ABSTRACT
INTRODUCTION: Whole blood is the established matrix for biological monitoring of inorganic lead; however blood sampling is an invasive procedure. Saliva offers a potential non-invasive alternative. This study determines lead in whole blood and saliva. A novel method for saliva sampling and preparation is presented. METHODS: Paired blood and saliva samples were obtained from 105 occupationally exposed UK workers. Saliva was collected using a StatSure sampling device, and a nitric acid digestion step was incorporated. The utility of the device for this application was evaluated. Whole blood was obtained by venepuncture. Analyses were carried out by ICP-MS. RESULTS: The limit of detection for lead in saliva was 0.011 µg/L. Mean blank-corrected recovery from 10 µg/L spiked saliva was 65.9%. The mean result from blank saliva extracted through the StatSure device was 2.86 µg/L, compared to 0.38 µg/L by direct analysis. For the paired samples, median blood lead was 6.00 µg/dL and median saliva lead was 17.1 µg/L. Pearson's correlation coefficient for saliva lead versus blood lead was 0.457 (95% C.I. 0.291-0.596). CONCLUSIONS: ICP-MS analysis allows sensitive determination of lead in saliva with low limits of detection. The StatSure device is effective for high occupational exposures, but contamination from the device could confound lower-level measurements. Saliva would only be effective as a surrogate for whole blood for highly-exposed populations, although with further work it may have applications as a biomarker of recent exposure.
