In Situ Equilibrium Polyethylene Passive Sampling of Soil Gas VOC Concentrations: Modeling, Parameter Determinations, and Laboratory Testing.

The use of low-density polyethylene (PE) sheets as equilibrium passive soil gas samplers to quantify volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene, and xylenes, and chlorinated solvents (e.g., trichloroethene and tetrachloroethene) in unsaturated subsurface environments was evaluated via modeling and benchtop testing. Two methods were devised to quantify such VOCs in PE. Key chemical properties, including PE-water (KPEw) and PE-air (KPEa) partition coefficients and diffusivities in the PE (Dpe), were determined. These KPEw, KPEa, and Dpe values were consistent with extrapolations of data based on larger compounds. Using these parameter values, field equilibration times of less than 1 day were estimated for such VOCs when using 70-100 µm thick PE sheets. Further, benchtop batch tests carried out in jars filled with VOC-contaminated soils, after 1 or 2 days, showed concentrations in soil air deduced from PE that were consistent with concentrations deduced by analyzing either water or headspace gases recovered from the same tests. Thus, PE-based measurements may overcome inaccuracies from using total soil concentrations and equilibrium partitioning models that may overestimate vapor phase concentrations up to 2 orders of magnitude.

Interlaboratory Study of Polyethylene and Polydimethylsiloxane Polymeric Samplers for Ex Situ Measurement of Freely Dissolved Hydrophobic Organic Compounds in Sediment Porewater.

We evaluated the precision and accuracy of multilaboratory measurements for determining freely dissolved concentrations (Cfree ) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in sediment porewater using polydimethylsiloxane (PDMS) and low-density polyethylene (LDPE) polymeric samplers. Four laboratories exposed performance reference compound (PRC) preloaded polymers to actively mixed and static ex situ sediment for approximately 1 month; two laboratories had longer exposures (2 and 3 months). For Cfree results, intralaboratory precision was high for single compounds (coefficient of variation 50% or less), and for most PAHs and PCBs interlaboratory variability was low (magnitude of difference was a factor of 2 or less) across polymers and exposure methods. Variability was higher for the most hydrophobic PAHs and PCBs, which were present at low concentrations and required larger PRC-based corrections, and also for naphthalene, likely due to differential volatilization losses between laboratories. Overall, intra- and interlaboratory variability between methods (PDMS vs. LDPE, actively mixed vs. static exposures) was low. The results that showed Cfree polymer equilibrium was achieved in approximately 1 month during active exposures, suggesting that the use of PRCs may be avoided for ex situ analysis using comparable active exposure; however, such ex situ testing may not reflect field conditions. Polymer-derived Cfree concentrations for most PCBs and PAHs were on average within a factor of 2 compared with concentrations in isolated porewater, which were directly measured by one laboratory; difference factors of up to 6 were observed for naphthalene and the most hydrophobic PAHs and PCBs. The Cfree results were similar for academic and private sector laboratories. The accuracy and precision that we demonstrate for determination of Cfree using polymer sampling are anticipated to increase regulatory acceptance and confidence in use of the method. Environ Toxicol Chem 2022;41:1885-1902. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Adsorption of Organic Compounds to Diesel Soot: Frontal Analysis and Polyparameter Linear Free-Energy Relationship.

Black carbons (BCs) dominate the sorption of many hydrophobic organic compounds (HOCs) in soils and sediments, thereby reducing the HOCs' mobilities and bioavailabilities. However, we do not have data for diverse HOCs' sorption to BC because it is time-consuming and labor-intensive to obtain isotherms on soot and other BCs. In this study, we developed a frontal analysis chromatographic method to investigate the adsorption of 21 organic compounds with diverse functional groups to NIST diesel soot. This method was precise and time-efficient, typically taking only a few hours to obtain an isotherm. Based on 102 soot-carbon normalized sorption coefficients (KsootC) acquired at different sorbate concentrations, a sorbate-activity-dependent polyparameter linear free-energy relationship was established: logKsootC = (3.74 ± 0.11)V + ((-0.35 ± 0.02)log ai)E + (-0.62 ± 0.10)A + (-3.35 ± 0.11)B + (-1.45 ± 0.09); (N = 102, R(2) = 0.96, SE = 0.18), where V, E, A, and B are the sorbate's McGowan's characteristic volume, excess molar refraction, and hydrogen acidity and basicity, respectively; and ai is the sorbate's aqueous activity reflecting the system's approach to saturation. The difference in dispersive interactions with the soot versus with the water was the dominant factor encouraging adsorption, and H-bonding interactions discouraged this process. Using this relationship, soot-water and sediment-water or soil-water adsorption coefficients of HOCs of interest (PAHs and PCBs) were estimated and compared with the results reported in the literature.

