Concept: International Agency for Research on Cancer
The International Agency for Research on Cancer convened a workshop on the relationship between body fatness and cancer, from which an IARC handbook on the topic will appear. An executive summary of the evidence is presented.
Glyphosate is the most commonly used herbicide worldwide, with both residential and agricultural uses. In 2015, the International Agency for Research on Cancer classified glyphosate as “probably carcinogenic to humans,” noting strong mechanistic evidence and positive associations for non-Hodgkin lymphoma (NHL) in some epidemiologic studies. A previous evaluation in the Agricultural Health Study (AHS) with follow-up through 2001 found no statistically significant associations with glyphosate use and cancer at any site.
In November 2014, experts from 16 countries met at the International Agency for Research on Cancer (IARC) to assess the cancer-preventive and adverse effects of different methods of screening for breast cancer. (The members of the working group for volume 15 of the IARC Handbook are listed at the end of the article; affiliations are provided in the Supplementary Appendix, available with the full text of this article at NEJM.org.) This update of the 2002 IARC handbook on breast-cancer screening(1) is timely for several reasons. Recent improvements in treatment outcomes for late-stage breast cancer and concerns regarding overdiagnosis call for reconsideration. . . .
The present paper scrutinises the European authorities' assessment of the carcinogenic hazard posed by glyphosate based on Regulation (EC) 1272/2008. We use the authorities' own criteria as a benchmark to analyse their weight of evidence (WoE) approach. Therefore, our analysis goes beyond the comparison of the assessments made by the European Food Safety Authority and the International Agency for Research on Cancer published by others. We show that not classifying glyphosate as a carcinogen by the European authorities, including the European Chemicals Agency, appears to be not consistent with, and in some instances, a direct violation of the applicable guidance and guideline documents. In particular, we criticise an arbitrary attenuation by the authorities of the power of statistical analyses; their disregard of existing dose-response relationships; their unjustified claim that the doses used in the mouse carcinogenicity studies were too high and their contention that the carcinogenic effects were not reproducible by focusing on quantitative and neglecting qualitative reproducibility. Further aspects incorrectly used were historical control data, multisite responses and progression of lesions to malignancy. Contrary to the authorities' evaluations, proper application of statistical methods and WoE criteria inevitably leads to the conclusion that glyphosate is ‘probably carcinogenic’ (corresponding to category 1B in the European Union).
Classification schemes for carcinogenicity based solely on hazard-identification such as the IARC monograph process and the UN system adopted in the EU have become outmoded. They are based on a concept developed in the 1970s that chemicals could be divided into two classes: carcinogens and non-carcinogens. Categorization in this way places into the same category chemicals and agents with widely differing potencies and modes of action. This is how eating processed meat can fall into the same category as sulfur mustard gas. Approaches based on hazard and risk characterization present an integrated and balanced picture of hazard, dose response and exposure and allow informed risk management decisions to be taken. Because a risk-based decision framework fully considers hazard in the context of dose, potency, and exposure the unintended downsides of a hazard only approach are avoided, e.g., health scares, unnecessary economic costs, loss of beneficial products, adoption of strategies with greater health costs, and the diversion of public funds into unnecessary research. An initiative to agree upon a standardized, internationally acceptable methodology for carcinogen assessment is needed now. The approach should incorporate principles and concepts of existing international consensus-based frameworks including the WHO IPCS mode of action framework.
Glyphosate is the most widely used herbicide worldwide. It is a broad spectrum herbicide and its agricultural uses increased considerably after the development of glyphosate-resistant genetically modified (GM) varieties. Since glyphosate was introduced in 1974, all regulatory assessments have established that glyphosate has low hazard potential to mammals, however, the International Agency for Research on Cancer (IARC) concluded in March 2015 that it is probably carcinogenic. The IARC conclusion was not confirmed by the EU assessment or the recent joint WHO/FAO evaluation, both using additional evidence. Glyphosate is not the first topic of disagreement between IARC and regulatory evaluations, but has received greater attention. This review presents the scientific basis of the glyphosate health assessment conducted within the European Union (EU) renewal process, and explains the differences in the carcinogenicity assessment with IARC. Use of different data sets, particularly on long-term toxicity/carcinogenicity in rodents, could partially explain the divergent views; but methodological differences in the evaluation of the available evidence have been identified. The EU assessment did not identify a carcinogenicity hazard, revised the toxicological profile proposing new toxicological reference values, and conducted a risk assessment for some representatives uses. Two complementary exposure assessments, human-biomonitoring and food-residues-monitoring, suggests that actual exposure levels are below these reference values and do not represent a public concern.
