Contact Exposure Research Articles

Guidelines for inorganic arsenic (Ⅲ, V, and Total) and chromium (Ⅲ, Ⅵ, and Total) in Chinese soils

Arsenic and chromium, common polyvalent heavy metals found in soil, are a growing environmental concern, yet research on soil threshold values for these metals is limited. This study presents a method for deriving soil guidelines based on published literature, considering two land types (parkland and industry), two exposure pathways (direct contact and food chain for mammalian and avian), and two toxicity levels (NOEC/LOAEL and EC50/LC50). Soil guidelines for inorganic arsenic (III & V) and chromium (III & VI) were derived separately for parkland and industry, factoring in direct contact and food chain exposures (applicable only to parkland) and both lower and upper toxicity levels from available data. The study discusses the similarities and differences between the proposed guideline values and international standards. Additionally, a new method is introduced for deriving soil guidelines for total arsenic and chromium, applicable to naturally occurring mixed valence states. Future research should refine these guidelines by addressing sample limitations, soil properties, and regional variations to enhance their accuracy and applicability in environmental management. Both methods can serve as references for managing other pollutants. These soil guideline values, particularly the total soil guidelines, offer valuable guidance for the Chinese government in managing arsenic and chromium levels in soil.

Evaluation of some physicochemical parameters and health risks associated with potentially toxic elements (PTEs) in agricultural soils from the southwest region of Ethiopia

In this study, soil samples collected from Burusa and Bure agricultural sectors were analyzed for their physicochemical parameters and potentially toxic elements (Fe, Mn, Zn, Cu, Co, B, Se, Ni, Cr, Pb, Cd, As, and Hg). Physicochemical parameters were analyzed according to AOAC methods. For quantification of PTEs, the soil samples were digested by using aquaregia (HCl: HNO3; 3:1) and 5 mL of H2O2 (30%) at a digestion temperature of 250°C for 3 hours prior to ICP-OES analysis. The percent recoveries (%R) and relative standard deviation (%RSD) of this method ranged from 83 to 106% and 0.39 to 9.2%, respectively. The LODs and LOQ values were in the range of 4.3 × 10-4-5.3 × 10-2 mg/L and 1.4 × 10-3-1.76 × 10-1 mg/L, respectively. The analyzed mean values of physicochemical parameter including pH, temperature, electrical conductivity, moisture, organic matter and nitrogen content were found in the range of 4.85-6.47, 20.5-21.4°C, 101.6-230.7 µS/cm, 8.67-20.7%, 0.677-1.81% and 5.81-6.85%, respectively. The average amount of potentially toxic elements found in the soil samples were ranged as 57073-81279, 1185-3255, 41.0-72.2, 12.6-29.2, 18.8-50.8, 25.0-40.5, 42.2-60.8, 13.6-34.5, 41.9- 67.2, 25.0-59.4, 9.92-13.3, 0.933-1.12 and 4.97-8.63 in mg/kg for Fe, Mn, Zn, Cu, Co, B, Se, Ni, Cr, Pb, Cd, As and Hg, respectively. The highest concentrations of among the entire PTEs were recorded for Fe, followed by Mn, in the analyzed soil samples. All the studied elements are below the FAO/WHO permissible limit except Fe, Se, Cd, and Hg for all analyzed soil samples and Mn for the Bure soil sample. The target hazard quotient (THQ) and hazard index (HI) values are <1, suggesting an insignificant non-carcinogenic risk of the heavy metals to the adults via ingestion, inhalation, and dermal contact exposure of agricultural soils. Likewise, the individual element incremental lifetime cancer risk (ILCR) occurrence for all studied soil samples is below 1 × 10-4. The total ILCR of potentially toxic heavy metals (Ni, Cr, Pb, Cd and As) resulting from ingestion, inhalation, and dermal contact exposure of agricultural soil by an adult population indicate a slightly higher potential cancer risk (> 1 × 10-4) for soil samples obtained from Bure S1, Bure S2, and Bure S3. Therefore, continuous monitoring of these harmful elements should be made by agricultural sectors and responsible government regulatory authorities are crucial to prevent PTEs related to agricultural soils in Ethiopia.

