The use of soil survey data to determine the magnitude and extent of historic metal deposition related to atmospheric smelter emissions across Humberside, UK.

When a smelter has ceased operation, and in the absence of historical emission data, high-resolution geochemical surveys of the soil can reveal historical loads to the surrounding land. We use measurements of lead and tin in the soil at two depths to estimate the total quantities of these metals deposited on 286 km(2) of land around the former Capper Pass smelter (north-east England). We subtracted median background concentrations for three parent material types outside the region of deposition from the data within it. We then constructed a statistical model of metal deposition based on the adjusted data. The data were from irregularly spaced sites and were strongly skewed with a spatial trend. We mapped the concentrations of the metals by lognormal universal kriging with the parameters for the trend and residuals modelled simultaneously by residual maximum likelihood (REML). The maps suggest that metal was deposited up to 24 km to the north-east of the smelter by the prevailing wind. We estimated total excess metal in the soil over the area of deposition to be 2500 t of lead and 830 t of tin.

Bioaccessibility of arsenic in soils developed over Jurassic ironstones in eastern England.

Jurassic ironstones outcropping over parts of eastern England give rise to soils with arsenic concentrations in excess of the UK soil guideline value of 20 mg kg(-1) for residential areas. Total arsenic concentrations were determined for 73 ironstone derived soils and bioaccessible arsenic determined using an in vitro physiologically based extraction test. The bioaccessible arsenic concentration for these soils was found to be well below the soil guideline value with a mean concentration of 4 mg kg(-1) and a range of 2-17 mg kg(-1). The bioaccessible fraction ranges from 1.2 to 33%. Data from a sequential extraction test based on the use of aqua regia as the main extractant is presented for a subset of 20 of the soils. Chemometric data reduction is used to demonstrate that the bioaccessible arsenic is mainly contained within calcium iron carbonate (sideritic) assemblages and only partially iron aluminosilicates, probably berthierine, and iron oxyhydroxide phases, probably goethite. It is suggested that the bulk of the non-bioaccessible arsenic is bound up with less reactive iron oxide phases.

The relationship between mucosal cyclooxygenase-2 (COX-2) expression and experimental radiation-induced mucositis.

Although cycloooxygenase-2 (COX-2) is upregulated by factors associated with oral mucositis, its role in the pathogenesis of mucositis has not been studied. We investigated the kinetics of mucosal COX-2 expression following radiation exposure, and assessed its relationship to the development of oral mucositis in an established animal model using immunohistochemical endpoints. While little or no COX-2 expression was observed in unirradiated mucosa or in tissue taken 2 days after radiation, COX-2 expression was dramatic on days 10 and 16, especially in submucosal fibroblasts and endothelium. The kinetics of COX-2 expression paralleled mucositis severity. A burst of angiogenic activity was seen on day 21 following peak COX-2 expression. The kinetics of COX-2 expression relative to mucositis progression suggests that COX-2 is not a primary driver of radiation injury, but instead plays an amplifying role.

The gene expression sequence of radiated mucosa in an animal mucositis model.

Oral mucositis is a common, dose-limiting, acute toxicity of radiation therapy administered for the treatment of cancers of the head and neck. Accumulating data would suggest that the pathogenesis of mucositis is complex and involves the sequential interaction of all cell types of the oral mucosa, as well as a number of cytokines and elements of the oral environment. While a number of studies have reported on gene expression of particular cell types in response to radiation, the overall response of irradiated mucosa has only been evaluated in a limited way. The present study was undertaken to evaluate the expression of a target group of genes using RNA quantification assays and, more broadly, to assess patterns of mucosal gene expression using DNA microarray hybridization. Our results demonstrate the sequential upregulation of a series of genes that, when taken collectively, suggest an intricate functional interaction.