On top of which, those numbers, when they're that tiny, have a lot of uncertainty in them. I'll put a dollar on the table, and I'm not a betting man, that they're not statistically different from zero. Most European countries have set their maximum arsenic levels at 20 parts per billion in water, Dr. Goyer said. But the cost would be less than half of the cost of reaching 10 parts per billion. But the cost would soar to more than double the cost of 10 parts per billion.
Someone has to make a call on when it's too expensive.
Dr. Kelman said the dilemmas were made clear to him years ago at a meeting on lead standards with officials from the E.P.A. and the National Institutes of Health. The economic impact came up at this meeting and it was very large. From my standpoint as a scientist, I realized that well nourished kids absorb less lead. At which point I figured I'd better sit down and shut up.