In March, the Environmental Protection Agency rescinded a proposed, tougher limit on arsenic in drinking water 3 days before it would have become final.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 On Oct. 31, EPA rescinded its March decision and again put forth the 10 ppb limit, which is planned for implementation in 2006.