Facility Volume and Changing Facilities for Postoperative Radiotherapy in Salivary Gland Cancer.

OBJECTIVES: Changing location of postoperative radiotherapy (PORT) after treatment at a high-volume facility (HVF) is associated with worse survival in various head and neck cancers. Our study investigates this relationship in salivary gland cancer (SGC). METHODS: The 2004-2016 National Cancer Database was queried for all cases of adult SGC treated with surgery and PORT with or without adjuvant chemotherapy. Patients with multiple cancer diagnoses, metastatic disease, or unknown PORT facility were excluded. Reporting facilities with >95th percentile annual case volume were classified as HVFs, the remainder were classified low-volume facilities (LVFs). RESULTS: A total of 7885 patients met inclusion criteria, of which 418 (5.3%) were treated at an HVF. Patients treated at an HVF had higher rates clinical nodal positivity (18.2% vs. 14.0%, p < 0.001) and clinical T3/T4 (27.3% vs. 20.7%, p = 0.001) disease. Patients at HVFs changed facility for PORT at lower rates (18.9% vs. 24.5%, p = 0.009). Patients treated at an HVF had higher 5-year overall survival (5-OS) than those treated at an LVF (79.0% vs. 72.0%, p = 0.042). Patients treated at an HVF that changed PORT facility had worse 5-OS (60.8% vs. 83.2%, p < 0.001). Radiation facility change was an independent predictor of worse survival in patients treated at an HVF (HR: 8.99 [3.15-25.67], p < 0.001) but not for patients treated at a LVF (HR: 1.11 [0.98-1.25], p = 0.109). CONCLUSIONS: Patients treated at an HVF changing facility for PORT for SGC experience worse survival. Our data suggest patients treated surgically at an HVF should be counseled to continue their PORT at the same institution. LEVEL OF EVIDENCE: 3 Laryngoscope, 2024.

Endoluminal Sigmoid Sinus Occlusion During Jugular Foramen Tumor Surgery: Novel Technique, Operative Nuances, and Clinical Experience With 33 Patients.

BACKGROUND AND IMPORTANCE: Surgery of jugular foramen tumors (JFTs) often requires vascular control by means of ligating the internal jugular vein and sigmoid sinus (SS) to allow intrabulbar access. Occlusion of the SS traditionally involves presigmoid and retrosigmoid durotomies allowing introduction of ligature devices, predisposing to cerebrospinal fluid (CSF) leakage and pseudomeningoceles. We describe a simple and novel endoluminal sigmoid sinus occlusion (ESSO) technique with Gelfoam that is entirely extradural. CLINICAL PRESENTATION: An extended anterolateral infralabyrinthine approach with ESSO was performed in 33 patients with JFTs. After ligating the internal jugular vein, the SS is opened and Gelfoam is placed endoluminally into the proximal SS. Care is taken to avoid occlusion of the venous outflow of the vein of Labbe to avoid temporal lobe venous infarction. Hemostatic gelatin matrix is injected distally to stop venous backflow from the inferior petrosal sinus. The jugular venous system is isolated, and the outer jugular wall can be opened to expose the JFT for resection. There were no complications of temporal lobe venous infarction or postoperative hematoma observed. Four patients with intradural tumor extension developed pseudomeningoceles. For patients with purely extradural JFTs, none developed postoperative incisional CSF leaks and one had pseudomeningocele. CONCLUSION: This ESSO technique is fast and effective, permitting occlusion of the SS during JFT surgery. It has the advantage of being entirely extradural, avoiding durotomy which can result in postoperative CSF leak. It is important to keep the Gelfoam distal to the transverse-sigmoid junction to avoid occlusion of the vein of Labbe inlet and temporal lobe venous infarction.

Bacterial diversity and composition on the rinds of specific melon cultivars and hybrids from across different growing regions in the United States.

