Biomonitoring of firefighting forces: a review on biomarkers of exposure to health-relevant pollutants released from fires

Figures & data

Figure 1. Air pollution components (a) (reproduced from Marris et al. (2020) under creative commons CC by license), and their potential mechanisms of carcinogenesis (b) (reproduced from Turner et al. (2020), copyright (2023), with permission from John Wiley and sons).

TSG: tumor suppressing genes.

Figure 2. Flow-chart of the literature selection method. *note: some studies characterized more than one biomarker and included different matrices.

Table 1. Identification of biomarkers of exposure determined in biological samples of firefighters.

Biological sample	Biomarkers
Urine	Polycyclic aromatic hydrocarbons metabolites Benzene and toluene metabolites Heavy metals and metalloids Phthalates Phenols Pyrethroid pesticides Herbicides Flame retardants metabolites Organophosphate esters 2-ethylhexyl-2,3,4,5-tetrabromobenzoate Organophosphorus insecticides metabolites Dioxin metabolites Dioxin-like polychlorinated biphenyls metabolites
Blood	Polycyclic aromatic hydrocarbons Heavy metals and metalloids Polybrominated diphenyl ethers Organochlorine pesticides Polychlorinated dibenzodioxins Polychlorinated dibenzofurans Polychlorinated biphenyls Perfluoroalkyl acids
Saliva	Polycyclic aromatic hydrocarbons
Exhaled Breath	benzene, ethylbenzene, styrene, toluene, o-xylene, m,p-xylene, 1,2,4-Trimethylbenzene; trifluorobenzene and decane.

Figure 3. Urinary concentrations (mean and/or median, expressed as µmol/mol creatinine) of the established PAHs biomarker of exposure 1-hydroxypyrene (1-OHPYR) in firefighters and instructors at pre- and post-exposure periods.

Type of exposure: A - Work day; B -Structure fires; C - Office workers at the fire station; D -Training exercises; E - Controlled fires; F - Wildland fires*.

Time of sample collection: I – Post-shift; II – Morning after; III - 14 days after; IV – (0-12h); V – (12-24h); VI – (24-50h); VII – post-2^nd exercise; VIII – 3h post-3^rd exercise.

Recommended occupational level of 0.93 µmol/mol creatinine (~2.5 µg/L) was proposed by the Biological Exposure Index Committee of the American Conference of Governmental Industrial Hygienists (ACGIH 2019).

Figure 4. Urinary concentrations (mean and/or median, expressed as µmol/mol creatinine) of PAHs biomarkers of exposure: a) 1-hydroxynaphthalene (1-OHNAPH); b) 2-hydroxynaphtalene (2-OHNAPH); c) 2-hydoxyfluorene (2-OHFLU); d) 3-hydroxyfluorene (3-OHFLU); e) 1-hydroxyphenanthrene (1-OHPHE) in firefighters and instructors at pre- and post-exposure periods.

Type of exposure: A - Prescribed burns; B - Live fire training (carbonaceous-fired simulation); C – Controlled fires; D – Training exercises.

Time of sample collection:

I – Post-shift; II – Morning after; III – 0-12h post-exposure; IV – 12-24h post-exposure; V – 24-50h post-exposure; VI – post-2^nd exercise; VII – 3h post-3^rd exercise.

Firefighters and type of fire: a) Simulated smoke; b) Oriented strand board; c) Pallet and straw; Fire service instructors d) Simulated smoke; e) Oriented strand board; f) Pallet and straw.

Figure 4. (Continued).

Table 2. Concentration (range, expressed as µg/L) of polycyclic aromatic hydrocarbons reported in firefighters’ saliva.

Continent, County	Exposure	Sampling	PAHs concentrations in saliva							Reference
			NAPH	ACEY	FLU	PHE	ANT	FLA	PYR
Europe, Spain	Training firefighting in a train and in a supermarket	Control	n.d.	n.d.	0.22–0.96	n.d.-0.8	n.d.	n.d.-0.32	n.d.-0.17	(Santos et al. 2019)
		0 hr post-exposure	n.d.-0.43	n.d.-1.45	0.44–1.48	0.53–3.3	n.d.-0.38	0.19–1.10	n.d.-0.86
		6 hr post-exposure	n.d.	n.d.-1.42	0.30–0.78	n.d.-1.2	n.d.	n.d.-1.06	n.d.-1.5
		12 h post-exposure	n.d.	n.d.-0.78	0.14–0.94	n.d.-0.24	n.d.	n.d.	n.d.

NAPH: Naphthalene; ACEY: Acenaphthylene; FLU: Fluorene; PHE: Phenanthrene; ANT: Anthracene; FLA: Fluoranthene; PYR: Pyrene.

n.d. – not detected.

Figure 5. Biological pathways for benzene metabolism, toxicity, and health effects. Reproduced from Bahadar, Mostafalou, and Abdollahi (2014), copyright (2023), with permission from Elsevier. note: CYP2E1: cytochrome P450 family 2 subfamily E member 1; ROS: reactive oxygen species.

Table 3. Concentrations of volatile organic compounds and/or their metabolites (excluding polycyclic aromatic hydrocarbons) in urine (median, expressed as μg/g creatinine except indicated otherwise) and exhaled breath (geometric mean expressed as ppbv, except indicated otherwise) of firefighters.

