A new Government Accountability Office (GAO) report concludes the Drug Enforcement Administration (DEA) has contributed to a shortage of prescription narcotics and stimulants. Controlled substances such as narcotics and stimulants are regulated by the DEA because of the potential for abuse and addiction.

To prevent diversion of controlled substances, the DEA sets quotas that limit the amount of certain substances that are available in the United States. The new report finds the DEA has not effectively managed the quota process, which has contributed to shortages, according to The Wall Street Journal.

“Each year, manufacturers apply to [the] DEA for quotas needed to make their drugs,” the GAO wrote. The “DEA, however, has not responded to [the drug makers] within the timeframes required by its regulations for any year from 2001 through 2014… Manufacturers who reported quota-related shortages cited late quota decisions as causing or exacerbating shortages of their drugs.”

The report says the DEA has “weak internal controls” that impede its ability to manage quotas, such as a lack of quality-control checks to verify the accuracy of data in year-end reports. The GAO recommended the DEA perform periodic data checks to better manage the quota process, and suggested the DEA and Food and Drug Administration (FDA) update an agreement that would help the agencies work together to combat shortages.

The DEA disputed some of the report’s findings, the article notes. The agency said the GAO does not understand how quotas are established, and said it has no control over drug manufacturers’ decisions. The DEA said there was no “causal relationship” between shortages and the agency’s procedures for establishing quotas.

The agency also said some of the shortages have resulted from disagreements with the FDA, including how to define prescription drug shortages.