Hydrophobic meshes for oil spill recovery devices.

Widespread use of petrochemicals often leads to accidental releases in aquatic environments, occasionally with disastrous results. We have developed a hydrophobic and oleophilic mesh that separates oil from water continuously in situ via capillary action, providing a means of recovering spilt oil from surface waters. Steel mesh is dip-coated in a xylene solution of low-density polyethylene, creating a hydrophobic surface with tunable roughness and opening size. The hydrophobic mesh allows oil to pass through the openings while preventing the concomitant passage of water. A bench-top prototype demonstrated the efficacy of such an oil recovery device and allowed us to quantify the factors governing the ability of the mesh to separate oil and water. Preliminary data analysis suggested that the oleophilic openings behave somewhat like capillary tubes: the oil flux is inversely proportional to oil viscosity, and directly proportional to the size of the mesh openings. An unpinned meniscus model was found to predict the water intrusion pressure successfully, which increased as the opening size decreased. The trade-off between water intrusion and oil flow rate suggests an optimal pore size for given oil properties and sea conditions.

Other physical consequences of disability.

Prevention of secondary complications of neurological disease is important in minimizing impairment and maximizing the long-term activity and participation of individuals. Immobility in itself has a range of adverse effects on the body and its functioning, which are outlined. A number of complications commonly encountered in the rehabilitation of individuals after neurological disease are discussed in more detail: osteoporosis, pressure ulcers, venous thromboembolism, and heterotopic ossification. For each of these, definitions/classifications, prevalence/incidence rates, diagnosis, prevention, and management are discussed. Every effort is made to provide information specific to the rehabilitation of neurological conditions and the evidence base behind practice is emphasized, with up-to-date references. Nutrition has also been shown to affect functional outcomes in a number of neurological conditions and the main issues in the rehabilitation setting are outlined. Tremor and ataxia are significant causes of limitation of activity and participation in individuals affected, and assessment and management of these are briefly discussed.

Showers, sweating and suing: Legionnaires' disease and 'new' infections in Britain, 1977-90.

Legionnaires' disease is now routinely discussed as an 'emerging infectious disease' (EID) and is said to be one of the earliest such diseases to be recognised. It first appeared in 1976 and its cause was identified in 1977, the same year that Ebola fever, Hantaan virus and Campylobacter jejuni arrived. The designation of Legionnaires' disease as an EID was retrospective; it was not and could not be otherwise as the category only gained currency in the early 1990s. In this article we reflect on the changing medical understanding and social profile of Legionnaires' disease in the decade or so from its recognition to the creation of EIDs, especially its ambivalent position between public health and clinical medicine. However, we question any simple opposition, between public health experts who approached Legionnaires' disease as a new and worrying environmental threat that could be prevented, and clinicians who saw it as another cause of pneumonia that could be managed by improved diagnosis and treatment. We argue that in the British context of public spending cuts and the reform of public health, the category of 'new' diseases, in which Legionnaires' disease was central, was mobilised ahead of the EID lobby of the early 1990s, by interested groups in medicine to defend infectious diseases services.

Comparison of polymeric samplers for accurately assessing PCBs in pore waters.

