Demographic changes in COVID-19 mortality during the pandemic: analysis of trends in disparities among workers using California's mortality surveillance system.

BACKGROUND: There is limited information on the extent and patterns of disparities in COVID-19 mortality throughout the pandemic. We aimed to examine trends in disparities by demographics over variants in the pre- and post-vaccine availability period among Californian workers using a social determinants of health lens. METHODS: Using death certificates, we identified all COVID-19 deaths that occurred between January 2020 and May 2022 among workers aged 18-64 years in California (CA). We derived estimates for at-risk worker populations using the Current Population Survey. The waves of COVID-19 mortality in the pre-vaccine availability period were March 2020-June 2020 (wave 1), and July 2020-November 2020 (wave 2), and in the post-vaccine availability period: December 2020-May 2021 (wave 3), June 2021-January 2022 (wave 4), and February 2022-May 2022 (wave 5). Poisson regression models with robust standard errors were used to determine wave-specific mortality rate ratios (MRRs). We examined the change in MRR across waves by including an interaction term between each demographic characteristic and wave period in different models. The role of potential misclassification of Race/ethnicity on death certificates was examined using probabilistic quantitative bias analysis as sensitivity analysis. RESULTS: Among the 24.1 million working age CA population included in the study, there were 26,068 COVID-19 deaths in the period between January 2020 and May 2022. Compared with their respective reference groups, workers who were 50-64 years old, male, Native Hawaiian, Latino, or African American, foreign-born; individuals who had lower education; and unmarried were disproportionately affected by COVID-19 mortality. While disparities by sex, race/ethnicity and foreign-born status narrowed in later waves (post-vaccine availability), disparities by age, education level and marital status did not change substantially across waves. CONCLUSION: Demographic disparities in COVID-19 mortality narrowed in the post-vaccine availability waves. However, the existence of disparities across all waves of the pandemic, even in an era of widespread vaccine coverage, could indicate remaining gaps in prevention and differential vulnerability. Addressing the underlying social, structural, and occupational factors that contribute to these disparities is critical for achieving health equity.

Risk factors for COVID-19 among Californians working outside the home, November 2020 - May 2021.

BACKGROUND: Higher incidences of COVID-19 mortality and outbreaks have been found in certain industries and occupations. Workplace factors, including working in close proximity to others and contact with the public can facilitate SARS-CoV-2 transmission, especially without appropriate protective measures. Limited information is available about workers at highest risk for SARS-CoV-2 infection. METHODS: A phone-based, nonprobability study was conducted between November 2020 and May 2021 among California workers who were tested for SARS-CoV-2. Participants were asked about demographics and workplace factors, including industry, occupation, and implementation of COVID-19 mitigation measures. Using the SARS-CoV-2 occupational exposure matrix, three exposure metrics and a combination index were used to categorize occupations. We assessed the association between workplace risks and SARS-CoV-2 test positivity using adjusted logistic regression. RESULTS: We enrolled 451 (13%) of 3475 potentially eligible workers in the study: 212 with positive and 239 with negative SARS-CoV-2 test results. Those working very close to others and with the highest combined exposure index had a positive association with SARS-CoV-2 positivity. Primarily indoor workers had a lower odds of test positivity compared to those with any outdoor work. There was no association between public-facing occupations and test positivity. Participants with employers who implemented mitigation measures in all three control categories-engineering, administrative, and personal protective equipment-had lower odds of test positivity than those with fewer mitigation measures. CONCLUSIONS: Worker groups with higher risk factors should be prioritized for outreach. Assessment of occupational risk factors collectively can provide insight to inform preventative actions for workers, employers, and public health entities.

Evaluating the association between in-person work and the risk of SARS-CoV-2 infection through June 2021.

