The U.S. Environmental Protection Agency (EPA)'s consequential 2016 revision of the Integrated Risk Information System (IRIS) risk value for ethylene oxide (EtO), significantly increasing the estimated cancer potency of the chemical. In this article, the authors discuss how this revised value will have wide-ranging ramifications for toxic tort litigation and lead to more conservative risk values and assessments for other substances. The article mentions that the revised value is much lower than naturally occurring ambient background levels of EtO and the average endogenous amount of EtO present in the human body. These actions have also influenced toxic tort lawsuits, where plaintiffs, both states and environmental groups, use the IRIS value to establish risk and causation. The article cites examples of EtO lawsuits against sterilization facilities, resulting in costly settlements.

The authors argue that regulatory risk assessments, such as the EPA's IRIS assessments, are designed to protect public health but should not be used to prove causation in toxic tort litigation. To explain the concepts of risk assessment and causation to a jury, the authors suggest that exposure assessments, dose characterization, and toxicological assessments should be conducted to estimate the actual risk of adverse health effects in individuals.

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