Application of Environmental Protection Agency (EPA) Model in Occupational Hazard Evaluation of UV-Curable Coating Production Project

This paper applies the EPA inhalation risk evaluation model—which has the advantage of the high safety margin value of the RfC value and considers long-term contact exposure to chemical toxicants for all protected populations—to objectively assess the risk level of acute and chronic occupational poisoning and tumors caused by respiratory exposure to chemical toxicants in a UV-curable coating production project, which is of guiding significance. The results reveal that the hazardous chemical elements in the air in the workshop of this UV-curable coating production project have no substantial influence on worker health; therefore, no further design is required.

Use of biosecurity practices to prevent chronic wasting disease in Minnesota cervid herds

The objective of this study was to evaluate biosecurity practices related to chronic wasting disease (CWD) transmission pathways and prevention in active cervid herds in Minnesota in 2019 by species, size and location of herds. A self-administered questionnaire was sent to all cervid producers in Minnesota to gather demographic, management, and biosecurity practices. Among producers (N=136), 63.2 % raised predominantly deer species and 36.8 % raised predominantly elk or reindeer. Survey responses were analyzed by herd species (deer or elk/reindeer), herd size (<20 or ≥20 animals), and location (southeast Minnesota or rest of the state) to determine statistical differences between strata. In terms of CWD transmission risks from other farmed cervids, 40.4 % (95 % Confidence Intervals (CI) 32.1–48.8) of Minnesota producers stated they introduced new cervids to the operation in the previous 3 years, though there were minimal other forms of direct contact. A higher percentage of larger sized elk/reindeer herds reported practices that indicate potential for indirect contact with other farmed cervids. Vehicles or trailers that entered the farm were used to transport other live cervids, cervid carcasses, or cervid body parts in past 3 years in 64.3 % (95 % CI 46.3–82.3) of larger elk/reindeer herds compared to 13.6 % (95 % CI 4.7–22.4) of smaller deer herds.For CWD transmission risks from wild cervids, limited potential direct contact was reported. Among all producers, 9.6 % (95 % CI 4.6–14.6) reported farmed cervid escapes in the past 3 years (even temporarily) and 0.7 % (95 % CI 0.0–2.2) of producers reported wild white-tailed deer (WTD) inside perimeter fencing. Additionally, 24.3 % (95 % CI 17.0–31.6) of producers observed wild WTD near the perimeter fencing in the past 12 months and 18.7 % (95 % CI 12.0–25.3) reported use of double perimeter fencing, indicating frequent proximity to wild deer and potential for direct and/or indirect contact exposures. Further, 14.3 % (95 % CI 6.7–21.9) of deer herds and 30.0 % (95 % CI 17.1–42.9) of elk herds reported potential access of wild cervids to hay/silage while stored on the farm, with similar results comparing smaller and larger size strata (13.8 % (95 % CI 6.1–21.4) and 29.6 % (95 % CI 17.3–42.0), respectively). Contact through hunting or taxidermy practices occurred infrequently, with the exception of 20.1 % (95 % CI 13.3–27.0) of producers reporting bringing outside hunted cervid parts/carcasses onto property in the past 3 years.Overall, results identified direct and indirect contact exposures from both farmed and wild cervids to Minnesota herds, with many producers reporting potential contact with wild cervids through direct and multiple indirect pathways. Many of these indirect exposures to wild and farmed cervids varied by herd size and species strata. Better understanding of these potential CWD transmission pathways and how differences between herd size and species affect these pathways will facilitate development of more effective biosecurity programs for cervid herds.

Physical collisions during elite rugby league match play and training: A stakeholder's perspective

