Battle lines have been drawn after the release of provocative, ostensibly educational billboards intended to encourage Los Angeles residents to get regularly tested for STDs.

With no points for subtlety, the advertisements, created by the LA-based AIDS Healthcare Foundation, depict two silhouetted pairs of people (one apparently heterosexual and the other homosexual), each with a word plastered onto their heads — “Tinder” and “Grindr” are shown on the right sided member of the couple, while “Chlamydia” and “Syphilis” are seen on the left sided person respectively. According to the AP, there are currently 12 full-sized billboards, and 45 bus bench signs that carry the foundation’s message.

"In many ways, location-based mobile dating apps are becoming a digital bathhouse for millennials wherein the next sexual encounter can literally just be a few feet away — as well as the next STD," Whitney Engeran-Cordova, senior public health director for the foundation, said in a statement announcing their campaign. “While these sexual encounters are often intentionally brief or even anonymous, sexually transmitted diseases can have lasting effects on an individual’s personal health and can certainly create epidemics in communities at large. We want to remind sexually active adults — especially young people — how easy it can be to contract an STD and the importance of undergoing regular screenings to protect their sexual health.”

Tinder has since sent a cease and desist letter to the foundation demanding that these billboards be taken down for their flagrant misrepresentation of the company.

“These unprovoked and wholly unsubstantiated accusations are made to irreparably damage Tinder’s reputation in an attempt to encourage others to take an HIV test by your organization,” Jonathan Reichman, an attorney representing Tinder, said in a letter to the foundation, according to the LA Times.

Meanwhile, Grindr has similarly stopped displaying the foundation’s advertisements on its app. "We were surprised at the approach [the foundation] took, and paused the campaign in order to speak with them and assess our relationship," Grindr told the LA Times in reference to their decision. The foundation has, for their part, refused to pull their punches in response.

In June, Medical Daily reported on research showing a link between increased rates of HIV infection and the introduction of Craigslist, a popular classifieds website, to new cities. Relatively little research, however, has looked at the specific influence of casual dating apps like Tinder, only released in 2012, on STD rates.

One 2014 study cited by the foundation that was published in the BMJ specialty journal, Sexually Transmitted Infections, did find that men who have sex with men and used Grindr-like apps to meet sexual partners in LA were more likely to test positive for gonorrhea and chlamydia when they visited a sexual health clinic than did those who only met their partners in-person or through the internet. However, there weren’t any significant differences in the infection rates of syphilis or HIV seen among any group of men.

What isn’t in dispute is that STD rates in many urban locations are rising across the board — though the HIV rate has generally leveled off or continues to decline — in recent years.

As previously reported by Medical Daily this August, community activists in New York City have linked the increase of STD infections in their city to the steady decline of funding for publicly-run sexual health clinics, citing years of compiled data. And other research has pointed to the still-ongoing proliferation of ineffective abstinence-only sexual education programs in many states; states that coincidentally tend to have the worst STD rates in the country.

That Tinder and similar apps are a primary contributor to higher STD rates, however, is a theory with shaky empirical grounding as of now.