Assessing the hazard posed by sediments contaminated with hydrophobic organic compounds is difficult, because measuring the freely dissolved porewater concentrations of such low-solubility chemicals can be challenging, and estimating their sediment-water partition coefficients remains quite uncertain. We suggest that more accurate site assessments can be achieved by employing sampling devices in which polymers, with known polymer-water partition coefficients, are used to absorb the contaminants from the sediment. To demonstrate the current accuracy and limitations of this approach, we compared use of three polymers, polydimethylsiloxane, polyoxymethylene, and polyethylene, exposed to a single sediment in two modes, one in which they were exhaustively mixed (tumbled) with the sediment and the other in which they were simply inserted into a static bed (passive). Comparing porewater concentrations of specific polychlorinated biphenyl (PCB) congeners with results obtained using air bridges, we found the results for tumbled polymers agreed within 20%, and the passive sampling agreed within a factor of 2. In contrast, porewater estimates based on sediment concentrations normalized to f(OC)K(OC), the weight fraction of organic carbon times the organic-carbon normalized partition coefficient, averaged a factor of 7 too high. We also found good correlations of each polymer's uptake of the PCBs with bioaccumulation by the polychaete, Neanthes arenaceodentata. Future improvements of the passive sampling mode will require devices that equilibrate faster and/or have some means such as performance reference compounds to estimate mass transfer limitations for individual deployments.

Effects of change in rectal cancer management on outcomes in British Columbia.

BACKGROUND: In a province-wide audit of patients undergoing treatment for rectal cancer in British Columbia in 1996, the 4-year rate of pelvic recurrence for stage 3 rectal cancer was 27%. The management guidelines were changed in 2002 to include adjuvant short-course preoperative radiation and total mesorectal excision surgical techniques. Education workshops were held to implement the protocol change. METHODS: We performed a provincial audit of rectal cancer cases for patients treated in the year after the protocol change, and we compared the pelvic recurrence rates with those from the audit performed in 1996. RESULTS: During a 12-month period beginning Oct. 1, 2003, a total of 367 patients underwent radical resection of rectal cancer with a curative intent. Preoperative adjuvant radiotherapy was used in 54% of cases (197/367). Median follow-up was 34.5 months, and 91% of patients were followed for at least 2 years. Relative to the 1996 cohort, there was a decreasing trend in 2-year overall pelvic recurrence rates in the 2003/04 cohort (9.6% v. 6.9%) and a significant decrease in recurrence among patients with stage 3 cancers (18.2% v. 9.2%; p = 0.020). Use of adjuvant radiation increased significantly (37% v. 65%; p < 0.001), and negative radial margins were achieved in 87% (319/367) of cases. CONCLUSION: The rates of pelvic recurrence were improved after changes in the management guidelines advocating increased use of total mesorectal excision surgery and preoperative radiation. Knowledge translation with an integrated strategy among surgeons and medical and radiation oncologists was successful in improving population outcomes among patients with rectal cancer.

Measurement of freely dissolved PAH concentrations in sediment beds using passive sampling with low-density polyethylene strips.

To assess hydrophobic organic chemical (HOC) contamination in sediments, a method was developed using polyethylene (PE) passive samplers inserted directly in the intact sediment beds to measure freely dissolved HOC concentrations. Performance reference compounds (PRCs: d10-phenanthrene, d10-pyrene, and d12-chrysene), impregnated into the PE before use, allowed porewater concentrations to be deduced after exposure times much shorter than would be required for sampler equilibration (days instead of months). Three diverse sediments were used in the laboratory, and PE-deduced porewater concentrations of six native PAHs (phenanthrene, anthracene, fluoranthene, pyrene, benz(a)anthracene, and chrysene) matched results from air-bridge testing and from direct porewater extractions after correcting for colloid effects. PE strips, deployed from a boat in Boston Harbor, yielded concentrations that were like those measured in porewaters from a sediment core collected nearby. Notably, equilibrium partitioning (EqP) estimates were always much higher (up to 100x) than those measured using the other methods, suggesting the large inaccuracy of that approach. Hence, PE passive sampling appears to greatly improve the accuracy of assessing the hazards posed by compounds like PAHs in sediment beds.

Polyethylene devices: passive samplers for measuring dissolved hydrophobic organic compounds in aquatic environments.

