SIRC monitors the regulatory and policy-making activity on styrene to inform members, ensure appropriate treatment by governmental and non-governmental bodies, and provide comments and expert opinion when warranted. For additional information regarding SIRC’s stance on current regulatory matters, please refer to SIRC’s statements in the public information section of the website.
Environmental Protection Agency (EPA)
Toxic Substances Control Act (TSCA)
The Frank R. Lautenberg Chemical Safety for the 21st Century Act significantly revised the Toxic Substances Control Act in 2016, including a requirement for EPA to conduct a risk evaluation of existing chemicals regulated under TSCA on a priority basis. TSCA directs EPA to focus first on chemicals listed in its 2014 Chemical Substances Work Plan, which includes styrene. EPA has moved forward on initial priority candidates for evaluation but has not yet selected styrene, one of the substances listed in the Work Plan not yet under review.
Integrated Risk Information System (IRIS)
The U.S. EPA’s Integrated Risk Information System characterizes the health hazards of chemicals and develops chronic toxicity values for use in the full range of EPA risk management programs. IRIS assessments represent EPA’s official position regarding a chemical substance’s carcinogenicity or toxicity. Styrene was last reviewed by the IRIS program in 1992 for non-cancer effects and assigned chronic oral and inhalation toxicity values of 0.2 mg/kg bw/day [milligrams per kilogram of body weight per day] and 1 mg/m3 [milligrams per cubic meter of air] (0.23 ppm [parts per million]), respectively. The IRIS program has not assessed styrene for carcinogenicity.
Toxics Release Inventory (TRI)
The U.S. EPA annually collects and compiles information on the release and management of select chemicals (i.e., recycling, energy recovery, and treatment) by U.S. manufacturing facilities and makes this Toxics Release Inventory information public. Styrene is one of many substances selected for TRI reporting as a hazardous air pollutant. Styrene dissipates rapidly when released into the air or water. TRI reports indicate that styrene air releases are declining over time, in part due to new control technology.
Endocrine Disruptor Screening Program (EDSP)
Styrene remains on the EPA’s “List 2” of chemicals slated for eventual review under its Endocrine Disruptor Screening Program.
Occupational Safety and Health Administration (OSHA)
The U.S. Occupational Safety and Health Administration regulates styrene as a hazardous substance because of short-term reversible central nervous system effects such as drowsiness and delayed reaction time that may be experienced from exposure to styrene in the workplace. The OSHA permissible exposure limit (PEL) for styrene, adopted in 1971, is 100 ppm , meaning that a worker should not be exposed to more than an average of 100 ppm styrene during a regular 8 hour workday, without respiratory protection.
In 1996, OSHA endorsed the styrene industry’s voluntary 50 ppm exposure level program. In 2011 based on new industry-sponsored research, SIRC recommended a 20 ppm guideline.
OSHA’s Hazard Communication Standard (HCS) requires chemical manufacturers and importers to provide hazard information to employees and customers by preparing safety data sheets. The HCS does not require any specific labeling or classification for styrene or products made from styrene. Each product’s safety and health characterizations are based on the manufacturer’s evaluation using criteria set by OSHA. While not an endorsement, it is common practice to list authoritative bodies’ (NTP and IARC) styrene classifications in Section 11 of the safety data sheet.
Food and Drug Administration (FDA)
The U.S. Food and Drug Administration closely regulates the use of food additives or substances that may migrate into foods from packaging, food preparation, or serving materials. FDA permits materials made from styrene to be used in contact with food products. These materials, such as polystyrene food service and packaging materials, must meet strict guidelines that ensure the consumer’s safety and health. The FDA has designated styrene as “Generally Recognized as Safe.”
While the agency approved styrene, in very small quantities, for use as a food additive for synthetic flavoring to enhance taste, industry reports show it has not been used as a flavoring substance for more than a decade. SIRC filed a petition to the FDA in May 2016 requesting removal of the clearance for styrene due to the abandonment of its use as a synthetic flavoring substance and adjuvant in food. FDA granted the request in October 2018.
National Toxicology Program (NTP)
The U.S. National Toxicology Program is an interagency program headquartered within the U.S. National Institute of Environmental Health Sciences, a part of the U.S. Department of Health and Human Services. Each year, NTP publishes the annual Report on Carcinogens (RoC). NTP listed styrene as “reasonably anticipated to be a human carcinogen” in its 12th ROC in June 2011.
In 2012, the U.S. Department of Health and Human Services engaged the U.S. National Academy of Sciences (NAS) to independently review styrene’s listing. Under the National Academies structure, the National Research Council (NRC) managed the review of the RoC listing of styrene. The NAS/NRC review was completed in July 2014 and validated NTP’s listing of styrene in the RoC.
Office of Environmental Health Hazard Assessment (OEHHA)—Proposition 65
California’s Office of Environmental Health Hazard Assessment added styrene to the state’s Proposition 65 list of chemicals “known to the state” to cause cancer on April 22, 2016. OEHHA’s decision to add styrene to the Prop 65 list was based on the 2011 decision of the U.S. National Toxicology Program—a Prop 65 “authoritative body”—to list styrene in its 12th Report on Carcinogens as “reasonably anticipated to be a human carcinogen.”
