Bernie Sanders, Elizabeth Warren, and 13 other Democratic US senators have a message for Amazon CEO Jeff Bezos: Change your business practices, or else.

In a public letter addressed to Bezos Friday, the senators urged Amazon to “overhaul [the] profit-at-all-costs culture at your company” and implement changes at the online retail giant. They also want Amazon to publish records of serious worker injuries.

“Amazon’s dismal safety record indicates a greater concern for profits than for your own workers’ safety and health,” the letter read.

The letter referenced safety records from Amazon’s warehouse network that appeared to show higher-than-average injury rates, even for the warehousing industry. Those rates were originally disclosed in a November article from the Center for Investigative Reporting’s Reveal group that was published in the Atlantic. Amazon argued at the time that the injury rates reflected its aggressiveness in recording injuries, and a spokesperson reiterated that stance in a statement on Monday.

The letter comes at a time when politicians, activists, and some of Amazon’s own employees have called Amazon out for the pace of work and labor conditions inside its warehouse and delivery networks. The criticism has become increasingly noteworthy as Amazon has expanded its reach into so many aspects of American life, from online retail to entertainment to the delivery of groceries and prescription drugs. Along the way, Bezos, the world’s richest man, has become a target for Warren and Sanders, who frame him and his riches as an example of capitalism gone awry.

“Nothing is more important to us than the safety and well-being of our employees,” Amazon spokesperson Kelly Cheeseman said. “OSHA is on the record as saying that underreporting of injuries is an industry-wide problem, and companies do this to keep their rates low — a former assistant secretary of OSHA estimated that 50 percent or more of severe injuries go unreported. Amazon does the opposite; we take an aggressive stance on recording injuries no matter how big or small. The invitation remains open for any of the Senators to come take a tour — last year over 300,000 people toured an Amazon fulfillment center and we appreciate that they took the time to learn the facts first-hand.”

Cheeseman confirmed to Recode that some of the senators who signed the letter have not taken Amazon up on touring one of its fulfillment centers. She declined to specify how many or which ones.

The letter, whose signatories also included Sherrod Brown (D-OH), Tammy Baldwin (D-WI), and Kamala Harris (D-CA), included seven other requests. One was to “reduce workers’ quotas and speed requirements,” and another asked Amazon to “cease including bathroom breaks as a ‘time off task,’” stemming from allegations that some Amazon workers have had to relieve themselves in bottles so their performance doesn’t suffer.

At least one of the requests — “Ensure workers ... have a guaranteed way to raise safety and health concerns” — appears to be one that Amazon already offers. On a visit to an Amazon fulfillment center last year, I observed a giant TV screen — called the Voice of Associate board — on which workers anonymously provided feedback to management. One of those pieces of feedback, highlighted in an episode of our Land of the Giants podcast about Amazon, was a worker telling management that they checked themself out of the hospital because they didn’t have someone to fill in for them. Cheeseman said these boards, whether digital screens or old-school whiteboards, are present in all Amazon warehouses.

The senators want a response by February 21.

News of the letter comes as Amazon’s head of communications and policy, Jay Carney, went on the offensive in a New York Times op-ed on Monday. In the piece, Carney argued that the company’s critics should acknowledge that “Amazon is doing many good things — for the economy, and for American workers.” Carney cited Amazon’s 2018 move to raise its minimum pay to $15 an hour as well as its Career Choice program, which “prepays up to 95 percent of tuition and fees — making it almost free for employees to learn new skills.”

He did not cite Amazon worker safety records.