Exposure assessment of carcass disposal options in the event of a notifiable exotic animal disease: application to avian influenza virus

We present a generalized exposure assessment of 28 disposal options for poultry carcasses in the event of a highly pathogenic avian influenza (HPAI) outbreak. The analysis supports a hereto unverified disposal hierarchy for animal carcasses, placing waste processing (e.g., incineration and rendering) above controlled disposal (e.g., landfill), above uncontrolled disposal (e.g., burial on-farm). We illustrate that early stages of the disposal chain (on-farm) pose greater opportunities for exposure to hazardous agents than later stages, where agents are generally contained, wastes are treated, and residues are managed by regulated processes. In selecting carcass disposal options, practitioners are advised to consider the full range of hazards rather than focusing solely on the HPAI agent, and to give preference to technologies that (i) offer high destruction efficiencies for target pathogens; (ii) do not give rise to significant releases of other pathogenic organisms; and (iii) do not release unacceptable concentrations of toxic chemicals. The approach offers an exposure assessment perspective for carcass disposal, thus providing a risk-informed basis for contingency planning and operational intervention. The authors recognize that relevant legislation, public perception, available capacity, and cost also need to be considered when selecting disposal options in the event of HPAI.     

Compound-specific factors influencing sorption nonlinearity in natural organic matter

Nonlinear sorption by natural organic matter may have a significant impact on the behavior of organic contaminants in soils and sediments. This study presents a molecular probe approach based on linear solvation energy relationships (LSERs) to identify and quantify the molecular interactions causing concentration-dependent sorption and proposes estimation methods for sorption nonlinearities. Sorption isotherms ranging over concentrations of more than 4 orders of magnitude were determined in batch systems for 23 and 16 chemically diverse probe compounds in a lignite sample and a peat soil, respectively. Each sorbent showed characteristic nonlinear sorption with Freundlich exponents (1/n) being 0.7-1. The LSER-based analysis revealed that the strength of nonspecific interactions did not vary with concentration for both sorbents. In lignite, specific interactions did not affect sorption nonlinearity either, suggesting that compound-independent factors of lignite were responsible for the nonlinear sorption. In the peat soil, by contrast, the specific interactions related to the solute polarizability/dipolarity parameter (S) decreased with increasing concentration. Consequently, compounds of higher S values were more susceptible to nonlinear sorption in the peat soil. Phenol probes have shown that hydrogen bond donating properties of sorbate compounds have a substantial impact on the overall strength of sorption with organic matter, but no significant influence on sorption nonlinearity. Heterocyclic aromatic compounds appear to undergo additional interactions that are not accounted for by the LSER. These additional interactions considerably enhance both sorption capacity and nonlinearity.     

Combined gel probes for the in situ determination of dissolved reactive phosphorus in porewaters and characterization of sediment reactivity

Diffusive equilibrium in thin films (DET) and diffusive gradients in thin films (DGT) were applied in situ to obtain high spatial resolution dissolved reactive phosphorus (DRP) sediment porewater profiles in two lagoons of the Gippsland Lakes (SE Australia) during summer. Although the DRP depth profiles were different in each lake, highlighting the sensitivity of DRP to the redox state of the sediment spatial DRP variations obtained from DET and DGT showed striking similarities with depth in each lake. Comparison of DRP concentrations obtained from DGT and DET allows an assessment of the reactivity of the sediment. A dynamic numerical model of DGT-induced flux in sediments (DIFS) quantified reactivity kinetics. Sediment response time (Tc) related to sedimentary phosphorus resupply resulting from DGT-induced lowering of the porewater DRP concentration was calculated. Values of Tc ranged from 4128 to 183 400 s and from 55 to 149 400 s for Lakes Victoria and Wellington, respectively. These results indicate the limited capacity of the sediment to quickly resupply DRP to the porewater, especially in surface sediment which was always characterized by the highest Tc. Adsorption and desorption rate constants were also calculated from DIFS with values ranging from 2 x 10(-3) to 2 x 10(-2) day(-1) and from 0.3 to 21 day(-1) for Lake Victoria and from 2 x 10(-4) to 0.8 day(-1) and from 0.6 to 1558 day(-1) for Lake Wellington, respectively. Diffusive fluxes estimated from the in situ DRP gradient at the sediment-water interface by DET were 558 and 1.2 micromol m(-2) day(-1) in lakes Victoria and Wellington, respectively. Despite only a single measurement, these fluxes highlight a substantial contribution of P from the sediment to the water column in summer for Lake Victoria which is likely to contribute to the recurring blooms of blue-green algae. These calculated fluxes obtained with minimal sediment disturbance and high spatial resolution were substantially different (by a factor of 6-180) from other reported values using more conventional quantitative assessments such as diffusive fluxes (from core slicing) and benthic chambers.     

