Scott Pruitt, head of the U.S. Environmental Protection Agency, promised in late April to raise standards for the science behind environmental regulations — restricting usable studies to those that can be replicated or independently verified. That's the rationale for a rule he proposed called "Strengthening Transparency in Regulatory Science." It sounds harmless on a superficial level, but there's always a trade-off: The more certainty required of the science, the greater the risk people may be exposed to dangerous pollutants or toxic products.

Pruitt has framed the discussion to focus on the possibility of false positives — studies that exaggerate risks. But any serious effort to improve the environmental science used to make regulations would need to start by determining if indeed there is an excess of false positive results, or if instead there's a problem with false negatives that underreport or miss real risks. If history is any guide, false negatives could prove to be more costly.

The focus on false positives is premised on the assumption that problems recently uncovered in psychology and some areas of medical research also extend to environmental science. In a 27-page document describing the rule, Pruitt made reference to the "replication crisis" — concerns over systematic reviews revealing that more than half of published studies could not be replicated, but only in those limited fields. There's no evidence so far that the same kind of crisis affects physics, astrophysics, chemistry, climatology and other fields.