At least two internal Amazon studies found a link between how quickly the online retailer’s warehouse workers perform tasks and workplace injuries, but the company rejected many safety recommendations out of concern the proposed changes might reduce productivity, according to a U.S. Senate committee report.

The 160-page review issued in December was compiled by the Democratic majority staff of the Senate Committee on Health, Education, Labor, and Pensions. The report is the final product of a probe into Amazon’s warehouse safety practices that U.S. Sen. Bernie Sanders initiated last year.

Amazon pushed back on the findings, saying in a blog post that Sanders “continues to mislead the American public” about the company’s safety practices and that the report was “wrong on the facts and features selective, outdated information that lacks context and isn’t grounded in reality.”

Amazon previously had undertaken another study, known as Project Soteria, in 2020 to identify risk factors for injuries and recommend policy changes that would improve worker safety. The multi-team initiative studied two policies Amazon implemented temporarily during the COVID-19 pandemic—giving workers more time off and pausing disciplinary measures “for workers who failed to meet speed requirements,” the report said.

The study found that both policies lowered injury risks and asked for their permanent adoption.

But company leaders denied the request, saying it might “negatively impact” productivity, according to Amazon documents cited in the Senate committee report. Amazon leaders also changed the focus of the Project Soteria study by telling the people conducting the review to provide recommendations on how to improve productivity without worsening worker injuries, the report said.

Amazon disputed the report’s characterization of the events.

“Project Soteria is an example of this type of team evaluation, where one team explored whether there’s a causal link between pace of work and injuries and another team evaluated the methodology and findings and determined they weren’t valid,” Amazon spokesperson Kelly Nantel said in a written statement.

The Senate committee report also alleged that Amazon manipulates its workplace injury data to portray its warehouses as safer than they are, an allegation the company disputed.

This article was provided by The Associated Press.