Biologic responses to low level lead exposure.

Abstract

School of Medicine, Keio University, Tokyo, Japan The purpose of this study was to examine the dose-response relationship in low level lead exposures. Four groups of workers were exposed to four different levels of lead in ambient air. The first group composed of industrial lead workers were exposed to about 7μg/m3, 6 hrs per day, 6 days per week, in an electric wire producing factory. A second group consisting of police-men was exposed to lower lead levels of about 0.5 μg/m3. A third group of rubber hose workers was exposed to the highest lead level of 33 μg/m3 during working hours, and the fourth group (control) consisted of white collar workers from the same electric wire factory as the first group. In these four groups, ALA level in urine, which is believed to indicate the earliest un-desirable biologic effect due to lead, revealed about the same values in all four groups. Only one parameter, blood lead level, was significantly different among the groups. Blood lead level in the rubber hose workers revealed 32 μg/100 ml. The other three groups showed from 15 to 17 μg/100 ml. The lowered hemo-globin level in electric wire workers was found to be related to the educa-tional level of the workers but not to lead in blood, since the control workers showed higher hemoglobin values. Thus it was concluded that the lead level in ambient air which results in recognizable increase of blood lead might exist between 3 to 6 μg/m3.