The U.S. Environmental Protection Agency says it plans to regulate dozens of specific uses of five common phthalate chemicals after completing a new round of risk evaluations that found unreasonable risks to workers and the environment.

The chemicals under review are Butyl Benzyl Phthalate, Dibutyl Phthalate, Dicyclohexyl Phthalate, Diethylhexyl Phthalate, and Diisobutyl Phthalate. These phthalates are widely used to make plastics more flexible and appear in a range of industrial and building-related applications.

EPA’s evaluations focused on how these chemicals are used in real-world workplace and environmental settings. According to the agency, its analysis shows that certain industrial uses expose workers or the environment to levels that exceed health-based safety thresholds. At the same time, EPA emphasized that risk depends on exposure levels and that not all uses of these chemicals pose a problem.

Under the Toxic Substances Control Act, EPA’s review looked only at uses regulated under federal chemical safety law. That means exposures tied to food, food packaging, cosmetics, medical devices, and other consumer products overseen by the Food and Drug Administration or Consumer Product Safety Commission were not part of this evaluation. For consumer uses included in the TSCA review, EPA found no unreasonable risk to the general public.

The agency also conducted a cumulative exposure analysis to understand how people may be exposed to multiple phthalates at the same time. This assessment covered individuals aged four and older, with additional modeling used to account for infants and toddlers, including behaviors such as toy mouthing. EPA says these conservative methods were designed to ensure protections for vulnerable populations, even where national biomonitoring data is limited.

EPA’s findings vary by chemical and by use. In some cases, the agency identified risks only to workers. In others, both worker and environmental risks were identified, particularly for chemicals with broader industrial applications.

The next step will be rulemaking. EPA says it will work with workers, businesses, labor organizations, and communities to develop targeted requirements aimed at reducing or eliminating the identified risks. Options under consideration include personal protective equipment, engineering controls, and alternative approaches, depending on the specific use and setting.

EPA notes that its risk determinations are based on several factors considered together, including real-world exposure levels, health and environmental impacts, who is exposed, how severe the potential harm is, and where scientific uncertainty remains. The agency says that combination, rather than any single factor, guides whether a chemical use is considered an unreasonable risk.