Occupational agriculture organic dust exposure and its relationship to asthma and airway inflammation in adults

Abstract

Objective Recent studies have made advances into understanding the complex agriculture work exposure environment in influencing asthma in adults. The objective of this study is to review studies of occupational agricultural exposures including dust, animal, and pesticide exposures with asthma in adult populations. Data Sources PubMed databases were searched for articles pertaining to farming, agriculture, asthma, occupational asthma, airway inflammation, respiratory disease, lung disease, pesticides and organic dust. Study Selections Studies chosen were published in or after 1999 that included adults and asthma and farming/agricultural work or agricultural exposures and airway inflammatory disease measurements. Results The data remains inconclusive. Several retrospective studies demonstrate agricultural work to be protective against asthma in adults, especially with increased farming exposure over time. In contrast, other studies find increased risk of asthma with farming exposures, especially for the non-atopic adult. Mechanistic and genetic studies have focused on defining the wide variety and abundance of microorganisms within these complex organic dusts that trigger several pattern recognition receptor pathways to modulate the hosts’ response. Conclusion Asthma risk depends on the interplay of genetic factors, gender, atopic predisposition, type of livestock, pesticide exposure, and magnitude and duration of exposure in the adult subject. Longer exposure to occupational farming is associated with decreased asthma risk. However, studies also suggest that agricultural work and multiple types of livestock are independent risk factors for developing asthma. Prospective and longitudinal studies focusing on genetic polymorphisms, objective assessments, and environmental sampling are needed to further delineate the influence of agriculture exposure in the adult worker.

Endotoxin and particulate matter emitted by livestock farms and respiratory health effects in neighboring residents

“…It might be that this pattern represents protective and adverse effects of endotoxin and that exposure characteristics determine the effect. This would be in line with suggestions made that (besides individual susceptibility) dose, duration and frequency of exposure largely determines the response (Gautam et al, 2018;Liu, 2002;Wunschel and Poole, 2016). Besides a plausible causative agent, endotoxin is also a marker for livestock-related microbial exposures in general.…”

Pollutants in the workplace: Effect on occupational asthma

“…The timing and magnitude of the exposure plays a significant role because greater endotoxin levels, which serve as a surrogate measure of bacterial burden, have been associated with lower lung function in asthma cases among adult farmers. 7 Interestingly, this relationship is modified by early-life farm exposures because those not born on a farm had greater rates of asthma compared with adult farmers who were born and raised on a farm. 7 Similarly, exposure to swine and dairy confinements are risk factors for new-onset nonallergic asthma and worsening lung function over time, whereas being born and raised on a farm reduces this risk.…”

“…7 Interestingly, this relationship is modified by early-life farm exposures because those not born on a farm had greater rates of asthma compared with adult farmers who were born and raised on a farm. 7 Similarly, exposure to swine and dairy confinements are risk factors for new-onset nonallergic asthma and worsening lung function over time, whereas being born and raised on a farm reduces this risk. 7 Finally, the use of various types of pesticides, including but not limited to organophosphorus pesticides, 8 should be highlighted because pesticides are LMW agents that can be important independent risk factors to explain workplace-exacerbated asthma among exposed adults.…”

“…Microbial components within agricultural dust extracts activate pathogen recognition receptor signaling pathways to elicit strong inflammatory responses marked by neutrophil and T H 1/T H 17 lymphocyte influx, as well as trigger airway hyperresponsiveness. 7 Neutrophilic inflammation has also been associated with airway dehydration in asthmatic patients, which is hypothesized to contribute to bronchoconstriction. Endotoxins can also enhance histamine release caused by allergens and potentiate eosinophilic inflammation.…”

Organic Dust Exposure Induces Stress Response and Mitochondrial Dysfunction in Monocytic Cells

“…Persistent exposure to OD has been linked to the development of chronic inflammatory conditions, such as chronic obstructive pulmonary disease (COPD) and asthma, including lung tissue damage and decline in lung function (Charavaryamath and Singh, 2006;Wunschel and Poole, 2016). Despite several research groups using both in vitro and in vivo models of OD exposure, precise cellular and molecular mechanisms leading to chronic lung disease remain largely unknown.…”