Simultaneous determination of hexabromocyclododecanes, polybrominated diphenyl ethers, and dechlorane-related compounds in boxed sushi meals using a developed analytical method

Tamaki Sato; Kazuhiro Tobiishi; Tsuguhide Hori; Tomoaki Tsutsumi; Hiroshi Akiyama; Toshiro Matsui

doi:10.3136/fstr.FSTR-D-22-00204

Abstract

We investigated the concentrations of halogenated flame retardants (HFRs), which include hexabromocyclododecanes (HBCDDs), polybrominated diphenyl ethers (PBDEs), and dechloranes and related compounds (DRCs), in 25 typical ready-made boxed sushi meals (each divided into seafood and non-seafood portions) using a developed simultaneous analytical method involving accelerated solvent extraction and gel permeation chromatographic separation. The developed method yielded good recoveries of surrogates (72–122 %). HBCDDs, PBDEs, and DRCs were detected in all seafood portions. While DRCs were also frequently detected in non-seafood portions, HBCDDs and PBDEs were hardly detected. The estimated dietary intakes of HBCDDs, PBDEs, and DRCs from boxed sushi meals were well below the corresponding health-based guideline values. In conclusion, our study suggests that the intake of HFRs from boxed sushi meals poses low concern for consumer health and that the developed simultaneous analytical method is highly useful for determining HFRs in seafood-based meals.

Introduction

Flame retardants that possess halogens and phosphorus in organic forms as well as metal hydroxides and antimony in inorganic forms are widely used in commercially available polymers such as plastics, rubbers, and fibers (Kato, 1981; Nishizawa, 2006). Halogenated flame retardants (HFRs) are often added to plastics because of their excellent flame-retardant properties in plastic polymers (Alaee et al., 2003; Sakiyama and Nakano, 2016; Waters et al., 1977). Despite the flame retardant advantage of HFRs, serious concerns have been raised regarding hexabromocyclododecanes (HBCDDs) and polybrominated diphenyl ethers (PBDEs) owing to their environmental persistence and adverse health effects caused by their long-term bioaccumulation in the body (Sharkey et al., 2020). The health effects of HFRs have been reported previously. Exposure to HFRs may result in the progression of obesity due to a high-fat diet and hepatic disorders (Maia et al., 2022; Wen et al., 2019; Yanagisawa et al., 2014). Hence, the use of HFRs has been legally regulated by Annex A of the Stockholm Convention on Persistent Organic Pollutants, with their manufacture, use, and import/export being highly restrictedⁱ⁾. Dechlorane (or Mirex), a chlorinated flame retardant, which has been regulated since 1978 (Stockholm Convention on POPs, Text and Annexes, 2019), has been used as a pesticide or flame retardant for plastics worldwide, except in Japan. Dechlorane Plus (DP, syn-DP, and anti-DP), Dechlorane (Dec) 602, Dec 603, Dec 604, and Chlordene Plus (CP) are known substitutes for dechlorane. Dechlorane and related compounds (DRCs) were used until brominated flame retardants became popular.

HFR content has been widely reported in various foods (Gebbink et al., 2019; Grelli et al., 2021; Pietroń et al., 2017; Schecter et al., 2010) and in exposure through the diet (Abdel Malak et al., 2019; Aznar-Alemany et al., 2017; Lee et al., 2019; Lee et al., 2020; Nøstbakken et al., 2018). A total diet study (TDS) based on a market basket approach, also known as a market basket study, is a useful method for estimating the average dietary intake of contaminants in the population groups of interest. We previously conducted TDS and reported high HFR concentrations in seafood that substantially contributed to total daily intake (HBCDDs: 68.4–76.7 ng per d, PBDEs: 40.7–45.4 ng per d, DRCs: 3.1 ng per d) (Ashizuka et al., 2012; Murata et al., 2007; Yasutake et al., 2018). Our reports have strongly raised concerns regarding the health risks of HFR exposure in seafood diets in Japan. Japanese people consume comparatively large amounts of seafood, and ready-made meals, such as boxed sushi meals, are popular in Japan. However, HFR concentrations in boxed sushi meals have yet to be reported. These findings prompted us to investigate the concentration of HFRs in boxed sushi meals and to estimate the HFR intake resulting from their consumption.

