Discovery of firefighter chemical exposures using military-style silicone dog tags

Abstract

Occupational chemical hazards in the fire service are hypothesized to play a role in increased cancer risk, and reliable sampling technologies are necessary for conducting firefighter chemical exposure assessments. This study presents the military-style dog tag as a new configuration of silicone passive sampling device to sample individual firefighters' exposures at one high and one low fire call volume department in the Kansas City, Missouri metropolitan area. The recruited firefighters (n = 56) wore separate dog tags to assess on- and off-duty exposures (n_dogtags = 110), for a total of 30 24 h shifts. Using a 63 PAH method (GC-MS/MS), the tags detected 45 unique PAHs, of which 18 have not been previously reported as firefighting exposures. PAH concentrations were higher for on- compared to off-duty tags (0.25 < Cohen's d ≤ 0.80) and for the high compared to the low fire call volume department (0.25 ≤ d < 0.70). Using a 1530 analyte screening method (GC-MS), di-n-butyl phthalate, diisobutyl phthalate, guaiacol, and DEET were commonly detected analytes. The number of fire attacks a firefighter participated in was more strongly correlated with PAH concentrations than firefighter rank or years in the fire service. This suggested that quantitative data should be employed for firefighter exposure assessments, rather than surrogate measures. Because several detected analytes are listed as possible carcinogens, future firefighter exposure studies should consider evaluating complex mixtures to assess individual health risks.

Keywords: Firefighter; Occupational exposure; Passive sampling; Personal monitoring; Phthalates; Polycyclic aromatic hydrocarbons.

Figure 1.

Silicone dog tags (shown in yellow) were worn around the neck underneath firefighting personal protective equipment.

Figure 2.

The heat maps display each firefighter dog tag sample by fire department and by duty shift in conjunction with their exposure profiles for the A) PAH method and B) 1530 screening method. PAHs were grouped by the number of fused aromatic rings, and the screening method analytes were grouped by chemical category. No two tags had the same chemical exposure profile.

Figure 3.

Compared to earlier studies examining personal firefighter exposures, the dog tag samples identified 18 PAHs previously unassociated with firefighting using gas chromatography triple quadruple mass spectrometry (Anderson et al. 2015). Studies using gas chromatography mass spectrometry (GCMS) included (Alexander and Baxter 2014; Fabian et al. 2011; Shen et al. 2018; Sjostrom et al. 2019; Stec et al. 2018; Strandberg et al. 2018; Wingfors et al. 2018). Studies using liquid chromatography (LC) included (Fent et al. 2014; Fent et al. 2018; Oliveira et al. 2017).

Figure 4.

Bar graphs compare the PAH concentrations, ordered by the number of aromatic rings, between (A) on- and off-duty paired dog tags and (B) high and low call volume departments. Generally, occupational PAH concentrations were higher than non-occupational concentrations, and higher at the high compared to the low call volume department. Bold*: p<0.10. Bold**: p<0.05. Bold***: p<0.01 (2-sided p-value).

Figure 5.

Bar graphs compare the chemical concentrations (A, B) between on- and off-duty paired dog tags for A) summed chemical categories and B) target analytes and (C, D) between high and low call volume departments for A) summed chemical categories and B) target analytes. Bold*: p<0.10. Bold**: p<0.05. Bold***: p<0.01 (two-sided p-value). Abbreviations: DEHP – di(2-ethylhexyl) phthalate, DIBP – diisobutyl phthalate, DBP – di-n-butyl phthalate, DEP – diethyl phthalate, DEET – N,N-dietyl-m-toluamide, BBP – butyl benzyl phthalate, DNNP – di-n-nonyl phthalate.

Figure 6.

Exponentiated β parameter coefficients from the 19 PAH models are shown for occupation-related variables of A) number of fire attacks during the sampling period, B) firefighter rank, and C) years spent in the fire service. In Figures 6A and 6C, a positive change in PAH concentration was represented by the solid line at 10^β=1.0. Bold*: p<0.10. Bold**: p<0.05. Bold***: p<0.01.

Figure 7.

Exponentiated β parameter coefficients from the 12 screening method models are shown for occupation-related variables of A) number of fire attacks during the sampling period, B) firefighter rank, and C) years spent in the fire service. In Figures 7A and 7C, a positive change in chemical concentration was represented by the solid line at 10^β=1.0. Bold*: p<0.10. Bold**: p<0.05. Bold***: p<0.01.