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Three chemicals were added to the Chemicals Under Review list this past month.
Cobalt and cobalt compounds
One new chemical was added, and two chemicals were updated in the ITSL/IRSL database [ http://www.deq.state.mi.us/itslirsl/ ] this past month with the following screening levels.
*These chemicals are included under footnote #40: The *”combined”* ambient impact of trimethyl borate (CAS #121-43-7), boron oxide (CAS #1303-86-2), sodium perborate (CAS #7632-04-4), and boric acid (CAS #10043-35-3) should be evaluated so that the combined impact does not exceed a hazard index value of one.
Fluorides and Fluoride salts were removed from the Chemicals Under Review List. At this time, there will not be an ITSL derived for fluorides / fluoride salts as a group. This was determined after reviewing the existing ITSLs for fluorinated TACs. There was such variety in the determined toxicity and corresponding ITSLs, that a grouping was determined not to be helpful. However, a footnote will be used to group the inorganic fluorides that have ITSLs derived from the same health benchmarks. This has been deemed to be appropriate since some of these TACs have already been reviewed under that same permit application. Footnote #41: The *”combined” *impact of sodium fluoride (CAS #7681-49-4), potassium fluoride (CAS #7789-23-3), sodium aluminum fluoride (CAS #15096-52-3), and sodium silicofluoride (CAS #16893-85-9) should be evaluated so that the combined impact does not exceed a hazard index value of one.
A screening level for 4-chlorophenol (CAS #106-48-9) because there is insufficient inhalation data and the available oral data was deemed inappropriate for route to route extrapolation because of the potential for significant first pass metabolism.
Indene (CAS #95-13-6) and benzofuran (CAS #271-89-6) are being removed from the Chemicals Under Review List. These toxic air contaminants (TACs) are rarely emitted to the air from industrial sources regulated by the Air Pollution Control Rules. Air emissions of these TACs will be assessed on a case-by-case basis.
The AQD is provided a 30-day formal public comment period from December 21, 2018 to January 21, 2019 for a list of chemicals that had been added or updated in the last six months. No comments were received.
To view the Chemicals Under Review list for February 2019, please visit the DEQ Air Quality Web page [ https://www.michigan.gov/deq/0,4561,7-135-3310—,00.html ]. Click on the Permits tab, followed by the Air Toxics Screening Levels tab located on the bottom left side of the page. The Chemicals Under Review [ https://www.michigan.gov/documents/deq-aqd-toxics-ChemRevList_164720_7.pdf ] list is the last item in this category.
Along with formal public review, we will continue our past practice of inviting and addressing questions or concerns about the Air Quality Division screening levels at any time. If you have further questions, please contact _Doreen Lehner_ <firstname.lastname@example.org>, Air Quality Division, at 5172846753.