Iranian Researchers Present Strong Evidence Showing Link between Household Fuel Use and GI Cancers

Sunday, June 21, 2020 - 11:40

Iranian researchers have investigated the relationship between indoor burning of biomass, kerosene, and natural gas with the subsequent risk of gastrointestinal (GI) cancers.

According to an ISCA report, an estimated 3 billion people still cook and heat their homes using open fires or leaky stoves fueled by kerosene, biomass, or coal (WHO 2018). Combustion of these fuels produces multiple carcinogenic compounds that can be absorbed through the respiratory and digestive tracts.

Based on the research, the International Agency for Research on Cancer (IARC) has recognized indoor emissions from coal combustion as carcinogenic to humans (Group 1), based on sufficient evidence from human and animal studies that documented the increased lung cancer risk resulting from indoor coal burning (IARC Working Group on the Evaluation of Carcinogenic Risks to Humans 2010).

However, despite the widespread use of biomass and kerosene fuels involving almost 40% of the human population, there is inadequate information on these exposures and their carcinogenicity.

According to the study, “during the period 2004–2008, a total of 50,045 Iranian individuals 40–75 years of age were recruited to this prospective population-based cohort. Upon enrollment, validated data were collected on demographics, lifestyle, and exposures, including detailed data on lifetime household use of different fuels and stoves. The participants were followed through August 2018 with <1% loss.”

“During the follow-up, 962 participants developed GI cancers. In comparison with using predominantly gas in the recent 20-y period, using predominantly biomass was associated with higher risks of esophageal [hazard ratio (HR): 1.89; 95% confidence interval (CI): 1.02, 3.50], and gastric HR: 1.83; 95% CI: 1.01, 3.31) cancers, whereas using predominantly kerosene was associated with higher risk of esophageal cancer (HR: 1.84; 95% CI: 1.10, 3.10).

“Lifetime duration of biomass burning for both cooking and house heating (exclusive biomass usage) using heating-stoves without chimney was associated with higher risk of GI cancers combined (10-y HR: 1.14; 95% CI: 1.07, 1.21), esophageal (10-y HR: 1.19; 95% CI: 1.08, 1.30), gastric (10-y HR: 1.11; 95% CI: 1.00, 1.23), and colon (10-y HR: 1.26; 95% CI: 1.03, 1.54) cancers.

“The risks of GI cancers combined, esophageal cancer, and gastric cancer were lower when biomass was burned using chimney-equipped heating-stoves (strata difference p-values=0.001, 0.003, and 0.094, respectively). Duration of exclusive kerosene burning using heating-stoves without chimney was associated with higher risk of GI cancers combined (10-y HR: 1.05; 95% CI: 1.00, 1.11), and esophageal cancer (10-y HR: 1.14; 95% CI: 1.04, 1.26).”

The result of the research, which has been published in Environmental Health Perspectives, reveals that “household burning of biomass or kerosene, especially without a chimney, was associated with higher risk of some digestive cancers. Using chimney-equipped stoves and replacing these fuels with natural gas may be useful interventions to reduce the burden of GI cancers worldwide.”

The research “Household Fuel Use and the Risk of Gastrointestinal Cancers: The Golestan Cohort Study” has been carried out by Mahdi Sheikh, Hossein Poustchi, Akram Pourshams, Masoud Khoshnia, Abdolsamad Gharavi, Mahdi Zahedi, Gholamreza Roshandel, Sadaf G. Sepanlou, Abdolreza Fazel, Maryam Hashemian, Behrooz Abaei, Masoud Sotoudeh, Arash Nikmanesh, Shahin Merat, Arash Etemadi, Siavosh Nasseri Moghaddam, Farhad Islami, Farin Kamangar, Paul D. Pharoah, Sanford M. Dawsey, Christian C. Abnet, Paolo Boffetta, Paul Brennan and Reza Malekzade.

This work was funded by the World Cancer Research Fund International (grant: WCRF 2016/1633, funding for this grant was obtained from Wereld Kanker Onderzoek Fonds (WKOF), as part of the World Cancer Research Fund International grant programme); Tehran University of Medical Sciences (grant: 81/15); Cancer Research UK (grant: C20/A5860); the Intramural Research Program of the U.S. National Cancer Institute, National Institutes of Health; and the IARC. The authors thank A. Feiz Sani and R. Shakeri from the Digestive Disease Research Institute of the Tehran University of Medical Sciences; the Golestan Cohort Study Center staff; the local health networks and health workers in the study area; and the Golestan University of Medical Sciences for their assistance and support.

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