Childhood exposures to Rn-222 and background gamma radiation in the uranium provinces of south Kazakhstan and northern Kyrgyzstan

The project was undertaken in southern Kazakhstan and Kyrgyzstan. It was speculated that the radiation doses in these areas would be sufficiently high and dispersed to facilitate a case–control study where the radiation doses to leukaemia subjects/their siblings could be compared with those received by control children. As a precursor a pilot project was undertaken to confirm radiation exposures in the region. This was undertaken in association with regional childhood cancer treatment centres. Children from families affected by childhood leukaemia were monitored for 1 month for external γ-radiation dose and for exposure to radon gas. 28 children from families in Kazakhstan and from 31 families in Kyrgyzstan were monitored. The median measured radon in air concentration recorded in Kazakhstan was 123 Bq m−3 and in Kyrgyzstan was 177 Bq m−3. These represent 24-h average indoor/outdoor values. In the case of the γ-doses the mean annual dose was 1.2 mGy for Kazakhstan and 2.1 mGy for Kyrgyzstan. Overall, the results suggest that the populations studied receive similar annual radiation doses to those received by populations living in other areas with enhanced natural radioactivity and that further study of Kazakh and Kyrgyz populations would not facilitate a successful case–control study for childhood leukaemia.