(Bloomberg) -- Amazon.com Inc. failed to provide adequate medical treatment to injured warehouse workers in Castleton, New York, federal workplace safety regulators alleged in their fourth citation against the online retailer this year as part of a widening probe of its operations.

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At least 10 workers with head and back injuries didn’t receive proper medical treatment, some returned to work and were hurt further as a result, according to the citation issued Friday by the US Occupational Safety and Health Administration.

OSHA has previously notified Amazon about deficient medical practices in its warehouses in Robbinsville, New Jersey and Deltona, Florida, indicating regulators are worried about systemic problems in the company’s operations rather than scattershot mismanagement.

“Returning a worker with a back injury or possible concussion to their job without proper medical evaluation and care can lead to prolonged injuries and lifelong suffering,” OSHA Assistant Secretary Doug Parker said in a statement. “The examples uncovered by our investigation demonstrate a callous disregard for the well-being of Amazon’s Castleton employees that is completely unacceptable.”

OSHA proposed $15,625 in penalties against Amazon. The agency has 20 open inspections at company facilities around the country. Amazon has 15 days in which to contest the findings, the regulators said.

Amazon spokesperson Maureen Lynch Vogel said the company would appeal the citation.

“Our policy is to encourage anyone who wants or needs outside medical attention to get it immediately, and our on-site clinics are just for first aid — not formal medical diagnosis,” Lynch Vogel said. She added that injury rates in Amazon facilities have dropped since 2019 as a result of $1 billion invested in safety initiatives.

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