LIST OF SCREENING LEVELS (ITSL, IRSL, AND SRSL) for MICHIGAN'S AIR TOXIC RULES

The list of screening levels (ITSLs, IRSLs, and SRSLs) are developed by the Air Quality Division and are updated via these webpages on a weekly basis. These screening levels are presented in alphabetical and CAS number order. The screening levels were developed from the best toxicological data available at the time of the calculation date, and are subject to change as new data becomes available. A description of the information contained in each column follows.

CAS No. = Chemical Abstracts Service number.

Chemical = Name of the chemical.

ITSL = Initial Threshold Screening Level.

ITSL Avg. Time = Averaging period for the Initial Threshold Screening Level.

ITSL Basis = Source of data upon which the Initial Threshold Screening Level is based. TLV means the ITSL was determined from the Threshold Limit Value (TLV) established by the American Conference of Governmental Industrial Hygienists (ACGIH). NIOSH means the ITSL was determined from the Recommended Exposure Level established by the National Institute for Occupational Safety and Health (NIOSH). EPA means the ITSL was established from a reference concentration or reference dose developed by the U.S. Environmental Protection Agency (EPA). AQD means the ITSL was developed by the Air Quality Division (AQD). AQD/SAP means the ITSL is based on the recommendations of the AQD's Scientific Advisory Panel.

ITSL Date = The date when the Initial Threshold Screening Level was determined.

IRSL = Initial Risk Screening Level.

SRSL = Secondary Risk Screening Level.

IRSL Avg. Time = Averaging time period for the Initial Risk Screening Level and Secondary Risk Screening Level.

IRSL Basis = Source of data upon which Initial Risk Screening Level and Secondary Risk Screening Level is based. AQD means the IRSL and SRSL were determined by the Air Quality Division (AQD). EPA means the IRSL and SRSL were determined from unit risk values established by the U.S. Environmental Protection Agency (EPA). AQD/SAP means the ITSL is based on the recommendations of the AQD's Scientific Advisory Panel.

IRSL Date = The date when Initial Risk Screening Level and Secondary Risk Screening Level was calculated.