The ATSDR said the risks of formaldehyde are "low" at 10 parts per billion. The agency said the risks of irritation from formaldehyde are "medium" at 100 parts per billion.
After Simonton's testimony about formaldehyde, West Virginia American Water issued a statement that said, "It is misleading and irresponsible to voice opinions on potential health impacts to residents of this community without all of the facts.
"Procedures for water analysis are carefully prescribed, outlined and certified," the water company statement said. "West Virginia American Water will continue working with governmental health and environmental professionals and, in conjunction with these professionals, we and public health agencies will make public any reliable, scientifically sound information relating to risks to public health, if any."
In his testimony, Simonton also said he is still concerned with the 1 part per million standard for Crude MCHM that the federal Centers for Disease Control and Prevention has said is safe in water for everyone except pregnant women.
The vast majority of the most recent test results posted by the state Division of Homeland Security show a "not detected" level of Crude MCHM in water samples. The state has said it can detect the chemical down to 10 parts per billion, although officials in Louisville, Ky., have said their tests can detect the chemical at concentrations down to 1 part per billion.
Scharman said that is just the nature of testing.
"For any test that we do," she said, "different labs have different lower thresholds, so you can always find a level that can test just slightly under."
In a letter sent Tuesday to Sen. Jay Rockefeller, D-W.Va., West Virginia American Water President Jeff McIntyre emphasized that the most recent testing using the state's method has shown "non-detectable levels of MCHM in multiple pressure zones, accounting for approximately 85 percent of our local service area.
"In remaining areas where testing results are above the non-detectable limit, they are still extremely low and only a fraction of the CDC-established 1 ppm health-protective limit," McIntyre wrote.
Last week, Adjutant Gen. James Hoyer of the West Virginia National Guard said the Guard had done some testing in hospitals but had no plans to test in individual homes or businesses.
"I'd have Guardsmen on duty for the rest of my career," Hoyer said.
The water company also has said it has no plans to provide customers with home testing of their tap water.
In his legislative testimony Wednesday, Simonton stressed what other outside public-health officials have already made clear: Little is known about the chemicals involved in the leak.
"We don't know what happens to this stuff once it gets into the environment," he said. "What happens when it reacts with makeup or soap or shampoo or anything else that we come into contact with everyday?"
He also said the flushing period recommended by West Virginia American and state officials wasn't enough and that the chemical is sticking to pipes in the system.
Starting Jan. 13, water company officials and the state 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.
But 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 ATSDR that residents be advised to flush their plumbing systems until the chemical odor is gone.
Simonton said people have flushed for hours and hours, and the odor still remains.
"We know the stuff is sticking," he said. "Exactly where it is or how it's happening is unclear right now."
The U.S. 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.
In a letter sent Monday to the Federal Emergency Management Agency, Tomblin acknowledged that the public lacks faith in the safety of the region's water supply.
"Despite the best efforts of the company and government many people no longer view their tap water as safe and are continuing to demand bottled water to meet their potable water needs," the governor wrote to FEMA Regional Director MaryAnn Tierney. "It is impossible to predict when this will change, if ever."
Reach David Gutman at david.gut...@wvgazette.com or 304-348-5119.
Reach Ken Ward Jr. at kwar...@wvgazette.com or 304-348-1702.