Etude préliminaire des concentrations du radon-222 (222rn) et de l’évaluation du risque de cancer du poumon dans les habitations: le cas d'Ebolowa, région du Sud-Cameroun

Abstract

This work presents the study of exposure to radon-222 and the assessment of the risk of lung cancer in different dwellings in the city of Ebolowa, region of southern Cameroon.Measurements of radon-222 concentrations in these dwellings were carried out using radon trace detectors (RADTRACK2), which are detectors by chemical etching, consisting of a CR-39 plastic film (PADC) contained in a support antistatic in closed configuration. Radon concentrations in homes ranged from 23 to 2620 Bq m−3 with an arithmetic mean (AM) of 135.06 Bqm−3 and a geometric mean (GM) of 63 Bqm−3. These averages were higher than 40Bqm−3 and 30 Bqm−3 which are respectively theAMand theGMgiven by UNSCEAR 2000.By comparing the AM value to the values of theWorld Health Organization (WHO) and the International Commission on Radiological Protection (ICRP), it proved to be higher than the reference value of 100 Bq m−3 given by the WHO but remained below 300 Bq m−3 which is the reference value given by the ICRP. The ambient doses inside and outside the dwellings were between 0.15 and 0.38 mSv year−1 with an average of 0.26 mSv year−1. The annual effective doses in homes due to the inhalation of radon were between 0.43 mSv year−1 and 49.6 mSv year−1. The corresponding arithmetic mean of these doses was 2.6 mSv an−1. This average value revealed that the annual effective dose values in the homes of Ebolowa were generally lower than 3-10 mSv an−1 which are the action levels recommended by the WHO and the ICRP respectively. The Excess Lifetime Cancer Risk of lung cancer (ELCR) ranged from 1.39 % to 158% with a mean value of 8.2% which was approximately 6 times greater than 1.33% which is the reference value given by the United State Environmental Protection Agency (USEPA) . According to these results, the existence of a risk of lung cancer due to the inhalation of radon-222 during exposure to low doses of radiation should be studied in the population of the town of Ebolowa.