3.2. Exposure biomarkers
We collected blood and urine from 55 recycling workers and 10 office workers at the first sampling occasion and from 25 recycling workers and 7 office workers at follow-up. We failed to collect blood samples from two recycling workers at the first occasion. The median blood concentrations of Pb (32 μg/l; range: 9.5–230 μg/l) and Cr (1.4 μg/l, range: 0.34–5.0 μg/l) were significantly higher (p b 0.05) in recycling workers than in the office workers, as shown in Table 4 and supplementary Table S2. At the second sampling occasion, only the Pb median concentration (33 μg/l, range: 7.1–240 μg/l) remained significantly higher among the recycling workers, but also