Initial results for urban metal distributions in house dusts of Syracuse, New York, USA.

A program of house dust sample collection and analysis has begun in Syracuse, New York, USA, in order to determine the feasibility of a geography-based exposure assessment for urban metals. The sampling program, and the protocols it employs, is described for two different types of wipe media, Ghost Wipes and Whatman Filters. Preliminary results show that strong spatial patterns of floor dust loading (mg dust per square foot) can be observed for data aggregated at a spatial scale of about 1600 m (approximately 2.5 km2). Floor dust metal concentrations were similar to those found in other urban environments, with some regional variation. The median floor dust Pb concentration was approximately 108 mg x kg(-1) for this initial data set of approximately 264 sampled residential locations, and varied from 50 to 1100 mg Pb x kg(-1).

Bone biopsy in the horse. 2. Evaluation of histomorphometric examination.

The histomorphometrical examination of a series of bone biopsies from the wing of ilium of foals and older horses is reported. Biopsies were obtained from 20 clinically normal horses, which had previously been infused with tetracycline intravenously twice at a 7 day interval at a dose rate of 10 to 15 mg kg-1. The horses were divided into 2 groups. Group 1 consisted of 10 foals (mean age: 4 +/- 1 months) which were biopsied at 3 different sites in the wing of ilium. Group 2 comprised 10 older horses (mean age: 91 +/- 63 months) which were biopsied from only one site in the left ilium. A systematic evaluation of intra-observer, intra-core, intra-bone and inter-bone errors was made to investigate parameter variations that might affect interpretation of bone biopsies. The measurements carried out included cancellous bone volume (Cn-BV/TV), osteoid surface (OS/BS), eroded surface (ES/BS), mean wall thickness (W.Th), mean osteoid thickness (O.Th), distance between labels (Ir.L.Th) and mineralizing surface (MS/BS). The intra-observer variance, the variance between sections, the variance between adjacent biopsies and that between right and left sides proved to be smaller than the inter-individual variance. The estimate of errors associated with the histomorphometrical analysis of bone biopsies is important for correct interpretations of changes due to disease.

Bone biopsy in the horse. 3. Normal histomorphometric data according to age and sex.

Histomorphometrical analysis of bone biopsies from the wing of ilium in 35 clinically normal horses are reported according to age. The biopsies were collected from 20 mixed-bred foals (mean age 6 +/- 1 months) and 15 older horses (mean age 73 +/- 62 months). No gender differences were found in the group of foals examined, but a significant difference (p less than 0.001) in a number of the primary measurements occurred between them and the older horses. The parameters which altered with age were the extent of osteoid surface (OS/BS), the extent of resorption (erosion) surface (ES/BS), the osteoid thickness (O. Th), the mineral appositional rate (MAR), which corresponds to the rate of matrix mineralisation and, if no mineralisation defects exist reflects the amount of bone laid down per day, and the extent of labelled surfaces (MS/BS). These data indicate a much greater rate of bone remodelling in the foals. This was also reflected in a number of the derived parameters (i.e. the extent of quiescent surfaces [QS/BS] and the activation frequency [Ac.f]).