To date, we have reported appropriate analytical methods for the individual detection of HFRs, such as HBCDDs, DRCs, and PBDEs, based on mass spectrometry (MS) detection (Ashizuka et al., 2008; Murata et al., 2007; Nakagawa et al., 2010; Yasutake et al., 2018). However, separately analyzing each of these three HFR groups involves costs, time, organic solvents, and sufficient mass of samples. Meanwhile a simultaneous analysis method for HFR groups could reduce the burden of the above requirements by about one-third. Therefore, multi-residue analysis using a simultaneous extraction and clean-up method is needed to investigate the concentrations and intakes of HBCDDs, DRCs, and PBDEs more efficiently. Previous studies have reported multiresidue analysis of HFRs in fish (Kakimoto et al., 2012; Kakimoto et al., 2014; Tavoloni et al., 2020). However, these analytical methods have the disadvantage of targeting a small number of HFR groups and a small number of congeners/compounds within each group. Therefore, an analytical method for the simultaneous determination of HFRs, including HBCDDs, PBDEs, and DRCs, which are contaminants of high concern in food, should be developed.

In this study, we developed a highly selective and sensitive simultaneous analytical method for HBCDDs, PBDEs, and DRCs based on single sample preparation using accelerated solvent extraction (ASE) and gel permeation chromatographic separation, followed by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our analytical method was used to determine concentrations of HBCDDs, PBDEs, and DRCs in commercially available boxed sushi meals (divided into seafood and non-seafood portions) in Japan. We also estimated HFR intake resulting from the consumption of boxed sushi meals.

Materials and Methods

Sample collection　　Twenty-five boxed sushi meals (including three seafood bowls), each of which was sold as a single serving, were subjected to a fact-finding investigation. These samples were obtained from supermarkets and commercial facilities in Fukuoka, Japan between June and September 2020. Three to four identical products were purchased for each boxed sushi meal to prepare a composite sample. The edible parts of each sample were divided into seafood (such as fish, shrimp, and squid; it was not possible to distinguish between wild and farmed) and non-seafood (such as rice, chicken eggs, and vegetables) portions. Each divided portion was blended using a food processor or hand mixer to prepare a total of 50 analytical samples (25 seafood and 25 non-seafood portions) from 25 boxed sushi meals and stored below −20 °C until use for analysis.

Chemicals　　Non-labeled and ¹³C₁₂-labeled PBDE analytical standard mixtures (BFR-CVS, BFR-LCS, BFR-ISS) as well α-, β-, and γ-HBCDD, ¹³C₁₂-labeled α-, β-, γ-HBCDD, γ-HBCDD-d₁₈, CP, and DP (non-labeled and ¹³C₁₀-labeled) standards were purchased from Wellington Laboratories (Guelph, Canada). Dechlorane (non-labeled and ¹³C₁₀-labeled) and Dec 602 (¹³C₁₀-labeled) standard were obtained from the Cambridge Isotope Laboratories (Andover, United States). Dec 602, Dec 603, and Dec 604 were obtained from Santa Cruz Biotechnology (Dallas, United States). Each standard was mixed and diluted with the appropriate amount of acetonitrile. Dichloromethane, n-hexane, acetone, cyclohexane, distilled water, and acetonitrile of mass analysis-grade were from Kanto Chemical (Tokyo, Japan). ISOLUTE® HM-N, which was used as a dispersing agent for accelerated solvent extraction, was purchased from Biotage (Uppsala, Sweden). Sulfuric acid, 44 % sulfuric acid-impregnated silica gel, anhydrous sodium sulfate, 1 mol L⁻¹ ammonium acetate solution of HPLC grade, and fluvalinate were purchased from Fujifilm Wako Pure Chemical Industries (Osaka, Japan).

Preparation of the test solution　　The test solutions were prepared by a combined method of parts of the individual analytical methods for HBCDDs or DRCs previously reported by our group (Nakagawa et al., 2010; Yasutake et al., 2018), with slight modification. Each 10 g sample was mixed with a dispersing agent and freeze-dried. The dried samples were extracted with dichloromethane and n-hexane (1:3, v/v) using an ASE-350 accelerated solvent extractor (Thermo Fisher Scientific, Waltham, United States). The extraction temperature, pressure, static time, and number of cycles were 100 °C, 10 342 kPa (1 500 psi), 10 min, and 2 cycles, respectively. Each extract was concentrated and re-dissolved in 20 mL dichloromethane and n-hexane (1:3, v/v). Then, 5 mL of each extract spiked with ¹³C-labeled standard mixtures as the surrogates (¹³C₁₂-labeled α-, β-, and γ-HBCDDs, 5 ng each; ¹³C₁₂-labeled PBDEs, 0.25 ng each; ¹³C₁₀-labeled Dechlorane, 0.25 ng; ¹³C₁₀-labeled Dec 602, 0.25 ng; and ¹³C₁₀-labeled DPs, 0.25 ng each) was treated with sulfuric acid and then washed with distilled water. The extracts were concentrated and re-dissolved in 5 mL acetone and cyclohexane (3:7, v/v). Lipid purification was performed using gel permeation chromatography (GPC). Two milliliters of extract was loaded onto a column (CLNpak EV-2000 AC; Showa Denko, Tokyo, Japan) with a guard column (CLNpak EV-G AC; Showa Denko) and eluted with acetone and cyclohexane (3:7, v/v) at a column temperature of 40 °C and a flow rate of 5 mL min⁻¹. The eluate was fractionated for 20 min immediately after the elution of fluvalinate, which was used as an indicator. The fraction was evaporated to dryness and redissolved in 1 mL n-hexane. The solution was loaded onto a mini-column (1 g of 44 % sulfuric acid-impregnated silica gel) and eluted with 8 mL dichloromethane and n-hexane (3:7, v/v). The eluate was concentrated and re-dissolved in 0.1 mL acetonitrile containing syringe spike: γ-HBCDD-d₁₈, 2 ng; ¹³C₁₂-PBDEs, 0.1 ng; and ¹³C₁₂-labeled PentaCB-111, 0.1 ng.

