R 299.1 Definitions; A to I.

Rule 1. As used in this part: (a) “Act” means 1994 PA 451, MCL 324.101 to 324.90106, known as the Natural Resources and Environmental Protection Act. (b) "Acute toxicity" means the ability of a hazardous substance to cause a debilitating or injurious effect in an organism as a result of a single or short-term exposure. (c) “Ambient air” means the atmosphere outside of buildings. (d) “Applicable criterion” means a cleanup criterion for a relevant pathway. A criterion is not an applicable criterion if the exposure pathway is not a relevant pathway at the facility or if the exposure it addresses is reliably restricted by a restrictive covenant or institutional control or other mechanism allowed for under part 201 of the act and these rules. (e) “Aquifer” means a geological formation, group of formations, or part of a formation capable of yielding a significant amount of groundwater to wells or springs. (f) "Best available information" means, when used in relation to a risk assessment or the development of cleanup criteria, the most scientifically credible and relevant data available about a particular hazardous substance. Such information may include, but is not limited to, any of the following: (i) The peer reviewed scientific literature. (ii) Information sources recognized by the risk assessment community, such as the integrated risk information system database maintained by the United States environmental protection agency or other scientifically reliable databases. (iii) Other scientific studies that are acceptable to the department. (g) “Cancer slope factor” means a plausible upper-bound estimate of the probability of a response per unit dose of a hazardous substance over a lifetime. The cancer slope factor is used to estimate an upper bound probability of an individual developing cancer as a result of a lifetime exposure to a particular level of a potential carcinogen. (h) "Carcinogen" means a hazardous substance which, based on the weight of evidence, causes an increased incidence of benign or malignant neoplasms in animals or humans or that substantially decreases the time in which neoplasms develop in animals or humans. (i) "Chronic toxicity" means the ability of a hazardous substance to cause an injurious or debilitating effect in an organism that results from repeated exposure to the hazardous substance for a time period representing a substantial portion of the natural life expectancy of the organism. (j) “Csat” means the concentration in soil at which the solubility limits of the soil pore water, the vapor phase limits of the soil pore air, and the absorptive limits of the soil particles have been reached. As used in these rules, Csat is a theoretical threshold above which a free-phase liquid (non-aqueous phase liquid) hazardous substance may exist. (k) “Direct contact” means exposure to hazardous substances through ingestion or dermal contact. (l) “Generic residential” means the cleanup criteria established by the department under section 20120a(1)(a) of the act and these rules. (m) “Groundwater” means water below the land surface in a zone of saturation. (n) "Increased cancer risk of 1 in 100,000" means the 95% upper bound on the calculated risk of 1 additional cancer above the background cancer rate per 100,000 individuals continuously exposed to a carcinogen at a given average daily dose for a 70-year lifetime. (o) “Inhalation unit risk factor” means the additional lifetime cancer risk occurring in a population in which all individuals are exposed continuously for life to a concentration of 1 microgram per cubic meter of the hazardous substance in the air they breathe. The inhalation unit risk factor shall be calculated under the provisions of part 55 of the act and the rules promulgated under that part. (p) “Initial threshold screening level” means a concentration in air of a toxic air contaminant which is used to evaluate noncarcinogenic health effects and is calculated under part 55 of the act and the rules promulgated under that part. (q) “Institutional control” means a measure which is approved by the department, which takes a form other than a restrictive covenant, and which limits or prohibits certain activities that may interfere with the integrity or effectiveness of a remedial action or result in exposure to hazardous substances at a facility, or which provides notice about the presence of a hazardous substance at a facility in concentrations that exceed only an aesthetic-based cleanup criterion. (r) "Ionizing organic hazardous substance" means an organic hazardous substance that has functional chemical groups that become ions when exposed to varying pH conditions.