Section 620.605  Issuance of a Health Advisory

a)         The Agency must issue a Health Advisory for a chemical substance if the following conditions are met:

1)         A community water supply well is sampled and the chemical substance is detected and confirmed by resampling;

2)         There is no standard in Section 620.410 for the chemical substance; and

3)         The chemical substance is toxic or harmful to human health according to the procedures specified in Appendix A, B, or C.

b)         The Health Advisory must contain a general description of the characteristics of the chemical substance, the potential adverse health effects, and a guidance level to be determined as follows:

1)         If disease or functional impairment is caused due to a physiological mechanism for which there is a threshold dose below which no damage occurs, the guidance level for the chemical substance is the Maximum Contaminant Level Goal (MCLG) adopted by USEPA for the substance, 40 CFR 136, appendix B, 40 CFR 141.80, 40 CFR 141.61, and 40 CFR 141.62, incorporated by reference in Section 620.125.

2)         If there is no MCLG for the chemical substance, the guidance level is either the Human Threshold Toxicant Advisory Concentration (HTTAC) or Human Nonthreshold Toxicant Advisory Concentration (HNTAC) for the substance as determined in compliance with Appendix A, whichever is less, unless the lower concentration  is less than the substance's lowest appropriate LLOQ specified in "Test Methods for Evaluating Solid Wastes, Physical/Chemical Methods", EPA Publication No. SW-846 (SW-846), incorporated by reference in Section 620.125, or the substance's lowest appropriate LCMRL specified in the drinking water methods incorporated by reference in Section 620.125.

3)         If the lower concentration between the HTTAC and HNTAC of the chemical substance under subsection (b)(2) is less than its lowest appropriate LLOQ or LCMRL, the guidance level is the lowest appropriate LLOQ or LCMRL.

(Source:  Amended at 49 Ill. Reg. 4488, effective March 28, 2025)