The goal of this study was to characterize the bacterial diversity on different melon varieties grown in different regions of the US, and determine the influence that region, rind netting, and variety of melon has on the composition of the melon microbiome. Assessing the bacterial diversity of the microbiome on the melon rind can identify antagonistic and protagonistic bacteria for foodborne pathogens and spoilage organisms to improve melon safety, prolong shelf-life, and/or improve overall plant health. Bacterial community composition of melons (n = 603) grown in seven locations over a four-year period were used for 16S rRNA gene amplicon sequencing and analysis to identify bacterial diversity and constituents. Statistically significant differences in alpha diversity based on the rind netting and growing region (p < 0.01) were found among the melon samples. Principal Coordinate Analysis based on the Bray-Curtis dissimilarity distance matrix found that the melon bacterial communities clustered more by region rather than melon variety (R2 value: 0.09 & R2 value: 0.02 respectively). Taxonomic profiling among the growing regions found Enterobacteriaceae, Bacillaceae, Microbacteriaceae, and Pseudomonadaceae present on the different melon rinds at an abundance of ≥ 0.1%, but no specific core microbiome was found for netted melons. However, a core of Pseudomonadaceae, Bacillaceae, and Exiguobacteraceae were found for non-netted melons. The results of this study indicate that bacterial diversity is driven more by the region that the melons were grown in compared to rind netting or melon type. Establishing the foundation for regional differences could improve melon safety, shelf-life, and quality as well as the consumers' health.

Ultrahigh Areal Capacity Li Electrodeposition at Metal-Solid Electrolyte Interfaces under Minimal Stack Pressures Enabled by Interfacial Na-K Liquids.

The need for higher energy density rechargeable batteries has generated interest in metallic electrodes paired with solid electrolytes. However, impedance growth at the Li metal-solid electrolyte interface due to void formation during cycling at practical current densities and areal capacities, e.g., greater than 0.5 mA cm-2 and 1.5 mAh cm-2 respectively, remains a significant barrier. Here, we show that introducing a wetting interfacial film of Na-K liquid between the Li metal and the Li6.75La3Zr1.75Ta0.25O12 (LLZTO) solid electrolyte permits reversible stripping and plating of up to 150 µm of Li (30 mAh cm-2), approximately 10 times the areal capacity of today's lithium-ion batteries, at current densities above 0.5 mA cm-2 and stack pressures below 75 kPa, all with minimal changes in cell impedance. We further show that this increase in the accessible areal capacity at high stripping current densities is due to the presence of Na-K liquid at the Li stripping interface; this performance improvement is not enabled in the absence of the Na-K liquid. This design approach holds promise for overcoming interfacial stability issues that have heretofore limited the performance of solid-state metal batteries.

Elective Neck Dissection for cT1-4 N0M0 Head and Neck Verrucous Carcinoma.

OBJECTIVE: To investigate the survival benefit of elective neck dissection (END) over neck observation in cT1-4 N0M0 head and neck verrucous carcinoma (HNVC). STUDY DESIGN: Retrospective cohort study. SETTING: The 2006 to 2017 National Cancer Database. METHODS: Patients with surgically resected cT1-4 N0M0 HNVC were selected. Linear, binary logistic, Kaplan-Meier, and Cox proportional hazards regression models were utilized. RESULTS: Of 1015 patients satisfying inclusion criteria, 223 (22.0%) underwent END. The majority of patients were male (55.4%) and white (91.0%) with disease of the oral cavity (67.6%) classified as low grade (90.0%) and cT1-2 (81.8%). The minority of ENDs (4.0%) detected occult nodal metastases. The rate of END increased from 2006 to 2017 for both cT1-2 (16.3% vs 22.0%, p = .126, R2 = 0.405) and cT3-4 (41.7% vs 70.0%, p = .424, R2 = 0.232) disease but these trends were not statistically significant. Independent predictors of undergoing END included treatment at an academic facility (adjusted odds ratio [aOR]: 1.75, 95% confidence interval [CI]: 1.19-2.55), cT3-4 disease (aOR: 3.31, 95% CI: 2.16-5.07), and tumor diameter (aOR: 1.09, 95% CI: 1.01-1.19) (p < 0.05). The 5-year overall survival (OS) of patients treated with and without END was 71.3% and 70.6%, respectively (p = .661). END did not significantly reduce the 5-year hazard of death (adjusted hazard ratio: 1.25, 95% CI: 0.91-1.71, p = .172). END did not significantly improve 5-year OS in univariate and multivariate analyses stratified by several patient, facility, tumor, and treatment characteristics. CONCLUSION: END does not confer an appreciable survival benefit in HNVC, even after stratifying univariate and multivariate analyses by several patient, facility, tumor, and treatment characteristics. LEVEL OF EVIDENCE: Level 4.

