The developmental and reproductive data indicate that styrene does not cause birth defects, and provides little support for the idea that styrene exposure could lead to developmental or reproductive toxicity, including potential endocrine disruptor effects.
In 1995, SIRC sponsored Dr. Nigel Brown of the University of London, U.K. to conduct an update of a previously-published review of the published studies related to styrene’s potential, if any, for reproductive and developmental effects. Dr. Brown’s paper concluded “the potential developmental toxicity of styrene has been tested in several mammalian experimental species, but only one study is of good quality. Throughout all studies, there is no evidence for teratogenicity [birth defects]. There are reports of increases in embryonic, fetal, and neonatal death … but these effects are restricted to exposures that are maternally toxic. There is a lack of well-replicated studies, but the bulk of information suggests that styrene does not exert any specific developmental toxicities.” [Insert footnote]
In 2006 the U.S. National Toxicology Program (NTP), in a comprehensive review [Insert footnote] of the science related to developmental and reproductive effects, determined that there is “negligible concern” for adverse developmental and reproductive effects resulting from styrene exposures in humans.
Despite these findings, styrene has been recommended for classification as a Category 2 reproductive toxicant under ANNEX XV of the European Classification and Labelling (CLP) Directive and as a Category 3 reproductive toxicant under the European Dangerous Substances Directive (DSD).
In late 2012, the Risk Assessment Committee (RAC) of the European Chemicals Agency adopted an opinion [Insert footnote] in which the RAC recommended that styrene’s classification should be changed to include a “Category 2” designation for reproductive toxicity (“suspected of damaging the unborn child”), hazard code H361d, under the CLP Directive and a “Category 3” designation (“toxic to reproduction”), hazard code R63 (development), under the DSD regulation.
These actions are expected to be published by the European Commission by the end of 2013 and then come into effect eighteen months thereafter.
In SIRC’s view, the developmental and reproductive data indicate that styrene does not cause birth defects (is not teratogenic), and provides little support for the idea that styrene exposure could lead to developmental or reproductive toxicity, including potential endocrine disruptor effects (see following section). [Insert link] Despite this disagreement, industry will fully comply with these updated classification and labeling actions as they come into force.