The Health, Education, Labor and Pensions (HELP) Committee is investigating Amazon over warehouse safety after numerous incidents.

HELP Committee Chair Bernie Sanders sent a letter to Amazon CEO Andy Jassy informing him of an investigation into the company’s warehouse conditions. Senator Sanders says Amazon is prioritizing profit over worker safety, despite the disastrous consequences to workers.

I write to initiate an investigation into the dangerous and illegal conditions at Amazon’s warehouses. The company’s quest for profits at all costs has led to unsafe physical environments, intense pressure to work at unsustainable rates, and inadequate medical attention for tens of thousands of Amazon workers every year. Amazon is well aware of these dangerous conditions, the life-altering consequences for workers injured on the job, and the steps the company could take to reduce the significant risks of injury. Yet the company has made a calculated decision not to implement adequate worker protections because Jeff Bezos, Amazon’s founder, and you, his successor as Chief Executive Officer, have created a corporate culture that treats workers as disposable. At every turn—from warehouse design and workstation setup, to pace of work requirements, to medical care for injuries and subsequent pressure to return to work—Amazon makes decisions that actively harm workers in the name of its bottom line.

Senator Sanders also says the company is already under investigation for its warehouse conditions and has been cited multiple times.

These practices have not gone unnoticed. The Department of Labor’s Occupational Safety and Health Administration (OSHA) and state regulators have repeatedly cited the company for egregious violations of workplace safety laws. Amazon is also currently under investigation by the United States Attorney’s Office for the Southern District of New York for potentially misrepresenting the scope of workplace injuries.2 Yet Amazon has made no effort to change its illegal practices. Instead, the company has used its outsized power as the country’s second largest private-sector employer to deny workers their right to a safe workplace.

The letter goes on to say that some of the challenges and dangers workers face are because of the specific demands Amazon places on them, as well as the repetitive nature of the work.

The work is physically demanding. Workers in Amazon warehouses are always on their feet. Some walk up and down narrow aisles pulling products from bins, logging upwards of 10 miles a day. Others stand at tables packing boxes, making the same repetitive movement for the entirety of their 10-hour shift. And others are constantly bending and twisting to lift boxes—some light, some dangerously heavy—with few meaningful breaks. Warehouse workers have to complete these tasks as quickly as possible. Amazon requires workers to meet aggressive productivity goals, but rarely tells workers exactly what these goals are. What workers do know is that they will be disciplined or terminated if they cannot keep up. Afraid to lose their jobs, warehouse workers move as fast as they can to try to meet these goals — a process referred to by Amazon workers as “making rate.”

Senator Sanders makes the case that if Amazon can afford to spend $6 billion in stock buybacks in 2022 then it can certainly afford to improve employee safety.

Amazon has until July 5 to respond to the letter, but a spokesperson for the company told CNBC that it strongly disagrees with the Senator’s conclusions.