HRGC/HRMS analysis　　The concentrations of PBDEs and DRCs were determined using the internal standard method with HRGC/HRMS. HRGC/HRMS analysis was performed using a Thermo Scientific DFS mass spectrometer coupled to a Thermo Scientific Trace 1310 GC. The GC conditions were as follows: capillary column, Rtx-1614 (0.25 mm i.d. × 15 m, 0.1 μm film thickness; Restek, Bellefonte, United States); column temperature program, 120 °C (held for 1 min) to 210 °C at 20 °C min⁻¹ and to 300 °C (held for 10 min) at 10 °C min⁻¹; carrier gas, helium; flow rate, 1.0 mL min⁻¹; injection mode, splitless; injector temperature, 280 °C; and injection volume, 1 μL. The MS conditions were as follows: ionization mode, electron ionization mode; electron energy, 45 eV; ion source temperature, 280 °C; internal mass reference, perfluorokerosene; and resolution, 10 000. The monitored ions for each target compound are shown in Table 1.

Table 1 Monitoring ions for DRCs and PBDEs used in this study.

Compound	Monitor ions (m/z)		Surrogate
Compound	Quantification	Qualification	Surrogate
Dechlorane	271.8102	273.8072	¹³C₁₀-Dechlorane
Dec602	271.8102	273.8072	¹³C₁₀-Dec602
syn-DP	271.8102	273.8072	¹³C₁₀-syn-DP
anti-DP	271.8102	273.8072	¹³C₁₀-anti-DP
CP	271.8102	273.8072	¹³C₁₀-Dec602
Dec603	262.8570	264.8540	¹³C₁₀-Dec602
Dec604	419.7006	417.7026	¹³C₁₀-Dec602
¹³C₁₀-Dechlorane	276.8269	-	-
¹³C₁₀-Dec602	276.8269	-	-
¹³C₁₀-syn-DP	276.8269	-	-
¹³C₁₀-anti-DP	276.8269	-	-
¹³C₁₂-PentaCB-111	337.9207	-	-
TriBDE-17, -28, -30	405.8027	407.8006	¹³C₁₂-TriBDE-28
TetraBDE-47, -49, -66, -71	485.7111	483.7132	¹³C₁₂-TetraBDE-47
TetraBDE-77	485.7111	483.7132	¹³C₁₂-TetraBDE-77
PentaBDE-85, -100	563.6216	565.6196	¹³C₁₂-PentaBDE-100
PentaBDE-99	563.6216	565.6196	¹³C₁₂-PentaBDE-99
PentaBDE-119, -126	563.6216	565.6196	¹³C₁₂-PentaBDE-126
HexaBDE-154	483.6955	485.6934	¹³C₁₂-HexaBDE-154
HexaBDE-138, -139, -140, -143, -153, -156	483.6955	485.6934	¹³C₁₂-HexaBDE-153
HexaBDE-169	483.6955	485.6934	¹³C₁₂-HexaBDE-169
HeptaBDE-171, -180, -183, -184, -191	561.6060	563.6039	¹³C₁₂-HeptaBDE-183
OctaBDE-196, -197, -201, -203, -204	641.5145	643.5124	¹³C₁₂-OctaBDE-197
OctaBDE-205	641.5145	643.5124	¹³C₁₂-OctaBDE-205
NonaBDE-206, -207, -208	719.4250	721.4230	¹³C₁₂-NonaBDE-207
DecaBDE-209	799.3335	797.3355	¹³C₁₂-DecaBDE-209
¹³C₁₂-TriBDE-28	417.8429	-	-
¹³C₁₂-TetraBDE-47, -77, -79	497.7514	-	-
¹³C₁₂-PentaBDE-99, -100, -126	575.6619	-	-
¹³C₁₂-HexaBDE-153, -154, -169, -139	495.7357	-	-
¹³C₁₂-HeptaBDE-183, -180	573.6462	-	-
¹³C₁₂-OctaBDE-197, -205	653.5547	-	-
¹³C₁₂-NonaBDE-207, -206	731.4652	-	-
¹³C₁₂-DecaBDE-209	811.3737	-	-

