(in German)

Introduction: For employees performing activities using lead and its compounds, lead content is measured in whole blood to determine an individual’s lead exposure. However, lead content in whole blood reacts very slowly to changes in exposure and can therefore not be used to verify the short-term efficacy of protective measures or the impact of acute changes or events. Therefore, a study has been performed to address routes of exposure to lead and to investigate alternative biomarkers for lead exposure.

Methods: For our cross-sectional study, we recruited employees from four lead-processing companies and one company, where employees performed activities using lead, in Germany. A total of 64 employees participated in the first measurement campaign (M1) of the study, a total of 61 employees was included in the second measurement campaign (M2). 43 employees (M1) vs. 42 employees (M2) consented to take part in biomonitoring. Biomonitoring was carried out for several parameters in whole blood, plasma, and urine at specific times during the workweek (Day 1 (after work-free time) and Day 4, both before starting a shift and at the end of the shift). We collected wipe samples from the employees’ hands to measure dermal exposure. Furthermore, airborne lead concentration as inhalable particle fraction (stationary and personal sampling) has been measured.

Results: This study surveyed a wide spectrum of workplaces at which work activities with lead and its inorganic compounds are performed and at which various protective measures are taken. Air concentrations and dermal measured values, as well as the biomonitoring results, showed a wide range: personal workplace measurements (lead concentration in the air): 0.08–
2519 μg/m³; dermal lead exposure of the hands (wipe samples): 0.026–2400 μg/min of work, lead in whole blood: 7.7–511 μg/l.

In case of personal measurements across the entire collective, the MAK value was exceeded in 83 % of cases; the new EU-wide BOELV was exceeded in 68 % of cases. In 24 % of cases, the measured values were above the previously applicable BOELV.

The BLV of 150 μg/l (EU limit value in force starting in 2029) showed a lack of compliance in 46 % of cases. With respect to alternative exposure markers, a positive correlation could be shown between the lead concentrations (Pb) in whole blood and plasma, Pb (whole blood) and Pb (urine), as well as Pb (plasma) and Pb (urine). This positive correlation was more pronounced for the parameters Pb (plasma) – Pb (whole blood) and Pb (urine) –Pb (plasma) at the end of the workweek compared to the beginning. The parameter Pb (urine) and Pb (whole blood) showed a similarly strong correlation at the beginning and at the end of the workweek. Throughout the course of the workweek, the lead concentrations in plasma generally exhibited only moderate changes. Lead concentrations in urine exhibited no clear temporal trend throughout the workday or workweek and, independent of sampling time, showed a strong correlation with blood lead levels.

In the entire collective, the biomonitoring parameters (lead in whole blood, lead in plasma, and lead in urine) correlated significantly and positively with the dermal exposure of the hands. In the subgroup of employees who worked without respiratory protection, significant and positive correlations were shown between lead air concentrations at the corresponding workplace and Pb (whole blood), Pb (plasma), or Pb (urine). In the subgroup of employees who did use respiratory protection, the quotients calculated from the lead concentration in urine and the lead concentration in whole blood only yielded a significant correlation with dermal exposure of the hands for the post-shift urine samples on Days 1 and 4. It can therefore be concluded that the urinary excretion of lead shows a relatively strong relationship with current dermal exposure on a given workday.

In all four multiple linear regression models which examined Pb (whole blood) as a target parameter, a significant influence of dermal lead exposure on the hands could be determined.

Conclusion: Especially, lead biomonitoring is important for the protection of workers and, in light of the reduction of lead exposure limit values according to EU Directive 2024/869, will become even more essential in the future.

Based on the results of our study, no biomonitoring parameter could be identified that can be reliably used to monitor short-term exposure. Since the concentration of lead in urine showed a strong correlation with the concentration of lead in whole blood, the determination of lead in urine may present a practical alternative to the determination of lead in whole blood. The quotient calculated from the urinary lead concentration and the lead concentration in whole blood could potentially serve as a surrogate for shortterm changes in external lead exposure. However, the current data basis is not sufficient to allow for a final evaluation and further scientific studies in larger collectives are required. 

Dermal lead exposure of the hands proved to be an independent determinant of internal lead exposure in workers; this finding clearly shows that occupational safety at workplaces with lead exposure must continue to be considered a significant challenge.

Please download the complete report "Derivation of suitable biomonitoring methods to determine the current work-related lead exposure of employees" (in German only).