Environmental Exposures and Asthma in Active Duty Service Members

Burn pit-related smoke causes developmental and behavioral toxicity in zebrafish: Influence of material type and emissions chemistry

Combustion of mixed materials during open air burning of refuse or structural fires in the wildland urban interface produces emissions that worsen air quality, contaminate rivers and streams, and cause poor health outcomes including developmental effects. The zebrafish, a freshwater fish, is a useful model for quickly screening the toxicological and developmental effects of agents in such species and elicits biological responses that are often analogous and predictive of responses in mammals. The purpose of this study was to compare the developmental toxicity of smoke derived from the burning of 5 different burn pit-related material types (plywood, cardboard, plastic, a mixture of the three, and the mixture plus diesel fuel as an accelerant) in zebrafish larvae. Larvae were exposed to organic extracts of increasing concentrations of each smoke 6-to-8-hr post fertilization and assessed for morphological and behavioral toxicity at 5 days post fertilization. To examine chemical and biological determinants of toxicity, responses were related to emissions concentrations of polycyclic hydrocarbons (PAH). Emissions from plastic and the mixture containing plastic caused the most pronounced developmental effects, including mortality, impaired swim bladder inflation, pericardial edema, spinal curvature, tail kinks, and/or craniofacial deformities, although all extracts caused concentration-dependent effects. Plywood, by contrast, altered locomotor responsiveness to light changes to the greatest extent. Some morphological and behavioral responses correlated strongly with smoke extract levels of PAHs including 9-fluorenone. Overall, the findings suggest that material type and emissions chemistry impact the severity of zebrafish developmental toxicity responses to burn pit-related smoke.

Associations between psychological and respiratory distress in post-deployment Veterans

Since September 11, 2001, over 2.7 million United States service members have deployed to South-West Asia and the Middle East and have been exposed to environmental hazards and psychological trauma. Many of these service members have returned with medical and psychological illnesses, some of which have proved complex and resistant to treatment. One notable constellation of symptoms is post-deployment respiratory illness, which has become a focus of research and policy efforts. The present study sought to examine the impact of post-deployment psychological distress on respiratory symptom severity. Data were obtained from the Veterans Affairs Airborne Hazards and Open Burn Pit Registry (AHOBPR) health surveillance database (N =107,403). Psychological factors were compared against common organic and environmental predictors of post-deployment respiratory distress. Psychological distress following deployment was a stronger predictor of 12-month shortness of breath severity than general respiratory pathology or level of exposure to environmental hazards, controlling for gender, age, race, and tobacco use. Additionally, psychological distress was a better predictor of shortness of breath severity than documented respiratory illnesses including asthma, chronic obstructive pulmonary disease, and chronic bronchitis. Implications and directions for future research are discussed, as well as potential alterations to existing treatment and health surveillance paradigms.

Association of urinary organophosphate metabolites with adult asthma patients: a cross-sectional population-based study

Human health is adversely affected by exposure to organophosphate (OP) pesticides. This study aims to investigate the correlation between urinary OP metabolites and the prevalence of asthma. In cross-sectional studies, data from the National Health and Nutrition Examination Survey (NHANES) projects conducted between 2003-2008, 2011-2012, and 2015-2018 were analyzed. Multiple logistic regressions and restricted cubic spline (RCS) regressions were utilized to examine the relationship between four urinary OP metabolites, namely dimethyl phosphate (DMP), diethyl phosphate (DEP), dimethyl phosphorothioate (DMTP), and diethyl phosphorothioate (DETP), and the prevalence of asthma. Additionally, quantile g-computation (QG-C) regression was employed to evaluate the association between urinary OP metabolites (both individual and combined exposures) and asthma prevalence. The results showed that a total of 9316 adults, including 1298 participants with asthma, were included in the analysis. The median age of the participants was 47.37 years, and 50.27% were female. In the comprehensive model, the third tertile of DMP and DEP exhibited a positive association with asthma prevalence compared to the first tertile (odds ratio [95% confidence interval]: 1.26 [1.01-1.57], Ptrend = 0.036; and 1.25 [1.07-1.51], Ptrend = 0.008, respectively). Moreover, a linear relationship was observed between DMP, DEP, and asthma prevalence (P for nonlinearity = 0.320 and 0.553, respectively). The QG-C regression revealed a positive association between the mixture of urinary OP metabolites and asthma prevalence (OR = 1.04 [1.01-1.07], P = 0.025), with DEP contributing the most substantial effect (weight = 0.564). Our findings suggest that exposure to OP pesticides is associated with an increased prevalence of asthma, with DEP demonstrating the strongest impact.

Contributions of particulate and gas phases of simulated burn pit smoke exposures to impairment of respiratory function

OBJECTIVE

Inhalation of smoke from the burning of waste materials on military bases is associated with increased incidences of cardiopulmonary diseases. This study examined the respiratory and inflammatory effects of acute inhalation exposures in mice to smoke generated by military burn pit-related materials including plywood (PW), cardboard (CB), mixed plastics (PL), and a mixture of these three materials (MX) under smoldering (0.84 MCE) and flaming (0.97 MCE) burn conditions.

