title: Comparison of digestion procedures and methods for quantification of trace lead in breast milk by isotope dilution inductively coupled plasma mass spectrometry.
abstract: Measurement of lead in breast milk is an important public health consideration and can be technically quite challenging. The reliable and accurate determination of trace lead in human breast milk is difficult for several reasons including: potential for contamination during sample collection, storage, and analysis; complexities related to the high fat content of human milk; and poor analytic sensitivity at low concentrations. Breast milk lead levels from previous published studies should therefore be reviewed with caution. Due to the difficulty in identifying a method that would successfully digest samples with 100% efficiency, we evaluated three different digestion procedures including: (1) dry ashing in a muffle furnace, (2) microwave oven digestion, and (3) digestion in high pressure asher. High temperature, high pressure asher digestion was selected as the procedure of choice for the breast milk samples. Trace lead analysis was performed using isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS). Measured lead concentrations in breast milk samples (n= 200) from Mexico ranged from 0.2 to 6.7 ng ml-1. The precision for these measurements ranged from 0.27-7.8% RSD. Use of strict contamination control techniques and of a very powerful digestion procedure, along with an ID-ICP-MS method for lead determination, enables us to measure trace lead levels as low as 0.2 ng ml-1in milk (instrument detection limit = 0.01 ng ml-1).
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA.
authors.forename: Chitra J
authors.initials: CJ
authors.lastname: Amarasiriwardena
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA.
authors.forename: Innocent
authors.initials: I
authors.lastname: Jayawardene
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA.
authors.forename: Nicola
authors.initials: N
authors.lastname: Lupoli
authors.affiliation: University Research Institute for Analytical Chemistry, 85 N. Whitney Street, Amherst, MA 01002, USA.
authors.forename: Ramon M
authors.initials: RM
authors.lastname: Barnes
authors.affiliation: Instituto Nacional de Salud Publica, 655 Avenida Universidad, Cuernavaca 62508, Morelos, Mexico.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Hernandez-Avila
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, 155 College Street 6th Floor, Toronto, M5T 3M7, Ontario, Canada.
authors.forename: Howard
authors.initials: H
authors.lastname: Hu
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, 665 Huntington Ave, Boston, MA 02115, USA ; Department of Chronic Disease Epidemiology, Yale School of Public Health, 60 College Street 4th floor, New Haven, CT 06510, USA. ; Tel: +1-203-764-9375.
authors.forename: Adrienne S
authors.initials: AS
authors.lastname: Ettinger