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.

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.

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.

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.

Effect of emergent presentation on outcome from rectal cancer management.

BACKGROUND: We have previously reported outcomes for all rectal cancers in BC in 1996. We found that our local recurrence rates and survival were suboptimal relative to current standards in recent literature. METHODS: In this retrospective, population-based study, we report the influence of emergent presentation (obstruction, perforation, massive hemorrhage) on outcomes, types of surgical procedures and use of staging investigations, and use of adjuvant radiation and chemotherapy. RESULTS: There were 452 invasive adenocarcinomas of the rectum of which 45 were emergent and 407 nonemergent. Disease-specific survival at 4 years for emergent and nonemergent stage II cancers were 66% versus 80%, respectively, and for stage III cancers, 60% versus 73%, respectively (P <0.04). Local recurrence rates at 4 years for emergent and nonemergent stage II cancers were 20% versus 15%, respectively, and for stage III cancers, 70% and 20%, respectively (P <0.05). Surgical resection more frequently involved a stoma for emergent (60%) than for nonemergent (35%) cases (P <0.01). Percent of patients having complete staging investigations were similar between emergent (42%) and nonemergent patients (39%). Adjuvant radiation was given in similar proportion to emergent (61%) and nonemergent (55%) patients. Adjuvant chemotherapy was given to a slightly higher proportion of emergent patients (63%) than nonemergent patients (43%). CONCLUSIONS: We conclude that outcome from rectal cancer management is worse for emergent than nonemergent presentation. Since there is no difference in use of staging investigations or adjuvant therapy, the difference in outcome is likely due to difference in surgical technique between emergent and nonemergent cases.

Effects of positive resection margin and tumor distance from anus on rectal cancer treatment outcomes.

PURPOSE: Rectal cancer outcome depends on stage, technical aspects of surgical excision, and use of adjuvant chemoradiation. Here, we examine effects of positive resection margin and tumor distance from the anus in stage 2 and 3 cancers on 4-year disease-specific survival and recurrence. METHODS: We reviewed all 495 rectal cancer patients registered in British Columbia in 1996. RESULTS: There were 481 cases analyzed: 29 in situ, 134 stage 1, 107 stage 2, 100 stage 3, 83 stage 4, and 28 unknown stage. Survival was significantly affected by presence of positive resection margin in stage 2 and 3 cancers, P = 0.0001. Lower tumor distance from the anus for stage 2 and 3 cancers worsened survival, P = 0.0007, and overall recurrence, P =0.016, but not local recurrence, P = 0.11. Adjuvant postoperative combined radiation and chemotherapy in stage 2 and 3 cancers significantly improved survival, P = 0.070 and local recurrence, P = 0.018, but not overall recurrence, P = 0.19. CONCLUSIONS: Presence of positive resection margin and tumor distance from the anus affect survival, local recurrence, and overall recurrence. Adjuvant postoperative combined radiation and chemotherapy improved our outcomes. Our local recurrence rates for rectal cancers are worse than currently reported standards of less than 10%. Improved surgical excision and use of adjuvant preoperative radiation and chemotherapy may improve outcome.

Dependency of polychlorinated biphenyl and polycyclic aromatic hydrocarbon bioaccumulation in Mya arenaria on both water column and sediment bed chemical activities.

The bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) by the filter-feeding soft-shell clam Mya arenaria was evaluated at three sites near Boston (MA, USA) by assessing the chemical activities of those hydrophobic organic compounds (HOCs) in the sediment bed, water column, and organisms. Polyethylene samplers were deployed to measure the activities of HOCs in the water column. Sediment activities were assessed by normalizing concentrations with sediment-water sorption coefficient values, including adsorption to black carbon in addition to absorption by organic carbon. Likewise, both lipids and proteins were considered in biota-water partition coefficients used to estimate chemical activities in the animals. Chemical activities of PAHs in M. arenaria were substantially less than those of the corresponding bed sediments in which they lived. In contrast, chemical activities of PCBs in M. arenaria often were greater than or equal to activities in the corresponding bed sediments. Activities of PAHs, such those of pyrene, in the water column were undersaturated relative to the sediment. However, some PCBs, such as congener 52, had higher activities in the water column than in the sediment. Tissue activities of pyrene generally were in between the sediment and water column activities, whereas activity of PCB congener 52 was nearest to water column activities. These results suggest that attempts to estimate bioaccumulation by benthic organisms should include interactions with both the bed sediment and the water column.

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.

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.

Presidential address, 2001. Advice to young surgeons.

In his 2001 presidential address to the Canadian Association of General Surgeons, the author offers advice to young surgeons, based on his lifetime experience as a surgical educator, researcher and practitioner. He offers the following samples of wisdom for young surgeons: they should be prepared for a lifetime of learning and be willing and able to adapt to new advances; they should listen to their patients as they describe their presenting complaints and not be tempted to interrupt; they should take time in an emergency situation and remember that split-second decisions can affect the patient for a lifetime; they should be willing to take advice from fellow professionals; they should take time to maintain a quality family life and take adequate time away from the workplace; they should be active be a role model in their community; and, finally, they should get involved and adopt an advocacy role in their profession.

Effect on biopsy technique of the breast imaging reporting and data system (BI-RADS) for nonpalpable mammographic abnormalities.

OBJECTIVE: To determine if the breast imaging reporting and data system (BI-RADS) defines a group of patients with mammographic abnormalities in whom stereotactic core needle biopsy (SCNB) is appropriate. DESIGN: A blinded retrospective validation sample. SETTING: A university-affiliated hospital. PATIENTS: One hundred and nine consecutive patients who underwent fine-wire localization breast biopsy (FWLB) between Jan. 1, 1994, and June 1, 1999, with a known final pathological diagnosis. INTERVENTION: Blinded mammographic review and classification using the BI-RADS; review of corresponding pathological findings from FWLBs. OUTCOME MEASURES: Correlation of pathological findings with each BI-RADS category and analysis of the predictive value of clinical and radiologic features. RESULTS: BI-RADS findings were as follows: 0 malignant lesions in 10 category 3 cases, 18 malignant lesions (3 in situ, 15 invasive) in 68 category 4 cases and 24 malignant lesions (8 in situ and 16 invasive) in 31 category 5 cases. There was 1 malignant lesion in 22 category 4 cases in women younger than 50 years. CONCLUSIONS: SCNB should be applied to BI-RADS categories 3 and 4 (< 50 yr of age). FWLB should be reserved for category 4 (> 50 yr of age) and category 5 cases. This algorithm will reduce the morbidity and cost of breast biopsies in patients with nonpalpable mammographic abnormalities.