Legislation and regulatory guidelines related to styrene exist and may vary from state to state. These requirements govern the manufacture, sale, transportation, use, and/or disposal of styrene.
Information about state activity related to styrene in Texas and California is provided in some detail below. In addition, SIRC monitors regulatory and legislative activity related to styrene in all 50 states. This activity includes:
- “Chemicals of Concern” – during the past few years, several states have enacted legislation which authorizes the development of regulations which identify lists of “chemicals of concern.” These lists are primarily based on existing lists developed by other authorities, such as the U.S. EPA, U.S. National Toxicology Program, the European Union, etc. Styrene is often included in such lists, but has not been identified to date as a candidate substance for further action by any U.S. state that has developed a list of this type.
- Air emission standards – the U.S. federal Clean Air Act Amendments of 1990 regulate air emissions for hazardous air pollutants through technology-based standards that do not address potential health effects. A majority of the states have adopted these standards for a number of chemicals, including styrene.
- State-developed standards – nine states have established regulations specifically for styrene that establish health-based emission standards or guidelines. Current guidelines in six of these states are at least partially based on outdated information provided by U.S. EPA in the 1980s.
For more information on state legislation or regulations related to styrene not provided below, please contact us.
Texas Commission on Environmental Quality (TCEQ) Review
In 2007, TCEQ began to consider whether the state should modify its fence-line exposure limit for styrene. This review was completed in 2008 and the existing limit was left unchanged at 110ug/m³. This value is based on odor detection.
At the same time, TCEQ also conducted a comprehensive review of the scientific information related to styrene (Lee, 2008)  and styrene’s potential to impact human health. Regarding carcinogenicity, TCEQ concluded “data are inadequate for an assessment of human carcinogenic potential.”
Styrene was added to California’s Prop 65 list of chemicals “known to the state” to cause cancer on April 22, 2016. California EPA’s Office of Environmental Health Hazard Assessment (OEHHA) announced Feb. 27, 2015 its intent to add styrene to the list of chemicals under the Safe Drinking Water and Toxic Enforcement Act of 1986, better known as Proposition 65. OEHHA based its decision to add styrene on the chemical’s June 2011 listing as “reasonably anticipated to be a human carcinogen” in the U.S. National Toxicology Program’s (NTP’s 12th Report on Carcinogens (RoC). Using NTP as an “authoritative body,” OEHHA contends styrene should be listed.
In 2013, OEHHA withdrew a proposal to list styrene under the Labor Code listing mechanism.
The primary mechanisms for adding substances to the Proposition 65 list are an independent review and assessment through a state scientific advisory board, referencing a listing by an “Authoritative Body,” and a provision that references sections of the California Labor Code. The Labor Code provisions reference the International Agency for Research on Cancer (IARC) and the OSHA HCS. In Styrene Information and Research Center, Inc. v. OEHHA, 148 Cal.App.4th 1082 (2012), the California appellate court agreed that “known” to the state requires sufficient scientific evidence to support a listing [read PDF].
Because IARC found that styrene had less than sufficient (limited or inadequate) evidence of carcinogenicity, OEHHA was not permitted to list styrene under the Labor Code mechanism.
Public Health Goal
In 2010, California’s Office of Environmental Health Hazard Assessment (OEHHA) established a state Public Health Goal (PHG) of 0.5 parts per billion (ppb) (0.5 micrograms/liter [μg/L]) for styrene in drinking water.
According to OEHHA’s PHG report on styrene, the state’s PHG is based on “carcinogenicity in rodents.” OEHHA also stated “there is sufficient evidence that styrene causes cancer in animals and limited evidence in humans. For these reasons, it is prudent to assume carcinogenicity for the purposes of risk assessment” (OEHHA 2010). 
California’s own test data on drinking water samples taken from some 15,000 water sources in the state indicated that styrene was undetectable in all but one sample of drinking water.
Moreover, SIRC maintains that the scientific basis that OEHHA used to set the very low PHG for styrene of 0.5 parts per billion (ppb) is neither appropriate nor scientifically supportable. This is because research available to OEHHA at the time it established the PHG indicates the finding of lung tumors in mice (but not in rats or humans) exposed to styrene is not relevant for human risk assessment. This view is similar to the conclusion reached by the European Union and several other regulatory agencies. Additional information can be found under “Styrene Metabolism & Mode of Action” on the Human Health page of this website.
- Lee, J.S., Development Support Document, Styrene, Texas Commission on Environmental Quality (TCEQ), 23 p., 7 Aug 2008; http://tceq.com/assets/public/implementation/tox/dsd/final/styrene_100-42-5_final.pdf.↵
- OEHHA 2010, Public Health Goals for Chemicals in Drinking Water, Styrene, Proposition 65, Office of Environmental Health Hazard Assessment (OEHHA), State of California, 285 p., Dec. 2010; https://oehha.ca.gov/water/public-health-goal/public-health-goal-styrene.↵