Evaluation of trace elements in human lung tissue. I. Concentration and distribution.

The lungs of eight individuals were investigated for 27 elements by neutron activation analysis and atomic absorption spectrometry. Thirteen segments of each lung pair were analyzed, together with hilar lymph nodes. The trace element distribution in the lungs and the inter-individual concentration differences reveal the existence of two groups of elements. A similar situation is observed in the lymph nodes. The elements Br, Cs, Cu, K, Na, Rb, Se and Zn are relatively homogeneously distributed over a lung pair and show little inter-individual concentration differences. On the other hand, Cd, Co, Cr, Pb, Sb, Sc and V are very inhomogeneosly distributed. The inhomogeneity and the concentrations increase with age. The existence of a concentration gradient within the lung and of relatively higher levels in the lymph nodes point to an enrichment in the lung tissue by inhaled atmospheric contaminants.

Evaluation of trace elements in human lung tissue. III. Correspondence analysis.

The concentrations of 22 trace elements in 13 segments of both lungs of eight individuals were subjected to correspondence analysis, a display method based on principal components analysis. Sample groups were isolated which coincide with the age of the individuals. The firmness of the clusters decreased however with aging. The elements Br, Cd, Co, Cr, Cs, Pb, Sc, Se and V had the most important influence on the grouping. It can be assumed that they are enriched in the tissue by inhaled particulate matter, deposited and accumulated in an insoluble form. The correlation between the elements is proof for their similar behaviour in the lungs: Co, Cr, Sb, Sc and V have a long biological half-life in the tissue, whereas Zn and K are easily removed.

Evaluation of trace elements in human lung tissue. II. Recovery and analysis of inhaled particulates.

Inhaled particulate material, deposited in the lungs of eight Belgian individuals, is differentiated from the tissue with a digestion procedure using the enzyme ficin. This method is simple and efficient and yields a small amount of insoluble dust. The total element concentration of the tissue samples was determined by neutron activation analysis. The radioactive residues obtained after the digestion of the tissue were counted and are considered to represent the insoluble dust fraction. A major part of the Co, Cr, Sb and Sc was recovered in the residues, but only small fractions of the Cs, Rb and Zn. These findings confirm the assumption that Co, Cr, Sb and Sc are enriched in the lungs as a result of the accumulation of atmospheric contaminants. Further proof can be derived from the analogy between the elemental composition of the residue and that of atmospheric particulate matter collected in Belgium.