Roughly half a million Medicare beneficiaries receive high amounts of opioids, with nearly 90,000 of those at “serious risk” from the medications, a federal watchdog warns.

The Office of Inspector General for the Department of Health and Human Services released a report on Thursday documenting its concerns over “extreme” painkiller use and questionable prescribing practices among healthcare providers.

The OIG found that one in three Medicare Part D enrollees received a prescription opioid in 2016, with roughly 500,000 beneficiaries receiving high amounts of the drugs. The report also showed about 90,000 enrollees to be at “serious risk” with some receiving extreme amounts of opioids, while others appeared to be engaged in doctor shopping.

The report also found 400 providers had “questionable” prescribing patterns for those beneficiaries most at risk from the drugs. Those findings are troubling, the OIG said, since the drugs can increase the risk of confusion, falls and fractures among seniors. The drugs also carry the risk of abuse, misuse and diversion without healthcare facilities.

To improve opioid prescribing practices among seniors, the OIG called on prescribers to be “vigilant” about making sure the drugs are properly prescribed, and at the appropriate levels. The watchdog also urged a “multifaceted approach” to combating the opioid epidemic, including improving pain management alternatives and public health surveillance.

Long-term care’s role in the national opioid crisis has been previously called into question by experts who say the drugs’ benefits, such as alleviating chronic pain, outweigh their risks to institutionalized older adults.