Sen. Richard Blumenthal (D-Conn.) and Rep. Anna Eshoo (D-Calif.,), ranking member of the House Communications Subcommittee, are accusing the FCC of failing to enforce safety guidelines on cell tower worker exposure to radiofrequency radiation, saying they are putting the

health and safety of a quarter of a million workers at risk.

An FCC source said the commission continues to address the safety issues, enforce its rules, and to look for an order on exposure issues by year's end.

In a letter to FCC Chairman Tom Wheeler, the powerful Democrats said that "even though the FCC recommends that wireless carriers control exposure to harmful RF radiation using safety protocols such as signs, barricades, and training, it has come to our attention that these recommendations have not consistently been implemented to protect workers."

They said beyond the hazards to cell tower workers of free-standing structures, the towers are now found atop all kinds of buildings from apartments and schools to hospitals, churches and fire stations, "putting RF technicians but also roofers, water proofers, electricians, carpenters, building maintenance personnel, HVAC technicians, painters, firefighters" and others at risk from the radiation.

"[w]’ve received the letter and are reviewing it," said an FCC spokesperson.

The senators recognized that in March 2013, the FCC issued a report and order reminding FCC licensees of their obligations regarding worker exposure, including fully informing them of the risk and their control over that exposure. But the FCC also issued a further notice with specific requirements for exposure limits in various categories.

The senators want the FCC to finalize that NPRM and to consult with OSHA to make sure it has teeth.

"It is unacceptable that RF warning signs have been found missing, mislabeled, unintelligible, or out-of-date, and that strategies to control access (e.g. barricades, locks, and fences) are in disrepair, they said.

The FCC has made deploying wireless broadband a priority, including easing tower citing. But the legislators don't want that to come at the expense of safety.

"We look forward to hearing what next steps you have planned to make sure that the expansion of our telecommunications infrastructure does not come at the expense of the health and safety of hardworking Americans," they wrote.

An FCC source said staffers are actively working on the issue, and that they are coordinating with OSHA as well as the FDA and EPA.

The commission has also taken enforcement actions regarding rooftop exposure signage. As to the NPRM: The source said look for an order by the end of the year.

PCIA, whose members are responsible for building out that wireless infrastructure, said it was also concerned, but also was working with the FCC on answers.

"PCIA shares Senator Blumenthal and Representative Eshoo’s concerns for the health and safety of wireless industry workers," PCIA said in a statement. "Since the FCC’s renewed action in this space in 2013, PCIA has remained engaged in this important discussion. In fact, last month, we met with FCC’s Office of Engineering and Technology and its Enforcement Bureau to discuss the Commission’s proposal to revise the Maximum Permissible Exposure-based exemption threshold criteria for fixed transmitter sites located on rooftops. Rooftops are by their nature varied, with different layouts, different landlords, and a variety of workers, regular and transient, requiring access.  Because of this variety there is no one-size-fits-all solution.

"We will continue to work with federal, state, and local policymakers to ensure that the industry is doing everything it can to ensure the health and safety of its workers, including the provision of ongoing education and compliance training."

“CTIA is not a scientific organization and we defer to the appropriate and qualified experts, such as the Federal Communications Commission," said CTIA: The Wireless Association SVP and general counsel Tom Power in response to the legislators' letter. "The Food and Drug Administration, the American Cancer Society and the World Health Organization (WHO), on RF safety. As the WHO has observed, '[f]rom all evidence accumulated so far, no adverse short- or long-term health effects have been shown to occur from the RF signals produced by base stations.' In light of this guidance, and the fact that  the wireless industry makes every effort to comply with the FCC’s existing rules in this area, there is no evidence to conclude that the existing rules are inadequate.”