Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-4 (of 4 Records) |
Query Trace: Menchaca K[original query] |
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Reducing ultrafine particulate emission from multiple 3D printers in an office environment using a prototype engineering control
Dunn KL , Hammond D , Menchaca K , Roth G , Dunn KH . J Nanopart Res 2020 22 (5) Recent studies have shown that high concentrations of ultrafine particles can be emitted during the 3D printing process. This study characterized the emissions from different filaments using common fused deposition modeling printers. It also assessed the effectiveness of a novel engineering control designed to capture emissions directly at the extruder head. Airborne particle and volatile organic compound concentrations were measured, and particle emission rates were calculated for several different 3D printer and filament combinations. Each printer and filament combination was tested inside a test chamber to measure overall emissions using the same print design for approximately 2 h. Emission rates ranged from 0.71 × 107 to 1400 × 107 particles/min, with particle geometric mean diameters ranging from 45.6 to 62.3 nm. To assess the effectiveness of a custom-designed engineering control, a 1-h print program using a MakerBot Replicator+ with Slate Gray Tough polylactic acid filament was employed. Emission rates and particle counts were evaluated both with and without the extruder head emission control installed. Use of the control showed a 98% reduction in ultrafine particle concentrations from an individual 3D printer evaluated in a test chamber. An assessment of the control in a simulated makerspace with 20 printers operating showed particle counts approached or exceeded 20,000 particles/cm3 without the engineering controls but remained at or below background levels (< 1000 particles/cm3) with the engineering controls in place. This study showed that a low-cost control could be added to existing 3D printers to significantly reduce emissions to the work environment. |
Evaluation of emissions and exposures at workplaces using desktop 3-dimensional printers
Stefaniak AB , Johnson AR , du Preez S , Hammond DR , Wells JR , Ham JE , LeBouf RF , Menchaca KW , Martin SBJr , Duling MG , Bowers LN , Knepp AK , Su FC , de Beer DJ , du Plessis JL . J Chem Health Saf 2019 26 (2) 19-30 There is a paucity of data on additive manufacturing process emissions and personal exposures in real-world workplaces. Hence, we evaluated atmospheres in four workplaces utilizing desktop "3-dimensional" (3-d) printers [fused filament fabrication (FFF) and sheer] for production, prototyping, or research. Airborne particle diameter and number concentration and total volatile organic compound concentrations were measured using real-time instruments. Airborne particles and volatile organic compounds were collected using time-integrated sampling techniques for off-line analysis. Personal exposures for metals and volatile organic compounds were measured in the breathing zone of operators. All 3-d printers that were monitored released ultrafine and fine particles and organic vapors into workplace air. Particle number-based emission rates (#/min) ranged from 9.4 times 109 to 4.4 times 1011 (n = 9 samples) for FFF 3-d printers and from 1.9 to 3.8 times 109 (n = 2 samples) for a sheer 3-d printer. The large variability in emission rate values reflected variability from the printers as well as differences in printer design, operating conditions, and feedstock materials among printers. A custom-built ventilated enclosure evaluated at one facility was capable of reducing particle number and total organic chemical concentrations by 99.7% and 53.2%, respectively. Carbonyl compounds were detected in room air; however, none were specifically attributed to the 3-d printing process. Personal exposure to metals (aluminum, iron) and 12 different organic chemicals were all below applicable NIOSH Recommended Exposure Limit values, but results are not reflective of all possible exposure scenarios. More research is needed to understand 3- d printer emissions, exposures, and efficacy of engineering controls in occupational settings. |
Temporal patterns in chlamydia repeat testing in Massachusetts