Continent, Country	Exposure/Subjects (n)		Sampling	Concentration	Reference
Urine
Asia, North Korea	Firefighters (34) Fire suppression activities		Immediately after the fire	Thiazolidine-4-carboxylic acid: 0.296^a Toluene: 0.336 m-Cresol: 2.377 S-benzylmercapturic acid: 5.642 Benzene: 0.124 Phenol: 215.367 S-phenylmercapturic acid: 0.123 Ethylbenzene: 0.078 2-phenylethanol: 99.892 4-methylbenzyl alcohol: 0.808 Styrene: 0.212 (1-phenyl-2-hydroxyethyl)-L-cysteine + N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine: 5.020 p-Isopropyltoluene: 0.010	(Kim et al. 2021)
			Three weeks after the fire
				Thiazolidine-4-carboxylic acid: 0.319^a Toluene: 0.191 m-Cresol: 1.308 S-benzylmercapturic acid: 5.463 Benzene: 0.077 Phenol: 232.337 S-phenylmercapturic acid: 0.216 Ethylbenzene: 0.058 2-phenylethanol: 107.013 4-methylbenzyl alcohol: 0.578 Styrene: 0.101 (1-phenyl-2-hydroxyethyl)-L-cysteine + N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine: 0.990 p-isopropyltoluene: 0.010
Europe, Norway	Firefighters (9) Fire drill, timber-framed timber house		Pre-drill Post-drill	S-phenylmercapturic acid: 0.6 S-benzylmercapturic acid: 5.9	(Rosting and Olsen 2020)
Exhaled breath
America, USA	Controlled structure burns/firefighters (12)		Control sample	Benzene: 11.1; Ethylbenzene: 0.5; Styrene: 1.2; Toluene:1.2; o-xylene: 0.5; m, p-xylene: 0.5	(Wallace et al. 2019)
			Pre-exposure	Benzene: 19.2; Ethylbenzene: 1.1; Styrene: 2.1; Toluene: 5.1; o-xylene: 1.0; m, p-xylene: 1.0
			Post-exposure	Benzene: 32.4; Ethylbenzene: 0.9; Styrene: 2.3; Toluene: 5.4; o-xylene: 0.8; m, p-xylene: 0.8
			1 hr post-exposure	Benzene: 19.7; Ethylbenzene: 1.0; Styrene: 1.9; Toluene: 4.6; o-xylene: 0.9; m, p-xylene: 0.9
America, USA	Controlled structure burns/firefighters (6)		Pre- to Post-exposure	Benzene (post-burn): 4.3 (1.8–8.9)^b	(Fent et al. 2015)
America, USA	Training exercises				(Fent et al. 2019)
	Fire Instructors (10)
		Scenario 1: Simulated smoke	Pre 1^st exercise	Benzene: 4.9; Ethylbenzene: 0.3; Styrene: 0.9; Toluene: 2.1.
			Post 2^nd exercise	Benzene: 3.0; Ethylbenzene: 0.1; Styrene: 0.2; Toluene: 1.1
			Post 3^rd exercise	Benzene: 8.7; Ethylbenzene: 0.5; Styrene: 4.6; Toluene: 4.4
		Scenario 2: Oriented strand board	Pre 1^st exercise	Benzene: 2.4–3.7; Ethylbenzene: 0.1–0.2; Styrene: 0.2–0.8; Toluene: 0.9–1.1
			Post 2^nd exercise	Benzene: 4.7–13.9; Ethylbenzene: 0.2–0.3; Styrene: 0.4–1.0; Toluene: 1.–2.1
			Post 3^rd exercise	Benzene: 4.7–9.1; Ethylbenzene: 0.3; Styrene: 2.0–4.5; Toluene: 1.9–2.1
		Scenario 3: Pallet and straw	Pre 1^st exercise	Benzene: 3.3; Styrene: 0.1; Toluene: 0.9
			Post 2^nd exercise	Benzene: 4.5; Ethylbenzene: 0.2; Styrene: 0.3; Toluene: 1.2
			Post 3^rd exercise	Benzene: 4.0; Ethylbenzene: 0.2; Styrene: 1.6; Toluene: 1.2
	Firefighters (24)
		Scenario 1: Simulated smoke	Pre-exposure	Benzene: 4.5; Ethylbenzene: 0.1; Styrene: 0.4; Toluene: 1.5
			Post-exposure	Benzene: 3.7; Ethylbenzene: 0.1; Styrene: 0.2; Toluene: 1.2
		Scenario 2: Oriented strand board	Pre-exposure	Benzene: 2.4–2.9; Ethylbenzene: 0.1–0.2; Styrene: 0.1–0.9; Toluene: 0.9–1.0
			Post-exposure	Benzene: 7.2–25.2; Ethylbenzene: 0.3–0.4; Styrene: 0.8–1.0; Toluene: 2.0–4.0
		Scenario 3: Pallet and straw	Pre-exposure	Benzene: 2.6; Styrene: 0.1; Toluene: 0.7
			Post-exposure	Benzene: 5.5; Ethylbenzene: 0.2; Styrene: 0.2; Toluene: 1.2
America, USA	Firefighters (12) Controlled residential fires; Job assignment:		pre- to post-firefighting change ^c		(Fent et al. 2020)
	Attack/Search			Benzene: 105; Ethylbenzene: -25; Styrene: 4.6; Toluene: 7.8; (o- + m, p-)xylene: -32
	Outside vent			Benzene: 40; Ethylbenzene: -19; Styrene: 14; Toluene: -2.5; (o- + m, p-)xylene: -12
	Command/Pump			Benzene: 33; Ethylbenzene: -27; Styrene: -18; Toluene: -14; (o- + m, p-)xylene: -22
	Overhaul			Benzene: 28; Ethylbenzene: -10; Styrene: 0.5; Toluene: -6.4; (o- + m, p-)xylene: -3.5

n.r. – not reported; n.d. not detected; ppbv: parts per billion per volume. ^a Data are presented as geometric mean, expressed as mg/g creatinine; ^b: Data are presented mean (range), expressed as ppb; ^c: Data are presented as median pre- to post-firefighting change expressed in %.