The purpose of this study was to explore rugby league stakeholders’ perspectives of the tackle event, utilising qualitative approaches to gain further insight into this phenomenon. Nineteen stakeholders, comprising tactical coaches (n = 5), physiotherapists (n = 5), doctors (n = 5) and strength and conditioning coaches (n = 4) from every European 2023 Super League team (ESL), were recruited to participate in an online semi-structured interview, via the Microsoft Teams platform, facilitated by a moderator. Braun and Clarke's (2019) reflexive thematic analysis was performed to code and analyse the transcribed data; this established pattern-based interpretation and reporting from the dataset. The research findings can be divided into five crucial segments that illuminate our understanding of collision in rugby league: 1) simultaneous contact and the three-person tackle, 2) tackle height – calibration is critical, 3) the fundamental factors influencing tackle-related risks. 4) the graded exposure and philosophical approaches to contact training and games, 5) replacing toughness with resilience - the impact of game identity. The themes generated here provide comprehensive insights into stakeholders’ perceptions of the optimal ways to perform collisions. This has implications for the identity of the game, and the subsequent law changes/ behavioural change models that aim to make the game safer, specific to rugby league. In line with previous research, the conclusions underline high-risk events in match play (blind-sided collisions and fatigue), providing a focus for areas of future research. Lastly, psychology in the tackle event is explored, highlighting the need for graded contact exposure from a physical and psychological perspective during tackle technique training.

Microbial keratitis in north-western Spain: a review of risk factors, microbiological profile and resistance patterns.

To review the risk factors, clinical characteristics, and microbiological profiles of microbial keratitis cases, as well as the antibiotic resistance patterns of bacterial isolates in the region of Galicia, Spain. This retrospective case series includes patients with culture-positive non-viral microbial keratitis between 2010 and 2020, treated at nine hospitals within the region of Galicia, North-West Spain. The standard protocol involved Gram staining for bacterial infections and calcofluor white staining for fungal or amoebal infections, identification by MALDI-TOF mass spectrometry or microscopy, and antimicrobial susceptibility interpreted according to EUCAST or CLSI guidelines. 780 microorganisms were isolated from corneal scraping cultures from 654 patients. 36.9% resided in urban areas, and 63.1% in rural areas. Isolates were more frequently collected in spring and summer. The median time to corneal scraping was 0 days (IQR 0-2), and the median time to epithelialisation was 24.0 days (IQR 11-49). Most cases had a single corneal infiltrate (509 cases; 77.8%) and affected the stroma (432; 66.1%), with small (< 3mm) epithelial defects (347; 53.1%). Significant risk factors included contact lens wear (24.2%) and exposure to organic matter (4.9%). The most frequent bacteria was CoNS (207; 26.4). Fungi (77; 9.9%) and amoebae (6; 0.8%) were less common. Steroid use and eyelid disease increased resistance in CoNS species. An increase in the percentage of MRSA (compared to MSSA) was detected over the study period (p = 0.045). In Galicia (Spain), microbial keratitis was mostly attributed to CoNS. An increase in MRSA keratitis was observed. Analysis of risk factors may help in suspecting antibiotic resistance. Surveillance programs for detecting the development of antimicrobial resistance are necessary to provide treatment guidelines based on local data.

Evaluation of the toxicity of translaminar insecticides against the soybean tentiform leafminer (Lepidoptera: Gracillariidae), a potential new pest of soybean.

Macrosaccus morrisella (Fitch) (Lepidoptera: Gracillariidae) is a leaf-mining microlepidopteran native to North America recently reported feeding on soybean in the United States and Canada. Control methods for the management of this pest remain unknown. The insecticides Agri-Mek SC (abamectin) and Endigo ZXC (lambda-cyhalothrin + thiamethoxam) were evaluated for: (i) effects against immature stages of M. morrisella in potted soybean plants; (ii) effects against adults of M. morrisella through different routes of exposure; and (iii) efficacy of field applications against M. morrisella. In the experiment with immature stages, when either insecticide was applied to potted plants with M. morrisella in serpentine or blotch mines, significantly fewer adults emerged compared to the untreated plants. In contrast, adult emergence from potted plants treated with either insecticide when M. morrisella was in tentiform mines did not differ from untreated plants. In the experiment with adults, the survival of M. morrisella exposed to either insecticide through oral exposure or residual contact + oral exposure was significantly lower than that for residual contact exposure alone, which in turn was lower than the untreated control. Within each exposure route, the response to the 2 insecticides did not differ. In the field experiment, at 21 days after insecticide application, the mean percentage of leaf area mined was significantly lower in plots treated with Endigo ZCX compared to plots treated with Agri-Mek SC or those left untreated. These results suggest that Endigo ZXC and to a lesser extent Agri-Mek SC may have potential for management of M. morrisella.

Management implications of latent TB among under-five children at risk: Insights from a community study in Mumbai, India.

