By Gregory Wallace, CNN

The Environmental Protection Agency’s new plan for dealing with hazardous non-stick PFAS chemicals has advocates for safe drinking water asking: Why not do more, and why not act sooner?

The agency said Thursday it will develop and set a limit — known as a maximum containment level, or MCL — for two of the chemicals, but advocates say it will take years of regulatory work before the standard will be set.

Acting EPA Administrator Andrew Wheeler, who has been nominated to lead the agency, told reporters while unveiling the plan that he believes the agency’s 70 part per trillion health advisory level is “a safe level for drinking water.”

“As we go forth with the MCL we will be looking to see if lower levels are required according to where the science directs us,” Wheeler said.

The 70 part per trillion level is seven to 10 times higher than the levels considered safe by the Agency for Toxic Substances and Disease Registry, an arm of the Department of Health and Human Services. Several states have set lower levels or are currently considering lower levels.

The class of perfluoroalky and polyfluoroalkyl substances — known by shorthand names like PFAS, PFOA and GenX — and have been used in a variety of non-stick, cleaning, packaging, and other household products, as well as firefighting foam. The toxic firefighting foam has contaminated drinking water at dozens of is a particular problem around military bases.

The water supplies for nearly 110 million Americans may be contaminated with PFAS chemicals, according to the Environmental Working Group.

As part of an EPA stewardship program, US manufacturers began phasing out the chemical 19 years ago, although it is still manufactured overseas and imported.

Given the long-standing concerns, some safety advocates are asking why the EPA hasn’t acted faster to set the legally-binding limits.

“The EPA’s long-awaited involvement on this issue is welcomed, but any actual relief from this ‘Action Plan’ to all the sick American residents, marginalized communities, overburdened state agencies, and underfunded cities and states will likely be years away,” said Ansje Miller of the Center for Environmental Health, which advocates against toxic chemicals.

Wenonah Hauter, the executive director of Food and Water Watch, called it a “non-action plan” that benefits “polluting corporations, not the people affected by this industrial waste in their drinking water supplies.”

Advocates want to see the agency regulate PFAS chemicals as a class, rather than individually, as Wheeler indicated. The Environmental Working Group says there are more than 5,000 chemicals in the PFAS class.

“We’re focused on two chemicals. It’s the wrong focus,” Mayor Rob Allen of Hoosick Falls, New York, told CNN. He is a father of four children who said he entered politics after being stunned by tests showed his family tested far above the national level.

He said he was concerned the EPA would “trumpet some action on two chemicals that should have been acted on 15 to 20 years ago.”

The American Chemistry Council, whose membership includes major chemical manufacturers, said Thursday morning it would review the plan.

It said in a statement that “EPA is best positioned” to regulate PFAS chemicals, which would “uniform standards across the country” — pushing back on a patchwork of tighter regulations either in place or under development in several states.

Wheeler did not set a target date for finalizing the maximum limit, citing the complicated regulatory process and the need to set a level that stands up to any court challenges. The EPA has not set a MCL since the Safe Drinking Water Act was amended in 1996, he said.

He said in the meantime, the agency will enforce the 70 part per trillion advisory level and is working with the Defense Department to make sure it is “wisely” spending funds to clean up contaminated water near bases.

EPA will also “explore data availability for listing PFAS chemicals” on the Toxics Release Inventory.

CNN’s Nadia Kounang contributed to this report.