More than 50 naked extras taking part in “graphic sexual situations” on the set of HBO’s Westworld today are being well-paid for touching one another’s genitals – up to $600, according to a source familiar with the shoot.

SAG-AFTRA scale for background performers is $157 a day, but sources say that adjustments bringing the pay to $600 are being tacked on because of the unprecedented amount of simulated sex the extras are being asked to perform. Westworld was among the projects awarded California tax credits in June.

As Deadline reported this morning, each of the 57 union extras hired for today’s filming of the sci-fi series had to sign consent forms acknowledging that they might be asked to “appear fully nude; wear a pubic hair patch; perform genital-to-genital touching; have your genitals painted; simulate oral sex with hand-to-genital touching; contort to form a table-like shape while being fully nude; pose on all fours while others who are fully nude ride on your back; ride on someone’s back while you are both fully nude; and other assorted acts the Project may require. The Project will also include language and sexual situations that some may consider personally objectionable or uncomfortable.” The consent form appeared under the letterhead of Central Casting, which casts extras for the show.

Several background performers contacted by Deadline say they have never seen anything like what the extras are being asked to do on the show, and that it appears to be exploitative of the most easily exploited members of the cast.

“It’s very disheartening,” said one veteran background player.“I was dumbfounded,” said another. “There’s been nudity in TV and film for decades, but I have never seen this kind of waiver before. I would be surprised if principal performers were handed a document like this. It appears kind of coercive. Background people want to work, and they will do most anything they are asked, even when it makes them uncomfortable. And when they’re handed something like this, they are not going to say no.”

SAG-AFTRA, which has a representative on the set to monitor the situation, recognizes that the producers have a constitutional right to film graphic scenes like this but is expressing concern nonetheless.

“We believe in the First Amendment and support a creator’s right to tell their story, but this seems to go far beyond the scope of what background actors are asked to do in the course of their day,” said Terri Becherer, the union’s National Director of Specialty Performers. “I don’t know that they are taking any protective measures for that level of intimacy. Obviously, we are concerned about safety and health issues when there is that much nudity and exposure.”

She said that the guild also is concerned that background actors “may find the consent form intimidating and could be construed by our members that they don’t have the right to withdraw that consent.”

The producers have assured SAG-AFTRA that they are complying with the union’s Television Agreement, which provides that consent to appear in scenes requiring nudity or sex acts may be withdrawn at any time; that the set must be closed to anyone not having business with the production, and that no still photography may be authorized without the consent of the background actor.

Calls to Central Casting and production company Autonomy Productions were not returned.