Figure 6. Heavy metals toxicological mechanisms and consequent health effects. Reproduced from Mitra et al. (2022), under creative commons CC by license.

IL-1: Interleukin 1; IL-6: Interleukin 6; IL:8: Interleukin 8; NF-κB: necrose factor kappa B; NO: nitric oxide; P53: Tumor suppressor protein 53; TNF-α: Tumor necrosis factor alpha.

Figure 7. Concentration of heavy metals and metalloids reported in urine (a) and blood (b) of firefighters.

Figure 8. Toxicological pathways for polybrominated diphenyl ethers (PBDEs): (a) endocrine disruption; (b) development consequences; (c) carcinogenesis. Reproduced from Wu et al. (2020), copyright (2023), with permission from Elsevier.

AhR: Aryl hydrocarbon receptor; ALL: Acute lymphoblastic leukemia; BDE-28: 2,4-Dibromo-1-(4-bromophenoxy)benzene; BDE-47: 2,2‘4,4’-tetrabromodiphenyl ether; BDE-99: 2,2‘,4,4’,5-Pentabromodiphenyl ether; BDE-209: Decabromodiphenyl ether; CYP1A1: Cytochrome P450 Family 1 Subfamily A Member 1; CYP1B1: Cytochrome P450 Family 1 Subfamily B Member 1; EDCs: Endocrine disrupting chemicals; ERR_γ: Estrogen-related receptor γ; ER_α: Estrogen receptor alpha; GDM: Gestational diabetes mellitus; IQ: Intelligence quotient; ME: Methyl group; mRNA: messenger RNA; PBDEs: Polybrominated diphenyl ethers; PR: Progesterone receptor; ROS: Reactive oxygen species; TH: Thyroid hormone; TR: Thyroid hormone receptor; TR-DBD: Thyroid hormone receptor DNA binding domain; TRE: Thyroid hormone response element.

Table 4. Concentrations of biomarkers of exposure of flame retardants (unmetabolized and metabolized compounds presented as geometric mean (95% CI), unless indicated otherwise) reported in firefighters.