Effect of obesity on outcomes after open laryngeal surgery including total laryngectomy: A NSQIP database analysis.

BACKGROUND: The impact of obesity on outcomes after open laryngeal surgery has not been well-described. METHODS: The NSQIP database was queried for all open laryngeal surgeries including total laryngectomies between 2005 and 2018. Outcomes of patients identified as obese or nonobese by BMI were compared. RESULTS: Of 1865 patients, 20.1% classified as obese. The most common operation performed was total laryngectomy with or without radical neck dissection (73.2%). Operation time and length of hospital stay were significantly less for obese patients. On multivariate analysis, obesity was associated with less bleeding transfusions occurrences (aOR, 0.395, p = 0.0052), surgical complications (aOR, 0.604, p < 0.001), and any complication (aOR, 0.730, p = 0.0019). CONCLUSION: Though there may be an inverse association of obesity with complications and bleeding transfusion occurrences, as well as decreased operation time and length of hospital stay, several confounders and bias may exist; therefore, it is difficult to conclude that the obesity paradox is present.

Assessing the Association Between Time to Surgery and Survival in Sinonasal Squamous Cell Carcinoma.

INTRODUCTION: To assess the association between time to surgery (TTS) and survival in sinonasal squamous cell carcinoma patients (SSCC). METHODS: We queried the 2004-2016 National Cancer Database for all cases of adult SSCC undergoing primary surgical treatment. Patients with missing TTS information were excluded. We conducted a multivariate analysis of patient demographic and clinicopathological characteristics' effect on overall survival (OS) using a Cox proportional hazards model enhanced with cubic spline non-linear approximation. Bootstrapping methods were utilized to detect the aggregate risk of TTS delay on patient OS. RESULTS: A total of 2,881 patients met the inclusion criteria. The majority of patients were male (63.5%), White (86.3%), and over the age of 60 (58.4%). Parametric cubic spline approximation Cox hazard model detected a non-linear association between patient OS and TTS below 30 days with the lowest risk occurring at 18 days and steadily increasing subsequently. To analyze the aggregate risk and identify the optimal TTS cut-off after 30 days of surgical delay, the cohort sample was bootstrapped and dichotomized. The largest increase in aggregated risk was identified at 59 days (Hazards Ratio [HR] = 1.006 [0.839-1.084], p = 0.003). 60 days were used as the optimal TTS cut-off for analyzing the survival rate using the Cox proportional hazard model. Undergoing surgery within 60 days translated to a 14.6% decreased chance of death (HR: 0.854 [0.83-0.96]). CONCLUSIONS: Increasing TTS is associated with worse overall survival in patients with SSCC. Our study suggests that surgery should be done within 60 days to achieve optimal survival results. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:3389-3395, 2023.

Opioid prescription trends among American Head and Neck Society fellowship graduates.

