Lead levels in fur of rats treated with inorganic lead measured by inductively coupled argon plasma mass spectrometry

Abstract

The aim of this study was to investigate the relationship between continuous lead exposure and the concentration of this metal in fur. The two main questions we wanted to answer were: 1) Are the fur lead concentrations different according to exposure level? 2) Is the kinetics of lead concentration linear in different compartments?For 12 weeks, 6 rats were force-fed with water containing lead acetate in the following quantities: 0.5 and 50 µg/day. Furs were sampled every two weeks. The lead content of the samples was measured by inductively coupled argon plasma mass spectrometry (ICP-MS).There was a statistical difference (p<0.0001) between fur lead concentration and the three groups (control, low level exposure and high level exposure), between fur lead concentration and time exposure (p<0.0001), and between fur lead concentration and each exposure group at different time exposure (p<0.0001). Thus the level exposure factor and the time exposure factor have an effect on fur lead concentration. Since the determination coefficients were weak for the two exposed groups (0.032 and 0.032), a linear correlation cannot be concluded. The kinetic curves of fur lead concentration are similar for all the exposition groups. Two peaks (at 2 and 8 weeks of exposure) were noted for the two exposed groups.This experimental study cannot conclude a linear relationship to exist between fur lead concentration and exposition duration. It highlights the lack of understanding of mechanisms involved in hair incorporation of metals and raises the question of a cyclic accumulation in hair. A better understanding of the kinetic incorporation of lead in body growths is required.

Keywords: fur lead; hair lead; rat; spectrometry.

Figure 1

Lead content in fur of rats treated with lead acetate

Figure 2

Relationship between fur lead concentration (µg lead/g hair) and time exposure (days) for low level (0.5 µ/day) lead exposure. Regression equation: Fur lead concentration (µg/g) = 2.868 – 0.017 × time exposure (days). Coefficient of determination: R²=0.032

Figure 3

Relationship between fur lead concentration (µg/g) and time exposure (days) for high level (50 µ/day) lead exposure. Regression equation: Fur lead concentration (µg/g) = 17.23 + 0.35 × time exposure (days). Coefficient of determination: R²=0.175.