Latent tuberculosis infection (LTBI) management is crucial to WHO's End TB Strategy. Indian guidelines recommend treating under-five children with household TB contacts after ruling out active TB, regardless of TBI testing. However, the precise LTBI burden among children in high TB burden settings like India is unknown. A community-based study in Mumbai's urban slums screened and managed under-five children at LTBI risk to understand its epidemiology and inform TB control interventions. Total 369 eligible under-five children were enrolled for the study. LTBI screening was done using Tuberculin skin test and Interferon gamma release assay. Active TB was ruled out before initiation of TB preventive therapy among LTBI positives. Statistical tests like chi-square, logistic regression analysis and Hosmer-Lemeshow test were used. Overall, LTBI prevalence among under-five children was 12.4% by IGRA and 21.4% by TST. Undernourished children had significantly lower LTBI positivity by IGRA (p = 0.027), while those with household contacts, longer contact duration and drug-resistant tuberculosis (DR-TB) exhibited proportionally greater IGRA positivity (p = <0.001). The study found a lower LTBI prevalence among under-five children compared to adults, with key risk factors being HHC, DR-TB contact, and prolonged exposure. These findings suggest the need to revise or revisit the TPT framework for this age group in India, particularly by implementing a test-and-treat approach.

Occurrence and seroprevalence of infectious viral, bacterial, and protozoal diseases among patients attending the Ore General Hospital in southwestern Nigeria

Infectious diseases caused by viruses, bacteria, protozoans, and fungi continue to pose significant challenges globally, with transmission routes including person-to-person contact, animal vectors, and environmental exposure. Despite global efforts to control these diseases, limited studies and resource constraints in Ore, Nigeria, have led to increasing prevalence, highlighting the need for targeted public health interventions. This study aimed to determine the distribution of infectious diseases among patients attending General Hospital Ore, Odigbo, Nigeria. Serum samples from consenting patients were assayed for the presence of malaria parasites, human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), Salmonella infection, Helicobacter pylori infection, high vaginal swab (HVS) results, and urinary tract infections (UTIs). The subjects included 1900 males (38.8%) and 3000 females (61.2%). The overall prevalence rates were as follows: HIV (40%), malaria (35%), typhoid (37.5%), HBsAg (20%), H. pylori (6.3%), HVS (45%), and UTIs (10%). The high rates of infectious diseases observed in this study, compared to rates reported elsewhere, suggest the need to strengthen public health measures and infection prevention strategies in the area. In addition, routine screening for these diseases and early passive or active immunization for vaccine-preventable diseases are essential to further reduce the burden of these infections.

Side effects of semi-synthetic insecticide spinetoram on the whitefly parasitoid Encarsia formosa.

Insecticide risk assessment for biological control agents is essential for implementing integrated pest management (IPM) programs. Spinetoram is a naturally derived insecticide used to control a variety of agricultural sap-sucking insect pests, and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) plays a key role in the biocontrol of greenhouse whiteflies. Despite its presumed safe ecotoxicological profile, the side effects of spinetoram on E. formosa are partially unknown, especially at sublethal doses. In the laboratory, we estimated the lethal concentrations (LC) of spinetoram on E. formosa by topical exposure of pupae and 48 h residual contact exposure of emerged adults. Afterwards, we assessed the impact of spinetoram LCs on the life history traits (juvenile development, adult longevity, parasitism, adult emergence) and population growth parameter (the instantaneous rate of increase, ri) of the parasitoid. Probit analysis allowed the estimation of LC10 = 0.10 mg/L, LC50 = 0.56 mg/L, and LC90 = 3.28 mg/L. Spinetoram at LC10 had no impact on the observed parameters of E. formosa. Conversely, spinetoram at LC50 and LC90 significantly reduced adult longevity by 19.2% and 40.6%, total parasitism by 33.4% and 38.7%, and total adult emergence by 29.6% and 39.1%, respectively. Also, the ri of E. formosa was significantly affected by spinetoram LC50 and LC90 with a reduction of 8.17 and 29.83%, respectively. Our results suggested that spinetoram significantly threatens the effectiveness of E. formosa when applied at the field recommended rate. However, further validation of spinetoram under greenhouse conditions is required for a comprehensive risk assessment for E. formosa in IPM programs. © 2024 Society of Chemical Industry.

