LANSING, MI -- The Michigan Department of Environmental Quality is asking for public input on setting allowable levels of PFAS chemicals in factory emissions.

The DEQ is taking public comment until April 16 on ambient air concentrations for PFOS and PFOA, two per- and polyfluoroalkyl substances called PFAS or PFCs that are currently getting more attention around Michigan as drinking water pollutants.

The DEQ has established an industrial emissions screening level for PFOS and PFOA that mirrors the existing state's new limit of 70 parts-per-trillion for the chemicals in groundwater that is used as a source of drinking water.

That level, in turn, mirrors the Environmental Protection Agency health advisory level of 70-ppt for PFOS (perfluorooctanoic sulfonic acid) and PFOA (perfluorooctanoic acid) in drinking water.

"For right now, we're using the EPA numbers," said Doreen Lehner with the DEQ Air Quality Division. However, that could change based on public feedback.

Unlike rigid cleanup levels for contamination on soil and groundwater set under the state's Part 201 law, the air quality division has greater authority over its regulated chemical list and can more nimbly adjust allowable emission levels to reflect recent studies.

The PFAS levels went into effect on Feb. 16 but the DEQ's justification for 70-ppt on average over 24-hours as the standard is presently open for comment.

Exposure to PFAS has been linked in human studies to some cancers, thyroid disorders, elevated cholesterol and other diseases.

The DEQ's justification memos identify EPA studies that set federal guidelines based on increased liver weight and reduced bone density in lab rats.

"We may get comments that there's a new study we haven't looked at, which could make the number go lower," Lehner said. "We're always open to that. The values can change when new science becomes available."

Presently, she said the DEQ doesn't know of any facilities emitting PFAS into the air, but the standard would limit any future permitted emissions.

"We look at all the available science a chemical and then we look at the study that has a (health) affect at the lowest level. We perform a risk assessment on the values that study found out to make sure we're health-protective."

"If it goes into the air, the public can potentially be exposed to it," Lehner said. "We have the authority to look at it and determine at what level is safe to emit."

Click here for instructions on how to comment.