Amazon's obsession with "speed and productivity" leads to high rates of debilitating injuries and makes safety procedures "nearly impossible to follow", a new investigation has found.
A report by the US Senate Committee on Health, Education, Labor and Pensions, published this week, found Amazon also discouraged injured workers from seeking outside medical care.
The company was found to have multiple internal practices designed to "delay workers from receiving needed medical care" and force them to return to work too soon.
The report also accused Amazon of "cherrypicking data rather than grappling with its uniquely dangerous warehouses".
"[The Committee found] Amazon chooses misleading comparisons in an effort to obscure the fact that company's warehouses have significantly higher injury rates than both the industry average and non-Amazon warehouses," the report said.
"An analysis … shows that Amazon warehouses recorded over 30 per cent more injuries than the warehousing industry average in 2023.
"The committee also found that in each of the past seven years, Amazon workers were nearly twice as likely to be injured as workers in warehouses operated by the rest of the warehousing industry."
More than two-thirds of Amazon warehouses across the US had injury rates higher than the industry average, according to the report.
It added that injury numbers were allegedly "deflated" when reporting to federal regulators and that injured workers on medical leave often had their employment terminated.
The committee was led by Democratic senator Bernie Sanders, who said in a statement the conditions at Amazon were "shockingly dangerous".
"Amazon's executive repeatedly chose to put profits ahead of the health and safety of its workers by ignoring recommendations that would substantially reduce those injuries," he said.
Amazon spokesperson Kelly Nantel has since called the report "wrong on the facts", accusing the committee and Mr Sanders of using out-of-date information and anecdotes from staff.
"The facts are [that] our expectations for our employees are safe and reasonable," she said.
"We've made and continue to make meaningful progress on safety, improving our recordable incident rates by 28 per cent in the US since 2019 and our [most serious] injury rates by 75 per cent."
She added the company had repeatedly asked Mr Sanders to visit Amazon facilities to see working conditions first-hand, but its invitations had "gone unanswered".
Amazon has also appealed citations by the Occupational Health and Safety Administration (OSHA), which proposed more than $US100,000 ($156,863) in fines across multiple warehouses.
OSHA accused Amazon of exposing workers to a high risk of back injuries and musculoskeletal disorders in at least six US locations.
According to the committee report, Amazon's speed obsession "permeates every aspect of its warehouse culture".
One worker told the committee they had personally given up using Amazon.
"I'd rather wait … than have some poor employee in an Amazon warehouse get battered and bruised so I can get my book within 6 hours," they said in an interview.
"People don't see that, they just think it appears by magic [but] it doesn't, it appears by blood, sweat and tears."
Other warehouse workers told the committee they were made to repeat the same movements hundreds or thousands of times each shift.
The repetitive motions, sometimes as often as "3,000 times per hour" — doing things such as scanning items, picking up packages and stowing them on shelves — caused injuries to workers' knees, backs, elbows, shoulders, wrists, fingers and other areas.
"Amazon has undertaken at least two internal studies that each independently found a relationship between worker speed and injuries," the report said, adding it had seen "no evidence" of Amazon acting on these studies.
"In fact, the documents show that Amazon rejected policy changes that would improve worker safety because of concerns they might limit productivity."
Amazon said one of its internal studies, Project Soteria, determined there was no link between pace of work and the number of injuries.
"A senior PhD economist at Amazon who examined Soteria testified last summer in the Washington State proceedings that his team found 'no' causal relationship between pace of work and higher injury rates," Ms Nantel said.
She also denied the company under-reported injuries.
The report added the process to accommodate injured employees and workers with a disability was "confusing, convoluted, and sometimes even cruel".
"The accommodations process is so difficult that, from workers' perspectives, it sometimes appears to discourage them," the report said.
"Multiple workers alleged Amazon unlawfully retaliated against them for engaging in protected conduct, such as filing complaints with enforcement agencies or seeking accommodations.
"A number of other workers expressed fears that they would face [discipline] from the company for their participation in this investigation — a pattern the committee finds alarming."