Monday, February 10, 2014

Screening for Toxic Chemicals

Ken Ward, as usual, had a very interesting article at this weekend about the continued controversy over what constitutes a ‘safe level’ of Crude MCHM in the drinking water of Charleston, WV. The combination of politics, analytical chemistry and chemphobia is never a pretty picture and when you add in drinking water safety you have a perfect storm of controversy.

The CDC last week published a rather detailed technical discussion of how they came, a second time, to set the safe drinking water limits at 1 ppm. There is also a rather detailed, and even more technical, page of information about 4-Methylcyclohexanemethanol, a major constituent of Crude MCHM, available from the National Institute of Health.

There is a very legitimate debate about the methodology that the CDC employed when they established the 1 ppm safe drinking water limit. I happen to agree with their method, but there is more than a little element of judgment call involved and that certainly calls for a public discussion. Unfortunately, the CDC was pressed for an answer by many of the same people who are now questioning the decision.

The problem, was of course, that there was an ongoing problem with over 300,000 people not being able to bathe, wash their clothes or prepare food with the water in their municipal water system. There was a great deal of political pressure to come up with a safe drinking limit based upon limited evidence. Any way the CDC went; setting the current limit, setting a stricter limit, or calling for more information; would have been met with legitimate complaints.

This is not a decision that should be made when there are problems with a contaminated water system. This is process that should be clearly established by a public rule making process that allows for a complete discussion of all of the ramifications that affect the decision and the outcomes based upon that decision.

This is why I described a process in my alternative to S1961 by which there would be a standard method established for determining the safe level of a contaminant in drinking water and a requirement for minimum standards for toxicity testing for chemicals that are likely to contaminate drinking water.

While there is certainly a technical component for testing and limit setting discussion, it is mainly a political decision. Political discussions take time to resolve. They should not be made in the heat of the moment when people are in desperate straits; seeking an immediate answer to a complicated problem.

Finally, we have to acknowledge that there is no perfect answer to the question of what is a safe exposure level. There are just too many differences in each of our bodies for there to be a single answer. This is why there should be a government funded and run epidemiological study of every instance where a chemical like this gets into a public water supply. We know that hindsight is 20-20; but it is only clear when a detailed and dispassionate investigation is made.

It will only be through such studies that we will be able to refine the rules and standards by which we determine what are safe levels of contamination in public drinking water.

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