Biological monitoring of occupational exposure to inorganic lead: a comparison between salivary, blood and airborne lead levels

Background: Inorganic lead exposure is a relevant occupational health issue in many industry sectors. European regulations set specific limits for time-weighted chemical airborne exposure and for biological exposure. While blood lead monitoring is the current standard, saliva sampling offers a less invasive alternative for biomonitoring. This study evaluates the potential of salivary lead assessment as an alternative biological matrix for occupational exposure monitoring. Methods: An observational study was conducted at a lead-acid battery production facility in Central Italy from July to December 2024. Ninety-two male workers participated: 46 occupationally exposed and 46 non-exposed workers. Salivary lead levels were measured using ICP-MS in all participants. Blood lead levels and personal airborne lead assessments were performed in the exposed group. Socio-demographic data were collected through self-administered questionnaires. Results: Mean salivary lead levels were significantly higher in exposed workers (23.3 ± 41.4 ng/swab) compared to non-exposed workers (0.3 ± 0.6 ng/swab, p < 0.001). A moderate positive correlation was found between environmental and salivary lead levels (ρ = 0.5587, p = 0.0003). No significant correlations were observed between blood and salivary lead levels or between environmental and blood lead levels. Occupational exposure and alcohol consumption were significant predictors of salivary lead levels. Conclusions: Saliva appears to be a promising alternative matrix for recent lead exposure monitoring, showing better correlation with environmental exposure than blood lead levels. Further research is needed to establish reference values and standardize salivary lead biomonitoring protocols.