National Academy of Sciences strongly affirms science showing styrene is a human carcinogen

Richard Denison, Ph.D., is a Lead Senior Scientist. 

It’s been a ridiculously long road to get here, because of the delay tactics of the chemical industry.  But yesterday a panel of the National Academy of Sciences (NAS) fully backed the National Toxicology Program’s (NTP) listing of styrene as “reasonably anticipated to be a human carcinogen.”

We have blogged earlier about this saga.  In June 2011, after years of delay, the NTP released its Congressionally mandated 12th Report on Carcinogens (RoC), in which it upgraded formaldehyde to the status of “known to be a human carcinogen,” and for the first time listed styrene as “reasonably anticipated to be a human carcinogen.”  The chemical industry launched an all-out war to defend two of its biggest cash cows, filing a lawsuit to try to reverse the styrene listing (which it lost), and seeking to cut off funding for the RoC.  

In late 2011, the industry managed to get its allies in Congress to slip into the Consolidated Appropriations Act of 2012, without any debate, a rider that mandated NAS to review the styrene and formaldehyde listings in the 12th RoC.  Yesterday’s NAS report on styrene is the first installment, with the second one on formaldehyde expected shortly.

The NAS report could not be more supportive of the NTP’s listing of styrene, finding “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.” (emphasis added) 

The NAS committee both peer-reviewed the RoC listing and conducted its own independent review of the styrene literature – and in both cases found strong evidence to support NTP’s original finding.  According to NAS’ release:

The committee that wrote the report found that the listing is supported by “limited but credible” evidence of carcinogenicity in human studies, “sufficient” evidence from animal studies, and “convincing relevant information” in mechanistic studies that observed DNA damage in human cells that had been exposed to styrene. 

Note that a chemical can be classified as “reasonably anticipated to be a human carcinogen” if there is sufficient evidence in animals or limited evidence in human studies; in the case of styrene, NAS affirmed that there are both types of evidence.

Moreover, NAS found that the available mechanistic evidence could actually support an even stronger classification of styrene, noting that “a strong argument could be made to support the listing of styrene as a known human carcinogen if data derived from the study of human tissues or cells alone were considered sufficient.”

In the end, the chemical industry managed to buy itself 3 years of delay, and temporarily tarnished the reputation of one of the world’s leading authoritative bodies, one that reaches its conclusions only after an exhaustive scientific assessment process entailing reviews by four separate groups of expert scientists for each chemical.

One can only hope that this sorry episode and waste of public resources will help to expose the narrow self-interest of the industry, which for years it has deceptively sought to wrap in a mantle of sound science.  Now we know whose science is sound, and whose isn’t.

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  1. cfrwhite
    Posted July 29, 2014 at 5:04 pm | Permalink

    So, what kinds of exposure were tested? Surely nobody is ingesting the stuff. Eating food presented in it? Standing next to it? For how long? Etc? Rather important information.

    • ChemEngGos
      Posted August 6, 2014 at 3:23 pm | Permalink

      Congrats to EDF…….Its in Black and White. Are you pushing for another study cfrwhite?
      Example: Infrastructure projects that use a thermoset polyester or vinyl-ester, risk evacuating homes and business. Evaluations of these projects will show substantial releases in the water and air. There is StyRedux to economically control toxic releases and of course other technologies. Engineers and contractors must be liable for specifications and avoiding the mitigation of toxic releases for the safety of the public and environment. Monitoring has shown readings of 250-1550 ppm during transport. During cure, readings of 500-1,000 ppm are common (steam/water cure). Workers will work inside pipelines without air supplied breathing apparatuses exposed to high concentrations of styrene. The excuse that strawberries, cinnamon and even polystyrene are low in concentration but it is a persons choice. FYI, polystyrene will read 2 ppm in a coffee cup (not heated) to 15 ppm for packaging material, (no big deal). White-out, if any uses this anymore but it was in one of the daycare’s evacuated, measured 25 ppm. House readings during evacuations have ranged upward of 150 ppm for CIPP. Child care facilities have been evacuated at 75 ppm without penalties or concerns from the local Fire Chief (the municipality was owner of the project). Another that comes to mind, a childcare facility, near a hospital (daycare for nurses and doctors) was evacuated for several days due to 9-90 ppb. Second hand smoke? “nobody is ingesting the stuff” its offensive. Some have chemical sensitivities and engineers and contractors save a few cents on the dollar. Contractors will test their own projects are sensitized to the odor even at 50 ppm. They try to convince the home/business owner that their plumbing is faulty. “Treat the source” has been conveniently and consistently overlooked. With all the above mentioned, it is time to have pollution control standards for the available technologies to limit public and environmental disruptions. Not pollution by dilution ( a pound of feathers = pound of gold).
      See: Fiberdome – OSHA (50 ppm). OSHA has no regulations over the general public exposure. Contractors and marketeers will state the home had less than 100 ppm! Keep your toxics confined and have mitigation plans in place.