Radiological Quality and Dangerousness of Ferrous and Non-ferrous Metals Waste in Cotonou (Benin)

Abstract

The peoples in Cotonou give themselves to sorting and recycling activities of scrap metal for lack of financial means. The uncontrolled use of this scrap metal has effects on the health of users (waste pickers, sorters, recyclers …). It was to assess the radiological quality and the degrees of dangerousness of this scrap metal waste that we conducted a study on the urban scrap storage site in Cotonou. Thus, this study is a contribution to improving the health of scrap metal collectors, sorters and recyclers in Cotonou. To achieve this objective, measurements of the dose rates of ionizing radiation from scrap metal were measured using a radiation survey meter. Measurements are made on contact and from a distance. In addition, analyzes of the waste of the powder samples by gamma spectrometry were also carried out. It emerges from this study that the quantities of ionizing radiation doses vary ranging from 7.14 msv for simple copper to 7.17 msv for iron per year. Thus the quantities of ionizing radiation doses increase with burnt copper 22 msv per year and stainless steel 53 msv per year. These doses are significantly higher than the standard of the dose threshold accepted by the IAEA, which is 100 msv over 5 years for workers or on average 20 msv on contact. Ionizing radiation emitted by scrap metal, engine batteries and battery cells cannot be detected by our survey meter beyond 95 cm. In the case of powder waste, it appears that the powder waste contains radionuclides such as K40, Pb 214 and Ra 226, which give off variable energies and exhibit various activities. These effective doses being clearly above the thresholds accepted by the IAEA confirms the fact that scrap metal is dangerous to the health of workers.