In 2019, SIRC completed and published an updated comprehensive human health risk assessment as a capstone to our 30-year research program and to update the 2002 Harvard risk assessment. The project, like all SIRC-funded research, serves to fulfill our product stewardship mission.
SIRC’s goals were to review the scientific literature on styrene, develop hazard and exposure assessments, and assess potential toxicological risk—with a focus on workers in environments where styrene is made or used in manufacturing as well as the general population from environmental and consumer exposures.
Distinct areas of study included: cancer and toxicity to the nervous system, immune system, and reproduction and development. Independent scientists with relevant expertise prepared the various sections of the assessment.
The completed assessment was published by the Journal of Toxicology and Environmental Health, Part B: Critical Reviews in July 2019. This assessment updates a 2002 styrene risk assessment conducted by Harvard University.
For this assessment, SIRC assembled a group of independent experts to:
- systematically review the scientific literature on styrene
- develop hazard and exposure assessments
- assess the current science on styrene and human health—with a focus on workers in environments where styrene is made or used in manufacturing as well as general population exposures from environmental and consumer product sources
Major conclusions of the project
Styrene in consumer products
Consumer products made with styrene remain safe. There is negligible concern or risk from exposures to styrene through everyday use of consumer products.
Styrene in the workplace
The risk assessment concluded occupational risks are within acceptable ranges for most workers.
Styrene in the environment
The general population is unlikely to experience adverse health outcomes associated with styrene environmental or consumer exposures.
Does styrene cause cancer?
There are no strong or consistent indications that styrene causes any form of cancer in humans. Although some studies suggest that styrene-exposed workers may be at increased cancer risk, the human evidence for styrene carcinogenicity is inconclusive.
What about other health effects?
Hearing impairment—ototoxicity—is an area of concern for certain workplace exposures. Simultaneous exposure to noise and styrene appears to increase potential adverse effects. Noise protection is important for workers exposed to styrene.
What is the distinction between hazard and risk?
“Hazard” refers to anything that has the potential to cause harm or an adverse effect under a particular circumstance. By analogy, a wet floor poses a hazard because someone could slip and fall. “Risk” is the likelihood that a hazard will cause harm to someone or something. Determining risk requires consideration of whether, how, and how much a person is exposed to a substance or activity. Using the same analogy, the risk of slipping and falling is minimal if the wet area is blocked off and the moisture is removed. However, leaving an area of a floor wet presents a fall risk for people walking through the area. A risk assessment seeks to quantify the probability that harm may occur based on both a known hazard and the probability of exposure to that hazard.
Download a printable fact sheet on the 2019 styrene risk assessment.