In March, the Environmental Protection Agency rescinded a proposed, tougher limit on arsenic in drinking water 3 days before it would have become final. That proposed limit would have lowered acceptable concentrations of the cancer-causing pollutant from 50 parts per billion to just 10 ppb. On Oct. 31, EPA rescinded its March decision and again put forth the 10 ppb limit, which is planned for implementation in 2006.
A Sept. 21 review of arsenic risks by the National Academy of Sciences seems to have initiated the reversal. "Even very low concentrations of arsenic in drinking water appear to be associated with a higher incidence of cancer," noted Robert Goyer, a retired pathologist and chairman of the academy's arsenic-review committee. That group found that routinely drinking water laced with even 3 ppb arsenic would pose a 1 in 1,000 risk of bladder or lung cancer.