OBJECTIVES: Recent studies have evaluated COVID-19 outbreaks and excess mortality by occupation sectors. Studies on SARS-CoV-2 infection across occupation and occupation-related factors remain lacking. In this study, we estimate the effect of in-person work on SARS-CoV-2 infection risk and describe SARS-CoV-2 seroprevalence among working adults. METHODS: We used Wave 1 data (May to June 2021) from CalScope, a population-based seroprevalence study in California. Occupation data were coded using the National Institute for Occupational Safety and Health Industry and Occupation Computerized Coding System. Dried blood spot specimens were tested for antibodies to establish evidence of prior infection. We estimated the causal effect of in-person work on SARS-CoV-2 infection risk using the g-formula and describe SARS-CoV-2 seroprevalence across occupation-related factors. RESULTS: Among 4335 working adults, 53% worked in person. In-person work was associated with increased risk of prior SARS-CoV-2 infection (risk difference: 0.03; [95% CI: 0.02-0.04]) compared with working remotely. Workers that reported job loss or who were without medical insurance had higher evidence of prior infection. Amongst in-person workers, evidence of prior infection was highest within farming, fishing, and forestry (55%; [95% CI: 26%-81%]); installation, maintenance, and repair (23%; [12%-39%]); building and grounds cleaning and maintenance (23%; [13%-36%]); food preparation and serving related (22% [13%-35%]); and healthcare support (22%; [13%-34%]) occupations. Workers who identified as Latino, reported a household income of <$25K, or who were without a bachelor's degree also had higher evidence of prior infection. CONCLUSIONS: SARS-CoV-2 infection risk varies by occupation. Future vaccination strategies may consider prioritizing in-person workers.

Reported Exposures Among In-Person Workers With Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection in 6 States, September 2020-June 2021.

BACKGROUND: Surveillance systems lack detailed occupational exposure information from workers with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. The National Institute for Occupational Safety and Health partnered with 6 states to collect information from adults diagnosed with SARS-CoV-2 infection who worked in person (outside the home) in non-healthcare settings during the 2 weeks prior to illness onset. METHODS: The survey captured demographic, medical, and occupational characteristics and work- and non-work-related risk factors for SARS-CoV-2 infection. Reported close contact with a person known or suspected to have SARS-CoV-2 infection was categorized by setting as exposure at work, exposure outside of work only, or no known exposure/did not know. Frequencies and percentages of exposure types are compared by respondent characteristics and risk factors. RESULTS: Of 1111 respondents, 19.4% reported exposure at work, 23.4% reported exposure outside of work only, and 57.2% reported no known exposure/did not know. Workers in protective service occupations (48.8%) and public administration industries (35.6%) reported exposure at work most often. More than one third (33.7%) of respondents who experienced close contact with ≥10 coworkers per day and 28.8% of respondents who experienced close contact with ≥10 customers/clients per day reported exposures at work. CONCLUSIONS: Exposure to occupational SARS-CoV-2 was common among respondents. Examining differences in exposures among different worker groups can help identify populations with the greatest need for prevention interventions. The benefits of recording employment characteristics as standard demographic information will remain relevant as new and reemerging public health issues occur.

Severe Acute Respiratory Syndrome Coronavirus 2 and Respiratory Virus Sentinel Surveillance, California, USA, May 10, 2020-June 12, 2021.

State and local health departments established the California Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and Respiratory Virus Sentinel Surveillance System to conduct enhanced surveillance for SARS-CoV-2 and other respiratory pathogens at sentinel outpatient testing sites in 10 counties throughout California, USA. We describe results obtained during May 10, 2020‒June 12, 2021, and compare persons with positive and negative SARS-CoV-2 PCR results by using Poisson regression. We detected SARS-CoV-2 in 1,696 (19.6%) of 8,662 specimens. Among 7,851 specimens tested by respiratory panel, rhinovirus/enterovirus was detected in 906 (11.5%) specimens and other respiratory pathogens in 136 (1.7%) specimens. We also detected 23 co-infections with SARS-CoV-2 and another pathogen. SARS-CoV-2 positivity was associated with male participants, an age of 35-49 years, Latino race/ethnicity, obesity, and work in transportation occupations. Sentinel surveillance can provide useful virologic and epidemiologic data to supplement other disease monitoring activities and might become increasingly useful as routine testing decreases.

COVID-19 Outbreaks and Mortality Among Public Transportation Workers - California, January 2020-May 2022.

