Lead exposure, urinary δ-aminolevulinic acid concentrations and haematological parameters of road sweepers working in congested areas of Bangkok

Abstract

Road sweepers are especially exposed to environmental pollution. This study investigates the lead exposure, urinary δ-aminolevulinic acid concentration (ALA) and haematological parameters of road sweepers working in traffic-congested areas of Bangkok. One hundred and ninety-four apparently healthy road sweepers aged 20-59 years were investigated. One hundred and thirty-nine staff from an academic institution served as controls. Both male and female road sweepers had slightly, but significantly, lower mean corpuscular haemoglobin concentration (MCHC) values. The white blood cell count (WBC) in female road sweepers was significantly higher compared with the female controls. The proportion of reticulocytes was higher in male and female road sweepers compared with the controls, while no difference was found in blood lead levels and ALA between male road sweepers and controls. Female road sweepers had slightly higher blood lead levels compared with the controls. ALA was no different between both groups of females. The proportion of road sweepers with basophilic stippling was more than double in comparison with the controls, contrary to expectations, obvious signs and symptoms of lead poisoning were not evident in the group of road sweepers. There are, however, more discrete indications that working in this heavily polluted environment is not without health risks.