Reevaluation of mortality risks from nasopharyngeal cancer in the formaldehyde cohort study of the National Cancer Institute

Overall, our reanalysis provided little evidence to support NCI's suggestion of a causal association between formaldehyde exposure and mortality from NPC. NCI's conclusion of a possible causal association was driven heavily by anomalous findings in one study plant (Plant 1). An independent and larger study of Plant 1 by the current authors concluded the NPC excess was not associated with formaldehyde exposure. Our findings cast considerable additional uncertainty regarding the validity of NCI's suggested causal association.