Abstract
This paper describes a retrospective cohort study comparing 60 workers occupationally exposed to inorganic lead and 60 matched controls. All subjects were assessed using data obtained from a specially designed Questionnaire for lead exposure and toxic effects assessment, physical examination, spirometry, ECG, and laboratory tests including blood lead level (BLL) and biomarkers of lead toxic effects. Muscle pain, droopiness, and work-related nasal symptoms were significantly more frequent in lead workers. The prevalence of lung symptoms was higher in lead workers than in controls, but not significantly (20 % vs. 6.6 %, respectively). Mean values of BLL and delta-aminolevulinic acid (ALA) were significantly higher in lead workers. The activity of delta-aminolevulinic acid dehydratase (ALAD) in lead workers was significantly lower than in controls. Abnormal of BLL, ALAD, and ALA were more frequent in lead workers, with statistical difference for BLL and ALAD. Inverse correlation was found between BLL and ALAD, and positive correlation between BLL and age, years of employment, and years of exposure. Inverse correlation was found between ALAD and age, years of employment, years of exposure, blood pressure, alcohol consumption, and years of alcohol consumption. Changes in spirometry correlated inversely with BLL. A positive correlation was found between BLL and erythrocyte count and haemoglobin concentration, whereas it was inverse for ALAD and haemoglobin concentration. A significant difference was found for BLL and ALAD, with a very high odds ratio (14.64 and 7.23, respectively) and high relative risk (4.18 and 3.08, respectively). Our data have confirmed the association between occupational lead exposure and deviation in specific biological markers of lead effect and between the role of occupational exposure in the development of adverse effects.
Highlights
This paper describes a retrospective cohort study comparing 60 workers occupationally exposed to inorganic lead and 60 matched controls
Biological markers of lead effects are the activity of δ-aminolevulinic acid dehydratase (ALAD), free erythrocyte protoporphyrin (FEP), pirimidin-5’nucleotidase in erythrocytes, and the concentration of aminolevulinic acid (ALA) and coproporphyrin in urine [15]
Of eight ALAD gene variants, we focused on one polymorphism that yields two alleles, designated ALAD-1 and ALAD-2, which exhibit a codominant pattern of inheritance [40]
Summary
This paper describes a retrospective cohort study comparing 60 workers occupationally exposed to inorganic lead and 60 matched controls. The beginning of production in the lead smelting plant “MHK Zletovo” in the municipality of Veles in 1972 gave rise to issues related to occupational exposure to inorganic lead. At an average or high lead exposure FEP and zinc protoporphyrine (ZPP) concentrations increase, but are not sufficiently sensitive or specific to be primary indicators of lead effects [16, 17]. In her study of occupational lead exposure in the smelting plant in Veles in 1997, Isjanovska found a statistically significant difference between average ALAD blood values in the exposed and unexposed workers (p
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