Let’s say you open up a lab report you’ve received, one containing the analysis of a sample of your drinking water, or a sample of the indoor air where you work. You navigate the maze of acronyms and unfamiliar words to find some numbers. Now… what the heck do they mean? The only thing you’re interested in is whether those numbers represent a threat to your health.

To make that judgment, we rely on the health standards determined by government agencies—in the US, it’s usually the Environmental Protection Agency. (States set their own standards, but they largely reflect the EPA’s numbers.) Below those standards, exposure is presumed to be acceptable and safe.

The EPA was created in 1970 to deal with the glaringly obvious pollution that spurred the passage of the Clean Air Act and Clean Water Act. The agency brought health research to bear on that pollution, setting safe limits and ensuring that air and water were cleaned up when these weren't met. It also limited what a facility was allowed to release into the environment for the first time.

Lead pollution in air, a result of leaded gasoline (and discovered because of its interference with radiometric dating labs), was high on the list of things to clean up. When lead in gasoline was banned, concentrations of lead in children’s blood began to drop precipitously—an unambiguous success. In this and other cases, the early progress was easy because there was simply so much progress to be made. (“There’s lead in the air? OK… maybe we shouldn’t do that.”)

Since then, things have gotten a lot more complicated. While still dealing with the toxic legacy of 1940s to 1960s, regulators have faced a flood of new compounds hitting the market (as has the Food and Drug Administration) on top of expanding responsibilities. The result has been lots of criticism directed at the EPA’s process for setting health standards. Last year, Congress ordered the EPA to address the concerns detailed in a report issued by the National Academy of Sciences.

In a recent comment published in Nature, George M. Gray of George Washington University and Joshua T. Cohen from Tufts Medical Center provide their own view of how the EPA must change to, in their words, “become fit for purpose again.” Gray and Cohen are both experts in public health who have experience with EPA’s process.

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.”

As an example, they point to the dry cleaning solvent n-propyl bromide. Dry cleaning has a long and sordid history of releasing toxic chemicals. Many of the groundwater and soil contamination cases around the country are related to the dry cleaning solvent PCE, a compound with neurological and carcinogenic effects. Tightening down the regulatory screws has pushed the industry to find alternatives (along with outright encouragement).

One of those alternatives is n-propyl bromide. Because EPA provides no information on this compound, it has been pitched as a safe alternative. However, the available research indicates that n-propyl bromide may actually be considerably more dangerous to human health than PCE. If the EPA had pulled this information together and made it available, n-propyl bromide might never have been considered as a viable alternative in the first place.

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.

“In our view,” Gray and Cohen write, “the problem is the EPA’s use of assumptions that it claims are ‘public health protective’, which err on the side of overstating risk when data are lacking. Take dioxin, for example. In its assessment, the EPA assumed the worst case—that low levels of dioxin cause cancer—because that possibility cannot be ruled out. Yet other agencies, including the World Health Organization, interpret the biological studies of dioxin as suggesting that it is unlikely to cause cancer at low levels because of the way the chemical behaves within cells.”

The authors believe that the EPA should disclose uncertainty where it exists, and also summarize the conclusions reached by other organizations. The increased information should give states and other parties the information they need to make good decisions. And they need all the help they can get, since good decisions are hard. Setting a standard unnecessarily low greatly increases cleanup and operational costs without benefiting human health, and can take focus away from higher priorities. Of course, setting a standard too high exposes people to potential health risks.

The EPA has an incredibly difficult task that is also crucially important. Dealing with so many unknowns, imperfect data, complicated legal responsibilities, and limited resources, the agency has to provide the best information possible. And it is acting on the criticisms of the National Academy of Sciences, trying to revamp its process. However, Gray and Cohen believe there is still substantial room for improvement that could result in a more effective agency—one that is as much an agent of progress as it was in the 1970s.

Nature, 2012. DOI: 10.1038/489027a (About DOIs).