oa Clean Air Journal = Tydskrif vir Skoon Lug - Formaldehyde toxicology - occupational versus environmental HAP? : scientific paper

Volume 17, Issue 2
  • ISSN : 1017-1703



As a ubiquitous air pollutant in both indoor and outdoor air the potential adverse health effects from formaldehyde exposure have been subject to numerous critical public health reviews by regulatory agencies. Public health advisories have, however, been based primarily on the linear extrapolation of dose-response data from occupational studies where repeated elevated levels of exposure have led to both respiratory irritation and sensitisation as well as probable increased incidences of nasopharyngeal cancers.

In this paper the inadequacies in the interpretation of occupationally derived dose-response relationships to derive safe levels for public exposure to a key HAP in the absence of a detailed understanding of dose-response mechanisms are explored. Issues around the 2004 IARC reclassification of formaldehyde as Class 1 'carcinogenic to humans' are discussed and the technical background as to why public cancer incidence rates from formaldehyde exposure have historically been overestimated by a number of international regulatory agencies. The latest knowledge of formaldehyde toxicology and carcinogenesis is discussed to illustrate the limitations in simple linear extrapolation of occupational data to derive cancer risk estimates and safe exposure limits for assessment of ambient air quality monitoring data and public health risk assessment. Occupational and ambient limits for formaldehyde in South Africa are tabled for review and debate.

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