Abstract
It has been reported in previous research that the lead isotopic composition of blood, urine and feces samples statistically differed from the given lead sources in Sprague-Dawley (SD) rats. However, the reason for this phenomenon is still unclear. An animal experiment was performed to investigate the lead isotope fractionation in diverse biological samples (i.e., lungs, liver, kidneys, bone) and to explore the possible reasons. SD rats were intratracheally instilled with lead acetate at the concentrations of 0, 0.02, 0.2, and 2 mg/kg body weight. Biological samples were collected for lead isotope analysis using an inductively coupled plasma mass spectrometry (ICP-MS). Significant differences are observed in lead isotope abundances among the diverse biological samples. The lead isotope abundances (206Pb, 207Pb and 208Pb) in diverse biological samples show different degrees and directions of departure from the given lead source. The results suggest that differences in enrichment or depletion capacity for each lead isotope in the various tissues might lead to the variation in lead isotopic abundances in tissues. Moreover, a nonlinear relationship between the blood lead level and the lead isotope abundances in liver and bone is observed. When the whole-blood level is higher than 50 ng/mL, the lead isotopic compositions of biological samples tend to be the same. Thus, the data support the speculation of a fractionation functional threshold.
Highlights
Lead (Pb) poisoning is a long-standing and serious environmental problem for living organisms and can induce adverse health effects [1,2]
Due to its small fractional mass differences, it is generally assumed that lead isotopes do not fractionate measurably in biological systems [6,7], and can be utilized as a tracer of Pb provenance in a variety of complex environments [4,8,9]
Lead acetate solutions of different concentrations were prepared from lead acetate trihydrate
Summary
Lead (Pb) poisoning is a long-standing and serious environmental problem for living organisms and can induce adverse health effects [1,2]. A key strategy for reducing human health risk of lead poisoning is to identify and control the lead sources. There are four naturally occurring stable isotopes of lead (204Pb, 206Pb,207Pb and 208Pb), three of which are radiogenic and produced by the radioactive decay of uranium and thorium [4]. The fourth isotope of lead (204Pb) is non-radiogenic. The isotopic composition of lead from any geologic sources was fixed when the ore was formed [5]. Each geologic source has a characteristic isotopic ‘‘signature’’ consisting of variable abundances of four stable isotopes. Due to its small fractional mass differences, it is generally assumed that lead isotopes do not fractionate measurably in biological systems [6,7], and can be utilized as a tracer of Pb provenance in a variety of complex environments [4,8,9]
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