On June 1, 2015 the peer-reviewed journal Carcinogenesis published a supplement issue on “Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead”. In a series of 11 reviews and one summary paper, 174 international scientists report on the Halifax Project Task Force’s findings how everyday chemicals, present at low levels in the human environment including food, can lead to malignant cancers. A total of 85 chemicals not considered carcinogenic to humans were investigated during two years in a project initiated by the non-profit group Getting to Know Cancer.
The Halifax Project scientists applied a novel approach, using the Hallmarks of Cancer conceptual framework which describes on a molecular level how normal human cells transition into malignant cancer cells (Hanahan and Weinberg 2000, 2011). These different “rules” include for example evasion of growth suppression, cell immortality, sustained proliferative signaling, and tissue invasion and metastasis. Different chemicals can affect various steps of cancer formation, and when present together in a mixture or ‘cocktail’, their concerted action on different Hallmarks of Cancer can lead to the malignant disease, according to scientist William H. Goodson III and colleagues. Therefore, understanding how individual chemicals contribute on a molecular level to the intrinsically complex process of cancer formation can help with assessing chemical safety and preventing cancer from developing at all. Notably, 59% of the investigated 85 chemicals showed no evidence for a threshold, while 15% did. For the remainder (26%), no dose information was available. Several of the substances are also present in food contact materials, like phthalates and bisphenol A.
“The relative contribution of the environment, genetic susceptibility and DNA replication errors to cancer causation has been a longstanding area of investigation in the fields of molecular epidemiology of cancer and carcinogenesis”, writes Curtis C. Harris, Editor-in-Chief of Carcinogenesis. The novel approach outlined and applied by the Halifax Project can be instrumental in improving understanding of how large the contribution of everyday (environmental) chemicals at low doses actually is on the development of cancer.
The primary recommendation of the Halifax Project Task Force is focused on research and regulatory risk assessment practices worldwide: using their novel approach, priority mixtures of (non-carcinogenic) chemicals can be identified that have substantial carcinogenic relevance. This information can then be utilized in the development of new regulatory strategies focusing on primary cancer prevention.
Read more
Australian Associated Press (June 23, 2015). “Exposure to mixture of common chemicals may trigger cancer, scientists find.” The Guardian
Jamie Morton (June 23, 2015). “Cancer threat from everyday chemicals.” New Zealand Herald
Gail Wells (July 20, 2015). “Common chemicals may act together to increase cancer risk, study finds.” Oregon State University
References
Brooks Robey, R. et al. (2015). “Metabolic reprogramming and dysregulated metabolism: cause, consequence and/or enabler of environmental carcinogenesis?” Carcinogenesis, 36(Suppl 1), S203-S231.
Carnero, A. et al. (2015). “Disruptive chemicals, senescence and immortality.” Carcinogenesis, 36(Suppl 1), S19-S37.
Casey, S. C. et al. (2015). “The effect of environmental chemicals on the tumor microenvironment.” Carcinogenesis, 36(Suppl 1), S160-S183.
Engström, W. et al. (2015). “The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling.” Carcinogenesis, 36(Suppl 1), S38-S60.
Goodson, W. H. et al. (2015). “Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead.” Carcinogenesis, 36(Suppl 1), S254-S296.
Hanahan, D. and R. A. Weinberg (2000). “The hallmarks of cancer.” Cell 100(1): 57-70.
Hanahan, D. and R. A. Weinberg (2011). “Hallmarks of cancer: the next generation.” Cell 144(5): 646-674.
Harris, C. C. (2015). “Cause and Prevention of Human Cancer.” Carcinogenesis, 36(Suppl 1), S1. doi: 10.1093/carcin/bgv047
Hu, Z. et al. (2015). “Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: focus on the cancer hallmark of tumor angiogenesis.” Carcinogenesis, 36(Suppl 1), S184-S202.
Kravchenko, J. et al. (2015). “Chemical compounds from anthropogenic environment and immune evasion mechanisms: potential interactions.” Carcinogenesis, 36(Suppl 1), S111-S127.
Langie, S. A. S. et al. (2015). “Causes of genome instability: the effect of low dose chemical exposures in modern society.” Carcinogenesis, 36(Suppl 1), S61-S88.
Nahta, R. et al. (2015). “Mechanisms of environmental chemicals that enable the cancer hallmark of evasion of growth suppression.” Carcinogenesis, 36(Suppl 1), S2-S18.
Narayanan, K. B. Et al. (2015). “Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death.” Carcinogenesis, 36(Suppl 1), S89-S110.
Ochieng, J. et al. (2015). “The impact of low-dose carcinogens and environmental disruptors on tissue invasion and metastasis.” Carcinogenesis, 36(Suppl 1), S128-S159.
Thompson, P. A. et al. (2015). ”Environmental immune disruptors, inflammation and cancer risk.” Carcinogenesis, 36(Suppl 1), S232-S253.