LC-MS/MS analysis　　HBCDD concentrations were determined by the internal standard method using a Waters Acquity UPLC H-Class Plus Binary equipped with a Waters Xevo TQ-XS (LC/MS/MS; Waters, Milford, United States). The LC conditions were as follows: column, Waters Acquity UPLC BEH C18 (2.1 mm i.d. × 100 mm, 1.7 μm); column temperature, 40 °C; injection volume, 2 μL; mobile phase, 2 mmol L⁻¹ ammonium acetate (A) and acetonitrile (B); gradient condition, A/B (%) 45/55, which was gradually changed to 5/95 (held for 6 min) over 8 min; flow rate, 0.2 mL min⁻¹. The MS conditions were as follows: ionization mode, electron spray ionization mode (negative); capillary voltage, 2.0 kV; cone voltage, 20 V; collision energy, 20 eV; scan type, selected reaction monitoring (SRM); SRM transition, m/z 638.6 > 78.9 and 640.6 > 78.9 transition for non-labeled HBCDDs, m/z 650.7 > 78.9 and 652.7 > 78.9 for ¹³C₁₂-labeled HBCDDs, and m/z 658.7 > 78.9 for γ-HBCDD-d₁₈.

HFR intake estimation　　The intake of HFRs per meal was calculated based on the weight of one serving of boxed sushi meals as follows: (1) multiplying the HFR concentrations by the weight of each portion in each meal; (2) obtaining the sum of each calculated intake. The estimate assumed a value of zero when the concentration was below the detection limit (not detected [ND] = 0). (3) An average adult body weight of 50 kg was used for comparison with health-based guideline values.

Results and Discussion

Quality assurance and quality control　　The MS chromatograms of HFRs (non-labeled and ¹³C-labeled) of standard solutions are shown in Fig. 1, and the chromatograms of representative seafood portion samples are shown in Fig. S1. Except for the PBDEs HexaBDE-156/169 and OctaBDE-204/197, each compound was well separated under the analytical conditions. The two overlapping peaks were quantified by summing them. As shown in Fig. S1, no interfering peak was observed in the chromatogram of any of the compounds in the seafood samples. First, we confirmed that ¹³C-labeled HFRs were recovered under the ASE and GPC operating conditions in the absence of matrix components. Good recoveries (78–145 % and 83–122 %) were observed for the ¹³C-labeled HFRs from these instruments. HBCDDs are reportedly subject to thermal rearrangement at high temperatures, resulting in a specific mixture of stereoisomers (Barontini et al., 2001). However, the peak intensity ratios of HBCDD isomers before and after ASE extraction were compared, and no change was observed under the ASE operation conditions in this study.

Fig. 1.

MS chromatograms of HFRs in standard solution.

(a) HBCDDs; upper: Non-labeled, lower: ¹³C-labeled, (b) PBDEs; upper: Non-labeled, lower: ¹³C-labeled in each congener, (c) DRCs; upper: Non-labeled, lower: ¹³C-labeled

Table 2 shows the recovery rates of ¹³C-labeled DRCs, HBCDDs, and PBDEs added to the extracts of seafood and non-seafood portions from all analyzed boxed sushi meals (n = 25 each). The average recovery of each ¹³C-labeled compound ranged from 72–122 %, with relative standard deviations between 5.0 and 14.7 %. These values were considered satisfactory. A procedural blank sample was used for each sample preparation batch. The detection limits calculated for the S/N of 3 were 1, 10, and 1–10 pg g⁻¹ wet wt. for DRCs, HBCDDs, and PBDEs, respectively.

Table 2 Recovery rate of ¹³C-labeled HFRs in targeted samples.

