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BackgroundRecently, the International Agency for Research on Cancer (IARC) Programme for the Evaluation of Carcinogenic Risks to Humans has been criticized for several of its evaluations, and also for the approach used to perform these evaluations. Some critics have claimed that failures of IARC Working Groups to recognize study weaknesses and biases of Working Group members have led to inappropriate classification of a number of agents as carcinogenic to humans.ObjectivesThe authors of this Commentary are scientists from various disciplines relevant to the identification and hazard evaluation of human carcinogens. We examined criticisms of the IARC classification process to determine the validity of these concerns. Here, we present the results of that examination, review the history of IARC evaluations, and describe how the IARC evaluations are performed.DiscussionWe concluded that these recent criticisms are unconvincing. The procedures employed by IARC to assemble Working Groups of scientists from the various disciplines and the techniques followed to review the literature and perform hazard assessment of various agents provide a balanced evaluation and an appropriate indication of the weight of the evidence. Some disagreement by individual scientists to some evaluations is not evidence of process failure. The review process has been modified over time and will undoubtedly be altered in the future to improve the process. Any process can in theory be improved, and we would support continued review and improvement of the IARC processes. This does not mean, however, that the current procedures are flawed.ConclusionsThe IARC Monographs have made, and continue to make, major contributions to the scientific underpinning for societal actions to improve the public's health.

Objectives To investigate the association between occupational lifting and the risk of rhegmatogenous retinal detachment (RRD) using data from a large population of men. Methods We used data from a national cohort of 49 321 Swedish men conscripted for compulsory military service in 1969–1970. We collected information on surgically treated RRD from the National Patient Register and we followed up the cohort between 1991 and 2009 at ages 40–60 years. Exposure to occupational lifting was assessed by applying a job exposure matrix to occupational data from the 1990 census. Incidence rate ratios (IRRs) and 95% CIs were estimated through Poisson regression models adjusted by degree of myopia, income and education level. Results We observed 217 cases of RRD in 7 80 166 person-years. In univariate analyses we did not observe an association between occupational lifting and RRD. However, after adjustment for myopia and socioeconomic factors, we found an increased risk of RRD (IRR 2.38, 95% CI 1.15 to 4.93) for subjects in the highest category of exposure compared with those in the lowest one. The incidence rate of RRD among subjects lifting heavy loads at least twice per week, aged between 50 years and 59 years, and affected by severe myopia was as high as 7.9 cases per 1000 person-years, compared with an overall rate of 0.28. Conclusions Our study supports the hypothesis that heavy occupational lifting is a risk factor for RRD. Information on myopia degree and socioeconomic status is necessary when studying the association between occupational lifting and RRD.

Background We aimed to investigate the role of vascular risk factors in the genesis of rhegmatogenous retinal detachment (RRD) using data from a large cohort of Swedish conscripts. Methods We used data from a nationwide cohort of 49 321 Swedish men born during 1949–1951, conscripted for compulsory military service in 1969–1970 with nearly complete follow-up to 2009. Information on surgically treated RRD between 1973 and 2009 was collected from the National Patient Register. We fitted Cox regression models stratified on myopia degree and including blood pressure levels, body mass index and cigarette smoking. Population attributable fractions of RRD were estimated through maximum likelihood methods. Results We observed 262 cases of RRD in 1 725 770 person-years. At multivariate analysis, the number of cigarettes per day showed a reverse association with the risk of RRD (p for trend 0.01). Conscripts with obesity presented a higher risk compared with normal subjects (adjusted HR 2.51, 95% CI 1.02 to 6.13). We found weak evidence of an association between blood pressure and RRD (HR for men with hypertension compared with normotension 1.41, 95% CI 0.93 to 2.13). All the observed associations were stronger when the analysis was restricted to non-myopic conscripts. In particular, the HR for hypertension was 2.33 (95% CI 1.30 to 4.19) compared with normotension. If this association is causal, we estimated that 42.0% of RRD cases (95% CI 11.5% to 62.0%) occurring among non-myopics are attributable to elevated blood pressure. Conclusions Vascular risk factors may be important determinants of RRD, particularly among non-myopics. Further investigations on the role of hypertension and obesity are needed.