Work-related factors can contribute to risk for exposure to and infection with SARS-CoV-2, the virus that causes COVID-19, and subsequent COVID-19-attributable outcomes, including death. Comparing COVID-19 metrics across industries can help identify workers at highest risk. Elevated COVID-19 mortality rates have been reported among all transportation workers, as well as specifically in public transportation industries (1-3). The California Department of Public Health (CDPH) calculated public transportation industry-specific COVID-19 outbreak incidence during January 2020-May 2022 and analyzed all laboratory-confirmed COVID-19 deaths among working-age adults in California to calculate public transportation industry-specific mortality rates during the same period. Overall, 340 confirmed COVID-19 outbreaks, 5,641 outbreak-associated cases, and 537 COVID-19-associated deaths were identified among California public transportation industries. Outbreak incidence was 5.2 times as high (129.1 outbreaks per 1,000 establishments) in the bus and urban transit industry and 3.6 times as high in the air transportation industry (87.7) as in all California industries combined (24.7). Mortality rates were 2.1 times as high (237.4 deaths per 100,000 workers) in transportation support services and 1.8 times as high (211.5) in the bus and urban transit industry as in all industries combined (114.4). Workers in public transportation industries are at higher risk for COVID-19 workplace outbreaks and mortality than the general worker population in California and should be prioritized for COVID-19 prevention strategies, including vaccination and enhanced workplace protection measures.

Two-year follow-up of exposure, engineering controls, respiratory protection and respiratory health among workers at an indium-tin oxide (ITO) production and reclamation facility.

OBJECTIVES: To determine whether engineering controls and respiratory protection had measurable short-term impact on indium exposure and respiratory health among current indium-tin oxide production and reclamation facility workers. METHODS: We documented engineering controls implemented following our 2012 evaluation and recorded respirator use in 2012 and 2014. We measured respirable indium (Inresp) and plasma indium (InP) in 2012 and 2014, and calculated change in Inresp (∆Inresp) and InP (∆InP) by the 13 departments. We assessed symptoms, lung function, serum biomarkers of interstitial lung disease (Krebs von den Lungen (KL)-6 and surfactant protein (SP)-D) and chest high-resolution CT at both time points and evaluated workers who participated in both 2012 and 2014 for changes in health outcomes (new, worsened or improved). RESULTS: Engineering controls included installation of local exhaust ventilation in both grinding departments (Rotary and Planar) and isolation of the Reclaim department. Respiratory protection increased in most (77%) departments. ∆InP and ∆Inresp often changed in parallel by department. Among 62 workers participating in both 2012 and 2014, 18 (29%) had new or worsening chest symptoms and 2 (3%) had functional decline in lung function or radiographic progression, but average KL-6 and SP-D concentrations decreased, and no cases of clinical indium lung disease were recognised. CONCLUSIONS: Increased engineering controls and respiratory protection can lead to decreased Inresp, InP and biomarkers of interstitial lung disease among workers in 2 years. Ongoing medical monitoring of indium-exposed workers to confirm the longer-term effectiveness of preventive measures is warranted.

Elevated exposures to respirable crystalline silica among engineered stone fabrication workers in California, January 2019-February 2020.

BACKGROUND: Workers fabricating engineered stone face high risk for exposure to respirable crystalline silica (RCS) and subsequent development of silicosis. In response, the California Division of Occupational Safety and Health (Cal/OSHA) performed targeted enforcement inspections at engineered stone fabrication worksites. We investigated RCS exposures and employer adherence to Cal/OSHA's RCS and respiratory protection standards from these inspections to assess ongoing risk to stone fabrication workers. METHODS: We extracted employee personal air sampling results from Cal/OSHA inspection files and calculated RCS exposures. Standards require that employers continue monitoring employee RCS exposures and perform medical surveillance when exposures are at or above the action level (AL; 25 µg/m3 ); exposures above the permissible exposure limit (PEL; 50 µg/m3 ) are prohibited. We obtained RCS and respiratory protection standard violation citations from a federal database. RESULTS: We analyzed RCS exposures for 152 employees at 47 workplaces. Thirty-eight (25%) employees had exposures above the PEL (median = 89.7 µg/m3 ; range = 50.7-670.7 µg/m3 ); 17 (11%) had exposures between the AL and PEL. Twenty-four (51%) workplaces had ≥1 exposure above the PEL; 7 (15%) had ≥1 exposure between the AL and PEL. Thirty-four (72%) workplaces were cited for ≥1 RCS standard violation. Twenty-seven (57%) workplaces were cited for ≥1 respiratory protection standard violation. CONCLUSIONS: Our investigation demonstrates widespread RCS overexposure among workers and numerous employer Cal/OSHA standard violation citations. More enforcement and educational efforts could improve employer compliance with Cal/OSHA standards and inform employers and employees of the risks for RCS exposure and strategies for reducing exposure.

Effectiveness of Abbott BinaxNOW Rapid Antigen Test for Detection of SARS-CoV-2 Infections in Outbreak among Horse Racetrack Workers, California, USA.

