When a doctor sticks a needle in you, you expect that the drugs it carries won’t be tainted. But, possibly owing to a strange gray area in federal law, thousands of patients last October got injections for back pain that contained highly dangerous fungal meningitis, and dozens of them died.

Members of the Senate Health, Education, Labor and Pensions Committee are now seeking to fix the government’s oversight of the obscure world of compounding pharmacies. The reforms they want are overdue.

Drug compounding used to be a corner-shop business, in which local pharmacists would mix a batch of drugs for specific patients with particular needs — and detailed prescriptions. That still happens. Over the years, however, compounding also turned into a much bigger industry.

Some compounders now operate more like large-scale drug manufacturers than small-time pharmacists, which is how the tainted back-pain injections found their way from a Framingham, Mass. compounding center to all over the country last year.

Yet these operations don’t face the same scrutiny from the Food and Drug Administration as do big drugmakers, and state-level regulation is inconsistent.

Since the meningitis outbreak, the FDA has tried to crack down more. Among its findings in recent inspections: “unidentified black particles floating in vials of supposedly sterile medicine; rust and mold in ‘clean rooms’ where sterile injectable medications were produced; technicians handling supposedly sterile products with bare hands”; and more.

Despite its recent efforts, the FDA says there’s only so much it can do, because its legal authority to regulate compounding is murky in some places and limited in others.

The Senate bill would distinguish “compounding manufacturers” from their small-scale cousins, put them under FDA control and require that they meet the same standards as large drugmakers. They would have to register with the federal government, disclose what they are producing and pay a small fee to cover the cost of inspections.

The bill is still in the draft phase. Lawmakers must ensure that large compounders have enough incentive to admit to the FDA that they qualify as manufacturers. The bill’s definition of compounding manufacturer, meanwhile, might leave out some pretty big operations that don’t ship their goods across state lines, though no definition is likely to be perfect.

The Senate should refine the language, then pass some version of this bill. The House, meanwhile, also should get to work.

Editorial by The Washington Post