Vinyl chloride industry in the courtroom and corporate influences on the scientific literature.

Pressure from the vinyl chloride (VC) industry on researchers involved in industry-sponsored studies and on regulatory agencies has been documented since 1970s. This commentary describes the influence of a lawsuit pursued by workers of an Italian VC plant on the recent scientific debate on VC exposure and risk of hepatocellular carcinoma (HCC). Original studies carried out by consultants of the public prosecutors and by independent researchers supported the above association. VC-industry consultants published two reviews during the lawsuit, claiming that liver angiosarcoma was the only VC-related cancer. The judges concluded that the evidence of the association between HCC and VC was still not convincing. After the trial, the risk of HCC was confirmed by a re-assessment of VC carcinogenicity from the International Agency for Research on Cancer, but other subsequent industry-funded reviews criticized the new evidence. Industry-funded authors cited each other, and rarely disclosed conflicts of interest. Based on a network of collaborating researchers, industrial interests can shape the literature enhancing the background noise surrounding the scientific evidence.