The Abbott BinaxNOW rapid antigen test is cheaper and faster than real-time reverse transcription PCR (rRT-PCR) for detecting severe acute respiratory syndrome coronavirus 2. We compared BinaxNOW with rRT-PCR in 769 paired specimens from 342 persons during a coronavirus disease outbreak among horse racetrack workers in California, USA. We found positive percent agreement was 43.3% (95% CI 34.6%-52.4%), negative percent agreement 100% (95% CI 99.4%-100%), positive predictive value 100% (95% CI 93.5%-100%), and negative predictive value 89.9% (95% CI 87.5%-92.0%). Among 127 rRT-PCR-positive specimens, the 55 with paired BinaxNOW-positive results had a lower mean cycle threshold than the 72 with paired BinaxNOW-negative results (17.8 vs. 28.5; p<0.001). Of 100 specimens with cycle threshold <30, a total of 51 resulted in positive virus isolation; 45 (88.2%) of those were BinaxNOW-positive. Our comparison supports immediate isolation for BinaxNOW-positive persons and confirmatory testing for negative persons.

Evidence for Environmental-Human Microbiota Transfer at a Manufacturing Facility with Novel Work-related Respiratory Disease.

Rationale: Workers' exposure to metalworking fluid (MWF) has been associated with respiratory disease.Objectives: As part of a public health investigation of a manufacturing facility, we performed a cross-sectional study using paired environmental and human sampling to evaluate the cross-pollination of microbes between the environment and the host and possible effects on lung pathology present among workers.Methods: Workplace environmental microbiota were evaluated in air and MWF samples. Human microbiota were evaluated in lung tissue samples from workers with respiratory symptoms found to have lymphocytic bronchiolitis and alveolar ductitis with B-cell follicles and emphysema, in lung tissue samples from control subjects, and in skin, nasal, and oral samples from 302 workers from different areas of the facility. In vitro effects of MWF exposure on murine B cells were assessed.Measurements and Main Results: An increased similarity of microbial composition was found between MWF samples and lung tissue samples of case workers compared with control subjects. Among workers in different locations within the facility, those that worked in the machine shop area had skin, nasal, and oral microbiota more closely related to the microbiota present in the MWF samples. Lung samples from four index cases and skin and nasal samples from workers in the machine shop area were enriched with Pseudomonas, the dominant taxa in MWF. Exposure to used MWF stimulated murine B-cell proliferation in vitro, a hallmark cell subtype found in the pathology of index cases.Conclusions: Evaluation of a manufacturing facility with a cluster of workers with respiratory disease supports cross-pollination of microbes from MWF to humans and suggests the potential for exposure to these microbes to be a health hazard.

Work-related adverse respiratory health outcomes at a machine manufacturing facility with a cluster of bronchiolitis, alveolar ductitis and emphysema (BADE).

OBJECTIVES: Four machine manufacturing facility workers had a novel occupational lung disease of uncertain aetiology characterised by lymphocytic bronchiolitis, alveolar ductitis and emphysema (BADE). We aimed to evaluate current workers' respiratory health in relation to job category and relative exposure to endotoxin, which is aerosolised from in-use metalworking fluid. METHODS: We offered a questionnaire and spirometry at baseline and 3.5 year follow-up. Endotoxin exposures were quantified for 16 production and non-production job groups. Forced expiratory volume in one second (FEV1) decline ≥10% was considered excessive. We examined SMRs compared with US adults, adjusted prevalence ratios (aPRs) for health outcomes by endotoxin exposure tertiles and predictors of excessive FEV1 decline. RESULTS: Among 388 (89%) baseline participants, SMRs were elevated for wheeze (2.5 (95% CI 2.1 to 3.0)), but not obstruction (0.5 (95% CI 0.3 to 1.1)). Mean endotoxin exposures (range: 0.09-28.4 EU/m3) were highest for machine shop jobs. Higher exposure was associated with exertional dyspnea (aPR=2.8 (95% CI 1.4 to 5.7)), but not lung function. Of 250 (64%) follow-up participants, 11 (4%) had excessive FEV1 decline (range: 403-2074 mL); 10 worked in production. Wheeze (aPR=3.6 (95% CI 1.1 to 12.1)) and medium (1.3-7.5 EU/m3) endotoxin exposure (aPR=10.5 (95% CI 1.3 to 83.1)) at baseline were associated with excessive decline. One production worker with excessive decline had BADE on subsequent lung biopsy. CONCLUSIONS: Lung function loss and BADE were associated with production work. Relationships with relative endotoxin exposure indicate work-related adverse respiratory health outcomes beyond the sentinel disease cluster, including an incident BADE case. Until causative factors and effective preventive strategies for BADE are determined, exposure minimisation and medical surveillance of affected workforces are recommended.

