At a news conference last week, federal officials repeatedly said they thought home testing would not be necessary or helpful. Tomblin did not specifically rule it out, but he was far from enthusiastic about the prospect.
He changed course a few hours after that news conference, saying his administration would look into home testing.
Asked what changed his mind, Tomblin said it was obvious that people wanted their homes tested. He said it was impossible to test every home in the region, but since the chemical's licorice smell has persisted in many places, they would do some home testing.
State and federal officials have said residents can resume using water from West Virginia American Water's regional system, citing test results showing levels of Crude MCHM were below a controversial 1-part-per-million "screening level" set by the federal Centers for Disease Control and Prevention. But government officials have done no testing inside people's homes.
West Virginia residents in the spill area increasingly have been asking why the state Department of Health and Human Resources and 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 only in very small amounts -- for some undetermined amount of time.
Whelton has compared pipes to a sponge, in which the chemicals could be quickly absorbed but perhaps not so quickly expelled over time.
At last week's news conference, officials from the U.S. Environmental Protection Agency said they have a study that disputes this theory, but they have not released a copy of the study.
EPA regional drinking-water chief Bill Arguto suggested a reporter could get a copy from West Virginia American Water. The water company has not responded to a request for the study.
On Tuesday the EPA declined to release the study, citing "water security" issues.
During a congressional hearing on Monday, state Bureau for Public Health Commissioner Dr. Letitia Tierney referenced the study and said that MCHM has a low "partition coefficient," meaning it is unlikely to stick to pipes. Tierney also said federal officials are still looking at the issue.
Whelton said he is familiar with the study cited by the EPA but said it doesn't have enough information to come to any conclusions.
"I would say we don't know," Whelton said when asked how sticky the chemical might be to home pipes. "There is no data for helping West Virginians understand chemical interaction with plumbing pipe materials.
"There are too many unknowns, and the health and safety of hundreds of thousands of West Virginians and U.S. citizens is in question."
Reach David Gutman at david.gut...@wvgazette.com or 304-348-5119.
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.