"The question that keeps coming up -- is your water safe? -- with all of the science, everything that we have . . . so far, I can say that you can use your water however you like," Popovic said.
Outside public-health experts, though, have questioned whether the CDC had anywhere near enough data to draw any reliable conclusions and if agency officials properly considered impacts on sensitive populations and great unknowns about the industry-produced data they did have on MCHM.
In recent days, West Virginia residents have increasingly been asking why the state Department of Health and Human Resources or the National Guard are testing water for MCHM only at the water treatment plant, at fire hydrants and in some public buildings, such as schools.
Outside experts have expressed concern that the MCHM and other chemicals from the leak could have been absorbed by home plumbing systems, where it could continue to leach into water -- even if in very small amounts -- for some undetermined amount of time.
Whelton, the Alabama engineer, has been testing water from area homes and arguing publicly that more information is needed about how chemicals from the leak interact with varying types of home pipes and tanks.
In an email interview Tuesday night, Whelton had said officials were making a mistake if they didn't conduct a broader study of MCHM's presence in homes impacted by the leak.
"Chemical exposures occur inside homes at kitchen faucets, showers, etc., not at a hydrant," Whelton said. "Plumbing systems do not operate the same as buried pipe networks. There are clear differences."
Last week, Whelton was awarded a $50,000 emergency grant from the National Science Foundation to study the way the MCHM from the leak acts when it enters home plumbing systems.
In announcing the grant, an NSF official called the Elk River leak "one of the largest human-made environmental disasters in this century." The foundation said one of the central unknowns about the leak's long-term impacts is how the chemicals interact with home plumbing systems.
At a U.S. Senate hearing Tuesday, an official from the Natural Resources Defense Council noted Whelton's research but said the grant provides "insufficient resources to conduct an extensive testing regime representative of the 300,000 customers affected."
During an interview Tuesday, Larry Cseh, an emergency response coordinator with the CDC and the Agency for Toxic Substances and Disease Registry, said any decision for the federal government to test for MCHM testing in homes would be up to the EPA.
In another interview Tuesday, EPA regional water-protection chief Jon Capacasa initially said he was under the impression that tap water was being tested inside homes.
"My understanding is that a lot of different types of monitoring and testing have been done in the schools, at the taps, in homes, and in distribution systems and finished water leaving the plant," Capacasa said. "We're encouraged by the fact that it shows diminished presence of these chemicals in the water, if not non-detect."
Told that neither the state nor the water company had been testing inside homes, Capacasa responded, "I can't speak definitely to it, but I'm aware of the school sampling, which I think was taps. I know all of the sample results have been published online for review. I'm encouraged by that."
Asked for specifics of the home testing he referred to, Capacasa finally said, "You bring up a good point. Let me do my homework on that before I comment. If that's a concern, we certainly will track that down and make sure we are getting the best information possible."
Several hours later, EPA spokeswoman Bonnie Smith said in an email to the Gazette, "Our drinking water program confirmed with WV Bureau of Public Health and WV American Water that none of the distribution system sampling was done in homes.
"Samples were collected at hydrants and other locations, where samplers could access water representative of particular pressure zones," Smith said. "These samples reflected water quality in the water mains, which is water that would be delivered to homes/buildings/etc."
Smith added, "[The] EPA has reviewed the home flushing protocol that the water company has developed, and believes that if properly implemented by homeowners, the flushing should result in water quality which is representative of what is being delivered to the homes."
Asked to comment on the EPA's statement, Whelton said, "To my knowledge, [the] EPA has not provided any field data to justify their conclusions. It is possible that [the] EPA is simply traveling in [to West Virginia] to reaffirm their position without conducting any unbiased testing to test their assumption.
"It is baffling why any official would make those statements without hard data, which they could have collected already," Whelton said.
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.