Contrasting effects of age on the plasma/whole blood lead ratio in men and women with a history of lead exposure

We examined the effect of age and sex on the relationship between the concentrations of Pb in blood (Pb-B) and in plasma (Pb-P) in an adult population with a history of lead exposure. Pb-P was determined by inductively coupled plasma mass spectrometry (ICP-MS) and Pb-B by graphite furnace atomic absorption spectrometry (GF AAS). We studied 154 adults (56 men and 98 women) from 18 to 60-year old. Pb-B levels varied from 10.0 to 428.01 mu g/L, with a mean of 761 mu g/L. Blood lead levels varied from 10.0 to 428.0 mu g/L in men (mean, 98.3 mu g/L) and from 10.0 to 263.0 mu g/L (mean, 62.8 mu g/L) in women. Corresponding Pb-Ps were 0.02-2.9 mu g/L (mean, 0.66 mu g/L) and 0.02-1.5 mu g/L (mean, 0.42 mu g/L) in men and women, respectively. The relationship between Pb-B and Pb-P was found to be curvilinear (r = 0.757, P < 0.001 Spearman's correlation). The two quantities are related by the line y = 0.0006x(1492) (y = Pb-P, and x = Pb-B). The %Pb-P/Pb-B ratio ranged from 0.03% to 1.85%. A positive association was found between %Pb-P/Pb-B ratio and Pb-B levels. When data were separated by sex, this association was also relevant for men (y = 0.0184x(0-702)) and women (y = 0.0534x(0.5209)) (y = %Pb-P/PbB and x = Pb-B). Moreover, we found an interesting positive correlation between Log (Pb-P/Pb-B) and age for women (r = 0.31; P < 0.0001) and a negative correlation for men (r = -0.164, P = 0.07). Taken together, these results suggest contrasting effects of age on the plasma/whole blood lead ratio in men and women with a history of lead exposure. Moreover, sex might play an important role in the metabolism of lead, implying further consideration on the kinetic models constructed of lead toxicity. (c) 2006 Elsevier Inc. All rights reserved.