Childhood leukaemia in Belarus, Russia, and Ukraine following the Chernobyl power station accident: results from an international collaborative population-based case-control study.

BACKGROUND: There is little evidence regarding the risk of leukaemia in children following exposure to radionuclides from the Chernobyl Nuclear Power Plant explosion on April 26, 1986. METHODS: This population-based case-control study investigated whether acute leukaemia is increased among children who were in utero or <6 years of age at the time of the Chernobyl accident. Confirmed cases of leukaemia diagnosed from April 26, 1986 through December 31, 2000 in contaminated regions of Belarus, Russia, and Ukraine were included. Two controls were matched to each case on sex, birth year, and residence. Accumulated absorbed radiation dose to the bone marrow was estimated for each subject. RESULTS: Median estimated radiation doses of participants were <10 mGy. A significant increase in leukaemia risk with increasing radiation dose to the bone marrow was found. This association was most evident in Ukraine, apparent (but not statistically significant) in Belarus, and not found in Russia. CONCLUSION: Taken at face value, these findings suggest that prolonged exposure to very low radiation doses may increase leukaemia risk as much as or even more than acute exposure. However the large and statistically significant dose-response might be accounted for, at least in part, by an overestimate of risk in Ukraine. Therefore, we conclude this study provides no convincing evidence of an increased risk of childhood leukaemia as a result of exposure to Chernobyl radiation, since it is unclear whether the results are due to a true radiation-related excess, a sampling-derived bias in Ukraine, or some combination thereof. However, the lack of significant dose-responses in Belarus and Russia also cannot convincingly rule out the possibility of an increase in leukaemia risk at low dose levels.

Children's perceptions of smokers and nonsmokers: a longitudinal study.

In a longitudinal study we investigated 5th- and 7th-grade children's perceptions of smokers and nonsmokers, changes in perceptions from 5th to 7th grades, and the degree to which these perceptions predict smoking in 9th grade. The participants were 1,663 students from 14 school districts in Washington state. The results showed large developmental shifts from 5th to 7th grade in children's perceptions of both smokers and nonsmokers: Students at 7th grade saw smokers in a much more positive light and nonsmokers in a much more negative light than they did at 5th grade. Children's positive perceptions at 5th grade of smokers predicted smoking 4 years later at 9th grade and were stronger predictors than positive perceptions at 7th grade. The results suggest that smoking prevention interventions must begin before 5th grade to counter perceptions predictive of subsequent smoking.