Utilization of organic waste from Chinar leaves as sustainable and eco-friendly adsorbent for fluoride removal.

Due to concerns about high water fluoride concentrations and their detrimental consequences on health, particularly dental and skeletal fluorosis, dependable and cost-effective defluoridation techniques are needed. Chinar leaves (Platanus orientalis), a common waste, might be utilized for the production of activated carbon. For Chinar leaf activated carbon (CLAC) manufacturing, two pre-pyrolysis chemical modification procedures were used: acidic HCl (H-activation) and alkaline NaOH (OH-activation). The success of fluoride removal suggests further research and implementation in locations with fluoride-related water quality issues. This study examines how CLAC dosage, fluoride concentration, temperature, pH, and contact exposure effect defluoridation efficiency. The pseudo-second-order non-linear kinetic model and Freundlich non-linear isotherm model with R2 = 0.99 fit the data, resulting in a peak adsorption capacity of 30.3mg/g for 0.3g CLAC. In the present work, the adsorption mechanism was regulated by more than intraparticle diffusion. Adsorption occurred spontaneously as exothermic monolayer chemisorption, according to thermodynamic studies. Adsorbent activated with HCl (H-activated) showed promising results, with 73% F- removal efficiency for OH-activated and 91% for H-activated CLAC.

The application of match-event and instrumented mouthguard data to inform match limits: An example using rugby union Premiership and rugby league Super League data from England.

The study aimed to illustrate how contact (from match-event data) and head acceleration event (HAE) (from instrumented mouthguard [iMG]) data can be combined to inform match limits within rugby. Match-event data from one rugby union and rugby league season, including all competitive matches involving players from the English Premiership and Super League, were used. Playing exposure was summarised as full game equivalents (FGE; total minutes played/80). Expected contact and HAE exposures at arbitrary thresholds were estimated using match-event and iMG data. Generalised linear models were used to identify differences in contact and HAE exposure per FGE. For 30 FGEs, forwards had greater contact than backs in rugby union (n=1272 vs. 618) and league (n=1569 vs. 706). As HAE magnitude increased, the differences between positional groups decreased (e.g., rugby union; n=34 and 22 HAE >40g for forwards and backs playing 30 FGEs). Currently, only a relatively small proportion of rugby union (2.5%) and league (7.3%) players exceeded 25 FGEs. Estimating contact and HAEs per FGE allows policymakers to prospectively plan and model estimated overall and position-specific loads over a season and longer term. Reducing FGE limits by a small amount would currently only affect contact and HAE exposure for a small proportion of players who complete the most minutes. This may be beneficial for this cohort but is not an effective HAE and contact exposure reduction strategy at a population level, which requires individual player management. Given the positional differences, FGE limits should exist to manage appropriate HAE and contact exposure.

Correlation of Pseudocholinesterase Level with Clinical, Biochemical Parameters Including Cardiac Profile and the Outcome in Organophosphorus Poisoning.

Poisoning is a significant health hazard and a leading cause of morbidity and mortality worldwide. India, being a predominantly agrarian country, routinely employs organophosphate (OP) pesticides in farming, and they are readily available "over the counter." OPs exert their toxicity by interfering with the normal function of acetylcholine, an essential neurotransmitter throughout the autonomic and central nervous systems. Due to the limited availability of facilities and resources in health-care systems, and economically restraining patients, it is necessary to rely more on clinical features to assess the severity of poisoning and manage the condition properly. It was a hospital-based prospective observational study that included patients aged >13 years in a tertiary care hospital. All patients were clinically evaluated based on their history and examination. The diagnosis was made based on characteristic clinical manifestations or evidence of exposure to organophosphorus compounds (corroborative evidence such as empty containers and the odor of gastric aspirates). Clinical severity was assessed and categorized according to the Peradeniya Organophosphorus Poisoning Scale (POP scale). A score of 0-3 is considered mild poisoning, 4-7 as moderate poisoning, and 8-11 as severe poisoning. Out of the 50 patients enrolled in the study, 17 (34.00%) were aged <20 years, 19 (38%) were in the 20-30 years age group, and 14 (28%) were aged >30 years. Ingestion is the only mode of exposure to poisoning. None of the patients had history of contact or inhalational exposure. Of the 50 cases, 12 (24.0%) were in the mild category, 26 (52.0%) in the moderate category, and 12 (24%) in the severe category on the POP grading. A comparison of the mean serum pseudocholinesterase, troponin-T, and pro-BNP levels with severity was performed. In mild OP poisoning, the mean serum PChE level was 2766.58 ± 1120.44; in moderate, it was 1969.35 ± 1330.07, and in severe, it was 701.83 ± 961.17. Pseudocholinesterase levels decreased progressively with increasing clinical severity from mild-to-severe cases, and this association was statistically significant (P < 0.001). Two-dimensional echocardiography screening done in all patients did not show any significant abnormalities. This study shows that serum PCE is reduced in OP poisoning and correlates with the clinical severity grading done by the POP scale and is also associated with an increase in the duration of intensive care unit stay. No significant evidence of direct cardiac injury was observed in this study. A low Glasgow Coma Scale score and an increased respiratory rate at presentation are associated with poor outcomes.