Dee EC , Hsu KK , Kruskal BA , Menchaca JT , Zambarano B , Cocoros N , Herrick B , Weiss MDP , Hafer E , Erani D , Josephson M , Young J , Torrone EA , Flagg EW , Klompas M . Am J Prev Med 2019 56 (3) 458-463 Introduction: National guidelines recommend test-of-cure for pregnant women and test-of-reinfection for all patients with chlamydia infections in order to interrupt transmission and prevent adverse sequelae for patients, partners, and newborns. Little is known about retesting and positivity rates, and whether they are changing over time, particularly in private sector practices. Methods: Electronic health record data on patients with chlamydia tests were extracted from three independent clinical practice groups serving ≅20% of the Massachusetts population. Records were extracted using the Electronic medical record Support for Public Health platform (esphealth.org). These data were analyzed for temporal trends in annual repeat testing rates by using generalized estimating equations after index positive chlamydia tests between 2010 and 2015 and for differences in intervals to first repeat tests among pregnant females, non-pregnant females, and males. Data extraction and analysis were performed during calendar years 2017 and 2018. Results: An index positive C. trachomatis result was identified for 972 pregnant female cases, 10,309 non-pregnant female cases, and 4,973 male cases. Test-of-cure 3–5 weeks after an index positive test occurred in 37% of pregnant females. Test-of-reinfection 8–16 weeks after an index positive test occurred in 39% of pregnant females, 18% of non-pregnant females, and 9% of males. There were no significant increases in test-of-cure or test-of-reinfection rates from 2010 to 2015. Among cases with repeat tests, 16% of pregnant females, 15% of non-pregnant females, and 16% of males had positive results. Conclusions: Chlamydia test-of-cure and test-of-reinfection rates are low, with no evidence of improvement over time. There are substantial opportunities to improve adherence to chlamydia repeat testing recommendations. |
Incidence and trends of sepsis in US hospitals using clinical vs claims data, 2009-2014
Rhee C , Dantes R , Epstein L , Murphy DJ , Seymour CW , Iwashyna TJ , Kadri SS , Angus DC , Danner RL , Fiore AE , Jernigan JA , Martin GS , Septimus E , Warren DK , Karcz A , Chan C , Menchaca JT , Wang R , Gruber S , Klompas M . JAMA 2017 318 (13) 1241-1249 Importance: Estimates from claims-based analyses suggest that the incidence of sepsis is increasing and mortality rates from sepsis are decreasing. However, estimates from claims data may lack clinical fidelity and can be affected by changing diagnosis and coding practices over time. Objective: To estimate the US national incidence of sepsis and trends using detailed clinical data from the electronic health record (EHR) systems of diverse hospitals. Design, Setting, and Population: Retrospective cohort study of adult patients admitted to 409 academic, community, and federal hospitals from 2009-2014. Exposures: Sepsis was identified using clinical indicators of presumed infection and concurrent acute organ dysfunction, adapting Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) criteria for objective and consistent EHR-based surveillance. Main Outcomes and Measures: Sepsis incidence, outcomes, and trends from 2009-2014 were calculated using regression models and compared with claims-based estimates using International Classification of Diseases, Ninth Revision, Clinical Modification codes for severe sepsis or septic shock. Case-finding criteria were validated against Sepsis-3 criteria using medical record reviews. Results: A total of 173690 sepsis cases (mean age, 66.5 [SD, 15.5] y; 77660 [42.4%] women) were identified using clinical criteria among 2901019 adults admitted to study hospitals in 2014 (6.0% incidence). Of these, 26061 (15.0%) died in the hospital and 10731 (6.2%) were discharged to hospice. From 2009-2014, sepsis incidence using clinical criteria was stable (+0.6% relative change/y [95% CI, -2.3% to 3.5%], P = .67) whereas incidence per claims increased (+10.3%/y [95% CI, 7.2% to 13.3%], P < .001). In-hospital mortality using clinical criteria declined (-3.3%/y [95% CI, -5.6% to -1.0%], P = .004), but there was no significant change in the combined outcome of death or discharge to hospice (-1.3%/y [95% CI, -3.2% to 0.6%], P = .19). In contrast, mortality using claims declined significantly (-7.0%/y [95% CI, -8.8% to -5.2%], P < .001), as did death or discharge to hospice (-4.5%/y [95% CI, -6.1% to -2.8%], P < .001). Clinical criteria were more sensitive in identifying sepsis than claims (69.7% [95% CI, 52.9% to 92.0%] vs 32.3% [95% CI, 24.4% to 43.0%], P < .001), with comparable positive predictive value (70.4% [95% CI, 64.0% to 76.8%] vs 75.2% [95% CI, 69.8% to 80.6%], P = .23). Conclusions and Relevance: In clinical data from 409 hospitals, sepsis was present in 6% of adult hospitalizations, and in contrast to claims-based analyses, neither the incidence of sepsis nor the combined outcome of death or discharge to hospice changed significantly between 2009-2014. The findings also suggest that EHR-based clinical data provide more objective estimates than claims-based data for sepsis surveillance. |
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