Comparing plasma, serum and whole blood indium concentrations from workers at an indium-tin oxide (ITO) production facility

Objective

Occupational exposure to indium compounds including indium-tin oxide (ITO) can result in potentially fatal indium lung disease. We compared plasma, serum and whole blood indium concentrations (In_P, In_S and In_B) from workers at a single ITO production facility to assess the comparability of these matrices used for biological monitoring of indium exposure.

Method

In_P, In_S and In_B were measured using inductively coupled mass spectrometry from consenting workers at an ITO production facility with specimen collection occurring during June–July 2014. Matched pairs from workers were assessed to determine the matrix relationships using the Pearson correlation, paired t-tests, per cent difference, linear regression and statistics.

Results

Indium matrices were collected from 80 workers. Mean (SD) In_P, In_S and In_B were 3.48 (3.84), 3.90 (4.15) and 4.66 (5.32) mcg/L, respectively. The In_S–In_P difference was 14%; In_S was higher in all but two workers. In_P and In_S were highly correlated (r=>0.99). The In_B–In_S difference was 19%; In_B was higher in 85% of workers. The In_B–In_P difference was 34%; In_B was higher in 66% of workers. In_B was highly correlated with both In_P and In_S (r=0.97 and 0.96, respectively). Statistics were 0.84, 0.83 and 0.82 for In_P, In_S and In_B, respectively, for individuals with each matrix ≥1 mcg/L (p<0.01).

Conclusions

While all matrices were highly correlated, we encourage the use of In_P and In_S to reliably compare studies across different populations using different matrices. The higher per cent difference and increased variability of In_B may limit its utility in comparisons with In_P and In_S in different populations.

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