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 call.
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 great-tasting water."
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 everybody's house.
"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.