[Study on the ecological association between natural radioactivity and childhood leukemia in Guangdong province].

Objective: This study was undertaken to evaluate the ecological association between terrestrial natural radionuclide, indoor radon concentration, natural radioactivity and leukemia incidence among children under 18 years of age.

Methods: Data were gathered from the disease surveillance program and literature reading while software SPSS 13.0 was used to calculate the Spearman's correlation.

Results: The incidence rates of childhood (0-18 year) leukemia showed significant differences in different places with the highest as 3.13/10(5) in Jiangmen area and the lowest as 0.42/10(5) in Maoming area. The incidence in Jiangmen was 7.45 times higher than that in Maoming. There was a rank correlation between the incidence of childhood leukemia and the mean concentrations of natural radio-nuclides in soil (226Ra and 232Th), with a positive correlation observed for overall leukemia (r(s) = 0.70, P = 0.011; r(s) = 0.66, P= 0.02 for 226 Ra and 232Th respectively) and acute lymphoblastic leukemia (ALL) (r(s) = 0.66, P = 0.019; r(s) = 0.64, P = 0.025 for 226 Ra and 232Th respectively). Associations between the incidence of childhood leukemia and the indoor gamma radiation dose rate, the total annual average effective dose equivalent from natural background radiationwere also analyzed (both r(s) = 0.59, P = 0.042).

Conclusion: The natural radioactivity was likely to be a causative factor for childhood leukemia in Guangdong.