We demonstrate the use of polyethylene devices (PEDs) for assessing hydrophobic organic compounds (HOCs) in aquatic environments. Like semipermeable membrane devices (SPMDs) and solid-phase microextraction (SPME), PEDs passively accumulate HOCs in proportion to their freely dissolved concentrations. Polyethylene-water partition constants (K(PEW)S) were measured in the laboratory for eight polycyclic aromatic hydrocarbons (PAHs), five polychlorinated biphenyls (PCBs), and one polychlorinated dibenzop-dioxin (PCDD), and these were found to correlate with octanol-water partition constants (K(OW)s; log K(PEW) = 1.13 log K(OW) - 0.86, R2 = 0.89). Temperature and salinity dependencies of K(PEW) values for the HOCs tested were well predicted with excess enthalpies of solution in water and Setschenow constants, respectively. We also showed that standards, impregnated in the PED before deployment, can be used to correct for incomplete equilibrations. Using PEDs, we measured phenanthrene and pyrene at ng/L concentrations and 2,2',5,5'-tetrachlorobiphenyl at pg/L concentrations in Boston Harbor seawater, consistent with our findings using traditional procedures. PEDs are cheap and robust samplers, competent to accomplish in situ, time-averaged passive sampling with fast equilibration times (approximately days) and simplified laboratory analyses.

An 18-year review of open and laparoscopic splenectomy for idiopathic thrombocytopenic purpura.

BACKGROUND: Laparoscopic splenectomy has become the preferred surgical procedure for the management of idiopathic thrombocytopenic purpura (ITP). However, there studies have directly compared the incidence of recurrent ITP secondary to missed accessory spleens in open versus laparoscopic splenectomy. METHODS: Open and laparoscopic splenectomies performed for ITP at 4 sites over 18 years were analyzed. The incidence of recurrent disease secondary to missed accessory spleens was compared between the open and laparoscopic splenectomy groups. RESULTS: A total of 105 splenectomies (54 open/51 laparoscopic) were performed. Accessory spleens were identified in 6 laparoscopic and 6 open cases (P = .57). Recurrent disease occurred in 27.6% of open and 14.6% of laparoscopic cases (P = .222). There were no cases of recurrent ITP secondary to a missed accessory spleen in either group. CONCLUSIONS: The incidence of missed accessory spleens causing recurrent disease is similar when splenectomy is performed either open or laparoscopically.

Ferrous iron oxidation rates in the pycnocline of a permanently stratified lake.

Ferrous iron was found year round at 2-4 mM in the anoxic hypolimnion of the Halls Brook Holding Area (HBHA), a small lake in eastern Massachusetts. Oxygenated epilimnion waters always had total iron concentrations of <80 nanomolar, implying nearly complete oxidation of ferrous iron as it mixed upward across the lake's pycnocline. Assuming conductivity was a conservative parameter, and using data on the lake's water balance, upward advection rates (0.02-0.05 m d(-1)) and vertical eddy diffusion coefficients (0.007-0.05 m2 d(-1)) were determined for the lake's pycnocline on five dates. Using the same advection and diffusion parameters, corresponding pseudo first-order rate coefficients for ferrous iron oxidation, k(ox) (s(-1)), on those dates were calculated (0.0004-0.007 s(-1)). The values of k(ox) (s(-1)) were always too large to reflect only homogeneous solution reactions; and on at least four dates they appeared too fast to be due to heterogeneous catalysis on iron oxyhydroxides. This suggested that ferrous iron oxidation in this lake's pycnocline was primarily due to catalysis by microorganisms, and this was supported by comparison of azide-poisoned vs. untreated batch tests. As a result of their continuous production, iron oxyhydroxide precipitates and any associated sorbates/coprecipitates are most likely continuously settling back into the lake's deep water and bed sediments, except when episodic storm events flush these solids out of the pycnocline and downstream via the Aberjona River.

Disseminated Mycobacterium tuberculosis infection due to interferon gamma deficiency. Response to replacement therapy.

The case of a previously healthy HIV seronegative woman with disseminated Mycobacterium tuberculosis infection and markedly reduced interferon gamma production is reported here. Complete healing of her disseminated lesions was seen only after addition of subcutaneous interferon gamma to her tuberculosis treatment.