They see two fundamental problems. First, the agency expends too much energy revising standards for compounds that already have one, and not enough on new compounds that have never been evaluated. “Rough-and-ready estimates are often sufficient for policy-making, and are better than nothing,” the authors suggest. Failing to set a standard carries its own risks: “Many people might assume that chemicals lacking [a risk estimate] are safer than those that have been assigned one, even if they are not.”
…The authors’ other concern is the certainty with which EPA sets its standards. Rather than transparently presenting the uncertainty present in the data, the EPA applies a “simpler is better” approach, providing one number that is judged to be the best estimate. However, judgments inevitably lead to disagreement.