Characterization of iron(III) in organic soils using extended X-ray absorption fine structure spectroscopy

The distribution of different iron (Fe) species in soils, sediments, and surface waters has a large influence on the mobility and availability of Fe, other nutrients, and potentially toxic trace elements. However, the knowledge about the specific forms of Fe that occurs in these systems is limited, especially regarding associations of Fe with natural organic matter (NOM). In this study, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to characterize Fe(III) in organic soils (pH 4.6-6.0) with varying natural Fe content. The EXAFS data were subjected to wavelet transform analysis, to facilitate the identification of the nature of backscattering atoms, and to conventional EXAFS data fitting. The collective results showed the existence of two pools of iron: mononuclear Fe(III)-NOM complexes and precipitated Fe(III) (hydr)oxides. In the soil with lowest pH (4.6) and Fe content mononuclear organic complexes were the completely dominating fraction whereas in soils with higher pH and Fe content increasing amounts of Fe (hydr)oxides were detected. These results are of environmental importance, as the different iron pools most likely have markedly different reactivities.     

Accumulation parameters and seasonal trends for PCBs in temperate and boreal forest plant species

The concentration of polychlorinated biphenyls (PCBs) in the air and vegetation was measured periodically in two alpine forests, during the growing season. Foliage samples from nine plant species typical of the temperate and boreal environment were collected and analyzed. Leaf concentrations of tri- and tetra-CBs showed fast response times with changing temperature and gas-phase concentrations, suggesting that a partitioning equilibrium is approached relatively rapidly (few days) in the field. Heavier compounds showed kinetically limited accumulation trends, not reaching equilibrium during the growing season. Results were used to estimate the bioconcentration factors or equilibrium plant/air partition coefficient (KPA) for each species. Values of log KPA (calculated on a mass/volume basis) ranged between 0.78 and 1.96 and were correlated to the log KOA. Uptake trends of the higher chlorinated compounds showed intraspecific differences which were partially explained by the specific leaf area (SLA).     

Proxies and measurement techniques for mineral dust in Antarctic ice cores

To improve quantitative interpretation of ice core aeolian dust records, a systematic methodological comparison was made. This involved methods for water-insoluble particle counting (Coulter counter and laser-sensing particle detector), soluble ion analysis (ion chromatography and continuous flow analysis), elemental analysis (inductively coupled plasma mass spectroscopy at pH 1 and after full acid digestion), and water-insoluble elemental analysis (proton induced X-ray emission). Antarctic ice core samples covering the last deglaciation from the EPICA Dome C (EDC) and the EPICA Dronning Maud Land (EDML) cores were used. All methods correlate very well among each other, but the ratios of glacial age to Holocene concentrations, which are typically a factor approximately 100, differ between the methods by up to a factor of 2 with insoluble particles showing the largest variability. The recovery of ICP-MS measurements depends on the digestion method and is differentfor different elements and during different climatic periods. EDC and EDML samples have similar dust composition, which suggests a common dust source or a common mixture of sources for the two sites. The analyzed samples further reveal a change of dust composition during the last deglaciation.     

