Blood lead and erythrocyte zinc protoporphyrin in mothers and newborn infants.

Blood lead (B-Pb) and erythrocyte zinc protoporphyrin (ZPP) were measured in 78 mothers at delivery and in cord blood from 48 infants living in an area with low atmospheric Pb pollution. Median B-Pb was 35 micrograms/l (range 6-63) in mothers and 20 micrograms/l (range 6-50) in infants (P less than 0.0001), and the values were significantly correlated (rs = 0.73, P less than 0.0001). Mean B-Pb infant/B-Pb mother ratio was 0.7 (range 0.2-1.4). Mothers had lower ZPP (median 1.6 microgram/g Hb) than infants (median 2.9) (P less than 0.0001). ZPP in mothers showed a stronger relation to iron status (serum transferrin, serum ferritin) than to B-Pb (rs = 0.22, P less than 0.05). B-Pb was correlated to serum iron both in mothers (rs = 0.28, P less than 0.02) and infants (rs = 0.33, P less than 0.03). The present B-Pb levels are lower than previously reported in Scandinavia, probably due to the general decline in atmospheric Pb pollution.