Continent, Country	Type of exposure		Subjects		Concentration		Reference
			n	Age
Urine
Metabolized compounds
Flame retardants metabolites - ng/mL
America, USA	Structural firefighting while wearing full protective clothing and self-contained breathing apparatus		146	n.r.	Bis-2-chloroethyl phosphate: 0.86 (n.d.-10)^a Bis-(1-chloro-2-propyl) phosphate: 0.24 (n.d.-2.9) ^a Bis-(1,3-dichloro-2-propyl) phosphate: 3.4 (0.30–44) ^a Di-n-butyl phosphate: 0.18 (n.d.-2.4) ^a Diphenyl phosphate: 2.9 (0.24–28) ^a Di-p-cresyl phosphate; 2,3,4,5-tetrabromobenzoic acid; DBuP-d18, di-benzyl-phosphate; DPhP-d10, di-o-cresylphosphate: n.d.		(Jayatilaka et al. 2017)
America, USA		Structural firefighting while wearing full protective clothing and self-contained breathing apparatus	146	n.r.	Bis-2-chloroethyl phosphate: 0.84 (n.d. - 9.8) ^a Bis-(1-chloro-2-propyl) phosphate: 0.24 (n.d. - 3.0) ^a Bis-(1,3-dichloro-2-propyl) phosphate: 3.3 (n.d.- 42) ^a Di-n-butyl phosphate: 0.12 (n.d. - 2.9) ^a Diphenyl phosphate: 4.0 (0.14–32) ^a 2,3,4,5-tetrabromobenzoic acid: 0.10 (n.d. - 0.13) ^a 2-((isopropyl) phenyl) phenyl phosphate: 0.11 (n.d. - 0.49) ^a 4-((tert-butyl) phenyl) phenyl phosphate: 0.17 (n.d. - 1.1)^a DBuP-d18, di-benzyl-phosphate and DPhP-d10, di-o-cresylphosphate: n.d.	(Jayatilaka et al. 2019)
America, USA	Controlled residential fire scenarios		36	36 (21–52)			(Mayer et al. 2021)
	Pre-fire
					Bis(1,3-dichloro-2-propyl) phosphate: 2.38 ± 2.12 ^b Diphenyl phosphate: 0.97 ± 1.98 ^b Bis(2-chloroethyl) phosphate: 0.28 ± 3.01 ^b
	3-12 hr post-fire
					Bis(1-chloro-2-propyl) phosphate: n.d.-0.57 ^c Bis(1,3-dichloro-2-propyl) phosphate: 2.13–2.70 ^c Diphenyl phosphate: 1.20–1.67 ^c Di-p-cresyl phosphate: n.d.-0.29 ^c Di-n-butyl phosphate: n.d.-5.50 ^c Bis(2-chloroethyl) phosphate: 0.17–0.34 ^c 2,3,4,5-Tetrabromobenzoic acid: n.d.-0.24 ^c
America, USA	Women Firefighters Biomonitoring Collaborative Cohort (WWBC: 2014–2015)		Firefighter		Bis(1,3-dichloro-2-propyl) phosphate: 4.08 ± 4.53^b Di-n-butyl phosphate: 0.41 ± 3.92 ^b Bis(2-chloroethyl) phosphate: 0.85 ± 5.74 ^b Di-p-cresyl phosphate, Di-o-cresyl phosphate, Dibenzyl phosphate, 2,3,4,5-tetrabromobenzoic acid: n.d.		(Trowbridge et al. 2022)
			86	47.5 ± 4.6
			Office workers		Bis(1,3-dichloro-2-propyl) phosphate: 0.96 ± 3.99^b Bis(2-chloroethyl) phosphate, Di-n-butyl phosphate, Di-p-cresyl phosphate, Di-o-cresyl phosphate, Dibenzyl phosphate, 2,3,4,5-tetrabromobenzoic acid: n.d.
			84	48.3 ± 10.5
America, USA	Women Firefighters Biomonitoring Collaborative cohort (WWBC: 2014–2015)		Firefighters		bis (1,3-dichloro-2-propyl) phosphate: 4.05 ± 4.59 ^b bis (2-chloroethyl) phosphate: 0.87 ± 5.72 ^b Di-n-butyl phosphate: 0.41 ± 3.95 ^b tetrabromobisphenol a, Di-p-cresyl phosphate: n.d.		(Clarity et al. 2021)
			84	47.4 ± 4.6
			Office workers		bis (1,3-dichloro-2-propyl) phosphate: 0.87 ± 3.85 ^b bis (2-chloroethyl) phosphate, dibutyl phosphate, tetrabromobisphenol a, Di-p-cresyl phosphate: n.d.
			79	48.5 ± 10.6
Blood
Unmetabolized compounds
Polybrominated diphenyl ethers (PBDEs) - pg/g lipid
America, USA	Regular working period including participation in different types of firefighting activities ¥		101	42.8 ± 0.9	PBDE-17: n.d. 2,4,4′-tribromodiphenyl ether (BDE-28): 1700 (1500 - 1930) PBDE-47: 32300 (27800 - 37500) PBDE-66: n.d. PBDE-85: n.d. PBDE-99: 6190 (5350 - 7170) PBDE-100: 5680 (4770 - 6750) PBDE-153: 15400 (12900 - 18300) 2,2“,3,3,”4,4“,6,6”-Octabromodiphenyl ether (BDE-197): 1350 (1180 - 1530) 2,2“,3,3,”4,4“,5,6,6”-Nonabromodiphenyl ether (BDE-207): 1440 (1270 - 1630) PBDE-154, PBDE-183, PBDE-197, PBDE-201, PBDE-202, PBDE-203, PBDE-206, PBDE-207, PBDE-208, and PBDE-209: n.d. Decabromodiphenyl ether (BDE-209): 28300 ΣPBDEs (Σ -28, -47, -99, -100, -153): 66200 (57400 - 76300)		(Park et al. 2015)
America, USA	Controlled residential fire scenarios		36	36 (21–52)			(Mayer et al. 2021)
	Pre-Fire
					PBDE-28: 530 ± 2250^d PBDE-47: 849 ± 2590 ^d PBDE-99: 1580 ± 2800 ^d PBDE-100: 1580 ± 2520 ^d PBDE-153: 5660 ± 2420 ^d PBDE-209: 2910 ± 1790 ^d
	Post-Fire
					PBDE-28: 540 ± 2150 ^d PBDE-47: 8370 ± 2570 ^d PBDE-99: 1490 ± 2760 ^d PBDE-100: 1670 ± 2280 ^d PBDE-153: 5530 ± 2440^d PBDE-209: 3010 ± 1570 ^d
Asia, South Korea	Structural firefighting (24 hr after fire exposure)		92	44 (27–60)	∑PBDES: 17100 (1580–95200)^e		(Ekpe et al. 2021)

n.d.: not detected.; n.r.: not reported.

^aData presented as median (range); ^b Data presented as geometric mean ± standard deviation (SD) and expressed as µg/g creatinine; ^c Data presented as geometric mean range (variation between 3 to 12 hr post-fire), expressed as µg/g creatinine; ^d: Data were converted from ng/g lipid and presented as geometric mean ± SD; ^e Data were converted from ng/g lipid and presented as arithmetic mean (range).

¥ full-time, active firefighters for at least 12 months that enter a large biomonitoring study: Firefighter Occupational Exposures (FOX) Project, samples were collected in 2010–2011, but the FOX project is still ongoing; § fire at a cable plant that included the emission of toxic chemicals.

Table 5. Concentration of other biomarkers of exposure (unmetabolized and metabolized compounds presented as geometric mean (95% CI), unless indicated otherwise) reported in firefighters.

