Biochemical changes during the initial stages of industrial lead exposure.

Biochemical measurements were carried out on 20 workers entering employment in a lead industry. Blood lead (Pb-B) urinary delta-aminolevulinic acid (ALA), and coproporphyrin (CP) levels were determined before entry and then at approximately weekly intervals for the first 12 weeks of employment. Levels of blood lead began to increase in all men within one week rising from an average pre-employment figure of about 1-1 mumol/l (22 mug/100 ml) to a value of about 2-9 mumol/l (60 mug/100 ml) at three weeks. Subsequently there was only a small increase in Pb-B values levelled for the rest of the period.