THE RISK OF OCCUPATIONAL LEAD EXPOSURE

We conducted a field survey on 53 workers in a battery factory, 52 solder workers, and 50 embroidery workers (control group). The average air lead levels at the workplaces of these three groups were 0.578 mg/m3, 0.0015 mg/m3 and 0.006 mg/m3 respectively. Clinical and biochemical studies revealed that the workers in Shanghai Navigation Battery Factory were affected somewhat by the toxic effects of lead. The solder workers showed no significant abnormalities compared with the control group. A significant dose-response relationship existed between air lead levels and toxic effects. The early clinical manifestations observed were dysfunction of the central nervous system, dyspepsia, joint pain, and myalgia in the extremities. A positive association was observed between the prevalences of fatigue, mild abdominal pain, and joint pain and the blood lead (PbB), urine lead (PbU), and zinc protoporphyrin (ZPP) levels. The symptomatic threshold values for PbB, PbU, and ZPP were 30 μg/dl, 0.045 mg/L, and 40 μg/dl, respectively. Although the PbB, PbU, δ-aminolevulinic acid dehydratase (ALAD), free erythrocyte protoporphyrin (FEP), and ZPP levels could be used as criteria of lead exposure, the measurement of ZPP is the first-choice screening test for a preventive monitoring program. The motor and sensory conduction velocities in the median nerve were slower in the exposure group than the control group (p<0.05). Conduction velocity and intensity of lead exposure were not significantly correlated. No apparent effects on behavioral function were observed among the solder workers.