Studies in humans, and particularly workers with high exposure to styrene products, show that the material is not associated with a consistent increase in death from any type of cancer, contradicting official listings, according to an industry-sponsored analysis conducted by environmental and risk science consulting firm Gradient.
The material was listed as “reasonably anticipated to be a human carcinogen” in the twelfth edition of the National Toxicology Program’s Report on Carcinogens. In Human and Ecological Risk Assessment: An International Journal Volume 19, Issue 1, Gradient contends that the listing was made on erroneous findings and limited evidence of carcinogenicity in humans. In contrast, there is sufficient evidence of carcinogenicity in experimental animals, the researchers said.
Gradient says that the NTP’s conclusions were not supported by the science, and were not consistent with NTP’s own established criteria for listing a substance as reasonably anticipated to be a human carcinogen. The NTP report claims that humans have an increased risk of hematopoietic cancers, not lung cancers, as are seen in mice, according to the Gradient team.
Gradient received financial support for the analysis from the Styrene Research and Information Center, a non-profit whose members represent about 95 percent of the North American styrene industry, according to SRIC’s website.
In September 2011, the Danish EPA also concluded that styrene data does not support a cancer-related concern.
In March last year, Gradient released a study that suggested that metal exposure from laundered shop towels may exceed the permissible levels allowed in drinking water. According to the Evaluation of Potential Exposure to Metals in Laundered Shop Towels, manufacturing workers using a typical number of towels may be exposed to metals such as lead, chromium, cadmium and antimony at levels many times above those allowed by the maximum contaminant levels or, in the case of lead, the action level for drinking water.