BACKGROUND: Opioids are commonly used to manage the pain of head and neck (HN) cancer patients. METHODS: Retrospective cohort of graduates from American Head and Neck Society accredited fellowships from 1997 to 2018. The Center for Medicare and Medicaid Services Part D Provider Utilization and Payment database 2014-2019 was cross-referenced with provider names to identify opioid prescription trends. RESULTS: From 2014 to 2019, there was no significant difference in the average number of opioid beneficiaries per provider (18.02 vs. 18.10, p = 0.586) or opioid claims per provider (28.06 vs. 26.73, p = 0.708). The average total opioid day supply per beneficiary declined from 11.09 to 7.05 days from 2014 to 2019 (p < 0.001). In 2019, providers in the Northeast had the lowest prescribed opioid day supply (3.67 days) compared to those from the South who had the highest (10.32 days). CONCLUSIONS: Opioid prescription length has significantly declined among HN surgeons, with variations across geographic regions.

Adjuvant Radiation and Survival Following Surgical Resection of Sinonasal Adenocarcinoma.

OBJECTIVES: This study aims to investigate the utility of adjuvant radiation in patients who undergo surgical resection for the management of node-negative sinonasal adenocarcinoma (SNAC). STUDY DESIGN: Retrospective database review. METHODS: The 2004-2016 National Cancer Data Base (NCDB) was used to extract patients with surgically resected node-negative SNAC. Kaplan-Meier survival analysis and Cox-Proportional Hazards Modelling were used to analyze the impact of adjuvant radiation on overall survival (OS) following surgery. RESULTS: 349 patients with SNAC underwent surgical resection. Of these patients, 154 (44.1%) received adjuvant radiotherapy (RT). Although there was no significant difference in race, age, or sex of those receiving RT, those receiving RT have more advanced diseases and are more likely to have positive margins. Kaplan Meier analysis showed no significant difference in 5-year OS in patient who received adjuvant RT in comparison to those who underwent surgical resection alone (65.7% vs. 72.6%, respectively; p = 0.378). In addition, when looking at only patients with positive margins, 5-year OS still did not have a significant difference (73.8% vs. 61.6%, respectively; p = 0.101). Only patients with clinical AJCC T4 showed a statistically significant survival benefit with adjuvant RT (56.9% vs. 29.9%, respectively; p = 0.009). CONCLUSIONS: Adjuvant RT does not appear to provide a significant survival benefit in patients with resected SNAC, with the exception of those with clinically AJCC T4 disease. LEVEL OF EVIDENCE: 4 Laryngoscope, 133:2603-2612, 2023.

Nagging Pain and Foot Ulcers Can be Treated into Remission.

Lower extremity ulcerations are very common in patients with diabetes. These wounds lead to amputation in a surprisingly large percentage of patients with diabetes. The mortality rate following amputation in a patient with diabetes is alarmingly high. Preventive treatment is pivotal to avoid the numerous complications associated with diabetic ulcerations. However, at the onset of ulceration, early treatment under the supervision and guidance of a specialist can result in remission. Diabetic peripheral neuropathy is also a life-altering and debilitating disease. Although some patients experience numbness, some experience pain that can be sharp, shooting, and tingling. Although treatment is challenging and often requires medication, newer modalities, such as stimulation and physical therapy, have shown promise in reversing the devastating effects of peripheral neuropathy.

Utility of Elective Neck Dissection in Clinically Node-Negative Parotid Malignancy.

