California’s Office of Environmental Health Hazard Assessment (OEHHA) has adopted two Maximum Allowable Dose Levels (MADLs) for n-hexane under Proposition 65—one for oral exposure and one for inhalation exposure.  

Also known as the Safe Drinking Water and Toxic Enforcement Act of 1986, Proposition 65 prohibits knowingly exposing any individual to a listed chemical without first providing a “clear and reasonable warning” to such individual. The law provides an exemption from the need to provide a warning where exposures are below a "safe harbor" level, which is known as the MADL for a reproductive toxicant.

OEHHA added n-hexane to the Proposition 65 list of reproductive toxicants on December 15, 2017. OEHHA has adopted the safe harbor values proposed in September 2018 of 28,000 micrograms per day for oral exposure and 20,000 micrograms per day for inhalation exposure. The MADLs will become effective on July 1, 2019. (More information is available on OEHHA’s website.)