The Occupational Burden of Nonmalignant Respiratory Diseases. An Official American Thoracic Society and European Respiratory Society Statement.

Rationale: Workplace inhalational hazards remain common worldwide, even though they are ameliorable. Previous American Thoracic Society documents have assessed the contribution of workplace exposures to asthma and chronic obstructive pulmonary disease on a population level, but not to other chronic respiratory diseases. The goal of this document is to report an in-depth literature review and data synthesis of the occupational contribution to the burden of the major nonmalignant respiratory diseases, including airway diseases; interstitial fibrosis; hypersensitivity pneumonitis; other noninfectious granulomatous lung diseases, including sarcoidosis; and selected respiratory infections. Methods: Relevant literature was identified for each respiratory condition. The occupational population attributable fraction (PAF) was estimated for those conditions for which there were sufficient population-based studies to allow pooled estimates. For the other conditions, the occupational burden of disease was estimated on the basis of attribution in case series, incidence rate ratios, or attributable fraction within an exposed group. Results: Workplace exposures contribute substantially to the burden of multiple chronic respiratory diseases, including asthma (PAF, 16%); chronic obstructive pulmonary disease (PAF, 14%); chronic bronchitis (PAF, 13%); idiopathic pulmonary fibrosis (PAF, 26%); hypersensitivity pneumonitis (occupational burden, 19%); other granulomatous diseases, including sarcoidosis (occupational burden, 30%); pulmonary alveolar proteinosis (occupational burden, 29%); tuberculosis (occupational burden, 2.3% in silica-exposed workers and 1% in healthcare workers); and community-acquired pneumonia in working-age adults (PAF, 10%). Conclusions: Workplace exposures contribute to the burden of disease across a range of nonmalignant lung conditions in adults (in addition to the 100% burden for the classic occupational pneumoconioses). This burden has important clinical, research, and policy implications. There is a pressing need to improve clinical recognition and public health awareness of the contribution of occupational factors across a range of nonmalignant respiratory diseases.

Workshop summary: Potential usefulness and feasibility of a US National Mesothelioma Registry.

The burden and prognosis of malignant mesothelioma in the United States have remained largely unchanged for decades, with approximately 3200 new cases and 2400 deaths reported annually. To address care and research gaps contributing to poor outcomes, in March of 2019 the Mesothelioma Applied Research Foundation convened a workshop on the potential usefulness and feasibility of a national mesothelioma registry. The workshop included formal presentations by subject matter experts and a moderated group discussion. Workshop participants identified top priorities for a registry to be (a) connecting patients with high-quality care and clinical trials soon after diagnosis, and (b) making useful data and biospecimens available to researchers in a timely manner. Existing databases that capture mesothelioma cases are limited by factors such as delays in reporting, deidentification, and lack of exposure information critical to understanding as yet unrecognized causes of disease. National disease registries for amyotrophic lateral sclerosis (ALS) in the United States and for mesothelioma in other countries, provide examples of how a registry could be structured to meet the needs of patients and the scientific community. Small-scale pilot initiatives should be undertaken to validate methods for rapid case identification, develop procedures to facilitate patient access to guidelines-based standard care and investigational therapies, and explore approaches to data sharing with researchers. Ultimately, federal coordination and funding will be critical to the success of a National Mesothelioma Registry in improving mesothelioma outcomes and preventing future cases of this devastating disease.

Case Investigations of Infectious Diseases Occurring in Workplaces, United States, 2006-2015.

Workers in specific settings and activities are at increased risk for certain infectious diseases. When an infectious disease case occurs in a worker, investigators need to understand the mechanisms of disease propagation in the workplace. Few publications have explored these factors in the United States; a literature search yielded 66 investigations of infectious disease occurring in US workplaces during 2006-2015. Reported cases appear to be concentrated in specific industries and occupations, especially the healthcare industry, laboratory workers, animal workers, and public service workers. A hierarchy-of-controls approach can help determine how to implement effective preventive measures in workplaces. Consideration of occupational risk factors and control of occupational exposures will help prevent disease transmission in the workplace and protect workers' health.