Continent, Country	Type of exposure		Subjects		Concentration		Reference
			n	Age
Urine
Unmetabolized compounds
Phthalates - µg/L
America, USA	Regular working period without participation in firefighting activities ¥		101	42.8 ± 0.9	Mono-benzyl phthalate: 8.18 (6.56–10.2) Dicyclohexyl phthalate: n.d. Di-n-octyl phthalate: 1.88 (1.46–2.42) Mono(2-ethyl-5-carboxypentyl) phthalate: 12.3 (10.1–149.9) Mono-ethyl phthalate: 52.9 (38.1–73.4) Mono-n-butyl phthalate: 10.6 (8.83–12.8)		(Biomonitoring California 2016)
Europe, Slovakia	Regular working period without participation in firefighting activities *		32	38 (24–53)	Mono-methyl phthalate:3.02 (1.70–30.71)^a Mono-ethyl phthalate: 64.55 (1.26–1251.61)^a Mono-isobutyl phthalate: 29.36 (75.68–75.68)^a Mono-n-butyl phthalate: 56.26 (5.26–170.78) ^a Mono-benzyl phthalate: 0.22 (n.d.-1.39) ^a Mono[2-ethylhexyl] phthalate: 5.94 (0.24–21.85) ^a Mono(2-ethyl-5-hydroxyhexyl) phthalate: 13.33 (0.81–53.99) ^a Mono(2-ethyl-5-oxohexyl) phthalate: 7.86 (0.69–25.02) Mono(2-ethyl-5-carboxypentyl) phthalate: 14.63 (0.30–39.22)^a Mono(2-carboxymethylhexyl) phthalate: 3.61 (0.15–11.21) ^a Mono-isononyl phthalate: 0.91 (0.28–9.36) ^a		(Kolena et al. 2020)
Phenols - µg/g creatinine
America, USA	Routine examinations during regular working periods without participation in firefighting activities		101	42.8 ± 0.9	Bisphenol A: 1.40 (1.18–1.67) Benzophenone-3: 69.8 (52.7–92.3) Triclosan: 18.0 (12.0–26.9) Methyl paraben: 41.7 (32.3–53.8) Ethyl paraben: n.d. Butyl paraben: n.d. n-propyl paraben: 4.08 (2.89–5.76)		(Waldman et al. 2016)
Pyrethroid insecticides – μg/L
America, USA	Regular working period without participation in firefighting activities ¥		101	42.8 ± 0.9	3-Phenoxybenzoic acid: 0.54 (0.43–0.67) 4-Fluoro-3-phenoxybenzoic acid: n.d.		(Biomonitoring California 2016)
Phenoxyacetic acid herbicides - µg/L
America, USA	Regular working period without participation in firefighting activities ¥		101	42.8 ± 0.9	2,4,5-Trichlorophenoxyacetic acid: n.d. 2,4-Dichlorophenoxyacetic acid: 0.27 (0.21–0.34)		(Biomonitoring California 2016)
Metabolized compounds
Organophosphorus insecticides metabolites – ng/mL
America, USA	Regular working period without participation in firefighting activities ¥		101	42.8 ± 0.9	Diazinon metabolite (2-Isopropyl-4-methyl-6-hydroxypyrimidine): 0.16 (0.12–0.20) Chlorpyrifos metabolite (3,5,6-Trichloro-2-pyridinol): 1.78 (1.47–2.15)		(Biomonitoring California 2016)
America, USA	Structural firefighting while wearing full protective clothing and self-contained breathing apparatus		145	n.r.	Dimethylphosphate: 9.9 (n.d. e 190) ^b Dimethylthiophosphate: 15 (n.d. - 300) ^b Dimethyldithiophosphate: 1.2 (n.d.– 11) ^b Diethylphosphate: 4.2 (n.d. - 60) ^b Diethylthiophosphate: 0.74 (n.d. - 5.0) ^b Diethyldithiophosphate: 0.22 (n.d. - 0.35) ^b		(Jayatilaka et al. 2019)
Blood
Unmetabolized compounds
Polychlorinated dibenzo‑p‑dioxins (PCDDs) - pg/g lipid
America, USA	Controlled residential fire scenarios		Maximum n = 9	n.r.			(Mayer et al. 2021)
	Pre-exposure
					2,3,7,8-Tetrachlorodibenzodioxin: 0.65 ± 1.57^f 1,2,3,7,8-Pentachlorodibenzodioxin: 2.50 ± 1.23 ^f 1,2,3,4,7,8-Hexachlorodibenzodioxin: 2.24 ± 1.14 ^f 1,2,3,6,7,8-Hexachlorodibenzodioxin: 12.76 ± 1.12 ^f 1,2,3,7,8,9-Hexachlorodibenzodioxin: 2.81 ± 1.12 ^f1,2,3,4,6,7,8- Hexachlorodibenzodioxin: 16.34 ± 1.14 ^f Octachlorodibenzodioxin: 99.23 ± 1.13 ^f
	Post-exposure
					2,3,7,8-Tetrachlorodibenzodioxin: 0.75 ± 1.12^f 1,2,3,7,8-Pentachlorodibenzodioxin: 2.49 ± 1.11 ^f 1,2,3,4,7,8-Hexachlorodibenzodioxin: 2.05 ± 1.25 ^f 1,2,3,6,7,8-Hexachlorodibenzodioxin: 12.49 ± 1.15 ^f 1,2,3,7,8,9-Hexachlorodibenzodioxin: 2.53 ± 1.13 ^f 1,2,3,4,6,7,8- Hexachlorodibenzodioxin: 15.73 ± 1.13 ^f Octachlorodibenzodioxin: 91.74 ± 1.19 ^f
