FLAVORINGS-RELATED LUNG DISEASE

Coffee Processing Facilities

Occupational asthma was thought to be the main respiratory risk for workers in coffee processing facilities. Previous studies identified green and roasted coffee bean dusts and castor bean dusts from contaminated shipping bags as asthmagens (Figley and Rawling 1950; Karr et al. 1978; Zuskin et al. 1979, 1985; Thomas et al. 1991). Asthmagens are substances that can cause asthma. In 2013, a severe lung disease called obliterative bronchiolitis was reported in former workers of a coffee processing facility that roasted, ground, and flavored coffee (CDC 2013).

Obliterative Bronchiolitis (Lung Disease)

Obliterative bronchiolitis is a severe, non-reversible lung disease that involves scarring of the very small airways called bronchioles in a patchy distribution throughout the lung. Symptoms may include cough, shortness of breath on exertion, and/or wheeze (NIOSH 2012a). In addition to coffee processing workers, this severe lung disease has been identified in flavoring manufacturing workers and microwave popcorn workers who worked with flavoring compounds like diacetyl (2,3-butanedione) or butter flavorings containing diacetyl (Kim et al. 2013; Kreiss 2013; Kanwal et al. 2006). 2,3-Pentanedione is a chemical similar to diacetyl that is sometimes used in place of diacetyl in the manufacturing of flavorings (Day et al. 2011; Boylstein 2012). Diacetyl and 2,3-pentanedione likely share the same mechanism of toxicity. Airway damage has been observed in laboratory animals after exposure to diacetyl or 2,3-pentanedione (Hubbs et al. 2008, 2012; Morgan et al. 2012). NIOSH has developed a pamphlet for healthcare providers about flavoring-related lung disease (NIOSH 2012a).

Alpha-Diketones 

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Air Sampling and Analysis for Diacetyl (2,3-Butanedione) and 2,3-Pentanedione

Air sampling at a coffee processing facility for diacetyl and 2,3-pentanedione can help determine if control measures are needed to reduce airborne concentrations of alpha-diketones. Both area and personal air sampling are important to characterize exposures. At one coffee processing facility evaluated, NIOSH found high mean area concentrations of diacetyl and 2,3-pentanedione in the grinding/packaging room and flavoring room. The hazard potential may increase when these chemicals occur in combination with each other, since having exposure to chemicals with the same functional alpha-diketone group may result in additive effects. The sum of the means of diacetyl and 2,3-pentanedione exposure in personal samples for grinders in the grinding/packaging room was 283 parts per billions (ppb), similar to the sum for mixers of 227 ppb and packer/helpers of 244 ppb in the flavoring room (Bailey et al. 2015). The American Conference of Governmental Industrial Hygienists (ACGIH) is a professional, not-for-profit, nongovernmental scientific association that reviews existing published, peer-reviewed scientific literature and publishes exposure guidelines. ACGIH notes that when two or more hazardous substances have a similar toxicological effect on the same system or organ (e.g., lungs), their combined effect should be given primary consideration rather than individually (ACGIH 2015).

Air sampling during specific tasks, such as roasting, grinding, opening storage bins or containers with roasted coffee beans, and pouring and adding flavorings, is important. There is potential for workers to have a low average personal exposure but high peak exposures to diacetyl and/or 2,3-pentanedione during certain tasks. For example, at a coffee processing facility, a 15-minute air sample collected at a small open hatch in the lid of a grinding/packaging room mezzanine hopper holding unflavored ground coffee above an active packaging line measured concentrations of 14,300 ppb diacetyl and 18,400 ppb 2,3-pentanedione; workers opened these hatches momentarily to monitor coffee levels in the hoppers (Bailey et al. 2015).

The Occupational Safety and Health Administration (OSHA) has published validated methods for air monitoring for diacetyl and 2,3-pentanedione. OSHA method 1013 is validated for diacetyl and acetoin (OSHA 2008a). OSHA method 1016 is validated for 2,3-pentanedione (OSHA 2010). OSHA method 1012 is validated for diacetyl (OSHA 2008b) but has a lower limit of detection; this method can also detect 2,3-pentanedione.

In addition to using the standard OSHA methods 1013/1016 and 1012, NIOSH has been using a modified OSHA method 1013/1016 that uses a mass spectrometer for improved detection limits (Simmons 2015). NIOSH has also been using evacuated canisters (LeBouf et al. 2012) with flow controllers to collect air samples for diacetyl and 2,3-pentanedione in workplaces.

