I would like to begin by thanking Benedetto Terracini for engaging with my work. Given his first-hand involvement in the IARC Monographs programme, including his participation in monograph meetings and his working connection to the programme’s creator, Lorenzo Tomatis, his perspective is undoubtedly informed by unique and personal insights. While some of his observations offer important food for thought, others are based on interpretations that do not align with the text, the data, or the historical record. The remarquable role played by the IARC and its members in cancer prevention deserves to be rigorously analysed. 

Instead of addressing each of these discrepancies individually, I would like to take this opportunity to contribute to the broader and more significant discussion raised throughout this review: the historical and conceptual differences between risk and hazard assessment in the regulation of carcinogens. I will then develop on other related topics.

The distinction between risk and hazard assessment occupies only a limited portion of my book, which covers many other issues, such as the decreasing capacity of the IARC to add new agents to its list, the construction of a transnational competitive field of carcinogen assessment from the 1970s onwards, the relationship between the IARC and economic actors, and the tensions arising from the emergence of mechanistic data throughout this period.1 Nevertheless, this topic is worth addressing in detail as it has emerged as a recurring subject of discussion – and occasionally misunderstanding – in debates surrounding my work. In addressing this topic, I will draw on a variety of materials used in the book, including observations of expert meetings, interviews with dozens of individuals involved in the history of the Monographs programme, and over 2,000 pages of historical archives containing correspondence between the Monographs secretariat and its interlocutors worldwide between the 1960s and the 1980s.

Two mistakes are often made when it comes to hazard (the capacity of an exposure to cause cancer) and risk (the probability of this hazard arising in certain circumstances). The first mistake is the idea that these categories and their distinction from one another are self-evident and the result of scientific evidence only. The second mistake is the idea that the political value of these categories is embedded within them. For example, one might wrongly consider hazard to be more preventative than risk per se, or risk to be a better technique for regulating carcinogenic exposure because it is seen as a more pragmatic and realistic tool (rather than banning a substance, risk allows the level of exposure to be regulated). Contrary to this essentialising view of these categories, what I demonstrate in the book is that: 

1. The distinction between risk and hazard has emerged from a contingent and conflictual history. From the 1970s onwards, the proliferation of lists of carcinogens worldwide forced IARC and other institutions to clarify the value and meaning of their own evaluations, which were initially barely distinguishable. IARC played a key role in this process, either disqualifying other competitors (pp. 106-107) or clearly defining the meaning of its classification system (pp. 101-103), which was developed in close collaboration with the Occupational Safety and Health Administration (OSHA). The IARC also made judgements that caused significant resistance, such as its 1976 evaluation of asbestos, which concluded that it was impossible to estimate a level of exposure below which there would be no risk of cancer. This led to strong opposition within and outside the institution, particularly from industrial stakeholders (pp. 92-95);

2. Hazard and risk were not only distinguished from each other, but also hierarchised. This historical evolution saw hazard assessment assigned to the first step of public health policy for cancer prevention. Unlike risk assessment, which was seen as a more realistic appraisal of carcinogenic exposure,2 hazard assessment was defined as not directly relevant to the production of regulation. Industrial actors played a role in this process, either indirectly, such as when an Imperial Chemical Industries representative drafted a letter in 1980 proposing such a hierarchy (pp. 118-119), or more directly, such as when a consortium of dye manufacturers contested FDA regulatory decisions based on hazard assessment in the US (p. 117);

3. This distinction and hierarchisation created institutional territories. Amidst these tensions, the IARC has chosen to, and has been pushed to, conduct hazard assessments only. While this enabled the institution to define its perimeter, it also condemned it to remaining distant from regulatory decisions. A striking example of this institutional pressure occurred during the 1980s, when the National Cancer Institute (NCI) responded to the IARC’s risk assessment of benzene by writing to Tomatis, the head of the IARC Monographs programme, stating that “risk is an area that also involves national policy decisions and is fraught with scientific and societal difficulties”. The NCI representative said to Tomatis that the IARC should “avoid going into the area of risk assessment” and made it clear that “no change in policy should be made as a result of a unilateral decision” by him (pp. 121-122);

4. This transnational competition has produced many methods of hazard or risk assessment, some of which are more preventive than others.3 The proliferation of hazard assessment methods inspired by the IARC’s classification worldwide has led to the development of various approaches as well. Numerous institutions are mentioned throughout the book, including the National Toxicology Program, the NCI, the Occupational Safety and Health Administration, the Environmental Protection Agency  and the European institutions – just to mention a few.

