Arsenic bio-accessibility and bioaccumulation in aged pesticide contaminated soils: A multiline investigation to understand environmental risk.

Bio-accessibility and bioavailability of arsenic (As) in historically As-contaminated soils (cattle tick pesticide), and pristine soils were assessed using 3 different approaches. These approaches included human bio-accessibility using an extraction test replicating gastric conditions (in vitro physiologically-based extraction test); an operationally defined bioaccessibility extraction test - 1.0M HCl extraction; and a live organism bioaccumulation test using earthworms. A sequential extraction procedure revealed the soil As-pool that controls bio-accessibility and bioaccumulation of As. Findings show that As is strongly bound to historically contaminated soil with a lower degree of As bio-accessibility (<15%) and bioaccumulation (<9%) compared with freshly contaminated soil. Key to these lower degrees of bio-accessibility and bioaccumulation is the greater fraction of As associated with crystalline Fe/Al oxy-hydroxide and residual phases. The high bio-accessibility and bioaccumulation of freshly sorbed As in pristine soils were from the exchangeable and specifically sorbed As fractions. Arsenic bioaccumulation in earthworms correlates strongly with both the human bio-accessible, and the operationally defined bioavailable fractions. Hence, results suggest that indirect As bioavailability measures, such as accumulation by earthworm, can be used as complementary lines of evidence to reinforce site-wide trends in the bio-accessibility using in vitro physiologically-based extractions and/or operationally defined extraction test. Such detailed knowledge is useful for successful reclamation and management of the As contaminated soils.

Arsenic solid-phase speciation and reversible binding in long-term contaminated soils.

Historic arsenic contamination of soils occurs throughout the world from mining, industrial and agricultural activities. In Australia, the control of cattle ticks using arsenicals from the late 19th to mid 20th century has led to some 1600 contaminated sites in northern New South Wales. The effect of aging in As-mobility in two dip-site soil types, ferralitic and sandy soils, are investigated utilizing isotopic exchange techniques, and synchrotron X-ray adsorption spectroscopy (XAS). Findings show that historic soil arsenic is highly bound to the soils with >90% irreversibly bound. However, freshly added As (either added to historically loaded soils or pristine soils) has a significantly higher degree of As-accessibility. XAS data indicates that historic soil arsenic is dominated as Ca- (svenekite, & weilite), Al-(mansfieldite), and Fe- (scorodite) like mineral precipitates, whereas freshly added As is dominated by mineral adsorption surfaces, particularly the iron oxy-hydroxides (goethite and hematite), but also gibbsite and kaolin surfaces. SEM data further confirmed the presence of scorodite and mansfieldite formation in the historic contaminated soils. These data suggest that aging of historic soil-As has allowed neoformational mineral recrystallisation from surface sorption processes, which greatly reduces As-mobility and accessibility.

Progesterone and estrogen receptors as prognostic variables in breast cancer.

Estrogen receptor (ER) and progesterone receptor (PR) levels have been measured in 374 tumors from patients with primary breast cancer and compared with axillary nodal status and other patient variables to determine their relationship to prognosis. Nodal status reliably predicted disease-free interval and overall survival, and both ER and PR status predicted overall survival both individually and within node-positive and node-negative subgroups. PR but not ER status was also able to predict disease-free survival both overall and in the node-positive subgroup. When the two receptor measurements were used in combination, a group of receptor-negative, (ER- and PR-negative), node-negative patients were identified with a significantly worse survival than that for an ER- and PR-positive group of node-positive patients. It is apparent that receptor status provides useful prognostic information in patients with early breast cancer and that ER and PR assays used in combination identify a subgroup of node-negative patients with poor prognosis who are likely to benefit from adjuvant therapy following mastectomy.