Association between urinary mixture metal levels and olfactory function in coal miners

Area of Science:

• Environmental Health
• Occupational Medicine
• Toxicology

Background:

• Limited evidence exists on the impact of occupational metallic mixtures on olfactory function.
• Coal mining involves exposure to diverse metals in coal dust, yet specific impacts on coal miners' olfaction remain understudied.

Purpose of the Study:

• To evaluate the association between urinary metallic mixtures and olfactory function in coal miners.
• To explore plasma olfactory marker protein (OMP) as a potential biomarker for olfaction in this population.

Main Methods:

• 376 coal miners provided urine samples (16 metals) and plasma (OMP), with olfactory function assessed using the UPSIT test.
• Statistical analyses included binary logistic regression, restricted cubic spline (RCS), Bayesian kernel machine regression (BKMR), and Quantile g-computation (QG-C).

Main Results:

• Urinary iron (Fe) showed a linear association, and lead (Pb) a non-linear association with olfactory function.
• The BKMR model indicated a significant positive association between overall metal mixture concentration and olfactory function.
• Metals Cr, Fe, Se, Sb, and Pb were identified as impacting olfactory performance, with Pb being the most significant contributor. Plasma OMP levels showed a weak correlation with urinary metals.

Conclusions:

• Occupational exposure to multiple metals is associated with olfactory dysfunction in coal miners.
• Lead (Pb) is identified as a key contributor to olfactory impairment in this cohort.
• Plasma OMP is not a suitable biomarker for assessing olfactory function in coal miners exposed to metallic mixtures.