Coffee production is a global industry with coffee bean roasteries in businesses throughout the world. Workers in this industry face a variety of inhalational hazards ranging from predominantly organic dust, endotoxin, and green and castor bean allergen exposures when working in primary processing factories, to dusts, gases, and vapors including α-diketones when working in coffee production facilities. Previously documented respiratory health effects include symptoms such as wheeze, cough, and dyspnea, bronchial hyperresponsiveness, and reduced spirometric parameters. In addition, these exposures can cause chronic lung diseases such as asthma and obliterative bronchiolitis.

Researchers from NIOSH and partners from several universities conducted investigations on the respiratory health consequences of exposures across the span of the coffee industry, from primary processing to coffee production, using well-planned, standardized data collection tools that enabled the pooling of data across multiple investigations. The series of papers were published in a special topic issue in Frontiers in Public Health.

Investigations in the primary coffee processing industry were conducted at 16 factories in two African countries where green coffee beans were cleaned, hulled, sorted, and prepared for shipment to roasting and packaging facilities. These assessments identified high levels of organic dust and endotoxin exposures that frequently exceeded their respective occupational exposure limits. Increased prevalence of chronic respiratory symptoms and lower forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) on spirometry were also reported among coffee workers compared to controls.

In the United States, extensive exposure assessments were conducted at 17 coffee roasting and packaging facilities. The assessments included sampling for diacetyl, 2,3-pentanedione, and volatile organic compounds during coffee handling, roasting, grinding, flavoring, packaging, shipping, quality control, and in cafés. Results showed exposure levels often exceeded the recommended exposure limits for diacetyl and 2,3-pentanedione, particularly in flavoring and grinding jobs. Exposure data were used to characterize emission factors and model exposure determinants using innovative Bayesian methods. The models identified factors leading to higher exposures including grinding and openly storing coffee beans; these processes may be amenable to modification. For example, a pilot study involving installation of ventilated enclosures on grinding equipment significantly reduced α-diketone exposures near grinders by 75 to 95 percent and in the rest of the facility by 15 to 61 percent. Overall, factors associated with lower exposures included the presence of local exhaust ventilation and general dilutional ventilation.

The health assessments identified a range of upper and lower respiratory symptoms, obstructive and restrictive abnormalities on spirometry, and abnormalities on impulse oscillometry suggestive of small airways dysfunction. Decrements in percent predicted FEV₁ and FVC were associated with various metrics of exposure to diacetyl, 2,3-pentanedione, and the sum of the two α-diketones. The patterns of symptoms and lung function abnormalities may indicate early disease markers or subclinical disease.

One of the articles in this series is a commentary on the impact of various factors and assumptions including choice of health effects, human or animal studies, quality of exposure assessments, and uncertainty factors on risk assessment. It emphasizes the need for transparency in assumptions and methods used to understand variability in exposure limits.

Finally, the compilation highlights the benefits of standardizing data collection and data pooling to increase sample size and achieve a more representative population to make robust inferences. Such integrative multi-disciplinary research can lead to more accurate health risk estimates and targeted exposure mitigation recommendations, ultimately resulting in a reduction in the burden of adverse respiratory health outcomes for workers.