We see it, therefore we are afraid of it.

In yesterday's news was a report by the Environmental Working Group on the nation's water supply. Their conclusion: pretty dismal.

Tap water in 42 states is contaminated with more than 140 unregulated chemicals that lack safety standards, according to the Environmental Working Group's (EWG's) two-and-a-half year investigation of water suppliers' tests of the treated tap water served to communities across the country.

I wonder. Did they test for DHMO?

In any event, a little perspective is in order:

...continued in full post...

EWG's analysis also found almost 100 percent compliance with enforceable health standards on the part of the nation's water utilities, showing a clear commitment to comply with safety standards once they are developed. The problem, however, is EPA's failure to establish enforceable health standards and monitoring requirements for scores of widespread tap water contaminants. Of the 260 contaminants detected in tap water from 42 states, for only 114 has EPA set enforceable health limits (called Maximum Contaminant Levels, or MCLs), and for 5 others the Agency has set non-enforceable goals called secondary standards. (EPA 2005a). The 141 remaining chemicals without health-based limits contaminate water served to 195,257,000 people in 22,614 communities in 42 states.

This sounds gruesome, but its bark is a lot worse than its bite. Piece by piece:

EWG's analysis also found almost 100 percent compliance with enforceable health standards on the part of the nation's water utilities...

Firstly: "Compliance" with enforceable health standards does not mean none of the chemical was present in the water – that the water was "uncontaminated" by that chemical. It means the level was below a level set by law or regulations, such as these. Under EPA standards, the maximum allowable level of arsenic in water is 10 µg/liter, or 10 parts per billion. Water that tests out as being contaminated with nine parts per billion of arsenic is "in compliance with enforceable health standards".

Even if the EPA implemented a standard for the remaining 141 chemicals the EWG found in the water, there's no reason to believe the levels would violate those standards.

Secondly, because a chemical is detected we can't assume it's a health hazard. To be sure, the press release describes some contaminants as "linked" to various health problems. These links usually involve small studies that are looking at things that will show up at the level of one in tens, maybe hundreds, of thousands of people. That's an awfully small signal to find in a noisy system. There may not be any significant health effect. In many cases, there just hasn't been enough research to ascertain how much of a health impact there is. The Junk Science page has links to articles showing that exposure to even large amounts of MTBE (one of the listed contaminants) has a relatively minimal and short-term effect on health.

Finally, in comparing the EWG list of detected chemicals with the EPA list, I find something that may be a bit misleading. One example that leaps to my attention is the third chemical listed – tritium.

Contaminant with no Enforceable Health Standard in Tap Water	Population Exposed (of 231,439,195)		Number of Water Systems (of 39,751)
	At any level	Above health limits	At any level	Above health limits
Tritium	32,230,006	0	80	0
	Pollutant from commercial nuclear reactors and research reactors, and government weapons production plants

Looks bad, doesn't it? Here's where the EWG palms a card.

Although "tritium" has no specific maximum standard for tap water under the EPA, the EPA does limit the levels of beta radiation in tap water. Your tap water is allowed to dose you with more than 4 millirem of beta particles and photons (gamma rays and x-rays) per year. If the only source of beta particles and photons in tap water is tritium, the maximum allowed is the quantity that will give you an annual dose of 4 mrem, or about 4% of the average natural background level.

How many of these chemicals are included under other standards? Maybe a very small fraction. Or maybe a lot of them. I haven't gone over this with a fine-toothed comb. But if I can spot one at a glance, I suspect it's not the only one.

Bottom line: there are things far more worthy of worrying about than the chemicals the EWG finds in the water.