Sampling of cortical and trabecular bone for lead analysis: method development in a study of lead mobilization during pregnancy.

The paper describes a methodological approach to the investigation of maternal-fetal transfer of lead in a non-human primate species, with particular focus on skeletal tissue, which is known to be a site of lead deposition. Eight female cynomolgus monkeys were dosed with lead acetate during gestation, and in four of the animals, the isotopic composition of the lead was modified by enriching the amount of the stable isotope 204Pb included in the dose. Biopsy and dissection procedures for the preparation of bone samples for lead analysis and stable lead isotope analysis are described. Emphasis is placed on the containment of potential contamination of the samples by lead during preparation. Containment procedures included: use of a Class 100 clean room, special cleaning regimes and use of Teflon containers and stainless steel instruments. Preliminary data of lead concentrations in adult bone (trabecular and cortical) and fetal bone subsequent to the dosing regimen of lead during pregnancy, suggest notable differences between the two bone "compartments" examined. The bone samples of fetuses from the dams which had received enriched 204Pb showed drastically reduced 206Pb/204Pb isotope ratios.

Development of dermal and respiratory sampling procedures for human exposure to pesticides in indoor environments.

No standard methods presently exist for measuring air and surface residues in indoor environments following pesticide applications. Four studies of chlorpyrifos broadcast applications for flea control were conducted to test preliminary sampling guidelines developed by Health and Welfare Canada. Air and wipe samples were collected for 24 hr following 0.5% or 0.48% chlopryifos applications. Ventilation from open doors or windows reduced air concentrations substantially. Air concentrations also varied with sampler height; i.e., greater near the floor than at one m above the floor. Wipe sampling from aluminum foil exhibited high precision (less than 10% coefficient of variation), and wipe sampling of carpets and other surfaces did not show variability in excess of the variability in initial pesticide deposits produced by the application procedures. Residues recovered from treated surfaces decreased by 60-70% over 24 hr, while residues on untreated surfaces increased 200-300% over this period. The Guidelines for Assessment of Indoor Occupant Exposure to Pesticides developed by Health and Welfare Canada have been revised in light of these findings, and provide a set of standard procedures for monitoring indoor air and surface residues. Further studies will be required to determine human exposures and health risks resulting from indoor pesticide applications.