Styrene is the latest chemical to require a label warning California consumers of possible carcinogens, but exactly what that means for products that contain it is unclear.
One styrene-based plastics product that will not need a label under California's latest Proposition 65 ruling is polystyrene.
“We clearly stated this does not cover polystyrene,” said Sam Delson, deputy director for external and legislative affairs in the state's Office of Environmental Health Hazard Assessment's (OEHHA).
Along with the announcement of styrene as a chemical “known to the state of California” to cause cancer, OEHHA issued a 39-page report agreeing that styrene is not the same as polystyrene and clearly stating that PS is not the subject of the proposed listing.
The EPS Industry Alliance, an expanded polystyrene industry group, called the report “reassuring.”
Along with the listing, OEHHA proposed a “No Significant Risk Level” of 27 micrograms per day for styrene.
With EPS, much like other products made with styrene, the amount of residual chemical after the point of manufacture is very small. In an EPS coffee cup, the relative exposure from styrene is only 5 to 10 parts per billion, the Alliance estimates. Reports published by the U.S. Food and Drug Administration and the U.S. Department of Health and Human Services consistently indicate the small amount of styrene typically found in PS products is not a concern and nowhere near the NSRL level proposed by OEHHA.
While those in the industry understand the difference between liquid styrene and PS, it's not something the average consumer necessarily knows.
Betsy Steiner, executive director of the EPS Industry Alliance, said she views the Prop 65 listing of styrene as adding a step in the already uphill climb to combat public and consumer misconceptions of EPS and polystyrene in general.
“EPS is 98 percent air — which from a recycling standpoint, is not a hot commodity,” she said. “But that doesn't mean it's not recyclable. It's not a human health concern. There are no studies that show it is somehow getting into the food chain. … These myths take on a life of their own and then they compound themselves every time a new piece of misinformation is added.”
EPS workers and consumers are not at risk for the NSRL under Prop 65, Steiner said, so it is not yet clear to the Alliance what types of products will require a label or what kind of risk styrene, outside of industrial situations in liquid form, poses. In addition to EPS, styrene is also found in ABS and styrene acrylonitrile resins along with synthetic rubbers and latex.
“Prop 65 in and of itself is curious — what are consumers doing with that information? Does it help them make better choices?” she said.
California's Proposition 65, approved by voters there in 1986, requires businesses to notify citizens when a significant amount of chemicals are present in products, workplaces, public spaces or released into the environment. OEHHA administers the Prop 65 program, including managing the list of potentially harmful chemicals.
The agency based its listing on the National Toxicology Program's (NTP) 2011 listing of the substance in its 12th edition of the Report on Carcinogens, which concluded that liquid styrene is “reasonably anticipated to be a human carcinogen based on limited evidence of carcinogenicity from studies in humans, sufficient evidence of carcinogenicity from studies in experimental animals, and supporting data on mechanisms of carcinogenesis.”
Adding styrene to the Prop 65 list has been in the pipeline for years and comes as no surprise to many in the industry, but the potential effects of listing the chemical and labeling products, as well as the uncertain future for those plans is irksome for many. Moreover, the labeling requirements in California under Prop 65 could soon change.
As for products that will require a label starting next year, OEHHA is no help.
“We don't test products or compile information on exposure levels for specific chemicals and products,” Delson said, via email. “It is up to the product manufacturers to determine if they are causing an exposure that would require a warning.”