Introduction Metal dust inhalation might be harmful for the respiratory system. We studied the association between urinary and toenail levels of metals, and respiratory symptoms (RS) among chemical and metal industry workers exposed to metals.

Methods Cross-sectional epidemiological study. We measured urinary (As, Ba, Be, Cd, Co, Cu, Hg, Li, Mo, Pb, Se, Sr, Tl, V, W and Zn), and toenail (same plus Al, Cr, Fe, Mn, Ni and U) metal levels. We obtainned information on respiratory symptoms (dry cough, productive cough, sour throat, metallic taste in mouth, nosebleed, nose ulcers, anosmia, dyspnea, wheezing, cheast pain, and hemoptysis) in the year prior to interview in 81 workers from the metal and chemical industry, and 43 workers from the services sector. 87% of workers were male. Metal levels were measured using multielemental ICP-MS analysis. We compared the median for each metal between those with and without each respiratory symptom (U Mann-Whitney test). We also used lineal regression models adjusted for age sex, study area, and type of industry.

Results Anosmia was associated with urinary levels of different metals (Sr p = 0.02; Tl p = 0–003; Cd p = 0.0002; Ba p = 0.02; Pb p = 0.004). Toenails levels of different metals were associated with nosebleed (As, Cd, Cu, Pb, Se and Tl), anosmia (Ba, Ni, Se, Sr, and Tl) and dyspnea (As, Cu and Fe). In the multivariate analysis, the most consistent association with respiratory symptoms were observed for toenail levels of As.

Conclusions Toenails resulted a better matrix to capture the association between respiratory symptoms and metals. Nosebleed, anosmia and dyspnea were the respiratory symptoms more consistently associated with a higher number of metals.