CHARLESTON, W.Va. -- Despite assurances from national public health officials and the local water company, concerns persist that a recent chemical spill continues to taint tap water for thousands of West Virginians.
Within hours of the crude MCHM leaking from a Freedom Industries storage container along the Elk River and flowing into a local water treatment facility, West Virginia American Water Co. told 300,000 customers not to drink their tap water.
Almost immediately, questions arose as to how much of the chemical in the water, if any, was safe to consume.
Officials with water company and state government repeatedly assured the public that any amount below 1 part per million in the water was safe to consume. They said that amount was from the U.S. Centers for Disease Control and Prevention.
Water company officials said the telltale licorice odor would remain until the chemical dropped below 0.1 parts per million.
After the first public statements from CDC officials as to how they reached that number, and a Daily Mail analysis of available test results, questions remain unanswered.
The CDC's math
The CDC made no public statement about the situation until Thursday. Wednesday evening, the state Bureau of Public Health announced "out of an abundance of caution" pregnant women should not drink any tap water until there was no sign of crude MCHM in the entire water company's system.
The recommendation came from a letter written by CDC Director Thomas Frieden.
Dr. Vikas Kapil, an executive with the CDC's National Center for Environmental Health, said Thursday the CDC stands by the threshold.
He parroted the "abundance of caution" phrase, but declined to say why the CDC decided to advise pregnant women against drinking tap water almost a week after the leak.
"This is a dynamic and evolving event and we have provided a screening level that we feel is ... not likely to be associated with any adverse health affects," Kapil said during a teleconference with reporters Thursday afternoon.
An advisory for pregnant women is common in an emergency, Kapil said, especially when little is known about a chemical.
Kapil said there is more than one study that the CDC used to make its determination involving the 1 part per million level. None were made available, and he said none address reproductive health or cancer.
"There are questions that we can't always answer," Kapil said.
This uncertainty and lack of information played a role in the CDC's creation of the 1 part per million level.
The formula involves "uncertainty factors," a study about the chemical's effect on rats and more guesswork.
"Welcome to the wild and woolly world of risk assessment, folks," said Richard Denison, a biochemist with the Environmental Defense Fund, in an email describing the methodology.
Using a level based on the animal study and factoring in the unknown, the CDC essentially determined the 1 part per million based on how much an average child weighs and how much water they might drink in a day.
There are issues with their formula, Denison said.
Using the term "safety factors" can be "especially problematic given that they cover variability and uncertainty and are not meant as a guarantee of safety," he wrote in the email.
Kapil emphasized the 1 part per million estimate is conservative and pregnant women who drank the water with any amount of the chemical will "likely" be fine.
Testing the water
There is a chance contaminated water is still being sent to zones considered in the clear.