OEHHA established a “No Significant Risk Level” for styrene (NSRL) of 27 micrograms per day in 2017.
Office of Environmental Health Hazard Assessment (OEHHA)—Public Health Goal
In 2010, California’s Office of Environmental Health Hazard Assessment established a state Public Health Goal of 0.5 parts per billion (ppb) (0.5 micrograms/liter [μg/L]) for styrene in drinking water.
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.
- Air emission standards—The U.S. Clean Air Act Amendments of 1990 regulate air emissions for hazardous air pollutants through technology-based standards that do not address potential health effects. Most states have adopted these standards for several chemicals, including styrene.
- Chemicals of concern—During recent 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, and the European Union.
- State-developed standards—Several states have established regulations specifically for styrene that establish health-based emission standards or guidelines.
American Conference of Governmental Industrial Hygienists (ACGIH)
In January 2020, the American Conference of Governmental Industrial Hygienists announced the adoption of threshold limit values (TLV) for styrene of 10 ppm TLV-TWA and 20 ppm TLV-STEL. In addition, notations of ototoxicant and A3 carcinogen (“confirmed animal carcinogen with unknown relevance to humans”) were also adopted for styrene.
In January 2023, ACGIH announced its adopted changes for styrene’s biological exposure index (BEI) values: 150 mg/g creatinine for mandelic acid plus phenygloxylic acid in urine (end of shift) and 20 µg/L styrene in urine (end of shift).
ACGIH is composed of state and federal governmental hygienists and is not a regulatory body. While its recommendations are not enforceable, ACGIH and its actions are important because the adopted TLVs are often used as voluntary exposure guidelines in the internal policies of some companies. However, industry is generally opposed to automatic or reflexive use of the guidelines for enforceable regulatory use because ACGIH does not consider feasibility and other regulatory criteria in its assessments.
Health Canada completed an assessment of styrene’s possible health and environmental effects in 1993. The review concluded that styrene is “non-toxic,” and as such does not require regulation under Canadian Environmental Protection Act. Health Canada found that “… styrene is not entering the environment in quantities or under conditions that may constitute a danger to the environment on which human life depends, or to human life or health.” Health Canada’s classification scheme for carcinogenicity lists styrene as a Class III “possible human carcinogen.”
Some of the provinces of Canada follow ACGIH guidelines for workplace exposure limits.
European Union (EU)
Styrene is unclassified as to carcinogenicity in Europe. Styrene has received the following EU GHS health hazard classifications: Acute Tox. 4 (inhalation), Skin Irrit. 2, Eye Irrit. 2, Asp. Tox. 1, Repr. 2, STOT SE 3, and STOT RE 1 (hearing organs).
There is no occupational exposure limit established for styrene by the European Chemicals Agency, but some individual member countries have limits.
Styrene is one of 60 “priority 1” substances on the EU’s endocrine list, but no regulatory action has been completed. Styrene is classified as a “Category 2” reproductive toxicant, effective December 2016.
Other global regulations
Many other nations have wide and varied regulations pertaining to styrene, including:
- The China State Administration of Work Safety classifies styrene as “Carcinogen Category 2, suspected human carcinogen.” Styrene is also classified as a suspected human reproductive toxicant in China.
- Styrene is not classified as a carcinogen by the Japan Industrial Safety and Health Law, but it is considered a “Category 2” based on the former IARC 2B classification. The Japan Society for Occupational Health classifies styrene as a Group 2 reproductive toxicant. Also, Japan has a 220 micrograms limit for indoor air exposure based on non-cancer endpoints. For more information, refer to the Japan Styrene Industry Association.
- Korea has enacted a law similar to the EU’s REACH. Styrene was included on its first “substances subject to regulation” list, submitted in 2018. Korea also lists styrene for volatile organic compounds air exposure.
- Chile gave styrene an A4, potential carcinogen notation.
- Many countries regulate styrene food contact exposure. There are various migration limits for styrene exposure via food contact materials in Japan, India, and Australia. Saudi Arabia has drinking water and ambient air quality guidelines.
- Workplace exposure limits for styrene are varied in the range of 20 ppm to 100 ppm among Japan, Australia, China, India, Malaysia, New Zealand, The Philippines, Thailand, Singapore, Turkey, and several Latin American countries.
International Agency for Research on Cancer (IARC)
The International Agency for Research on Cancer in Lyon, France, reviewed styrene in 1987, 1994, 2002, and most recently in 2018. IARC classified styrene as Group 2A, “probably carcinogenic to humans.” A final monograph was published in September 2019.
IARC classifications are based on hazard assessments and not risk assessments. IARC classifications are not indicators of real-world potential risk. The mere presence of, or exposure to, a chemical is not an indication of risk or potential harm. IARC classifications are not enforceable as regulations, but they are often used as a reference in regulatory actions and policies.