Pressed about the matter earlier this week, Tomblin said, "I'm not a scientist," adding that whether the detection limit is 10 parts per billion or 1 part per billion, the concentration involved "is still miniscule."
Dr. Vikas Kapil, chief medical officer for the CDC's National Center for Environmental Health, said he wasn't familiar with the different sampling methods being used and added a remark similar to Tomblin's.
"There are always these differences between methods," Kapil said. "When you get down to numbers that low, to some extent, I really don't think it's an issue."
The Morgantown-based consulting firm Downstream Strategies has been following the chemical leak closely, and is one of several companies that will perform home water testing, for a fee, to residents concerned about the leak.
Downstream Strategies is doing sampling that goes down to the same 10 parts per billion as the state, and similar to what other firms have reported for private home testing done in the wake of the leak.
Marc Glass of Downstream Strategies said his firm is working with laboratories that use gas-chromatograph and mass-spectrometer technologies to concentrate samples prior to analysis. Glass said he understands that Louisville Water is using a different method, called direct purge and trap.
Both methods use U.S. Environmental Protection Agency-approved protocols, Glass said, but chemists performing such analysis "have differing opinions" about which procedures are more accurate for MCHM.
Ben Gilmer, a project manager with Downstream Strategies, said the limited information about state sampling that's been released has made it hard to analyze the results and draw many firm conclusions.
For example, Gilmer said, complete information about the locations of sampling and timing of sampling related to "flushing" the system have not been made available. And, many samples appear to have been taken only at publicly available locations, such as fire hydrants, which might not necessarily represent the same water quality as that coming from a kitchen sink. It's also not clear if tests are being done only for Crude MCHM or also for any of that chemical's ingredients.
"We are really trusting the water company and the National Guard at this point," Gilmer said. "Until we receive more detailed descriptions of their sampling approach, and until we are able to map all existing test results to specific locations, and compare those tests with the region's water infrastructure and water-use advisory zones, it will remain difficult for outside experts to judge how well chemicals are being pushed out of the system."
Sen. Jay Rockefeller, D-W.Va., has asked West Virginia American Water to provide more detail about its test results.
"Many West Virginians are asking for maximum transparency throughout this process and would like to have details about sampling, testing and chemical levels in a timely manner," Rockefeller wrote in a letter to the company. "Please publicly post to your company's website, in real time, the sampling times, coordinates where samples are being taken, test results in [parts per billion], and the substance for which you are testing."
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.