Oceania, New Zealand	Call-outs to the pesticides production plant and/or were based at the fire station near the plant		39	60.7 (47–73)	2,3,7,8-tetrachlorodibenzo-p-dioxin: 1.6 ± 1.3^e 1,2,3,7,8-pentachlorodibenzo-p-dioxin: 3.6 ± 2.0^e 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin: 1.6 ± 1.1 ^e 1,2,3,6,7,8- hexachlorodibenzo-p-dioxin: 11.2 ± 7.2^e 1,2,3,7,8,9- hexachlorodibenzo-p-dioxin: 2.2 ± 1.5^e 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin: 17.5 ± 9.0^e Octachlorodibenzodioxin: 168.9 ± 125.5^e		(’T Mannetje et al. 2016)
Polychlorinated dibenzofurans (PCDFs) - pg/g lipid
America, USA	Controlled residential fire scenarios		Maximum n = 9	n.r.			(Mayer et al. 2021)
	Pre-exposure
					2,3,7,8-Tetrachlorodibenzofuran: 0.66 ± 1.83 ^f 1,2,3,7,8-Pentachlorodibenzofuran: 0.70 ± 1.99 ^f 2,3,4,7,8-Pentachlorodibenzofuran:5.09 ± 1.24 ^f 1,2,3,4,7,8-Hexachlorodibenzofuran: 4.07 ± 1.22 ^f 1,2,3,6,7,8- Hexachlorodibenzofuran:4.32 ± 1.21 ^f 1,2,3,7,8,9-Hexachlorodibenzofuran: 0.12 ± 1.72 ^f 2,3,4,6,7,8- Hexachlorodibenzofuran: 1.77 ± 1.35 ^f 1,2,3,4,6,7,8- Hexachlorodibenzofuran: 6.41 ± 1.19 ^f 1,2,3,4,7,8,9- Hexachlorodibenzofuran:0.27 ± 1.56 ^f Octachlorodibenzofuran: 0.27 ± 1.64 ^f
	Post-exposure
					2,3,7,8-Tetrachlorodibenzofuran: 0.47 ± 2.71 ^f 1,2,3,7,8-Pentachlorodibenzofuran: 0.60 ± 1.64 ^f 2,3,4,7,8-Pentachlorodibenzofuran: 4.37 ± 1.24 ^f 1,2,3,4,7,8-Hexachlorodibenzofuran:3.74 ± 1.31 ^f 1,2,3,6,7,8- Hexachlorodibenzofuran: 3.93 ± 1.25 ^f 1,2,3,7,8,9-Hexachlorodibenzofuran: 0.09 ± 1.17 ^f 2,3,4,6,7,8- Hexachlorodibenzofuran: 1.63 ± 1.29 ^f 1,2,3,4,6,7,8- Hexachlorodibenzofuran:6.09 ± 1.20 ^f 1,2,3,4,7,8,9- Hexachlorodibenzofuran: 0.27 ± 1.52 ^f
Oceania, New Zealand	Call-outs to the pesticides production plant and/or were based at the fire station near the plant		39	60.7 (47–73)	2,3,7,8-tetrachlorodibenzofuran: 0.9 ± 0.4^e 1,2,3,7,8-pentachlorodibenzofuran: 0.4 ± 0.3^e 2,3,4,7,8-pentachlorodibenzofuran: 4.0 ± 1.9^e 1,2,3,4,7,8-hexachlorodibenzofuran: 1.6 ± 0.7^e 1,2,3,6,7,8-hexachlorodibenzofuran: 1.7 ± 0.9^e 1,2,3,7,8,9-hexachlorodibenzofuran: 0.5 ± 0.3^e 1,2,3,4,6,7,8-heptachlorodibenzofuran: 3.1 ± 2.1^e 1,2,3,4,7,8,9-heptachlorodibenzofuran: 0.8 ± 0.5^e 2,3,4,6,7,8-heptachlorodibenzofuran: 0.8 ± 0.4^e Octachlorodibenzofuran: 1.6 ± 0.9^e		(’T Mannetje et al. 2016)
Polychlorinated biphenyls (PCBs) – pg/g lipid
America, USA	Regular working period including participation in different types of firefighting activities ¥		101	42.8 ± 0.9	PCB-66: 1170 (1090–1250) PCB-74: 1770 (1610–1950) PCB-99: 1760 (1610–1930) PCB-101; PCB-105: n.d. PCB-118: 2660 (2.46–2.87) PCB-138: 5530 (4980–6150) PCB-153: 12200 (10800–13700) PCB-156: 1840 (1610–2090) PCB-170: 3640 (3160–4190) PCB-180: 13400 (11700–15400) PCB-183: 1030 (930–1150) PCB-187: 2990 (2610–3420) PCB-194: 3370 (2890–3930) PCB-203: 3370 (2920–3890)		(Park et al. 2015)
Oceania, New Zealand	Call-outs to the pesticides production plant and/or were based at the fire station near the plant		39	60.7 (47–73)	PCB-77: 26 ± 51^e PCB-81: 21 ± 34^e PCB-105: 680 ± 648^e PCB-114: 204 ± 165^e PCB-118: 2991 ± 2178^e PCB-123: 36 ± 38^e PCB-126: 22 ± 10^e PCB-138: 19152 ± 12068^e PCB-153: 28128 ± 16389 ^e PCB-156: 4193 ± 2246^e PCB-157: 747 ± 438^e PCB-167: 960 ± 675^e PCB-169: 26 ± 14^e PCB-180: 31500 ± 4122 ^e PCB-189: 604 ± 266^e		(’T Mannetje et al. 2016)
Perfluoroalkyl acids (PFAAs) - ng/mL