OBJECTIVE: We sought to investigate the utility of elective neck dissection (END) in clinically node-negative parotid malignancy through the evaluation of factors that are associated with receiving END and survival analysis of patients who received END. STUDY DESIGN: Retrospective cohort database study. SETTING: The National Cancer Database (NCDB). METHODS: The NCDB was used to extract patients with clinically node-negative parotid malignancy. END was defined as having 5 or more lymph nodes examined pathologically, as previously defined in the literature. Univariate and multivariate analyses were used to compare predictors of receiving END, rates of occult metastasis, and survival. RESULTS: Of the 9405 included patients, 3396 (36.1%) underwent an END. END was most frequently performed for squamous cell carcinoma (SCC) and salivary duct histology. All other histologies were significantly less likely to undergo END compared to SCC (p < .05). Salivary ductal carcinoma and adenocarcinoma had the greatest rates of occult node disease (39.8% and 30.0%, respectively), followed by SCC (29.8%). Kaplan-Meier survival analysis showed a statistically significant increase in 5-year overall survival in patients who received END with poorly differentiated mucoepidermoid (56.2% vs 48.5%, p = .004) along with moderately and poorly differentiated SCC (43.2% vs 34.9%, p = .002; 48.9% vs 36.2%, p < .001, respectively). CONCLUSION: Histological classification is a benchmark for determining which patients should receive an END. We demonstrated an increase in overall survival in patients who undergo END with poorly differentiated tumors of mucoepidermoid and SCC histology. As such, histology should be considered along with clinical T-stage and rate of occult nodal metastasis to determine eligibility for END.

Facility volume and survival: Human papilloma virus positive oropharyngeal squamous cell carcinoma.

BACKGROUND: To analyze the impact of facility volume on survival for human papilloma virus positive oropharyngeal squamous cell carcinoma (HPV+ OPSCC) patients. METHODS: Patients treated for HPV+ OPSCC from 2010 to 2017 were queried from the National Cancer Database. Facilities of average annual case volume <50th percentile were categorized as low-volume (LV) and >95th percentile as high-volume (HV). RESULTS: 11,546 were included, with 10,305 patients (89.3 %) treated at LV and 1241 (10.7 %) at HV facilities. A greater proportion of cases involving resection of base of tongue and lingual tonsil were treated at HV (30.3 %) compared to LV (22.3 %) facilities (p < 0.001). Patients treated at a HV facility had greater percentage of clinical T4 (11.2 % vs. 8.6 %, p = 0.001) and N+ disease (90.5 % vs. 85.7 %, p < 0.001) patients. Survival analysis showed no statistically significant difference between five-year overall survival rates by facility volume (p = 0.388) for all patients. On multivariable analysis, facility volume was not associated with survival (HR: 0.968 [0.758-1.235], p = 0.791). These trends were found for both patients undergoing primary surgery or chemoradiotherapy. CONCLUSION: Our data indicates that patients with HPV+ OPSCC do not experience a survival benefit with treatment at HV facility, suggesting these patients may be adequately treated at LV centers.

Extent of Surgery for Follicular Thyroid Carcinoma.

OBJECTIVES: To examine the association between the extent of surgery and overall survival in follicular thyroid cancer (FTC) patients. STUDY DESIGN: Retrospective analysis of the National Cancer Database (NCDB). METHODS: Patients who underwent surgical intervention for FTC from 2004 to 2015 were selected. Patients were >18 years old, with tumor size 1-4 cm, no other malignancies, and >0 follow up time. Patients were divided into two cohorts based on extent of surgery: lobectomy (≥1 lobe resected) and thyroidectomy (total or near total resection). Pearson's chi-squared analysis was used to compare cohorts. Kaplan-Meier survival and Cox hazards models were utilized to determine overall survival between two cohorts with p < 0.05 used for significance. RESULTS: A total of 6871 patients were identified with FTC, of which 1507 patients underwent lobectomy and 5364 patients underwent total thyroidectomy. There were no significant differences in patient demographics, comorbidity index, local spread, or tumor grade. Patients undergoing lobectomy had mean survival of 12.94 versus 12.71 years for those undergoing thyroidectomy. Extent of surgery was not associated with a significant difference in survival (5 years OS = 96% in lobectomy and 95.5% in total thyroidectomy, p = 0.08). Stratification by tumor grade resulted in no significant difference in survival between lobectomy and thyroidectomy. CONCLUSION: Survival time was not significantly different in patients with more extensive resection of FTC. LEVEL OF EVIDENCE: 3 Laryngoscope, 133:993-999, 2023.

