1 research outputs found
Association between heavy metals and colon cancer: an ecological study based on geographical information systems in North-Eastern Iran
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, northeastern 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 β 58.36 with the coefficients for cobalt = 120.33; cadmium = 80.60;
selenium = β 6.07; nickel = β 3.09; and zinc = β 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.This study was supported by Golestan University of Medical Sciences (grant
number of 90β10β1-30209)