America, USA	Regular working period including participation in different types of firefighting activities ¥		101	42.8 ± 0.9	Perfluorooctanesulfonic acid: 12.50 (11.34, 13.78) Perfluorooctanoic acid: 3.75 (3.37, 4.17) Perfluorohexanesulfonic acid: 2.26 (2.00, 2.54) Perfluorononanoic acid: 1.15 (1.06, 1.25) Perfluorodecanoic acid: 0.90 (0.78, 1.03) Perfluoroheptanoic acid: 0.13 (0.11, 0.15) Perfluorooctanesulphonamide: 0.032 (0.027, 0.037) Methylperfluoro-1-octanesulfonamidoacetic acid: 0.16 (0.13, 0.18) N-ethyl-perfluoro-1 octanesulfonamido acetic acid: 0.016 (0.014, 0.018) Perfluoroundecanoic acid: 0.24 (0.21, 0.27) Perfluorododecanoic acid: n.d. Perfluorobutane sulfonic acid: n.d.		(Dobraca et al. 2015)
America, USA	Public water-system contamination due to aqueous film forming foam		17	n.r.	Total Perfluorooctanesulfonic acid (Σlinear perfluorooctane sulfonate + Σperfluoromethylheptane sulfonate isomers): 14.0 (10.4–19.0) Total Perfluorooctanoic acid (Σlinear and branched perfluorooctanoate): 3.1 (2.2–4.3) Perfluorohexanesulfonic acid: 16.0 (9.9–25.8) Perfluorononanoic acid: 0.47 (0.38–0.58) Perfluoroheptane sulfonate: 0.25 (0.17–0.38)		(Barton et al. 2020)
America, USA	Women Firefighters Biomonitoring Collaborative Cohort (WWBC: 2014–2015)		Firefighters		Perfluorohexanesulfonic acid: 3.79 (3.24–4.43) Perfluorooctanoic acid: 1.15 (1.05–1.25) Perfluorooctanesulfonic acid: 4.11 (3.68–4.59) Perfluorononanoic acid: 0.67 (0.61–0.74) Perfluorodecanoic acid: 0.25 (0.23–0.28) Perfluoroundecanoic acid: 0.18 (0.14–0.22) Perfluorobutane sulfonic acid: 0.13 (0.10–0.16) Perfluorododecanoic acid; Perfluorobutanoic acid, Perfluorohexanoic acid, Perfluoroheptanoic acid, Perfluorooctane sulfonamide acid: n.d.		(Trowbridge et al. 2020)
			86	47.5 ± 4.6
America, USA	Women Firefighters Biomonitoring Collaborative cohort (WWBC: 2014–2015)		Firefighters		Perfluorohexanesulfonic acid: 4.55 ± 2.82 ^c Perfluorooctanoic acid: 1.13 ± 1.70 ^c Perfluorooctane sulfonic acid: 4.33 ± 1.83 ^c Perfluorononanoic acid: 0.77 ± 1.98 ^c Perfluorodecanoic acid: 0.27 ± 1.77 ^c Perfluoroundecanoic acid: 0.23 ± 3.67 ^c Perfluorobutane sulfonic acid: 0.13 ± 4.19 ^c		(Clarity et al. 2021)
			84	47.4 ± 4.6
			Office workers		Perfluorohexanesulfonic acid: 2.94 ± 2.64 ^c Perfluorooctanoic acid: 1.19 ± 1.83 ^c Perfluorooctane sulfonic acid: 4.03 ± 2.35 ^c Perfluorononanoic acid: 0.61 ± 1.87 ^c Perfluorodecanoic acid: 0.24 ± 2.42 ^c Perfluoroundecanoic acid: 0.14 ± 5.19 ^c Perfluorobutane sulfonic acid: 0.13 ± 4.42^c
			79	48.5 ± 10.6
America, USA	Incumbent firefighters recruited between 2016 and 2019		197	n.r.	Perfluorohexanesulfonic acid: 2.50 (2.29–2.74) Linear perfluorooctanoate: 1.79 (1.68–1.89) Linear perfluorooctane sulfonate: 4.02 (3.74–4.32) Sum of perfluoromethylheptane sulfonate isomers: 2.06 (1.91–2.23) Perfluorononanoate: 0.44 (0.41–0.48) Perfluorodecanoate: 0.23 (0.22–0.25) Perfluoroundecanoate: 0.12 (0.11–0.13) Sum of branched isomers of perfluorooctanoate and 2-(N-methyl-perfluorooctane sulfonamido) acetate: n.d.		(Goodrich et al. 2021)
America, USA	Collaborative effort between the New Jersey Firefighter Cancer Assessment and Prevention Study (CAPS), the US Firefighter Cancer Cohort Study (FFCCS)		116	n.r.	Perfluorononanoic acid: 0.97 (0.89–1.05) Perfluorohexane sulfonic acid: 1.83 (1.61–2.09) Perfluorooctanoic acid acid: 2.07 (1.89–2.26) Perfluorooctanesulfonic acid: 4.25 (3.76–4.80) 2-(N-methyl-perfluorooctane sulfonamido) acetate: 0.08 (0.07–0.09) Perfluorodecanoic acid: 0.31 (0.29–0.33) Perfluoroundecanoic acid: 0.11 (0.10–0.12) Perfluorododecanoic acid: 0.14 (0.13–0.15)		(Graber et al. 2021)