Assessment of Alkylated and Unsubstituted Polycyclic Aromatic Hydrocarbons in Air in Urban and Semi-Urban Areas in Toronto, Canada.

22 alkylated polycyclic aromatic hydrocarbons (alk-PAHs) were characterized in ambient air individually for the first time in urban and semi-urban locations in Toronto, Canada. Five unsubstituted PAHs were included for comparison. Results from the measurements were used to estimate benzo[a]pyrene equivalent toxicity (BaPeq) of individual compounds in order to investigate the significance of a single compound in contributing to the overall toxic equivalency (TEQ) of air mixtures. To determine which compounds merit further investigation, BaPeq values of individual compounds were compared to the measured BaP toxicity. Our results showed that both unsubstituted and alkylated PAHs were more abundant in the urban area (38 and 30%, respectively). Benzo[a]pyrene levels at the urban location exceeded Ontario's 24 h guideline (40% of the events), and on average, it was 5 times higher than that at the semi-urban area. Gas-phase two- and three-ring compounds contributed up to 39% (urban) and 76% (semi-urban) of the TEQ of all compounds analyzed. Some alk-PAHs such as 7,12-dimethylbenzo[a]anthracene had a huge impact on the toxicity of urban air, and its BaPeq was on average 8 times higher than that of BaP. We emphasize that the toxic impact of alkylated and gaseous PAHs, which is not routinely included in many air monitoring programs, is significant and should not be neglected.

Understanding basal cell adenocarcinoma of the head and neck: Population-based study.

BACKGROUND: Using a population-based database, this study investigates the risk factors, epidemiology, and outcomes of basal cell adenocarcinoma (BCAC) of the head and neck. METHODS: The Surveillance, Epidemiology, and End Results database was analyzed for all patients with BCAC of the head and neck from 1973 to 2015. RESULTS: Three hundred and twenty-two cases of BCAC of the head and neck were identified. Mean age of diagnosis was 64.1 years. 52.5% were male and 77.3% were white. The most common primary site was the parotid gland (71.7%). Most patients underwent surgery alone (51.9%). Five-year disease-specific survival (5Y-DSS) was 95.6%, and 10Y-DSS was 90.3%. Highest survival was seen with surgery alone followed by combined surgery and radiation (10Y-DSS: 93.9% vs. 88.9%, p = 0.001). Age, primary site, T-classification, grade, and treatment type significantly affected survival. CONCLUSIONS: BCAC of the head and neck presents most frequently in the parotid glands. Surgery alone is associated with highest survival.

Exploratory analysis on the association of mental health disorders with in-hospital postoperative complications and mortality in head and neck cancer surgery.

BACKGROUND: The objective was to assess the association of mental health disorders with in-hospital complication and mortality rates in patients undergoing head and neck cancer surgery. METHODS: In this exploratory retrospective study, the Nationwide Inpatient Sample was queried from 2003 to 2014 for all patients with a diagnosis of head and neck cancer who underwent surgery. Univariate cross-tabulation, logistic regression, and propensity score matching (PSM) were used to compare demographics, procedure-related variables, and in-hospital postoperative complications and mortality between patients with and without selected comorbid mental health disorders. RESULTS: Of 39 600 included patients, 3390 (8.6%) had a selected comorbid mental health disorder diagnosis. After PSM, patients with selected mental health disorders had increased risk of overall medical complications on multivariable analysis (OR 1.28 [CI 1.12-1.46], P < 0.001) but not overall surgical complications or mortality. CONCLUSIONS: Patients with a mental health disorder diagnosis have increased risk of in-hospital medical, certain surgical, and total complications.

Understanding giant cell sarcoma of the head and neck: A population-based study.