The widespread distribution of unconventional oil and gas (UO&G) wells and other facilities in the United States potentially exposes millions of people to air and water pollutants, including known or suspected carcinogens. Childhood leukemia is a particular concern because of the disease severity, vulnerable population, and short disease latency. A comprehensive review of carcinogens and leukemogens associated with UO&G development is not available and could inform future exposure monitoring studies and human health assessments. The objective of this analysis was to assess the evidence of carcinogenicity of water contaminants and air pollutants related to UO&G development. We obtained a list of 1177 chemicals in hydraulic fracturing fluids and wastewater from the U.S. Environmental Protection Agency and constructed a list of 143 UO&G-related air pollutants through a review of scientific papers published through 2015 using PubMed and ProQuest databases. We assessed carcinogenicity and evidence of increased risk for leukemia/lymphoma of these chemicals using International Agency for Research on Cancer (IARC) monographs. The majority of compounds (>80%) were not evaluated by IARC and therefore could not be reviewed. Of the 111 potential water contaminants and 29 potential air pollutants evaluated by IARC (119 unique compounds), 49 water and 20 air pollutants were known, probable, or possible human carcinogens (55 unique compounds). A total of 17 water and 11 air pollutants (20 unique compounds) had evidence of increased risk for leukemia/lymphoma, including benzene, 1,3-butadiene, cadmium, diesel exhaust, and several polycyclic aromatic hydrocarbons. Though information on the carcinogenicity of compounds associated with UO&G development was limited, our assessment identified 20 known or suspected carcinogens that could be measured in future studies to advance exposure and risk assessments of cancer-causing agents. Our findings support the need for investigation into the relationship between UO&G development and risk of cancer in general and childhood leukemia in particular.
Circadian rhythms show universally a 24-h oscillation pattern in metabolic, physiological and behavioral functions of almost all species. This pattern is due to a fundamental adaptation to the rotation of Earth around its own axis. Molecular mechanisms of generation of circadian rhythms organize a biochemical network in suprachiasmatic nucleus and peripheral tissues, building cell autonomous clock pacemakers. Rhythmicity is observed in transcriptional expression of a wide range of clock-controlled genes that regulate a variety of normal cell functions, such as cell division and proliferation. Desynchrony of this rhythmicity seems to be implicated in several pathologic conditions, including tumorigenesis and progression of cancer. In 2007, the International Agency for Research on Cancer (IARC) categorized “shiftwork that involves circadian disruption [as] probably carcinogenic to humans” (Group 2A in the IARC classification system of carcinogenic potency of an agentagent) (Painting, Firefighting, and Shiftwork; IARC; 2007). This review discusses the potential relation between disruptions of normal circadian rhythms with genetic driving machinery of cancer. Elucidation of the role of clockwork disruption, such as exposure to light at night and sleep disruption, in cancer biology could be important in developing new targeted anticancer therapies, optimizing individualized chronotherapy and modifying lighting environment in workplaces or homes.
Radiofrequency radiation in the frequency range 30 kHz-300 GHz was evaluated to be Group 2B, i.e. ‘possibly’ carcinogenic to humans, by the International Agency for Research on Cancer (IARC) at WHO in May 2011. Among the evaluated devices were mobile and cordless phones, since they emit radiofrequency electromagnetic fields (RF-EMF). In addition to the brain, another organ, the thyroid gland, also receives high exposure. The incidence of thyroid cancer is increasing in many countries, especially the papillary type that is the most radiosensitive type.
Cancer remains the second leading cause of death in the United States, and the number of cases is expected to continue to rise worldwide. Cancer prevention strategies are crucial for reducing the cancer burden. The carcinogenic potential of dietary acrylamide exposure from cooked foods is unknown. Acrylamide is a by-product of the common Maillard reaction where reducing sugars (i.e., fructose and glucose) react with the amino acid, asparagine. Based on the evidence of acrylamide carcinogenicity in animals, the International Agency for Research on Cancer has classified acrylamide as a group 2A carcinogen for humans. Since the discovery of acrylamide in foods in 2002, a number of studies have explored its potential as a human carcinogen. This article outlines a systematic review of dietary acrylamide and human cancer, acrylamide exposure and internal dose, exposure assessment methods in the epidemiologic studies, existing data gaps, and future directions. A majority of the studies reported no statistically significant association between dietary acrylamide intake and various cancers, and few studies reported increased risk for renal, endometrial, and ovarian cancers; however, the exposure assessment has been inadequate leading to potential misclassification or underestimation of exposure. Future studies with improved dietary acrylamide exposure assessment are encouraged.