
water are important, even if they aren't a health concern."
Under federal law, water contaminants that present a public health
threat are supposed to be regulated through the setting of
enforceable "maximum contaminant levels," or MCLs. Other
standards, called "secondary maximum contaminant levels," or SMCLs
govern other concerns, such as taste, odor and color.
The EPA said it does not enforce the SMCLs. "They are established
only as guidelines to assist public water systems in managing
their drinking water for aesthetic considerations, such as taste,
color and odor," the EPA says on its website.
There are no federal or state MCLs or SMCLs for Crude MCHM.
The Tomblin administration and West Virginia American Water have
indicated that following the ATSDR's flushing advice could have
emptied the water system and, in the water company's words,
"caused customers to go without water that was already determined
to be under the health protective threshold for an indefinite
amount of time."
Dietrich said the ATSDR guidance to flush plumbing systems until
the water doesn't smell isn't a bad idea. However, she said,
because the lack of a previously determine odor threshold -- and
because people have different odor sensitivities -- that might
have been a complicated process.
Also, Dietrich said, it's sometimes better in such situations to
give the public more concrete advice, such as a specific amount of
time to flush their pipes.
Still, she said, residents also have had reasonable questions
about why public health officials have tested only at the water
plant and hydrants -- and not in individual homes.
"The plastic pipes, in part, can be a reservoir," Dietrich said.
"Even if it's not in the water hydrants or the mains, it could
still be in people's homes."
While it might not be practical to take samples in the homes of
100,000 West Virginia American Water customers, she said, it would
be possible to come up with a representative sample to meet public
concerns for home testing.
"The public officials need to address people's concerns," Dietrich
said. "That dialogue and that conversation are most important.
"It needs to go both ways," she said. "Everybody has constraints.
The public has the constraint that they want to know that the
water is safe, but it's not possible to do this testing in
"I do think the state, in terms of managing people's concerns,
should establish a dialogue and then address what can be done."
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.