BACKGROUND: Giant cell sarcomas (GCS) are rare head and neck neoplasms. METHODS: The Surveillance, Epidemiology, and End Results (SEER) database was analyzed for all patients who have been diagnosed with GCS from 1973 to 2014. RESULTS: Four hundred and forty cases of GCS of the head and neck were identified. The average age at diagnosis was 74.4 years, 86.8% were white, 82.5% were male, 70.7% were insured, and 88.2% lived in an urban metropolitan region. Connective tissue was the most frequent primary site (42.5%). The 5Y-DSS rate was 91.1%, while the 5Y-OS was 54.6% for all cases. Patients treated with surgery alone had the highest 5Y-DSS rate of 94.5. T-classification odds ratio was a significant predictor of survival accounting for confounding variables on multivariate analysis. CONCLUSIONS: GCS presents most frequently in connective tissue of the head and neck with overall high probability of survival. The treatment of choice is surgery alone.

The effects of plume episodes on PAC profiles in the athabasca oil sands region.

Summer intensive air measurements of alkylated polycyclic aromatic compounds (Alk-PACs), nitrated polycyclic aromatic hydrocarbons (NPAHs), and oxygenated polycyclic aromatic hydrocarbons (OPAHs) was conducted during the summer of 2013 at an air monitoring site near the community of Fort McKay in the Athabasca oil sands region (AOSR). This study uses the ambient air measurements in conjunction with supplementary meteorological and air quality data from coordinated ground- and aircraft-based sampling over the same period to characterize diurnal variations and changes in the organic air pollutant profiles associated with the plume episodes. Principal component analysis showed a distinct PAC profile during plume episodes, driven mainly by higher fluorenone (FLO) and 9,10-anthraquinone (ANQ) concentrations. During the plume episodes (August 23-24), means of NPAHs and OPAHs concentrations were 120 and 2020 pg/m3, respectively, which were 2.7 and 2.5 times higher than those measured on the other days, while Alk-PACs did not reach maxima. The relative constancy of Alk-PACs during the plume episodes and baseline air quality periods likely reflects a continuous and broad emission of Alk-PACs from the oil sands mining activities. Only four OPAHs, including FLO, ANQ, benzo(a)fluorenone, and benzanthrone, exhibited higher average daytime than nighttime concentrations (p-value < 0.05). Categorizing air samples into clean and polluted conditions demonstrated that the polluted condition air samples were characterized by higher percent composition of alkylated fluorenes, FLO, MANQ, and photochemically-derived 1M4NN. A comparison of PAC profiles in air samples and oil sand ore samples suggests that the NPAHs were likely influenced by atmospheric formation while the OPAHs were impacted by a combination of primary sources and atmospheric formation. The strong correlations found between a number of NPAHs and OPAHs, and PM2.5 and NOx in this study could support the modelling of ambient air burdens of these compounds across the region.

Multi-year Analyses Reveal Different Trends, Sources, and Implications for Source-Related Human Health Risks of Atmospheric Polycyclic Aromatic Hydrocarbons in the Canadian Great Lakes Basin.

Polycyclic aromatic hydrocarbons (PAHs) are of high concern to public health due to their carcinogenic and mutagenic properties. Here, we present the first comprehensive and quantitative analysis of sources, potential source regions according to source sectors and source-related human health risks of multi-year atmospheric measurements of PAHs in the Canadian Great Lakes Basin (GLB). The highest PAH concentrations were observed at a rural residential site (Egbert), followed by two regionally representative remote sites [Point Petre (PPT) and Burnt Island]. The levels of most PAHs in the GLB atmosphere significantly decreased between 1997 and 2017, broadly consistent with the decreasing trends of anthropogenic emissions. Coal, liquid fossil fuel, and biomass burning were the most common potential sources. The potential source regions for most source sectors were identified south or southwest of the sampling sites. Risk assessment suggests potential health risks associated with the inhalation of atmospheric PAHs. On a positive note, health risks from coal combustion, liquid fossil fuel combustion, and petrogenic sources at PPT significantly decreased, directly demonstrating the success of emission control in reducing health impacts. In contrast, the health risk from forest fire-related PAH emissions may play an increasing role in the future due to climate change.