Public Advocate Letitia James has accused Airbnb of enabling racial discrimination by failing to address "mounting" evidence that black users earn less than white users on the platform, and elicit fewer responses both as hosts and guests.

"Airbnb must implement safeguards to prevent the racism and bigotry that are pervasive on its platform," James, a long-time critic of the startup, stated Thursday.

Making her case to Airbnb's Chief Product Officer in an open letter [PDF] published earlier this week, James cited two recent Harvard University studies that concluded that the app enables users' racism.

Last year, Harvard researchers sent identical Airbnb requests to more than 6,000 Airbnb hosts in Baltimore, Dallas, Los Angeles, St. Louis, and Washington. The guests with "African-American" names got positive responses 42% of the time, while names that sounded more "white" were accepted 50% of the time. Tamika received fewer positive responses than Kristen, and Darnell received fewer positive responses than Brad.

The Twitter hashtag #AirbnbWhileBlack turns up personal stories that support these findings.

Quirtina Crittenden, a business consultant from Chicago, started using the hashtag to vent her frustration with the platform. She recently told NPR that her acceptance rate on Airbnb increased considerably when she shortened her name to 'Tina' and replaced her profile picture with a landscape. "Ever since I changed my name and my photo, I've never had any issues on Airbnb," she said.

In a 2014 Harvard Business School study focused specifically on New York City, researchers compared host's profile pictures and rental prices and found that "nonblack hosts" were able to charge about 12% more than black hosts for listings in comparable neighborhoods.

As of last November, there were 35,966 active Airbnb listings in New York City. The app's anti-discrimination policy states that "we prohibit content that promotes discrimination, bigotry, racism, hatred, harassment or harm against any individual or group."

The Public Advocate's accusations come less than a month after Airbnb launched a public relations campaign highlighting its positive economic impact on the city's predominantly-black neighborhoods—Crown Heights and Bed-Stuy in Brooklyn, as well as West Harlem and the Rockaways. According to the startup's internal analysis, the number of Airbnb guests in 30 NYC zip codes with the most black residents jumped 78% between 2014 and 2015, compared to 51% city-wide.

But local politicians and advocates, as well as independent data analysts, say that Airbnb has actually played a role in accelerating gentrification in the neighborhoods it purports to boost. These groups have long argued that the startup isn't doing enough to discourage illegal hotel operators—bad actors who flip entire apartments into year-round Airbnb listings, jeopardizing the safety of longterm tenants and snatching up a significant portion of the city's already-dwindling affordable housing stock.

"Airbnb has gone to great lengths to portray its platform and marketplace as a means for communities of color to pursue new economic opportunities," James wrote. "Therefore, I trust that Airbnb acknowledges that that race-based discrimination is an issue of great concern."

James asked Airbnb to disclose data on the number of responses non-white Airbnb users receive on their lodging requests, compared to white users. She also asked for data on the amount of revenue collected by non-white hosts, compared to white hosts. Such information would give a clearer picture of the demographics of Airbnb's users than the startup's own limited release of information.

To reduce the likelihood of race-based discrimination on the platform, she also suggested that Airbnb withhold guest and host names until after a reservation has been made, and eliminate the need for a profile picture—both suggestions previously made by Harvard professors.

In a public response to James, Airbnb's head of diversity and belonging David King said that while the company recognizes that "bias and discrimination present significant challenges," Airbnb has no plans to eliminate the profile picture.

"We are taking steps to address [these challenges]," King stated. "Profile photos are an important part of our community and are one of the many tools that help hosts and guests connect with one another. We welcome the opportunity to work with anyone that can help us reduce potential discrimination in the Airbnb community."