Canadian beach cohort study: protocol of a prospective study to assess the burden of recreational water illness

BackgroundRecreational water activities at beaches are popular among Canadians. However, these activities can increase the risk of recreational water illnesses (RWI) among beachgoers. Few studies have been conducted in Canada to determine the risk of these illnesses. This protocol describes the methodology for a study to determine the risk and burden of RWI due to exposure to fecal pollution at beaches in Canada.MethodsThis study will use a mixed-methods approach, consisting of a prospective cohort study of beachgoers with embedded qualitative research. The cohort study involves recruiting and enrolling participants at public beaches across Canada, ascertaining their water and sand contact exposure status, then following-up after seven days to determine the incidence of acute RWI outcomes. We will test beach water samples each recruitment day for culture-based E. coli, enterococci using rapid molecular methods, and microbial source tracking biomarkers. The study started in 2023 and will continue to 2025 at beaches in British Columbia, Manitoba, Ontario, and Nova Scotia. The target enrollment is 5000 beachgoers. Multilevel logistic regression models will be fitted to examine the relationships between water and sand contact and RWI among beachgoers. We will also examine differences in risks by beachgoer age, gender, and beach location and the influence of fecal indicator bacteria and other water quality parameters on these relationships. Sensitivity analyses will be conducted to examine the impact of various alternative exposure and outcome definitions on these associations. The qualitative research phase will include focus groups with beachgoers and key informant interviews to provide additional contextual insights into the study findings. The study will use an integrated knowledge translation approach.DiscussionInitial implementation of the study at two Toronto, Ontario, beaches in 2023 confirmed that recruitment is feasible and that a high completion rate (80%) can be achieved for the follow-up survey. While recall bias could be a concern for the self-reported RWI outcomes, we will examine the impact of this bias in a negative control analysis. Study findings will inform future recreational water quality guidelines, policies, and risk communication strategies in Canada.

Phthalates on indoor surfaces and associated exposure via surface touch behavior: Observation in university dormitories and its implications

Phthalates are typical emerging indoor pollutants and ubiquitously distributed in the indoor air, settled dust and on surfaces. Phthalates have the potential to be transported by human hands through surface touch behaviors. Although the contribution of subsequent exposure via hand-to-mouth contact in real indoor environments has not been thoroughly characterized, it is an important factor to consider. In this study, six commonly-used phthalates (dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), butyl benzyl phthalate (BBzP), di-2-ethylhexyl phthalate (DEHP), and di-n-octyl phthalate (DOP)) were measured in surface wipes, air and dust samples collected from university dormitories. Video-cameras were used to monitor occupants’ real surface touch behaviors. Primary surfaces being touched included desks, cellphones, keyboards and computer mice, with averaged touch frequencies ranging from 10.4 h−1 to 25.4 h−1. Phthalate levels on computer mice were the highest, with DEHP being present as the most predominant compound (mean: 2621 μg/m2). Exposures via inhalation, dust ingestion, dermal absorption and hand-to-mouth contact were further estimated using Monte-Carlo simulations. The results suggest that the exposure resulting from surface touching and subsequent hand-mouthing could contribute 35 %–55 % to total exposure for targeted phthalates, which were generally higher than intakes via dust ingestion. This study provides a better understanding of phthalate transfer through surface touch behavior, and highlights the significance of hand-to-mouth contact exposure in indoor environments.

