Drug and alcohol violations among employees at U.S. nuclear plants are on the rise, according to a new report. They have increased from about one a month to almost one a week over the last five years.

The findings come from the non-profit group Fairewinds Energy Education, according to the Tampa Bay Times. They found the majority of drug and alcohol violations occurred in southeastern states. The violations include drinking alcohol in a protected area, and positive tests for marijuana and cocaine.

The report looked at violations of the Fitness For Duty program, which nuclear reactor owners are required to implement to assure that all personnel who have access to their power plants are drug and alcohol free and have no psychological impairments that might comprise the safe operation of any U.S. nuclear power plant. The report found during the past five years, Fitness For Duty violations in the United States have more than doubled, led by alcohol related events, which have nearly quadrupled during the same time period.

“The data unequivocally demonstrates that workforce personnel and licensed reactor operators are under the influence of alcohol and illegal drugs while on-duty, despite the knowledge that such actions when caught can end careers, and that programs are in place that have been designed to identify those who are under the influence, indicating serious addictive issues not occasional social consumption of alcohol and drugs,” the report states. “Not only are workers under the influence of alcohol and/or drugs while on the job, they are also bringing that same contraband into work with them, in some cases with documented evidence to determine there was intent to distribute.”

According to Arnie Gundersen, a nuclear engineer who developed the study, the findings are particularly worrisome because major nuclear accidents, such as the one at Three Mile Island, occurred in part because of operator error.