Hadi Rahimzadeh1, Benyamin Hoseini2,3, Behzad Kiani4, Fatemeh Hashemi Amin4, Nasser Bagheri5, Robert Bergquist6, Ali Akbar Mohammadi7, Mahmood Yousefi8, Hossein Faraji9, Gholamreza Roshandel10, Somayeh Beirami11. 1. Department of Environmental Health Engineering, Faculty of Health and Environmental Health Research Center, Golestan University of Medical Sciences, Gorgan, Iran. Hadi_rahimzadeh@yahoo.com. 2. Pharmaceutical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. HoseiniB1@nums.ac.ir. 3. Department of Health Information Technology, Neyshabur University of Medical Sciences, Neyshabur, Iran. HoseiniB1@nums.ac.ir. 4. Department of Medical Informatics, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. 5. Visualization and Decision Analytics (VIDEA) lab, Centre for Mental Health Research, Research School of Population Health, College of Health and Medicine, The Australian National University, Canberra, Australia. 6. Ingerod, Brastad, Sweden (formerly with the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, World Health Organization), Geneva, Switzerland. 7. Department of Environmental Health Engineering, Neyshabur University of Medical Sciences, Neyshabur, Iran. 8. Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran. 9. Department of Environmental Health Engineering, Health Center, Babol University of Medical Sciences, Babol, Iran. 10. Golestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Gorgan, Iran. 11. Department of Environmental Health Engineering, Faculty of Health and Environmental Health Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
Abstract
BACKGROUND: Colorectal cancer has increased in Middle Eastern countries and exposure to environmental pollutants such as heavy metals has been implicated. However, data linking them to this disease are generally lacking. This study aimed to explore the spatial pattern of age-standardized incidence rate (ASR) of colon cancer and its potential association with the exposure level of the amount of heavy metals existing in rice produced in north-eastern Iran. METHODS: Cancer data were drawn from the Iranian population-based cancer registry of Golestan Province, north-eastern Iran. Samples of 69 rice milling factories were analysed for the concentration levels of cadmium, nickel, cobalt, copper, selenium, lead and zinc. The inverse distance weighting (IDW) algorithm was used to interpolate the concentration of this kind of heavy metals on the surface of the study area. Exploratory regression analysis was conducted to build ordinary least squares (OLS) models including every possible combination of the candidate explanatory variables and chose the most useful ones to show the association between heavy metals and the ASR of colon cancer. RESULTS: The highest concentrations of heavy metals were found in the central part of the province and particularly counties with higher amount of cobalt were shown to be associated with higher ASR of men with colon cancer. In contrast, selenium concentrations were higher in areas with lower ASR of colon cancer in men. A significant regression equation for men with colon cancer was found (F(4,137) = 38.304, P < .000) with an adjusted R2 of 0.77. The predicted ASR of men colon cancer was - 58.36 with the coefficients for cobalt = 120.33; cadmium = 80.60; selenium = - 6.07; nickel = - 3.09; and zinc = - 0.41. The association of copper and lead with colon cancer in men was not significant. We did not find a significant outcome for colon cancer in women. CONCLUSION: Increased amounts of heavy metals in consumed rice may impact colon cancer incidence, both positively and negatively. While there were indications of an association between high cobalt concentrations and an increased risk for colon cancer, we found that high selenium concentrations might instead decrease the risk. Further investigations are needed to clarify if there are ecological or other reasons for these discrepancies. Regular monitoring of the amount of heavy metals in consumed rice is recommended.
BACKGROUND:Colorectal cancer has increased in Middle Eastern countries and exposure to environmental pollutants such as heavy metals has been implicated. However, data linking them to this disease are generally lacking. This study aimed to explore the spatial pattern of age-standardized incidence rate (ASR) of colon cancer and its potential association with the exposure level of the amount of heavy metals existing in rice produced in north-eastern Iran. METHODS:Cancer data were drawn from the Iranian population-based cancer registry of Golestan Province, north-eastern Iran. Samples of 69 rice milling factories were analysed for the concentration levels of cadmium, nickel, cobalt, copper, selenium, lead and zinc. The inverse distance weighting (IDW) algorithm was used to interpolate the concentration of this kind of heavy metals on the surface of the study area. Exploratory regression analysis was conducted to build ordinary least squares (OLS) models including every possible combination of the candidate explanatory variables and chose the most useful ones to show the association between heavy metals and the ASR of colon cancer. RESULTS: The highest concentrations of heavy metals were found in the central part of the province and particularly counties with higher amount of cobalt were shown to be associated with higher ASR of men with colon cancer. In contrast, selenium concentrations were higher in areas with lower ASR of colon cancer in men. A significant regression equation for men with colon cancer was found (F(4,137) = 38.304, P < .000) with an adjusted R2 of 0.77. The predicted ASR of mencolon cancer was - 58.36 with the coefficients for cobalt = 120.33; cadmium = 80.60; selenium = - 6.07; nickel = - 3.09; and zinc = - 0.41. The association of copper and lead with colon cancer in men was not significant. We did not find a significant outcome for colon cancer in women. CONCLUSION: Increased amounts of heavy metals in consumed rice may impact colon cancer incidence, both positively and negatively. While there were indications of an association between high cobalt concentrations and an increased risk for colon cancer, we found that high selenium concentrations might instead decrease the risk. Further investigations are needed to clarify if there are ecological or other reasons for these discrepancies. Regular monitoring of the amount of heavy metals in consumed rice is recommended.
Entities:
Keywords:
Colon cancer; Geographical information systems; Golestan; Heavy metals; Iran; Ordinary least square; Regression model; Spatial analysis; Trace elements
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