Review of Occupational Exposure and Radioactivity Associated with Amang in Mineral Processing Industries in Peninsular Malaysia

Past history has explained the importance of Peninsular Malaysia as the greatest tin producing country in the world, with 30 – 50% of the world's annual tin production in the mid-1960s were produced from the rich-stanniferous areas; most notably in Kinta Valley and Klang Valley. However, due to the dramatic depletion of cassiterite reserves, a newly economic activity of amang processing industry has emerged. Amang is locally coined name for tin-tailing in Malaysia and has been classidied as TENORM after more than 5 decades of exploitation for commodity values. Amang composed of extremely high radionuclide concentrations from ²³⁸U and ²³²Th series, varies from a few hundred - 60,000 ppm. Radiological risk concern against radiation exposure to workers emerged due to elevated gamma radiation exposure, and high risk of radon inhalation as well as long-lived airborne radioactive dust. Highest gamma dose rate was recorded in amang processing plant was 400,000 nGy h^-1 attributed to huge open-air mineral stockpiles. Mineral separator machine has been identified as a source of releases of airborne alpha emitters with an exposure equivalent to few tenths – 281.27 mSv yr^-1. Substandard and poor operational practices e.g., feeding task of mineral into separators using hand and buckets could liberate more radioactive dust in air. Storing and dumping amang mineral inside storeroom have been identified as a source of high accumulation of radon and thoron ~ few Bq l^-1 to 160 Bq l^-1. The exacerbating circumstance arises as the industries practicing unsystematic working environment. Some plants have been spotted fail to comply with basic occupational health and safety legislation for example implementation of film badge, protective mask and cloth during operations. This paper review occupational exposure and radioactivity associated with amang processing minerals in Peninsular Malaysia with statistical evaluations of mineral inventories, cumulative probability analyses, and assessment of effective dose. (author)