Compound	Seafood portion		Non-seafood portion
Compound	Ave. (%)	%RSD	Ave. (%)	%RSD
¹³C₁₂-α-HBCDD	93	5.1	98	6.5
¹³C₁₂-β-HBCDD	90	5.0	91	6.8
¹³C₁₂-γ-HBCDD	98	6.2	107	6.6
¹³C₁₀-syn-DP	113	11.8	118	13.7
¹³C₁₀-anti-DP	104	9.3	107	10.3
¹³C₁₀-Dec602	97	6.7	94	6.9
¹³C₁₀-Dechlorane	85	6.4	86	6.3
¹³C₁₂-TriBDE-28	77	6.8	85	6.0
¹³C₁₂-TetraBDE-47	79	5.7	89	6.0
¹³C₁₂-TetraBDE-77	96	5.8	96	5.4
¹³C₁₂-PentaBDE-100	101	6.4	100	8.5
¹³C₁₂-PentaBDE-99	101	8.5	97	9.6
¹³C₁₂-PentaBDE-126	95	8.0	92	9.1
¹³C₁₂-HexaBDE-154	81	7.8	92	8.0
¹³C₁₂-HexaBDE-153	91	7.8	97	5.6
¹³C₁₂-HexaBDE-169	75	14.7	80	13.2
¹³C₁₂-HeptaBDE-183	93	13.3	105	9.3
¹³C₁₂-OctaBDE-197	122	11.7	122	12.0
¹³C₁₂-OctaBDE-205	104	9.6	105	8.0
¹³C₁₂-NonaBDE-207	89	8.9	94	7.5
¹³C₁₂-DecaBDE-209	76	8.6	72	9.0

n =25 each

HFR concentrations in boxed sushi meals　　The concentrations of HFRs in the 25 boxed sushi meals (seafood and non-seafood portions) are summarized in Tables S1 and S2. This method made it possible to analyze 35 HFR congeners/compounds simultaneously. The total HBCDD (Σ₃HBCDDs) concentration in each seafood sample ranged from 33–1 922 pg g⁻¹. The concentrations of the congeners were as follows: α-HBCDD, 33–1 808 pg g⁻¹ (detected in all samples); β-HBCDD, ND (<10)−12 pg g⁻¹ (detected in 1 of 25 samples); and γ-HBCDD, ND (<10)−102 pg g⁻¹ (detected in 6 of 25 samples). The ratio of a-HBCDD concentration to that of total HBCDDs ranged from 94–100 %, indicating that α-HBCDD was the most dominant HFR in all of the samples. These findings are in accordance with those in previous relevant studies on fish (Kakimoto et al., 2012; Nakagawa et al., 2010). Sample No.15 was the only sample with detectable β-HBCDD concentration. When β-HBCDD was detected, α-and γ-HBCDDs were detected at relatively high concentrations. By contrast, all HBCDD congeners were ND (<10 pg g⁻¹) in all the non-seafood samples.

A minimum of one PBDE congener was detected in each seafood sample, whereas PBDE congeners were not detected in any of the non-seafood portions except for one sample (Sample 21), which contained one congener (DecaBDE-209). DecaBDE-209 was the predominant PBDE congener in foods in a previous study (Chen et al., 2019). The average, median, and range of the total PBDE (Σ₃₅PBDEs) concentration were 430, 247, and 24–1 956 pg g⁻¹, respectively. For seafood samples, the most frequently detected congeners (detection frequency) were TetraBDE-47 (25/25) and TetraBDE-49 (25/25), followed by PentaBDE-100 (22/25), HexaBDE-154 (22/25), TriBDE-28 (16/25), and DecaBDE-209 (14/25). Among the congeners, TetraBDE-47, which was detected in all seafood portions in this study, is a known indicator of PBDE contamination in marine fish (Akutsu et al., 2001). The highest detected concentrations were those of DecaBDE-209 (average 284 pg g⁻¹, range ND (<10)−1 088 pg g⁻¹), followed by TetraBDE-47 (129 pg g⁻¹, 5–935 pg g⁻¹), HexaBDE-154 (53 pg g⁻¹, ND (<2)−364 pg g⁻¹), PentaBDE-100 (37 pg g⁻¹, ND (<2)− 247 pg g⁻¹), TetraBDE-49 (34 pg g⁻¹, 2–174 pg g⁻¹), and TriBDE-28 (10 pg g⁻¹, ND (<1)−2 pg g⁻¹). Relatively high concentrations of DecaBDE-209 were found in some fish and shellfish in Japan (Ashizuka et al., 2008), and TetraBDE-47 was the most abundant congener in many of them (Ashizuka et al., 2005). These findings are in good agreement with those in our study. Hepta to nonaBDEs were not detected despite their use in industrial products. This is probably due to debromination via the metabolism of these PBDEs stated in UNEP / POPS / POPRC.3 / 20 / Add.6.