METHODS

Mice were exposed nose-only for one hour on two consecutive days to whole or filtered smoke or clean air alone. Smoldering combustion emissions had greater concentrations of PM (∼40 mg/m3) and VOCs (∼5-12 ppmv) than flaming emissions (∼4 mg/m3 and ∼1-2 ppmv, respectively); filtered emissions had equivalent levels of VOCs with negligible PM. Breathing parameters were assessed during exposure by head-out plethysmography.

RESULTS

All four smoldering burn pit emission types reduced breathing frequency (F) and minute volumes (MV) compared with baseline exposures to clean air, and HEPA filtration significantly reduced the effects of all smoldering materials except CB. Flaming emissions had significantly less suppression of F and MV compared with smoldering conditions. No acute effects on lung inflammatory cells, cytokines, lung injury markers, or hematology parameters were noted in smoke-exposed mice compared with air controls, likely due to reduced respiration and upper respiratory scrubbing to reduce the total deposited PM dose in this short-term exposure.

CONCLUSION

Our data suggest that material and combustion type influences respiratory responses to burn pit combustion emissions. Furthermore, PM filtration provides significant protective effects only for certain material types.

Burn Pit Exposure Is Associated With Increased Sinonasal Disease

OBJECTIVE

The aim of this study was to determine whether self-reported burn pit exposure is associated with increased subjective and objective sinus disease.

DESIGN

A cross-sectional study was performed evaluating consecutive adult patients presenting to a US Military rhinology clinic. Demographics, medical histories, sinonasal quality-of-life scores, and nasal endoscopy examinations were obtained. Participants were divided into three cohorts based on self-reported exposure histories and outcomes compared.

RESULTS

One hundred eighty-six patients met the inclusion criteria, the majority of whom were male. Patients with burn pit exposure had worse Sinonasal Outcome Test-22 scores (49.9) compared with those deployed without burn pit exposure (31.8) or never deployed (31.5). Endoscopic findings demonstrated worse disease within those exposed (Lund-Kennedy score, 3.3) compared with the other cohorts (1.8 and 1.7, respectively).

CONCLUSIONS

These novel findings suggest that deployment-related burn pit exposure is associated with increased subjective and objective sinus disease.

Role of Particulate Matter from Afghanistan and Iraq in Deployment-Related Lung Disease

Approximately 3 million United States military personnel and contractors were deployed to Southwest Asia and Afghanistan over the past two decades. After returning to the United States, many developed persistent respiratory symptoms, including those due to asthma, rhinosinusitis, bronchiolitis, and others, which we collectively refer to as deployment-related lung diseases (DRLD). The mechanisms of different DRLD have not been well defined. Limited studies from us and others suggest that multiple factors and biological signaling pathways contribute to the onset of DRLD. These include, but are not limited to, exposures to high levels of particulate matter (PM) from sandstorms, burn pit combustion products, improvised explosive devices, and diesel exhaust particles. Once inhaled, these hazardous substances can activate lung immune and structural cells to initiate numerous cell-signaling pathways such as oxidative stress, Toll-like receptors, and cytokine-driven cell injury (e.g., interleukin-33). These biological events may lead to a pro-inflammatory response and airway hyperresponsiveness. Additionally, exposures to PM and other environmental hazards may predispose military personnel and contractors to more severe disease due to the interactions of those hazardous materials with subsequent exposures to allergens and cigarette smoke. Understanding how airborne exposures during deployment contribute to DRLD may identify effective targets to alleviate respiratory diseases and improve quality of life in veterans and active duty military personnel.

Association of Agricultural, Occupational, and Military Inhalants With Autoantibodies and Disease Features in US Veterans With Rheumatoid Arthritis

OBJECTIVE

To determine the association of inhalant exposures with rheumatoid arthritis (RA)-related autoantibodies and severity in US veterans.

METHODS

Participants in the Veterans Affairs Rheumatoid Arthritis (VARA) registry were mailed surveys assessing occupational, agricultural, and military inhalant exposures. Demographic characteristics, disease activity, functional status, and extraarticular features were obtained from the VARA registry, while HLA-DRB1 shared epitope (SE) status, anti-cyclic citrullinated peptide (anti-CCP) antibodies, and rheumatoid factor (RF) were measured using banked DNA/serum from enrollment. Associations between inhalant exposures and RA-related factors (autoantibodies, severity, and extraarticular features) were assessed using multivariable linear and logistic regression models adjusted for age, sex, race, and tobacco use and stratified by SE status. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Questionnaires were returned by 797 of 1,566 participants (50.9%). Survey respondents were older, more often White or male, and less frequently smokers, and had lower disease activity compared to nonrespondents. Anti-CCP positivity was more common among veterans exposed to burn pits (OR 1.66 [95% CI 1.02, 2.69]) and military waste disposal (OR 1.74 [95% CI 1.04, 2.93]) independent of other factors. Among participants who were positive for SE alleles, burn pit exposure (OR 5.69 [95% CI 2.73, 11.87]) and military waste disposal exposure (OR 5.05 [95% CI 2.42, 10.54]) were numerically more strongly associated with anti-CCP positivity. Several inhalant exposures were associated with the presence of chronic lung disease, but not with the presence of RF or the level of disease activity.

CONCLUSION

Military burn pit exposure and military waste disposal exposure were independently associated with the presence of anti-CCP antibodies in RA patients. These findings are consistent with emerging evidence that various inhalant exposures influence autoantibody expression and RA risk.