Effects of lead inhalation exposures alone and in combination with carbon monoxide in nonpregnant and pregnant rats and fetuses. I. Distribution of lead in blood and liver.

Nonpregnant and pregnant rats were continuously exposed for 3 weeks to an aerosol containing 1, 3 and 10 mg lead/m3 air and to a combination of 3 mg Pb/m3 and 500 ppm carbon monoxide. At the two lower lead doses, fetal blood lead levels exceeded those of the mothers. Active transport mechanisms were discussed to be responsible for these differences. A decrease of the fetal blood lead level below the maternal level in the high exposure group was explained by an increasing storage capacity of the fetal livers with increasing lead doses. Lead concentrations of the maternal livers exceeded the nonpregnant values at all 3 doses, probably caused by a higher ventilation and altered pharmacokinetics of lead in pregnancy. Additional CO-inhalation lowered the storage capacity of the livers of the adult animals and raised the blood concentration. In the fetuses additional CO-inhalation raised liver lead concentrations.