The concentrations of total DRCs (Σ₇DRCs) in seafood samples ranged from 12–220 pg g⁻¹. The concentrations of each compound were as follows: dechlorane, 5–158 pg g⁻¹ (detected in all 25 samples); Dec602, ND (<1)−29 pg g⁻¹ (detected in 23 of 25 samples); Dec603, ND (<1)−4 pg g⁻¹ (detected in 7 of 25 samples); Dec604, ND(<1)−2 pg g⁻¹ (detected in 1 of 25 samples); syn-DP, ND (<1)−18 pg g⁻¹ (detected in 19 of 25 samples); anti-DP, ND (<1)⁻4 pg g⁻¹ (detected in 1 of 25 samples); CP, ND (<1)−5 pg g⁻¹ (detected in 1 of 25 samples). The ratios of dechlorane concentration to the total DRCs ranged from 38–100 %, and dechlorane was the predominant component in all of the samples. The total DRC concentrations in the non-seafood portions ranged from ND (<1) to 10 pg g⁻¹, and most DRCs were dechlorane. Dechlorane, a chlorinated flame retardant, was frequently detected in non-seafood portions, whereas brominated flame retardants HBCDDs and PBDEs were rarely detected. One assumption is that the contamination of dechlorane in foods cannot be explained solely by bioaccumulation and can occur via a different contamination route from brominated flame retardants. The seafood portion (Sample No.14) containing the most HFRs consisted of salmon, sea bream, tuna, flying fish roe, and salmon roe.

Estimated intakes of HFRs resulting from the consumption of boxed sushi meals　　The intake of HFRs per meal was calculated based on the sample weight of one meal. Table 3 shows the HFR intake per meal (seafood and non-seafood portions and their sum). Seafood portions contributed most of the HFR intake in each meal. The average, median, and range of intake of total HBCDDs per meal were 34, 22, and 2–190 ng per meal, respectively. Compared to the hazard assessment value of 0.05 mg kg⁻¹ per dⁱⁱ⁾, the intake of total HBCDDs per meal was 0.00008–0.008 % of this value.

Table 3 Estimated intakes of HFRs resulting from the consumption of boxed sushi meals.

Sample No.	Store	Weight of one serving (g)^a		Fat content(%)		Intakes of HFRs (ng per meal)^b
		Weight of one serving (g)^a		Fat content(%)		HBCDDs			PBDEs			DRCs
		Seafood portion	Non-seafood portion	Seafood portion	Non-seafood portion	Seafood portion	Non-seafood portion	Total	Seafood portion	Non-seafood portion	Total	Seafood portion	Non-seafood portion	Total
1	A	66	218	4.9	0.8	10	0	10	68	0	68	3	1	4
2	A	101	226	5.5	0.6	66	0	66	22	0	22	7	1	8
3	B	64	225	11	0.6	52	0	52	33	0	33	6	0	6
4	B	82	199	5.8	0.4	31	0	31	24	0	24	5	1	6
5	C	99	260	4.4	0.8	11	0	11	21	0	21	8	3	11
6	C	59	183	8.3	0.7	4	0	4	11	0	11	1	0	1
7	D	96	176	5.1	0.2	25	0	25	24	0	24	5	0	5
8	D	66	283	4.5	0.3	2	0	2	4	0	4	1	1	3
9	E	95	127	2.1	0.5	19	0	19	7	0	7	4	1	5
10	E	74	215	5.1	0.1	11	0	11	16	0	16	6	1	8
11	F	86	201	9.1	0.4	27	0	27	43	0	43	9	2	10
12	G	89	174	8.8	0.1	23	0	23	13	0	13	4	1	6
13	G	59	202	5.6	0.9	10	0	10	72	0	72	5	1	6
14	H	147	253	8.9	0.3	190	0	190	288	0	288	32	3	35
15	H	87	182	9.3	0.1	167	0	167	80	0	80	13	1	14
16	I	98	269	4.0	0.4	4	0	4	17	0	17	2	2	5
17	I	72	204	7.2	0.5	24	0	24	45	0	45	4	1	5
18	J	80	225	2.7	<0.1	12	0	12	48	0	48	4	1	5
19	J	68	220	2.5	0.5	22	0	22	22	0	22	1	0	1
20	J	143	211	6.4	0.2	24	0	24	26	0	26	7	2	9
21	K	134	214	1.2	0.1	12	0	12	3	12	16	9	1	10
22	K	63	198	5.6	1.8	17	0	17	2	0	2	3	1	4
23	L	69	189	10	0.7	6	0	6	7	0	7	4	0	4
24	L	82	177	5.5	0.2	47	0	47	23	0	23	9	1	10
25	M	82	200	9.1	1.5	31	0	31	50	0	50	10	1	11
Average				6.1	0.5			34			39			8
Minimum				1.2	<0.1			2			2			1
Median				5.6	0.5			22			23			6
Maximam				11	1.8			190			288			35