Brown Superfund Basic research Program: a multistakeholder partnership addresses real-world problems in contaminated communities

The NIEHS funds several basic and applied research programs, many of which also require research translation or outreach. This paper reports on a project by the Brown University Superfund Basic Research Program (SBRP), in which outreach and research translation teams collaborated with state regulatory agency personnel and community activists on a legislative initiative to mitigate the financial impacts of living in a contaminated community. The Environmentally Compromised Home Ownership (ECHO) program makes home equity loans of up to $25,000 available to qualified applicants. This collaboration provides a case study in community engagement and demonstrates how research translation and outreach activities that are clearly differentiated yet well-integrated can improve a suite of basic and applied research. Although engaging diverse constituencies can be difficult community-engaged translation and outreach have the potential to make research findings more useful to communities, address some of the social impacts of contamination, and empower stakeholders to pursue their individual and collectively held goals for remediation. The NIEHS has recently renewed its commitment to community-engaged research and advocacy, making this an optimal time to reflect on how basic research programs that engage stakeholders through research translation and outreach can add value to the overall research enterprise.     

Comparison of antimicrobial resistance of Campylobacter jejuni and Campylobacter coli isolated from humans and chicken carcasses in Poland

Campylobacter-associated gastroenteritis remains an important cause of morbidity worldwide, and some evidence suggests that poultry is an important source of this foodborne infection in humans. This study was conducted to analyze the prevalence and genetic background of resistance of 149 Campylobacter jejuni and 54 Campylobacter coli strains isolated from broiler chicken carcasses and from stool samples of infected children in Poland from 2003 through 2005. Nearly all isolates were susceptible to macrolides and aminoglycosides. The highest resistance in both human and chicken strains was observed for ciprofloxacin (more than 40%), followed by ampicillin (13 to 21%), and tetracycline (8 to 29%). Resistance to ampicillin and tetracycline rose significantly between 2003 and 2005. Slight differences in resistance between human and chicken isolates indicate that although chicken meat is not the only source of Campylobacter infection in our population, it can be involved in the transmission of drug-resistant Campylobacter strains to humans.     

Sources of enterococci in Idiazábal-type cheese

Enterococci are a ubiquitous group and are natural constituents of the intestinal flora of nearly all animals and humans and can reach high levels in a variety of farmhouse cheeses. The purpose of this study was to determine the origin of the different enterococcal strains present in cheeses at different stages of ripening by typing the enterococci isolated from the raw milk, the cheeses, the cheesemaking environment, and from the faecal matter of the ewes and humans associated with cheese production. The potential presence of vancomycin-resistant enterococci (VRE) at all stages of the process and in the cheeses was also considered. The study was carried out at two separate cheesemaking dairy plants, and samples of the ewes' faeces, the shepherds' and cheesemakers' stools, teat cups, vat, brine, holding tank milk, vat milk, and the cheeses after brining and after 1, 15, and 60 days of ripening were collected. Cheesemaking procedures at the two plants were similar, yet the enterococcal levels and species observed differed at all the sample collection points, though E. faecalis predominated in all the milk and cheese samples. The traceability study performed for the species E. faecalis present at all the sample collection points suggested that the cheesemaker and the cheesemaking equipment were the source of the enterococci in the cheeses, though other possible non-faecal sources remain to be determined. VanC1 and vanC2/C3 enterococcal strains were isolated from the ovine faeces, teat cup, brine, and vat samples at cheesemaking dairy plant A, while only two vanC2/C3 strains were isolated from ovine faeces samples at dairy plant B. No VRE strains were detected in any of the milk or cheese samples.     

An 8-hour system for Salmonella detection with immunomagnetic separation and homogeneous time-resolved fluorescence PCR

We describe a system consisting of rapid sample enrichment and homogeneous end-point PCR analysis that enables the detection of Salmonella in various food matrices in 8 h. Sample preparation starts with 6 h enrichment step in supplemented broth, after which Salmonella cells are collected with immunomagnetic particles. The particles are washed and dispensed to ready-to-use PCR reaction vessels, which contain dried assay-specific reagents and an internal amplification control. PCR is performed with a novel instrument platform utilising the sensitive label technology of time-resolved fluorometry. Qualitative assay results are automatically interpreted and available in 45 min after sample addition. The overall accuracy, sensitivity and specificity of the Magda CA Salmonella system were 99.1%, 98.4% and 100.0%, respectively, based on the evaluation of 107 samples (beef, pork, poultry and ready-to-eat meals) artificially contaminated with sub-lethally injured Salmonella cells.