As more major U.S. retailers require their customers to wear masks, a growing number of store employees are being confronted by unruly and sometimes violent customers who refuse to comply. Now, the head of the largest union representing retail workers said businesses have unfairly burdened their employees with enforcing mask-wearing policies, to the detriment of workers and customers alike.

Employers bear the responsibility to provide a safe workplace, said Stuart Appelbaum, president of the Retail, Wholesale and Department Store Union, who called for companies to hire security staffers to enforce a store’s mask policies or task members of management with the role.

“Employees should not be expected to put their safety and their life on the line for the employer. That’s an unreasonable expectation,” Appelbaum told The Washington Post on Thursday.

In some instances, the union has negotiated for the right of workers to bow out of interactions with unmasked customers without reprisal. Employees without such protections have little choice, he said, but to endure a risky working environment on the front lines of the culture war over mask-wearing.

The United States now has more deaths from the novel coronavirus than any other country. Yet despite the growing death toll and the strong consensus from health experts that masks are an effective way to slow the spread of the virus, masks are highly politicized.

The lack of a federal mask mandate stands in contrast with numerous countries that require masks in public.

Instead, Americans are navigating a patchwork of regulations that vary by store, city and state. At least 30 states have instituted rules for wearing masks while shopping indoors. In states without mask requirements, people may still be required to wear one to shop in certain stores. As of mid-July, nine of the largest bricks-and-mortar retailers had announced mask rules.

Yet even among stores with mask policies, the rules are inconsistently enforced.

Retailers such as Walmart and Kroger did not address enforcement in the corporate announcements of their mask policies. Representatives for both stores did not immediately respond to questions about enforcing their mask policy, though multiple reports indicate guests aren’t being barred outright if they enter stores without a mask.

Trader Joe’s, with more than 500 stores across the country, has among the most strictly enforced safety requirements. If customers try to shop without a face covering, employees are expected to refuse them entry and ask them to return with a mask, Trader Joe’s spokeswoman Kenya Friend-Daniel told The Post via email. But a customer who refuses to wear a mask and tries to force their way in creates a separate issue altogether: “We would handle it as we would anyone causing a disruption in our stores, up to calling the police,” she said.

Like other retailers, Home Depot has a mask requirement supported by “social distancing captains,” but it doesn’t ban noncompliant customers for safety reasons, said Margaret Smith, a company spokeswoman.

“Our associates will offer masks to those who don’t have one, but it’s too dangerous to forcibly or physically deny entry,” Smith told The Post via email. Smith said “it’s not unusual” for the company to use third-party security at its stores but declined to give specifics about how security personnel are used.

The mélange of rules means front-line workers are left to deal with customers who are confused, angry or simply defiant over mask orders. Viral videos regularly appear on social media showing ugly exchanges between maskless customers and fellow shoppers or employees urging compliance, including a recent altercation at a Manhattan Trader Joe’s when two customers not wearing masks went on a rampage in the store and attacked employees, according to police.

According to the gun violence tracking website the Trace, at least seven people have been injured and four people have died in conflicts related to pandemic-related health restrictions, including mask, social distancing and shutdown rules.

Appelbaum, the union leader, said some stores appear more worried about inconveniencing customers than about public health and called the lax enforcement coupled with the burden on workers “outrageous.”

“I think retailers make the mistake that they are going to alienate customers by telling them they have to wear a mask and that it’s bad for business,” he said. “Not creating a safe environment is worse for business.”

Correction: This story was updated to reflect that the gun-violence injuries and deaths documented by The Trace stemmed from conflicts over pandemic-related health restrictions and not mask mandates exclusively.