## Facts

- Several chemical manufacturers produced or used four fluoroalkenes—vinyl fluoride, vinylidene fluoride, hexafluoropropene, and tetrafluoroethene—used as monomers to make specialty fluorocarbon polymers.
- Production and processing generally occurred in closed systems (pipes, reaction vessels, sealed areas), but EPA identified potential worker exposure during maintenance, leaks, and upset conditions.
- EPA found scientific indicators that the fluoroalkenes could be carcinogenic, including toxicological information and structure–activity comparisons to similar chemicals.
- EPA concluded that existing data were insufficient to evaluate long-term health effects, mechanisms of harm, and exposure profiles, and issued a TSCA § 4 rule requiring extensive testing.
- The manufacturers petitioned for judicial review, arguing the rule was unlawful, speculative, and unsupported by substantial evidence given allegedly minimal exposure in closed systems.

## Issues

1. Whether EPA’s TSCA § 4 test rule was supported by substantial evidence that the substances may present an unreasonable risk, that data were insufficient, and that testing was necessary.
2. Whether EPA exceeded TSCA authority by requiring testing based on speculation or “scientific curiosity” rather than a meaningful scientific basis.

## Decision

- The court denied the petitions for review and upheld the EPA test rule.
- The court held the rule was supported by substantial evidence in the administrative record.
- The court accepted EPA’s reliance on predictive scientific methods, including structure–activity relationships and analogical reasoning, to identify potential carcinogenic risk.
- The court concluded that potential worker exposure, even in largely closed-system operations, could support a test rule when combined with carcinogenic concern and data gaps.
- The court rejected the argument that TSCA requires proof of actual harm or a high probability of harm before EPA may order testing.

## Legal Principles

- TSCA § 4 permits EPA to require testing when a substance may present an unreasonable risk and existing information is inadequate to evaluate effects; testing may be ordered to generate needed data.
- EPA need not establish conclusive proof of harm before issuing a TSCA test rule, but must base the rule on more than mere curiosity; a documented scientific rationale is required.
- Structure–activity analysis and comparisons to similar chemicals can constitute substantial evidence supporting potential risk findings under TSCA.
- Judicial review of TSCA § 4 test rules is deferential on technical judgments; courts assess whether the record contains substantial evidence, not whether alternative scientific conclusions are possible.

## Conclusion

The Third Circuit upheld EPA’s TSCA § 4 testing requirements for fluoroalkenes, finding substantial evidence of potential carcinogenic risk, nontrivial worker exposure potential, and significant data gaps that made testing necessary, while recognizing that TSCA does not authorize testing demands grounded only in curiosity.


Ausimont U.S.A., Inc. v. EPA, 838 F.2d 93 (3d Cir. 1988)