Dozens of people who help coordinate travel for complex inspections of foreign drug-making factories have been let go, and though some have since been rehired, inspectors said the ongoing strain of policing an industry spread across more than 90 countries has exhausted staff and could compromise the safety of medications used by millions of people.

For years, inspectors have uncovered dirty equipment, contaminated supplies and fraudulent testing records in some overseas factories — serious safety and quality breaches that can sicken or kill consumers. Last month, ProPublica reported that a generic immunosuppression drug for transplant patients could dissolve too quickly when ingested, increasing the risk of kidney failure. The drug was made at an Indian factory with a history of quality violations that was banned from the U.S. market. The company previously told ProPublica it believes the medication is safe.