Keywords: hair, nails, NAA, neutron activation analysis, phosphate fertiliser plants, occupational exposure, discriminant function analysis, hard tissue samples, risk assessment, biomonitoring
Hard tissue samples as markers of occupational exposure in a phosphate fertiliser plant
This paper describes the results of study on testing of hair and nails samples as possible markers of occupational exposure in a phosphate fertiliser plant. The key objectives were to verify if: (1) elements originating from fertiliser production may accumulate in hard tissue and hence allow preliminary occupational exposure risk assessment; (2) linear discriminant function analysis (LDA) may be applied as a diversification tool in preliminary assessment of occupational exposure risk based on hard tissue samples analysis; and (3) both hairs and nails can be used successfully as an efficient biological sample in biomonitoring studies and as markers of occupational exposure in various types of plant. The complex data matrix (2025 observations) obtained by the determination of 25 elements by neutron activation analysis in hard tissue samples was treated by LDA. The obtained results indicated the presence of two discriminant functions (DFs). The data variance explained by the first DF is 78%, and that by the second DF is 22%. The first DF is highly related to S, W, Cu, K and Mg concentrations and separates hair from nails samples, and the second DF, being related to phosphate fertiliser precursors, separates the control group from the employees. Sm, Al, Mo and As accumulate in nails and hairs of fertiliser plant employees, whereas Cl and Ti are removed from hard tissues. The mean concentrations of Na, In, I, Au, Dy, Ca, La, U, Sb, V, Zn, Mn and Co in hard tissue samples do not discriminate employees and control group members and hence prove their ineffectiveness in occupational exposure assessment in phosphate fertiliser plants.