Flavorings-Related Lung Disease: A Brief Review and New Mechanistic Data.

Flavorings-related lung disease is a potentially disabling and sometimes fatal lung disease of workers making or using flavorings. First identified almost 20 years ago in microwave popcorn workers exposed to butter-flavoring vapors, flavorings-related lung disease remains a concern today. In some cases, workers develop bronchiolitis obliterans, a severe form of fixed airways disease. Affected workers have been reported in microwave popcorn, flavorings, and coffee production workplaces. Volatile α-dicarbonyl compounds, particularly diacetyl (2,3-butanedione) and 2,3-pentanedione, are implicated in the etiology. Published studies on diacetyl and 2,3-pentanedione document their ability to cause airway epithelial necrosis, damage biological molecules, and perturb protein homeostasis. With chronic exposure in rats, they produce airway fibrosis resembling bronchiolitis obliterans. To add to this knowledge, we recently evaluated airway toxicity of the 3-carbon α-dicarbonyl compound, methylglyoxal. Methylglyoxal inhalation causes epithelial necrosis at even lower concentrations than diacetyl. In addition, we investigated airway toxicity of mixtures of diacetyl, acetoin, and acetic acid, common volatiles in butter flavoring. At ratios comparable to workplace scenarios, the mixtures or diacetyl alone, but not acetic acid or acetoin, cause airway epithelial necrosis. These new findings add to existing data to implicate α-dicarbonyl compounds in airway injury and flavorings-related lung disease.

Severe lung disease characterized by lymphocytic bronchiolitis, alveolar ductitis, and emphysema (BADE) in industrial machine-manufacturing workers.

BACKGROUND: A cluster of severe lung disease occurred at a manufacturing facility making industrial machines. We aimed to describe disease features and workplace exposures. METHODS: Clinical, functional, radiologic, and histopathologic features were characterized. Airborne concentrations of thoracic aerosol, metalworking fluid, endotoxin, metals, and volatile organic compounds were measured. Facility airflow was assessed using tracer gas. Process fluids were examined using culture, polymerase chain reaction, and 16S ribosomal RNA sequencing. RESULTS: Five previously healthy male never-smokers, ages 27 to 50, developed chest symptoms from 1995 to 2012 while working in the facility's production areas. Patients had an insidious onset of cough, wheeze, and exertional dyspnea; airflow obstruction (mean FEV1 = 44% predicted) and reduced diffusing capacity (mean = 53% predicted); and radiologic centrilobular emphysema. Lung tissue demonstrated a unique pattern of bronchiolitis and alveolar ductitis with B-cell follicles lacking germinal centers, and significant emphysema for never-smokers. All had chronic dyspnea, three had a progressive functional decline, and one underwent lung transplantation. Patients reported no unusual nonoccupational exposures. No cases were identified among nonproduction workers or in the community. Endotoxin concentrations were elevated in two air samples; otherwise, exposures were below occupational limits. Air flowed from areas where machining occurred to other production areas. Metalworking fluid primarily grew Pseudomonas pseudoalcaligenes and lacked mycobacterial DNA, but 16S analysis revealed more complex bacterial communities. CONCLUSION: This cluster indicates a previously unrecognized occupational lung disease of yet uncertain etiology that should be considered in manufacturing workers (particularly never-smokers) with airflow obstruction and centrilobular emphysema. Investigation of additional cases in other settings could clarify the cause and guide prevention.

A field evaluation of a single sampler for respirable and inhalable indium and dust measurements at an indium-tin oxide manufacturing facility.