Effectiveness of respiratory protective equipment in reducing inhalation and contact exposure risks of dental workers during ultrasonic scaling

The high-concentration droplets produced from ultrasonic scaling treatments may carry many pathogens. The close contact between dental workers and patients significantly amplifies their exposure risk to these droplets. Although various types of respiratory protective equipment (RPE) are utilized by dental workers during treatments, their effectiveness in reducing the risks associated with inhalation and contact exposure remains uncertain. In this study, computational fluid dynamics technology was employed to investigate the impact of RPE type, surgery duration, air changes per hour (ACH), and air distribution on the risks related to inhalation and deposition exposure. The results revealed that wearing masks considerably reduced the risk of inhalation exposure for dental workers, with a decrease in inhalation fractions from 25.3 ppm (without RPE) to 1.3–4.5 ppm (with RPE). Combining blue surgical masks and face shields decreased the risk of inhalation fraction by 5% compared to wearing no RPE. Notably, there was over 60% of spray droplets landed on the patient's head; however, only approximately 5%, 6%, 8%, and 3% were deposited on the patient's body, doctor's body, floor, and dental chair, respectively. Increasing ventilation from 3 to 9 ACH decreased dental workers' inhalation fraction by 9.8 ppm. Type III (with the inlet and outlet at opposite walls) decreased the suspension fraction by 4.3% compared with Type II (with the inlet and outlet at the same wall) while achieving a near-zero inhalation fraction of dental workers. These findings offer valuable insights for mitigating cross-infection risks between dental workers and patients in dental clinics.

Persistently elevated joint contact stress after periacetabular osteotomy is associated with joint failure at minimum 10-year follow-up.

Periacetabular osteotomy (PAO) is a common treatment for prearthritic hip dysplasia. The goal of this investigation was to determine if computationally assessed hip contact mechanics are associated with joint failure at minimum 10-year follow-up. One hundred patients with hip dysplasia (125 hips) completed patient-reported outcomes an average of 13.8 years (range 10.0-18.0 years) after PAO. 63/125 hips were classified as having failed: 26 converted to total hip arthroplasty (THA) and 37 with significant disability indicated by modified Harris Hip Score (mHHS) ≤ 70. Differences in discrete element analysis-computed contact mechanics were compared between (1) preserved and failed hips, (2) preserved hips and hips that failed by THA, and (3) preserved hips and hips that failed by mHHS ≤ 70. Failed hips had significantly higher preoperative contact stress and exposure metrics (p < 0.001-0.009) than preserved hips. Failed hips also had significantly higher postoperative peak contact stress (p = 0.018), higher mean contact stress (p < 0.001), and smaller contact area (p = 0.044). When assessed based on type of failure, hips that failed by THA had significantly higher postoperative contact stress and exposure metrics than preserved hips (p < 0.001-0.020). In hips that failed by mHHS ≤ 70, mean postoperative contact stress exposure was significantly higher compared to preserved hips (p = 0.043). Despite improved radiographic measures of dysplasia after PAO, pathologic joint contact mechanics can persist and predict treatment failure at minimum 10 years after surgery. Operative and nonoperative techniques specifically intended to reduce harmful contact mechanics in dysplastic hips may have the potential to further improve clinical outcomes after PAO.

Smoldering ignition and transition to flaming in wooden mulch beds exposed to firebrands under wind

