Identification and apportionment of sources of lead in human tissue

A brief review of the use of stable lead isotope ratio measurements to identify and apportion sources of lead in human tissue is followed by examples of the use of inductively coupled plasma source mass spectrometry for such studies. Inductively coupled plasma source mass spectrometry (ICP-MS) has only recently been used for measurements of coupled ratios in body tissues and fluids and in environmental sources of lead. Generally, the inaccuracy of these measurements is about −0.2% and the imprecision less than 0.5%. This analytical performance is sufficient to detect the much larger changes in²⁰⁶Pb:²⁰⁷Pb ratios of −2% or higher, seen in environmental lead exposure and in childhood lead poisoning. Measurements of lead isotope ratios by ICP-MS have been used to identify specific sources of childhood lead poisoning and to indicate the relative importance of environmental sources, such as drinking water and lead from petrol. Populations in the United Kingdom with low lead uptake usually have²⁰⁶:Pb²⁰⁷Pb ratios in body tissues within the range 1.13 ± 0.01. Significant deviations from this range have been seen in response to increased uptake from lead in: drinking water in parts of Scotland (source ratio ∼1.18 and petrol lead in inner London (source ratio ∼1.07). The dominant source for some Scottish subjects with high concentrations of lead in blood or in teeth was water, which contributed approximately 60% to body lead. Petrol lead was shown to be a significant contributor (30–40%) to the body lead of inner London children.     

Exposure to trace elements of flamingos living in a biosphere reserve, the Camargue (France)

Recent research has shown that some adult flamingos Phoenicopterus roseus collected from the Camargue Biosphere Reserve had tissue metal concentrations considerably higher than the average for this species. As the range of these birds is large, the origin of the contamination was unknown. Blood and feather samples from nestling flamingos were therefore analysed for trace metals to determine the presence and origin of local contamination. A comparison of elemental concentration in the feathers of nestling and adult flamingos revealed higher concentrations of Cd, Cu, Pb and Se in adults, and higher concentrations of Zn in juveniles. This was attributed to increased exposure to atmospheric pollutants of adults, and either differences in Zn requirements and metabolism between adults and juveniles, or a local contamination of the juveniles' food supply by Zn. Concentrations of Zn in serum were also very elevated compared with human standards. Cd, Cu, Zn and Se concentrations were analysed in outer (O) and inner (I) barbs (i.e. barbs that are, respectively, exposed or not exposed to external deposits) of greater coverts of nestling flamingos. A comparison of elemental concentrations in these two feather components indicates a local atmospheric contamination by Cd, Cu and Pb.