Styrene trade group SIRC ‘will carefully review the conclusions and recommendations’
A federal research agency on 28 July upheld a 2011 ruling by government health officials that styrene is “reasonably anticipated to be a human carcinogen”, rejecting industry challenges to that categorisation.
The National Research Council (NRC) said that it agrees with a 2011 finding by National Toxicology Program (NTP) that styrene qualifies as a likely carcinogen in humans, in NTP parlance “reasonably anticipated to be a human carcinogen”.
The National Toxicology Program is part of the US Department of Health and Human Services (HHS).
The classification of styrene by NTP in its June 2011 Report on Carcinogens (RoC) triggered broad protests by styrene manufacturers and those industries that use styrene as a major feedstock.
An industry group, the Styrene Information and Research Center (SIRC), charged that the research done by NTP in reaching its carcinogen ruling on styrene was “scientifically bankrupt”.
SIRC filed suit in federal court seeking to overturn the NTP decision, and the group joined other styrene sector interests in asking the White House to order a comprehensive scientific review of the NTP decision by the National Academy of Sciences (NAS).
The lawsuit challenge was defeated in 2013 when a federal judge’s summary judgement upheld the NTP’s findings.
But the National Academy of Sciences did launch a review through its NRC subsidiary.
LIMITED BUT CREDIBLE
In the council’s decision announced on 28 July, the NRC said it found that the NTP listing of styrene as reasonably anticipated to be a human carcinogen was supported by “limited but credible” evidence in human studies, “sufficient” evidence from animal studies and “convincing relevant information” in mechanistic studies.
In the latter, mechanistic studies, NRC said that “DNA damage in human cells exposed to styrene” had been observed.
That independent assessment, said NRC, “found that ‘compelling evidence’ exists in human, animal and mechanistic studies to support listing styrene, at a minimum, as reasonably anticipated to be a human carcinogen”.
In responding to the NRC report, SIRC said on 28 July that it “will carefully review the conclusions and recommendations”.
In the wake of the June 2011 NTP ruling, some in the styrene industry warned that if the carcinogenic finding were allowed to stand, many US styrene producers and consumers would be forced to move operations offshore.