[Appraisal of the feasibility of the accepted Bulgarian MPEL for lead in the air of the working environment using modern criteria].

The MAC for lead in the workplace atmosphere adopted in Bulgaria, amounting to 0.01 mg/m3, appears to be much lower than abroad. Upon investigation of groups of workers employed in the lead mining and processing industry, working under conditions of lead exposure up to 0.10 mg/m3 and exceeding 0.11 mg/m3, no changes were found in the delta-amino-levulinic acid and coproporphyrin level in the urine--the early signs of lead damage--nor in plumburia mong the workers exposed to lead concentrations up to 0.10 mg/m3 which is a concentration exceeding ten times the MAC accepted in this country. A reassessment of the later on the basis of up-to-date biochemical criteria is deemed necessary.