If you've ever gotten a hair-straightening treatment at a salon, you might want to listen up. Two consumer-watchdog groups are suing the FDA for failing to investigate and regulate keratin services, which are known to contain formaldehyde — a carcinogen and allergen — and formaldehyde-releasing chemicals.The suit , filed by Environmental Working Group and Women’s Voices for the Earth, claims that the FDA violated its own regulations by failing to respond to a citizen petition filed more than five years ago. The petition provided “ample scientific evidence,” according to the suit, and asked the FDA to investigate the “real and serious health risks” associated with the service provided."For years, stylists have reported that the application of these hair treatments caused difficulty breathing, eye irritation, and nosebleeds," Tina Sigurdson, EWG assistant general counsel, said in a press release. "The FDA has been aware of the health hazards associated with the products since at least 2008 . Despite these dangers, the FDA has yet to take action to remove them from the market."The suit seeks a court order requiring the FDA to investigate and respond to the petition by a set date, to be determined by the court. "The groups hope a court order will motivate the agency to finally protect salon workers and the public from these dangerous products," the release said.