Since the Seattle Times continues to omit much of the arsenic story, I'll try to fill in what they miss.  In my first post, I noted that there was little danger from the previous standard of 50 parts per billion, and that the affair had been a political trap set by Bill Clinton for George W. Bush.  The Seattle Times has now partly caught up with me on the first point.

Dr. Catherine Karr, director of the University of Washington's Pediatric Environmental Health Specialty Unit, said the long-term risk to children would be very low.

Her rough calculation: If 1 million children, each day for five years, each drank one liter of water with arsenic slightly above the federal standard of 10 parts per billion (ppb), about 10 to 30 more cancers of the bladder or lungs would result.

But they continue to ignore Clinton's role in this fiasco, as you can see in that article and in this editorial.  And they probably always will ignore Clinton's role, since the Seattle Times, like many American newspapers, does not like to hold Democrats responsible for their misdeeds.  (I sent the reporter, Emily Heffter, an email after my first post, so she does know that Clinton was responsible; she just doesn't care to share that knowledge with her readers.)

But the Times, and their expert, Dr. Karr, are only partly right, because a complete account would include the fact that many experts do not believe there is any danger at all in this level of arsenic.  Here, for example, is what the Agency for Toxic Sustance and Disease Registry says about the research on the effects of arsenic in drinking water:

Can arsenic in drinking water affect my health?

Studies conducted in other countries found harmful health effects in persons who regularly for many years drank water containing arsenic at 100 ppb to 300 ppb.  Compared with other groups, more of these people developed several kinds of cancer (lung, liver, kidney, and prostate) and had darkening skin, thickening of the skin on palms of their hands and soles of their feet, skin cancer, and many small warts or corns.

A few studies found no harmful effects in persons in the United States who throughout their lifetimes drank water containing arsenic at levels of 50 ppb to 100 ppb.

They go on to say that reducing exposure below 50 ppb "can reduce the risk of harmful health effects", but you and I can look at the evidence they presented and add to that sentence this phrase: but it almost certainly won't.

The simplest explanation for those different results is that there is a threshold effect; arsenic can cause ill effects if your water contains more than 50 (or perhaps 100) parts per billion, but not below that.  There is nothing surprising about that explanation; many substances do show threshold effects.  For some reason, Karr chose not mention these US studies on the effects of lower levels of arsenic — or the Seattle Times chose not to report what she said.

Cross posted at Jim Miller on Politics.

(There is another possible explanation for these differing results: Because of "hormesis", tiny amounts of arsenic may actually be good for your health — and there is some experimental evidence to support that theory.

Some on the left, notably Ralph Nader, were honest enough to say that Clinton was setting a trap when he made this decisionr.  And, as a commenter pointed out after my first post, liberal journalist Michael Kinsley was honest enough to say that leaving the standard at 50 parts per billion was correct.)