Real-time or Near Real-Time Sampling for Diacetyl (2,3-Butanedione) and 2,3-Pentanedione

Some sampling methods can provide real-time or near real-time results of volatile compounds such as diacetyl and 2,3-pentanedione. These techniques can help identify sources of alpha-diketones (e.g., diacetyl and 2,3-pentanedione) and tasks associated with exposure; this information can be useful in identifying appropriate work practices and the development of exposure controls (NIOSH 2016-111, NIOSH 2015).

A photoionization detector (PID) is an example of a real-time monitor that can be used to measure total volatile organic compound (VOC) concentrations in air. The PID is a non-specific detector that will see a range of chemical compounds in air, including diacetyl and 2,3-pentanedione, that interact with the light source in the instrument. PIDs do not provide concentrations specific to any particular compound. They are often calibrated for isobutylene and can commonly detect total VOC concentrations from 1 to 2000 parts per million. Modern PIDs can be programmed to measure the concentration of VOCs at fixed time intervals (NIOSH 2016-111).

Fourier-transform infrared (FTIR) spectroscopy is another technique that is more selective allowing for multiple target chemicals to be simultaneously measured in air. The amount of infrared radiation absorbed over a range of wavelengths is indicative of the chemical concentration in air. FTIR analysis can produce real-time quantitation of flavoring chemicals in air although interferences can pose analytical difficulties in quantifying specific flavoring ingredients in environments with multiple organic chemicals present (NIOSH 2016-111).

NIOSH Exposure Limits for Diacetyl (2,3-Butanedione) and 2,3-Pentanedione

NIOSH has published RELs for diacetyl and 2,3-pentanedione in workplace air (NIOSH 2016-111). The NIOSH objective in establishing RELs for diacetyl and 2,3-pentanedione is to reduce the risk of respiratory impairment (decreased lung function) and the severe irreversible lung disease obliterative bronchiolitis associated with occupational exposure to these chemicals. On this basis, NIOSH proposed a REL of 5 ppb for diacetyl and 9.3 ppb for 2,3-pentandione (as a time-weighted average for up to 8 hours/day during a 40-hour workweek).The NIOSH proposed 15-minute STELs are 25 ppb for diacetyl and 31 ppb for 2,3-pentanedione (NIOSH 2016-111). The NIOSH proposed exposure standards do not differentiate between natural and synthetic chemical origin of diacetyl or 2,3-pentanedione.

Currently, there are no occupational exposure limits for 2,3-hexanedione or 2,3-heptanedione.>

Workplace Interventions

If elevated levels of diacetyl (2,3-butanedione) or 2,3-pentanedione are detected in workplace air, interventions should be put in place to reduce the levels. The effectiveness of these interventions should be verified by follow-up air sampling. Serial air sampling for diacetyl and 2,3-pentanedione can help evaluate the impact of interventions on exposures and identify where to prioritize any future interventions. In 2015, NIOSH published a best practices document that describes work interventions such as engineering controls, work practices, and exposure monitoring for occupational exposures to diacetyl and 2,3-pentanedione (NIOSH 2015).

Examples of workplace interventions include the following (click on the boxes below for more information):

NIOSH Health Hazard Evaluation Program

NIOSH has a health hazard evaluation program (NIOSH 2009) in which we respond to requests from employers, employees, or their authorized representatives (i.e., unions) to investigate possible workplace hazards and make recommendations. Often requests are handled by phone consultations and report reviews. When situations arise that are not already understood based on prior health hazard evaluations, site visits are often conducted that can include exposure and/or health evaluations to better understand potential hazards. NIOSH currently has ongoing health hazard evaluations at some coffee processing facilities to learn more about potential exposures to workers. NIOSH investigators published an article in the American Journal of Industrial Medicine about a health hazard evaluation at a coffee processing facility (Bailey et al. 2015). The investigators found elevated levels of butter flavoring chemicals diacetyl and 2,3-pentanedione in the air at the facility and identified three sources: 1) flavoring chemicals added to roasted coffee beans in the flavoring area; 2) grinding and packaging unflavored ground and whole bean roasted coffee in a distinct area of the facility, and 3) storing roasted coffee in hoppers, on a mezzanine above the grinding/packaging process, to off-gas. The current workers had excess shortness of breath and obstruction on spirometry, both consistent with undiagnosed lung disease. Respiratory morbidity was associated with exposure and not limited to the flavoring area.