Spotting ignition by firebrands is a significant fire spread pathway at the wildland-urban interface (WUI), where mulch products are commonly used as landscaping materials. Mulch is typically organic in nature, thus it may be easily ignited into a smoldering mode by firebrands and subsequently transition to flaming, leading to direct flame contact and radiant heat exposure to siding materials of adjacent structures. This work quantified the thresholds of smoldering ignition of four common types of commercially available mulch (black mulch (BM), forest floor (FF), redwood (RW), and fir bark (FB)) exposed to heating by smoldering firebrand piles, and their propensity for smoldering-to-flaming transition under external winds (up to 1.4 m/s). We found that there was a minimum mass of firebrand pile to achieve smoldering ignition of mulch (e.g., ∼0.1 g for FF). Beyond this minimum mass, the required wind speed to trigger smoldering ignition generally decreased as the mass of the firebrand pile increased, agreeing well with theoretical analysis. After smoldering ignition, smoldering-to-flaming transition could be observed when the wind speed exceeded a critical value (e.g., ∼1 m/s for FF), which was not affected by the initial spotting process. To achieve smoldering-to-flaming transition, the glowing mulch had to reach a critical temperature of around 850 °C. Mulch samples with larger particle sizes were more likely to smolder and transition to flaming, due to increased oxygen supply through larger inter-particle pores and channels and better firebrand accumulation due to a more crevice-like geometry on the fuel surface. This work advances the fundamental understanding of the ignition and burning behavior of landscaping mulches, and thus contributes to the prevention of extreme WUI fire events.

Reaching Structurally Vulnerable Populations Using Low-Barrier COVID-19 Testing Clinics Co-Created with Community-Based Organizations.

The COVID-19 pandemic disproportionately affected people from structurally vulnerable communities. There was a need to improve COVID-19 testing in these communities to reduce viral spread and connect to treatment. We created a partnership between an academic medical center and three community-based organizations (CBOs) to offer low-barrier COVID-19 walk-up testing clinics in Portland, Maine. Our objective was to examine whether the co-created testing clinics reached structurally vulnerable populations. The clinics offered COVID-19 rapid antigen tests three times a week outside CBO sites from January 2022 to May 2023. Clinic staff administered a brief survey on reason for testing and then instructed participants on how to self-swab. While staff processed the test, participants were invited to complete an additional survey about their demographics and testing perceptions. Adults seeking COVID-19 testing with specific outreach to people who are unhoused, immigrants, and low-income and/or uninsured. Number of tests conducted and result, reasons for testing, and testing perceptions. Of 246 completed tests, 18 were positive for COVID-19 (7%). Participants sought testing for a variety of reasons, including symptoms (60%), close contact exposure (29%), and/or need for a negative test result to access services or an activity (33%). Overall, people primarily tested due to symptoms with only 7% testing due to close contact exposure alone. The clinics reached vulnerable populations. Among the 130 people completing the participant survey, 39% were unhoused, 22% spoke a language other than English at home, 23% were uninsured, and 46% earned less than $20,000 in 2019. Qualitative field notes captured key elements of clinics that influenced reach, and how this collaboration with CBOs helped build trust with our target populations. Providing low-barrier walk-up clinics partnering with trusted CBOs was observed to be helpful in reaching structurally vulnerable populations for COVID-19 testing.

A - 33 Examining Neurocognitive Effects of Contact Exposure in High School Athletes

Abstract Purpose Concerns have been raised about the effect of repetitive head impacts and subconcussive blows in contact sports, though studies have largely focused on the effect in late-life or retired professional athletes. We examined the effect of extended participation (months-to-years) in low/non-contact vs high contact/collision sports within a sample of high school athletes on the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT). Method A multisport sample of 1650 athletes (34% Female; 1088 contact, 528 non-contact; age 14–18) without a history of concussion completed baseline ImPACT testing across two times points (time between administrations ranging from 7–45 months; M = 20.40), with active sport participation between administrations. Results Repeated mixed-measure ANOVA revealed increased performance across ImPACT administrations for all composites (p &amp;lt; 0.001; partial Œ∑2 = 0.02–0.23). With the exception of a very small effect on Impulse Control composites (partial Œ∑2 = 0.003), there was no statistically significant difference between high contact and low contact sport groups across composite scores (p &amp;lt; 0.05). Conclusions Our findings showed no meaningful changes in neurocognitive performance in high school athletes exposed to high degrees of contact sports for months/years, with both contact groups demonstrating a consistent mild–moderate practice effect over time. This also aligns with the recent systematic literature review finding no increased risk of neurological/neurocognitive disease in amateur contact athletes in later life (Iverson et al, 2023). Future prospective studies with longer follow up and incorporation of additional measures (e.g., mental health, expanded testing, and biomarkers) will be important to improve our understanding of the risk of contact exposure in athletes.