^a Average of 3 to 4 identical products

^b The intake of HFRs per meal calculated based on the weight of one serving of boxed sushi. The estimate is assumed to be zero when the concentration was under the detection limit (ND=0)

The average, median, and range of intake of total DRCs per meal were 8, 6, and 1–35 ng per meal, respectively. The intake of total DRCs was 0.01–0.35 % of the reference dose (Rfd) of dechlorane (0.0002 mg kg⁻¹ per d)ⁱⁱⁱ⁾, which contributed the most to the intake of total DRCs.

The average, median, and range of total intake of PBDEs per meal were 39, 23, and 2–288 ng per meal, respectively. The total PBDEs in each meal were compared with the hazard assessment value (50 ng kg⁻¹ per d for DecaBDE-209)^iv) and was 0.08–11.5 % of this value. For the consumption of the boxed sushi meal with the highest intake per meal three times per d, the ratios of total HBCDDs, total DRCs, and total PBDEs intake to the health-based guideline value would be 0.02, 1.1, and 34.5 %, respectively. These are conservative estimates, but these numbers were well below the corresponding health-based guideline values. Our estimated dietary intake of HFRs was similar to that reported in China (Shi et al., 2017), Korea (Barghi et al., 2016), Lebanon (Abdel Malak et al., 2019), and the United States of America (Schecter et al., 2012). Therefore, the consumption of one serving of boxed sushi meal containing seafood as the main dish poses a low risk to human health due to HFRs.

Conclusion

We investigated the concentrations of HBCDDs, PBDEs, and DRCs in 25 ready-made boxed sushi meals (each divided into seafood and non-seafood portions) using a developed simultaneous analytical method for HBCDDs, PBDEs, and DRCs based on single sample preparation. The developed method gave good recoveries of surrogates (72–122 %) and no interfering peaks in the chromatograms of any target congeners/compounds in the samples. HBCDDs, PBDEs, and DRCs were detected in all seafood portions within a wide range of concentrations. While DRCs were also frequently detected in non-seafood portions, HBCDDs and PBDEs were rarely detected. HFR intake from boxed sushi meals was 2–190 ng per meal for HBCDDs, 2–288 ng per meal for PBDEs, and 1–35 ng per meal for DRCs. When the HFR intakes per serving were compared with each health-based guideline value, the intakes of HBCDDs, PBDEs, and DRCs were 0.00008–0.008 %, 0.08–11.5 %, and 0.01–0.35 %, respectively. These values pose a negligible risk to human health from HFRs ingested via the consumption of a ready-made boxed sushi meal containing seafood as the main dish.

Acknowledgements　　This work was supported by a Health Sciences Research Grant from the Ministry of Health, Labour, and Welfare of Japan (19KA2001).

Conflict of interest　　There are no conflicts of interest to declare.

Table S1

(pg g⁻¹)

Concentrations of HFRs of 25 single serving samples (seafood portion)

