The carcinogenicity debate on formaldehyde: How to derive safe exposure limits?

Abstract

Matters of good epidemiological practice (BoVetta et al.2008; Clapp and Kriebel 2009; McLaughlin et al. 2009;Cogliano and Straif 2010) and consequences of potentialconXicts of interest (BoVetta et al. 2009; Hauptmann andRonckers 2009) have been topics of recent editorials andcorrespondence in scienti Wc journals publishing human tox-icity studies, including Archives of Toxicology (Slama2009; Slama et al. 2009; Morfeld 2009a, b, c). This discus-sion speciWcally aVected evaluations of a number of indus-trially or environmentally important chemicals, such asacrylonitrile, TCDD (BoVetta et al. 2008) and formalde-hyde (BoVetta et al. 2009; Hauptmann and Ronckers 2009;McLaughlin et al. 2009). In this context, also the currentevaluation of formaldehyde by the International Agency forResearch on Cancer (IARC (International Agency forResearch on Cancer) 2006; Baan et al. 2009), indicatingstrong evidence related to human sino-nasal cancer andmoderate evidence of human leukaemia, was questioned(McLaughlin et al. 2009).Key topics of the toxicity and carcinogenicity of formal-dehyde have been recently reviewed (Kupczewska-Dobecka2007; Sul et al. 2007; Duhayon et al. 2008). Thecarcinogenicity of formaldehyde and the derivation of asafe occupational exposure limit have been matters ofdocumentations by a number of scientiWc expert panels,including DFG (Deutsche Forschungsgemeinschaft)(2000), DECOS (Health Council of the Netherlands: DutchExpert Committee on Occupational Standards) (2003),Nordic Expert Group (2003) and SCOEL (ScientiWc Com-mittee on Occupational Exposure Limits) (2008). Justrecently, SCOEL (ScientiWc Committee on OccupationalExposure Limits) (2008) has considered formaldehyde tobe a “genotoxic carcinogen, for which a practical thresholdis supported” (category 3, according to Bolt and Huici-Montagud 2008) and has recommended a health-basedOccupational Exposure Limit of 0.2 ppm.By contrast to occupational exposure, scientiWcallybased recommendations for a h ealth-based limit of environ-mental formaldehyde exposure, especially for indoor airexposure, have been scarce. For many chemicals, recom-mendations of safe environmental exposure levels were tra-ditionally based on dividing recommended occupationallimits by a Wxed factor, e.g. a factor of 100. For formalde-hyde, the German