Indium-tin oxide production has increased greatly in the last 20 years subsequent to increased global demand for touch screens and photovoltaics. Previous studies used measurements of indium in blood as an indicator of indium exposure and observed associations with adverse respiratory outcomes. However, correlations between measurements of blood indium and airborne respirable indium are inconsistent, in part because of the long half-life of indium in blood, but also because respirable indium measurements do not incorporate inhalable indium that can contribute to the observed biological burden. Information is lacking on relationships between respirable and inhalable indium exposure, which have implications for biological indicators like blood indium. The dual IOM sampler includes the foam disc insert and can simultaneously collect respirable and inhalable aerosol. Here, the field performance of the dual IOM sampler was evaluated by comparing performance with the respirable cyclone and traditional IOM for respirable and inhalable indium and dust exposure, respectively. Side-by-side area air samples were collected throughout an indium-tin oxide manufacturing facility. Cascade impactors were used to determine particle size distribution. Several statistical methods were used to evaluate the agreement between the pairs of samplers including calculating the concordance correlation coefficient and its accuracy and precision components. One-way ANOVA was used to evaluate the effect of dust concentration on sampler differences. Respirable indium measurements showed better agreement (concordance correlation coefficient: 0.932) compared to respirable dust measurements (concordance correlation coefficient: 0.777) with significant differences observed in respirable dust measurements. The dual IOM measurements had high agreement with the traditional IOM for inhalable indium (concordance correlation coefficient: 0.997) but lower agreement for inhalable dust (concordance correlation coefficient: 0.886 and accuracy: 0.896) with a significantly large mean bias (-146.9 µg/m3). Dust concentration significantly affected sampler measurements of inhalable dust and inhalable indium. Results from this study suggest that the dual IOM is a useful single sampler for simultaneous measurements of occupational exposure to respirable and inhalable indium.

Dental Personnel Treated for Idiopathic Pulmonary Fibrosis at a Tertiary Care Center - Virginia, 2000-2015.

In April 2016, a Virginia dentist who had recently received a diagnosis of idiopathic pulmonary fibrosis (IPF) and was undergoing treatment at a specialty clinic at a Virginia tertiary care center contacted CDC to report concerns that IPF had been diagnosed in multiple Virginia dentists who had sought treatment at the same specialty clinic. IPF is a chronic, progressive lung disease of unknown cause and associated with a poor prognosis (1). Although IPF has been associated with certain occupations (2), no published data exist regarding IPF in dentists. The medical records for all 894 patients treated for IPF at the Virginia tertiary care center during September 1996-June 2017 were reviewed for evidence that the patient had worked as a dentist, dental hygienist, or dental technician; among these patients, eight (0.9%) were identified as dentists and one (0.1%) as a dental technician, and each had sought treatment during 2000-2015. Seven of these nine patients had died. A questionnaire was administered to one of the living patients, who reported polishing dental appliances and preparing amalgams and impressions without respiratory protection. Substances used during these tasks contained silica, polyvinyl siloxane, alginate, and other compounds with known or potential respiratory toxicity. Although no clear etiologies for this cluster exist, occupational exposures possibly contributed. This cluster of IPF cases reinforces the need to understand further the unique occupational exposures of dental personnel and the association between these exposures and the risk for developing IPF so that appropriate strategies can be developed for the prevention of potentially harmful exposures.

Burden of respiratory abnormalities in microwave popcorn and flavouring manufacturing workers.

OBJECTIVES: Diacetyl, a butter flavour compound used in food and flavouring production, is a respiratory toxin. We characterised the burden of respiratory abnormalities in workers at popcorn and flavouring manufacturing facilities that used diacetyl as evaluated through US National Institute for Occupational Safety and Health (NIOSH) health hazard evaluations. METHODS: We performed analyses describing the number and percentage of current and former workers from popcorn and flavouring manufacturing facilities where NIOSH administered a respiratory health questionnaire and spirometry testing who met case definitions of suspected flavouring-related lung disease. Case definitions were pathologist reported: lung biopsy pathology report stating supportive of/consistent with constrictive bronchiolitis or bronchiolitis obliterans; probable: obstructive/mixed spirometric pattern with forced expiratory volume in 1 s (FEV1) <60% predicted; possible: obstructive/mixed spirometric pattern with FEV1 ≥60% or any spirometric restriction; symptoms only: normal spirometry plus exertional dyspnoea or usual cough. RESULTS: During 2000-2012, NIOSH collected questionnaire and spirometry data on 1407 workers (87.0% current, 13.0% former) at nine facilities in eight states. After applying case definitions, 4 (0.3%) were classified as pathologist reported, 48 (3.4%) as probable, 234 (16.6%) as possible and 404 (28.7%) as symptoms only. The remaining 717 (51.0%) workers had normal spirometry without exertional dyspnoea or usual cough. Seven of 11 workers with biopsies did not meet the pathologist-reported case definition, although four met probable and three met possible. CONCLUSIONS: This approach demonstrates the substantial burden of respiratory abnormalities in these workers. A similar approach could quantify the burden of respiratory abnormalities in other industries that use diacetyl.