40 C.F.R. § 702.33
All definitions in TSCA apply to this subpart. In addition, the following definitions apply:
Act means the Toxic Substances Control Act (TSCA), as amended (15 U.S.C. 2601 et seq.).
Aggregate exposure means the combined exposures from a chemical substance across multiple routes and across multiple pathways.
Conditions of use means the circumstances, as determined by the Administrator, under which a chemical substance is intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used, or disposed of.
EPA means the U.S. Environmental Protection Agency.
Pathways means the physical course a chemical substance takes from the source to the organism exposed.
Potentially exposed or susceptible subpopulation means a group of individuals within the general population identified by EPA who, due to either greater susceptibility or greater exposure, may be at greater risk than the general population of adverse health effects from exposure to a chemical substance or mixture, such as infants, children, pregnant women, workers, the elderly, or overburdened communities.
Reasonably available information means information that EPA possesses or can reasonably generate, obtain, and synthesize for use in risk evaluations, considering the deadlines specified in TSCA section 6(b)(4)(G) for completing such evaluation. Information that meets the terms of the preceding sentence is reasonably available information whether or not the information is confidential business information, that is protected from public disclosure under TSCA section 14.
Routes means the ways a chemical substance enters an organism after contact, e.g., by ingestion, inhalation, or dermal absorption.
Sentinel exposure means the exposure from a chemical substance that represents the plausible upper bound of exposure relative to all other exposures within a broad category of similar or related exposures.
Uncertainty means the imperfect knowledge or lack of precise knowledge of the real world either for specific values of interest or in the description of the system.
Variability means the inherent natural variation, diversity, and heterogeneity across time and/or space or among individuals within a population.
40 C.F.R. §702.33