Characterisation of airborne Ce, Th and Cd in workplace and their correlation with their concentrations in body fluids and excreta of occupational workers using NAA, ICP-AES and XRF

Analysis of the respirable airborne particulate matter (APM) from the occupational settings at the zinc smelting, mineral beneficiation and mineral processing industries using nuclear and related analytical techniques, indicates elemental distribution specific to individual process. While the concentrations and their ratios in the raw material were reflected in the APM at the initial stages, these underwent significant modifications at subsequent stages. Detailed size characterisation studies showed that up to 50% of APM was below 2 μm in some process areas. Studies on the solubilisation of APM in lung serum simulant demonstrated fast and slow components for both Cd and Zn. Cadmium showed preferential solubilisation. Detailed analysis of the urine excreta of occupational workers showed significant correlation with APM. The study revealed usefulness of urine sample as biological integrator for monitoring the work place. The rate of excretion of Th and Ce through urine was related to the physico-chemical form of their respective APM. Cerium showed faster elimination when it was present as halides or hydrates. The study has been able to identify different chemical species and their relevance in the uptake, retention and biological elimination. The influence of specific site environmental background in the population was nearly 25% of the occupational levels for Th as revealed by analysis of urine samples and thoron in the exhaled breath. Participated in the Agency's intercomparison programmes. Results of NAT-3 Air Filters have been sent. Samples of lyophilised urine and welding fumes are being analysed. (author)