Overall, the book unveils the creation of a transnational system for controlling carcinogens consisting of interdependent institutions competing to identify and regulate chemicals. When it comes to such public health and regulatory institutions, it is important to bear in mind that they were not set up to oppose the chemical industry.4

They were designed to monitor the adverse health effects of industrial activity and help regulate them. They were also used to create common regulatory categories that facilitate the use and circulation of products within and between markets. This is why, for example, the European administration contacted the Monographs secretariat in its efforts to create a harmonised definition of a carcinogenic agent. In this context, industries were not the enemy, but normal participants and interlocutors. The Monographs Programme was no exception. For example, Tomatis wrote, at the beginning of the 1970s, that unnecessarily withdrawing substances from the market could cause significant damage and should only be considered legitimate if there is precise information on existing risks (p. 124). During the same period, one of his direct colleagues provided scientific material to the Polyurethane Manufacturers Association when they wanted to contest occupational health norms in the United States (p. 92). As described in the book, the programme then changed its relationship with private firms, but this has been a conflict-ridden and contingent history (pp. 90-96).

For decades, the IARC and other institutions have established norms and standards for evaluating the value of different types of study.5 In a sense, these norms are the official rules of this transnational, tension-inducing game. They make it possible to anticipate the moves of others and the potential outcomes of an assessment to a certain extent. As key players, past and current IARC members understand this process well. They can predict the direction in which an evaluation might go, based on the available data in the field. I used online publicly available documents to illustrate this actually normal and common institutional work, there is no confidentiality in this (pp. 76-78). For this reason, the estimates of these highly rigorous professionals are of interest: they are not secrets, but rather the result of the field and its institutional history. 

More broadly, this global history is rooted in conflict and power dynamics. What is at stake is the identification of carcinogens and the definition of carcinogenicity. There are more than 350,000 chemicals in circulation worldwide.6 Overcoming numerous and significant challenges, IARC has managed to assess about a thousand of those, adding fewer and fewer agents to its list and often concluding that it is impossible to draw conclusions (p. 58). This is where the notion of ‘production of ignorance’, as used in the book and in a large literature, comes in (pp. 12-14).7 It can address the structural, material, institutional, and symbolic constraints affecting the work of institutions in identifying toxic substances. It is not necessarily about individual intentions or lack of effort, as the IARC and the other expert committees responsible for assessing carcinogenicity are staffed by dedicated scientists.

The social sciences are not normative sciences. My research made no room for enthusiasm, regret or opinion regarding what IARC or other institutions should or should not do. My only hope is that this work will encourage further reflection on how to improve the efficiency of the global system for controlling carcinogens. 

References

Frickel S. Chemical Consequences: Environmental Mutagens, Scientist Activism, and the Rise of Genetic Toxicology. New Brunswick: Rutgers University Press; 2004.

Jas N, Boudia S (eds). Toxicants, Health and Regulation since 1945. London: Pickering & Chatto; 2013.

Rushefsky ME. Making Cancer Policy. Albany: State University of New York Press; 1986.

Hepler-Smith E. Molecular Bureaucracy: Toxicological Information and Environmental Protection. Environmental History 2019;24(3): 534-60

Demortain D. The Science of Bureaucracy: Risk Decision-Making and the US Environmental Protection Agency. Cambridge: The MIT Press; 2020.

Wang Z, Walker GW, Muir DCG, Nagatani-Yoshida K. Toward a Global Understanding of Chemical Pollution: A first Comprehensive Analysis of National and Regional Chemical Inventories. Environ Sci Tech 2020;54(5):2575-84.

Henry E, Thomas V, Angeli Aguiton S, Déplaude MO, Jas N. Introduction: Beyond the Production of Ignorance: The Pervasiveness of Industry Influence through the Tools of Chemical Regulation. Sci Technol Human Values 2021;46(5):911-24.

 

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