On July 22, 2016, the U.S. Environmental Protection Agency (EPA) posted on its website the first four Section 5(a)(3) determinations for premanufacture notices (PMN) under the Toxic Substances Control Act (TSCA) as amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act (Pub. L. No. 114-182) (new TSCA). All four of the new chemicals were determined to satisfy the "not likely to present an unreasonable risk" determination at Section 5(a)(3)(C). It is notable that all four determinations relied on structure activity relationship (SAR) analyses and data on analogs.

In all four cases, EPA found low potential for health hazards and low potential for environmental hazards (low/low). EPA estimated that each substance has some degree of persistence (from limited persistence to very persistent) and that all four have a low potential for bioaccumulation. Based on our experience with the new chemicals program under TSCA prior to new TSCA, when EPA made a low/low hazard call and either a low potential for persistence or a low potential for bioaccumulation, EPA "dropped" the submissions from further review, avoiding the time and expense of performing exposure assessments on substances of low potential hazard.

Under new TSCA, to make a Section 5(a)(3)(C) determination, EPA must identify potentially exposed or susceptible subpopulations (PESS) that are relevant under conditions of use. In these four Section 5(a)(3)(C) determinations, EPA identified known or reasonably foreseeable uses in addition to the uses identified in the PMNs. EPA identified the PESS under the intended use as workers for all four cases. We note that EPA identified consumers as a PESS if the substance notified in P-15-0281 was to be used as a lubricant or lubricant additive (the known or reasonably foreseen use that EPA identified). Even considering the PESS, EPA has concluded that a low hazard finding is sufficient to support a "not likely to present" finding under Section 5(a)(3)(C) and did not perform a formal exposure assessment. Since EPA has published the Section 5(a)(3)(C) findings, per Section 5(g), the submitters of these four PMNs may commence manufacturing without waiting for the remaining portion of the 90-day review period to expire.

Commentary

EPA determined that all four new chemicals satisfy the "not likely to present an unreasonable risk" determination under Section 5(a)(3)(C). The conditions of use for these chemicals indicate industrial scenarios that would point to workers as the PESS. The potential exposure to workers was not estimated. Instead, the determination of not likely to present an unreasonable risk hinges on the low hazard potential for these chemicals. Three of the four chemicals were estimated to be persistent with two categorized as very persistent. The chemicals were estimated to have low potential for bioaccumulation. No information was provided about potential releases to water.

It is reassuring that the SAR was used to reach determinations about persistence, bioaccumulation, and hazard potential, including mention of category analysis. This suggests that EPA intends to maintain SAR as a basic component in its evaluation of new chemicals consistent with the provisions at Section 4(h) to reduce vertebrate animal testing and to maximize the use of existing hazard information.