On May 4, California’s Office of Environmental Health Hazard Assessment (Oehha) approved the amendment of Proposition 65 to adopt the identification of the No Significant Risk Level (NSRL) for styrene of 27 micrograms per day (μg/day). This requirement will come into effect on July 1, 2017.

NSRL stands for the safe harbour level of a certain substance, so once the exposure exceed the NSRL, a warning would be required. In April, 2016, Oehha included Styrene in Proposition 65 for its carcinogenesis, and the regulation of May 4 adopted the recommended safe harbour level.

The industry group Styrene Information and Research Centre (Sirc) had advocated higher levels-2,100μg /day for inhalation exposure and 5,600μg/day for oral exposure. However, Oehha considered this proposal lack of statistical support. Or, more specifically, Oehha affirms that the physiologically based pharmacokinetic (PBPK) model employed by Sirc to obtain the data of their recommended levels is speculative and is unable to accurately simulate the “substantial elements of the available dataset”. Therefore, Oehha holds that this centre’s proposal is not effective in protecting human health and states again that the safe harbour level of 27μg/day is much more appropriate.

Besides, in response to comments received on polystyrene food packaging, Oehha stressed that it is only necessary to add a relevant warning if the exposures of styrene exceed its no significant risk level, while the amount of styrene remaining in the polystyrene food package is quite low in most cases.

In addition, if necessary, Oehha will supplement its safe use determinations (SUDs) of specific products, providing guidance for companies to meet the requirements of Proposition 65.

C&K Testing reminds the relevant companies to pay attention to California’s no significant risk level of styrene and to upgrade related products based on this level so as to react in time.

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