America, USA	All Firefighters (2018–2019)		47	39.15 ± 9.35	Perfluorooctanesulfonic acid: 8.63 (1.57–30.42) ^a Perfluorooctanoic acid: 2.15 (1.02–4.65) ^a Perfluorohexanesulfonic acid: 6.15 (0.84–22.49) ^a Perfluononanoic acid: 0.46 (0.20–1.36) ^a		(Leary et al. 2020)
	Airport Firefighters (support the military base airport.)		38	41.71 ± 7.57	Perfluorooctanesulfonic acid: 10.69 (4.28–30.42) ^a Perfluorooctanoic acid: 2.17 (1.10–4.65) ^a Perfluorohexanesulfonic acid: 6.45 (2.20–12.28) ^a Perfluononanoic acid: 0.45 (0.22–1.36) ^a
	Suburban Firefighters (crash and rescue, structure fires)		9	28.33 ± 8.63	Perfluorooctanesulfonic acid: 4.04 (1.57–9.34) ^a Perfluorooctanoic acid: 1.72 (1.02–3.07) ^a Perfluorohexanesulfonic acid: 3.15 (0.84–22.49) ^a Perfluononanoic acid: 0.47 (0.20–0.57) ^a
America, USA	Cross-sectional sample of Arizona Firefighters		38	49–54	2-(N-ethyl-perfluorooctane sulfonamide) acetic acid: 0.07 (0.07, 0.08) 2-(N-methyl-perfluorooctane sulfonamide) acetic acid: 0.21 (0.17, 0.26) Perfluorobutane sulfonic acid: 0.07 (0.07, 0.07) Perfluorodecanoic acid: 0.25 (0.22, 0.29) Perfluorododecanoic acid: 0.07 (0.07, 0.07) Perfluoroheptanoic acid: 0.07 (0.07, 0.08) Perfluorohexane sulfonic acid*: 3.07 (2.66, 3.55) Perfluorononanoic acid*: 0.93 (0.81, 1.06) Perfluorooctanoic acid: 3.33 (2.89, 3.84) Perfluorooctane sulfonic acid: 13.36 (11.64, 15.34) Perfluorooctane sulfonamide: 0.07 (0.07, 0.07) Perfluoroundecanoic acid*: 0.12 (0.10, 0.14)		(Khalil et al. 2020)
Oceania, Australia	Training activities with exposure to aqueous film forming foam		149	50 ± 9.3	Perfluorooctanesulfonic acid: 74 ± 61^e Perfluorooctanoic acid: 4.6 ± 2.4 ^e Perfluorohexanesulfonic acid: 33 ± 36^e Perfluorononanoic acid: 0.76 ± 0.3^e Perfluorodecanoic acid: 0.29 ± 0.13^e Perfluoroheptanoic acid: 0.10 ± 0.08^e Perfluoroundecanoic acid: 0.16 ± 0.08^e Perfluorododecanoic acid: <0.05 (<0.05–0.12)^e Perfluorobutane sulfonic acid: <0.02 (<0.02–0.09)^b Perfluorotridecanoic acid:<0.06 (<0.06–0.10)^b Perfluorodecanesulfonic acid: <0.003 (<0.003–0.07)^b		(Rotander et al. 2015)
Organochlorine pesticides (OCPs) – ng/g lipid
America, USA	Regular working period including participation in different types of firefighting activities¥		101	42.8 ± 0.9	4,4′-DDE: 177 (161 - 196) 4,4′-DDT: 1.34 (1.20 - 1.50) Hexachlorobenzene: 11.8 (11.3 - 12.4) Oxychlordane: 4.08 (3.64–4.56) Trans-nonachlor: 7.32 (6.57 - 8.15) β-Hexachlorocyclohexane: 2.19 (2.00 - 2.41)		(Park et al. 2015)

WWBC: Women Workers Biomonitoring Cohort; <LOD: below limit of detection; n.d.: not detected; n.r.: not reported.

^aData presented as arithmetic mean (range); ^b Data presented as median (range); ^c Data presented as geometric mean ± standard deviation (SD) and expressed as µg/g creatinine; ^d Data presented as geometric mean range (variation between 3 to 12 h post-fire), expressed as µg/g creatinine; ^e Data presented as mean ± SD; ^f Data presented as geometric mean ± SD.

¥ full-time, active firefighters for at least 12 months that enter a large biomonitoring study: Firefighter Occupational Exposures (FOX) Project, samples were collected in 2010–2011, but the FOX project is still ongoing; § fire at a cable plant that included the emission of toxic chemicals.

Figure 9. Perfluoroalkyl acids associated disruption in the brain, immune system organs, liver, and kidney. Reproduced from Starnes et al. (2022), under creative commons CC by license.

eGFR: Estimated glomerular filtration rate; PPAR: Peroxisome proliferator-activated receptor.

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Data availability statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study. The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.