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On 3 October 2007, 40 participants with diverse expertise attended the workshop Tamiflu and the Environment: Implications of Use under Pandemic Conditions to assess the potential human health impact and environmental hazards associated with use of Tamiflu during an influenza pandemic. Based on the identification and risk-ranking of knowledge gaps, the consensus was that oseltamivir ethylester-phosphate (OE-P) and oseltamivir carboxylate (OC) were unlikely to pose an ecotoxicologic hazard to freshwater organisms. OC in river water might hasten the generation of OC-resistance in wildfowl, but this possibility seems less likely than the potential disruption that could be posed by OC and other pharmaceuticals to the operation of sewage treatment plants. The work-group members agreed on the following research priorities: a) available data on the ecotoxicology of OE-P and OC should be published; b) risk should be assessed for OC-contaminated river water generating OC-resistant viruses in wildfowl; c) sewage treatment plant functioning due to microbial inhibition by neuraminidase inhibitors and other antimicrobials used during a pandemic should be investigated; and d) realistic worst-case exposure scenarios should be developed. Additional modeling would be useful to identify localized areas within river catchments that might be prone to high pharmaceutical concentrations in sewage treatment plant effluent. Ongoing seasonal use of Tamiflu in Japan offers opportunities for researchers to assess how much OC enters and persists in the aquatic environment.

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We have characterized at high temperature a model uniform heterogeneous catalyst for the oligomerization of hydrocarbons (a nickel-exchanged zeolite of initial composition Na59A159Si,330384 -xH,O treated with an aqueous solution of NiC1, so as to yield a homogeneous distribution of Ni, with Si/ Ni = 7) by recording the extended X-ray absorption fine structure (EXAFS) abov? the Ni edge and also its high-resolution diffraction pattern (at A = 1.5486 A). We have obtained unique insights into the microenvironment of the Ni'+ ions in the as-prepared and the dehydrated as well as the reduced state of the catalyst; in particular, values of atomic coordinates, site-occupancy and bond lengths, have been obtained. High-resolution X-ray diffraction, using a specially constructed environmental cell, has enabled the precise location of sorbed Xe atoms in a sodium-exchanged zeolite X adsorbent (1.5 atoms of Xe per unit cell) under a pressure of 1.75 bar at room temperature to be determined from a Rietveld refinement of the powder diffraction pattern. Direct proof of the role of the strongly polarizing Na+ ion located at the Sn site in firmly binding the Xe to the inner wall of the supercage is obtained.X-ray absorption near-edge structures (XANES) as well as parallel EXAFS studies above the Al, Si and Ga edges on a variety of other zeolites are also reported. Combined (Cia edge) XANES and EXAFS studies show that gallosilicate networks akin to those present in crystalline (gallo) zeolite X and Y are already formed in the precursor gel and are also present in the aqueous solution in contact with the colloidal-amorphous material, which together constitute the gel. We also report one of the first applications of A1 EXAFS for the semi-quantitative 3;Jdy of the dealumination of faujasitic zeolites.

A previously developed model for the evaluation of activity coefficient ratios in mixed dilute solution is employed with particular respect to ternary cation exchange in zeolites in the presence of up to three different coanions in solution. Potential errors arising from ignoring either completely or partially the non-ideality correction for the solution phase are evaluated and discussed. Exchanges involving counterions of the same valency, or involving ions of different valencies, are both considered. It is shown that when all the counter-ions have the same valency, the magnitude of the non-ideality correction is independent of the selectivity of the exchanger. When the valencies of the counter-ions are different it is essential to apply the mixed-salt activity correction for any accurate studies of ternary ion-exchange equilibria.T Throughout this paper, the term 'equivalent' denotes the number of moles of unit charge arising from a species in solution. Thus, for example, the number of equivalents of ion AZA+ in solution equals ZAmA. zA and mA are defined in the text.