On February 16, 2017 a Letter to the Editor was published in the Regulatory Toxicology and Pharmacology journal, responding to a commentary by Alan Boobis and colleagues which was published in October 2016 (FPF reported). In his commentary, Boobis criticized the hazard identification-based cancer classification schemes used by the International Agency for Research on Cancer (IARC), calling them ‘outmoded.’ In their response, Dana Loomis and colleagues from the IARC, Section of IARC Monographs, Lyon, France, emphasized the role of epidemiological data in the evaluation of carcinogenicity, largely omitted in the original commentary. Further, Loomis pointed out that “Boobis et al. inappropriately conflate the scientific evaluation of hazards with the broader socio-political process of risk management.”

Indeed, a critical evaluation of scientific findings, resulting in a hazard classification, is a necessary first step in the risk assessment process. Subsequent steps should then deal with the hazard characterization, followed by the risk assessment and risk management, as necessary (FPF article). Loomis and colleagues specifically point out that “hazard identification, incorporating the ‘real-world’ exposures measured in epidemiological studies . . . provides a vital platform for the subsequent steps of risk assessment and management.” They further note that “the suggestion by Boobis et al. for ‘further evaluation including full risk assessment’ before taking action to mitigate risk from a carcinogenic hazard is a political stance, not a scientific one.” Loomis and colleagues emphasize that “carcinogen classification schemes provide an unbiased review of scientific evidence and remain a necessary and valuable foundation for cancer prevention . . . incorporating the latest scientific understanding and conducted in the light of strict management of conflicts of interest.”

In their response to Loomis and colleagues’ letter, Boobis and co-authors maintain their accusation that “IARC processes . . . have encouraged the bypassing of hazard characterization and risk assessment [the stages not being handled by IARC], going straight from hazard identification to risk management.” They further suggest that the “IARC hazard identification scheme . . . may provide some value with poorly tested chemicals, or in the case of lifestyle factors,” but claim that IARC assessments should not be performed for “data-rich compounds that require regulatory approval.” Boobis and co-authors do not, however, elaborate further on which authority should be deciding whether a compound is still “poorly tested” or already “data-rich.”

Read more

Philip Lightowlers (March 9, 2017). “IARC answers crticism over ‘hazard-only’ carcinogen classification.Chemical Watch


Boobis, A., et al. (2016). “Classification schemes for carcinogenicity based on hazard-identification have become outmoded and serve neither science nor society.Regulatory Toxicology and Pharmacology 82: 158-166.

Loomis, D., et al. (2017). “Classification schemes for carcinogenicity based on hazard identification serve science and society.Regulatory Toxicology and Pharmacology (published February 16, 2017).

Boobis, A., et al. (2017). “Response to Loomis et al Comment on Boobis et al.Regulatory Toxicology and Pharmacology (published February 16, 2017).