“The perfect should not be the enemy of the good” is perhaps the most-repeated axiom you hear on Capitol Hill.

But when a bill is this crucial to public health and safety, there’s another axiom to heed: “The devil is in the details.”

This week, the Senate will likely begin consideration of a chemical safety bill with bipartisan sponsors (Sens. David Vitter, R-La., and Tom Udall, D-N.M.). The bill would mandate a new approach for the Environmental Protection Agency to oversee thousands of potentially dangerous chemicals and provide some resources to help accomplish that goal. Sens. Barbara Boxer, D-Calif., and Edward J. Markey, D-Mass., have also introduced a stronger, more protective bill, though it does not currently have bipartisan co-sponsorship.

The bill attempts to reform the Toxic Substances Control Act, rightly criticized for being too weak and ineffective. Since the law passed in 1976, the EPA has managed to regulate only a tiny fraction of the more than 80,000 chemicals in commercial use.

The Vitter-Udall bill, when first introduced in the last Congress, was far too weak. Over time, it has significantly improved. Let’s not ask ,“Is it perfect?” but rather “Is it good enough for enactment?”

Not yet.

But with a few more changes — and strong implementation — we can significantly benefit public health and safety.

Here are some of our concerns:

The bill’s timeline would regulate chemicals very slowly. Since 1976, the EPA has evaluated only 200 chemicals, and banned or restricted only five. If only 1 percent of chemicals in use today were considered unsafe, there would be 800 chemicals to address. Under the timelines specified by the bill, it would take the agency decades to reach that goal, without even considering any new chemicals that come along.

Independent science needs to play a stronger role. The bill as drafted does outline a science and peer review process, but could be stronger in ensuring its independence from chemical industry influence. To truly protect public health and safety, determinations on the safety of chemicals must be based on a clear, independent science process. The evidence must be peer-reviewed free from conflicts of interest. Also, the bill opens the door to many more challenges of science by industry — a recipe for slowing or halting the process of regulating dangerous chemicals.

The bill makes it more difficult for the states to take the lead on regulating chemicals. Current state chemical restrictions won’t be affected until the EPA takes action to regulate a specific chemical. But states will have a very hard time trying to regulate any additional unsafe chemicals after the law is passed because federal rules would largely pre-empt state authority to take future action to protect their citizens, and states wouldn’t even be allowed to enforce the federal rules. The bill specifically bars states from adopting and enforcing restrictions for unsafe chemicals that are identical with the EPA’s. All enforcement would rest with the EPA, which lacks the resources to conduct nationwide enforcement on its own.

Will shortcuts undermine the point of the law? The EPA may be tempted to speed up its chemical work by throwing hundreds of chemicals into the low-priority category, meaning the agency would decide it has enough information to consider the chemical “likely to meet the applicable safety standard.” Once a chemical lands in the low-priority basket, states have 60 days to challenge that decision. But citizens don’t have any avenue for compelling the EPA to reconsider.

What will it cost? And who pays? The bill would assess fees to cover some of the cost of chemical regulation. But the amount of industry fees would be capped at $18 million. Those fees are too low to support a robust program, which needs strong federal support as well. We know that chemical companies have annual profits that run into the billions of dollars, and protecting future generations from unsafe chemicals is a sound public investment

If the bill becomes law, the EPA will have major new responsibilities. But the agency is under concerted attack and enormous budget pressure from Congress. This bill must do all it can to ensure that the regulatory actions needed to protect public health and safety from chemicals are fully funded and serve the public good, not just private sector interests.

Several changes to the bill over two years have been positive, but we’re too close to the finish line to quit now. Before we move forward with this legislation, we can and must do better.

Ken Kimmell is president of the Union of Concerned Scientists and the former commissioner of the Massachusetts Department of Environmental Protection. Dr. Andrew A. Rosenberg directs the Center for Science and Democracy at the Union of Concerned Scientists.