Diacetyl Exposures at Four Microwave Popcorn Plants

Abstract

Exposure to the butter-flavoring compound diacetyl was assessed in four microwave popcorn manufacturing plants in the United States during multiple surveys from 2005-2007. Personal, breathing zone samples were collected and analyzed using NIOSH Method 2557. Samples were collected at the lapel, outside the powered air-purifying respirator used by any worker entering the slurry room. The data were evaluated for similarity of exposure across job duties and resulted in two exposure groups: (1) Mixers, those who routinely work in the slurry room mixing vegetable oil, salt, and flavorings, and (2) Non-mixers (all other production jobs). From 639 samples collected during surveys, summary estimates of exposures were calculated as the arithmetic mean and median of the data and by the geometric mean of lognormally distributed results. For Mixers, the range of the arithmetic mean exposures across the four plants was 0.057-0.860, and geometric means ranged from 0.029 to 0.231. For Non-mixers, the range of arithmetic mean exposures was 0.014-0.074 ppm, and geometric means ranged from 0.001-0.018. Because of concerns regarding reliability of the method with increasing humidity, mean exposures were also calculated for samples collected when relative humidity was 30% or less. For this restricted set of measurements, geometric statistics always produced higher summary metrics, compared with the full data set; the direction of change using arithmetic statistics was not uniform, being higher at two plants and lower at two plants. Overall, 49.1% of the 639 values were below the limit of detection; in the lower humidity analysis, 25.6% of 246 results were below the limit of detection. At one plant, ventilation changes were made in the slurry room; based on 39 additional samples (not included in the 639 values reported here) collected using the same protocol after the engineering change, exposure decreased from 0.614 to 0.061 ppm. Further work at these facilities to better characterize diacetyl exposure was not possible, as substitution resulted in diacetyl being removed from the product.

Diacetyl: Occurrence, Analysis, and Toxicity

“…Diacetyl is listed in the FDA’s GRAS (generally regarded as safe) list and has been used widely in the preparation of butter and related food products, at levels of 6–9 μg/g, because it possesses a unique, butter-like flavor with an odor threshold of 50 ppb. , On the other hand, NIOSH proposed limits on diacetyl exposure for factory workers, who might be exposed to vapor-phase diacetyl in related production factories. − Toxicities associated with diacetyl, such as interacting with other factors to cause lung damage and playing a role in oxidative stress, have also been reported . Determination of toxicity is the first avenue to establishing the safety level of chemicals.…”

Evaluation of the hypersensitivity potential of alternative butter flavorings

“…Artificial butter flavorings are proprietary mixtures which can contain more than 100 different volatile chemicals. Extensive environmental sampling initially identified the diketone diacetyl as the predominant component of the butter flavoring in plants with identified cases of BO (Boylstein et al, 2006; Martyny et al, 2008; White et al, 2010). …”

Respiratory follow-up pre- and post-engineering controls or cessation of added diacetyl at four microwave popcorn facilities

“…Given the 2003–2005 exposure controls, this assumption may underestimate pre-2005 exposures, resulting in a potential exposure misclassification. However, samples from a 2003 NIOSH Health Hazard Evaluation [12] in Plant 1 were similar to those obtained in 2005 [6]. Exposures in Plant 1 may not be representative of other facilities.…”

“…To reduce exposure, engineering and work practice changes were implemented in 2003–2005 including isolating the mixing rooms, increasing mixing room air ventilation, treating powders with 0.25% food grade oil to minimise dust, installing exhaust hoods for quality assurance operators, and in 2003, requiring mixers to wear powered air purifying respirators. Exposure monitoring began at all plants in 2005 [6]. Our previous job–exposure matrix [1, 6, 7] was utilised with these updates: additional ventilation controls in Plant 1 in June 2006 reduced mean exposures for nonmixers (0.07 to 0.02 ppm) and mixers (0.94 to 0.07 ppm); and subsequent sampling in Plant 2 demonstrated lower mean exposures for nonmixers (0.12 to 0.09 ppm) and mixers (0.84 to 0.61 ppm).…”

“…Exposure monitoring began at all plants in 2005 [6]. Our previous job–exposure matrix [1, 6, 7] was utilised with these updates: additional ventilation controls in Plant 1 in June 2006 reduced mean exposures for nonmixers (0.07 to 0.02 ppm) and mixers (0.94 to 0.07 ppm); and subsequent sampling in Plant 2 demonstrated lower mean exposures for nonmixers (0.12 to 0.09 ppm) and mixers (0.84 to 0.61 ppm). While these measurements are considerably lower than in other studies [2], they exceeded the subsequent 2016 NIOSH Recommended Exposure Limit of 5 ppb [2].…”