Agricultural Work Exposures and Pulmonary Function Among Hired Farm Workers in California (The MICASA Study)

ABSTRACT

Despite California’s dependence on hired farm labor, scarce research has been conducted on the respiratory health of hired farm workers. Agricultural exposures to inorganic and organic dusts can adversely affect an individual’s respiratory health and differ by farm type and job task. The purpose of the present analysis was to examine associations between agricultural work exposures and pulmonary function among 450 California farm workers. Data were collected as part of the Mexican Immigration to California: Agricultural Safety and Acculturation (MICASA) study, a prospective cohort study examining occupational risk factors and health of hired farm worker families in Mendota, California. Time-weighted self-reported average (TWSRA) dust scores were calculated from assessments of past-12-month agricultural work history. Other dust exposure indicator variables included months worked in agriculture in the past 12 months and years worked in agriculture. Multiple linear regression modeled FEV₁ (forced expiratory volume in 1 second), FEF_25–75% (forced midexpiratory flow rate), FVC (forced vital capacity), FEV₆, FEV₁/FVC, and FEV₁/FEV₆ separately. Seventy-six percent of participants had worked in agriculture in the past year. In models conducted for crops and tasks separately, high TWSRA dust score was associated with better FEV₆. Crop and task models showed associations between greater months worked in agriculture in the past year and better FEV₁, FEF_25–75%, and FEV₆. Both models also found greater years worked in agriculture to be associated with worse FEV₁/FEV₆. Results were generally in the opposite direction as expected given past research but not uncommon. Future research should investigate relationships between pulmonary function and agricultural dust exposure over a lifetime and changes in pulmonary function over time.

KEYWORDS:

• Agriculture
• Hispanic Americans
• respiratory function tests

ACKNOWLEDGMENTS

Appreciation and gratitude goes to the MICASA study participants, local field staff (Gloria Andrade, Alex Cervantes, Ana Cervantes, and Giselle Garcia), and the Western Center for Agricultural Health and Safety.