The Capitol dome in Washingtom. (J. Scott Applewhite/Associated Press)

The government is failing at protecting the public from dangerous chemicals. Congress tried to regulate the various questionable substances that manufacturers and industry use to produce the products Americans buy. But the 1976 Toxic Substances Control Act failed. Stuck with a lousy law, the Environmental Protection Agency moved slowly, and in 1991 a federal appeals court threw out the agency’s attempt to ban asbestos. The EPA has managed to ban only five chemicals since the 1970s, while thousands of others stay on the market with no review. We say “thousands” because it’s not even clear how many are out there. Congress has done little since to fix the problem.

Until now. After decades of lax oversight, Congress is nearly done with a comprehensive overhaul of the law — but Washington will finish the job only if lawmakers and the interests pressuring them don’t make the perfect the enemy of the good.

The House passed a chemicals reform bill last month by a near-unanimous vote. The Senate passed its own version out of the Environment and Public Works Committee in April with strong bipartisan support; its sponsors are working out a deal to bring it to the floor this month. Things seem to be progressing nicely, except that there are big differences between the two versions that have split public-health advocates, some backing the House’s version, others the Senate’s. This split could be productive. Or it could be toxic.

Both bills create a process to review chemicals that have sat on the market without oversight and another to examine new chemicals companies want to use in their products. But the Senate version does more than the House’s to preclude states from regulating chemicals that the EPA is looking at. That has earned it opposition from activists, including some major environmental groups, and Californians such as Sen. Barbara Boxer (D), whose state has been the most aggressive in regulating chemicals on its own. They want to see the Senate ditch the bill before it and just take up the House’s version.

That would be a bad idea. The Senate’s version isn’t some giveaway to industry; among other things, it allows states to apply for easily obtainable waivers from the federal government that would allow them to continue regulating even while the EPA does its work. Moreover, the Senate’s version has several valuable provisions that the House’s doesn’t, including one that raises money from industry fees to pay for chemical evaluations and another tasking EPA to prioritize its reviews.

This is a situation in which regular legislative order would lead to the best outcome. The House has passed its bill. Let the Senate pass its own version. Then the two sides can hash out differences in a conference committee, where the potential exists for lawmakers to combine the strengths of both bills.

As that process proceeds, public-health activists should keep this bottom line in mind: The system the nation currently has is thoroughly broken. It needs reform now.