Compound	No1	No2	No3	No4	No5	No6	No7	No8	No9	No10	No11	No12	No13	No14	No15	No16	No17	No18	No19	No20	No21	No22	No23	No24	No25
α-HBCD	149	635	794	390	111	11	263	33	205	145	300	264	164	1219	1808	45	331	153	318	166	89	261	85	574	376
β-HBCD	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	12	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
γ-HBCD	< 10	22	15	< 10	< 10	< 10	< 10	< 10	< 10	< 10	10	< 10	< 10	72	102	< 10	< 10	< 10	< 10	< 10	< 10	14	< 10	< 10	< 10
Σ₃ HBCD	149	657	809	380	111	71	263	33	205	145	310	264	164	1291	1922	45	331	153	318	166	89	275	85	574	376
TriBDE-30	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
TriBDE-17	< 1	< 1	3	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	4	7	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
TriBDE-28	< 1	4	12	9	< 1	< 1	3	< 1	< 1	2	17	2	2	52	¹⁸	< 1	13	3	< 1	4	< 1	< 1	3	7	12
TetraBDE-49	9	27	60	40	5	2	33	10	9	13	65	22	9	174	74	4	102	21	2	23	3	5	16	42	78
TetraBDE-71	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
TetraBDE-47	42	97	196	150	28	20	100	44	39	42	246	68	44	935	199	14	259	94	5	80	11	11	67	121	322
TetraBDE-66	< 2	5	8	4	< 2	< 2	< 2	< 2	< 2	< 2	16	< 2	< 2	57	23	< 2	11	< 2	< 2	< 2	< 2	< 2	< 2	6	6
TetraBDE-77	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
PentaBDE-100	11	28	51	34	3	< 2	18	3	8	9	75	17	12	247	62	< 2	77	25	< 2	22	3	2	11	35	69
PentaBDE-119	< 2	2	8	3	< 2	< 2	< 2	< 2	< 2	< 2	4	< 2	< 2	26	24	< 2	6	< 2	< 2	< 2	< 2	< 2	< 2	5	4
PentaBDE-99	< 2	< 2	16	4	< 2	< 2	< 2	< 2	< 2	< 2	7	< 2	< 2	63	30	< 2	26	4	< 2	11	< 2	< 2	< 2	< 2	41
PentaBDE-85	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
PentaBDE-126	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	3	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-154	14	50	60	46	3	< 2	38	< 2	20	13	64	24	53	364	150	2	56	18	< 2	26	8	5	6	65	74
HexaBDE-153	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	32	6	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-139	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-140	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-138	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-156/169	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HeptaBDE-184	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-183	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-191	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-180	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-171	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-201	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-204/197	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-203	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-196	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-205	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
NonaBDE-208	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
NonaBDE-207	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
NonaBDE-206	11	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
DecaBDE-209	943	< 10	103	< 10	176	157	55	< 10	< 10	137	11	< 10	1088	< 10	325	150	77	432	311	15	< 10	< 10	< 10	< 10	< 10
Σ₃₅ PBDEs	1032	220	518	295	215	179	247	62	76	217	505	141	1214	1956	919	171	628	597	319	182	25	24	103	283	610
Dec602	2	4	6	4	3	< 1	3	< 1	2	5	5	4	5	29	8	1	7	3	1	2	2	1	3	5	5
Dec603	1	1	< 1	1	< 1	< 1	< 1	< 1	1	< 1	< 1	< 1	< 1	4	< 1	< 1	2	< 1	< 1	3	< 1	< 1	< 1	< 1	< 1
Dec604	2	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
syn-DP	< 1	7	< 1	7	7	< 1	7	7	7	< 1	9	< 1	7	18	9	7	7	8	7	8	9	10	7	8	< 1
anti-DP	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	6	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
CP	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	5	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
Dechlorane	36	60	91	52	72	12	46	11	32	82	85	43	74	158	130	14	35	43	5	37	53	35	42	94	115
Σ₇ DRCs	42	72	97	64	83	12	56	18	42	87	99	48	86	220	146	22	51	54	13	49	65	47	52	108	120

Table S2

(pg g⁻¹)

Concentrations of HFRs of 25 single serving samples (Non-seafood portion)

Compound	No1	No2	No3	No4	No5	No6	No7	No8	No9	No10	No11	No12	No13	No14	No15	No16	No17	No18	No19	No20	No21	No22	No23	No24	No25
α-HBCD	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
β-HBCD	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
γ-HBCD	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
Σ₃ HBCDs	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
TriBDE-30	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
TriBDE-17	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
TriBDE-28	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
TetraBDE-49	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
TetraBDE-71	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
TetraBDE-47	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
TetraBDE-66	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
TetraBDE-77	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
PentaBDE-100	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
PentaBDE-119	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
PentaBDE-99	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
PentaBDE-85	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
PentaBDE-126	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-154	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-153	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-139	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-140	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-138	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HexaBDE-156/169	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2	< 2
HeptaBDE-184	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-183	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-191	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-180	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
HeptaBDE-171	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-201	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-204/197	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-203	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-196	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
OctaBDE-205	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4	< 4
NonaBDE-208	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
NonaBDE-207	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
NonaBDE-206	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10
DecaBDE-209	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	< 10	58	< 10	< 10	< 10	< 10
Σ₃₅ PBDEs	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	58	0	0	0	0
Dec602	< 1	< 1	< 1	< 1	5	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	4	< 1	< 1	< 1	< 1	< 1	4	< 1	< 1	< 1	< 1	< 1
Dec603	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	3	3	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
Dec604	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	4	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
syn-DP	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
anti-DP	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
CP	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1	< 1
Dechlorane	5	5	< 1	5	5	< 1	< 1	5	5	5	5	5	5	5	5	5	5	5	< 1	5	5	5	< 1	5	5
Σ₇ DRCs	5	5	0	5	10	0	0	5	5	5	8	8	5	10	5	9	5	5	0	9	5	5	0	5	5

Fig. S1

MS chromatograms of HFRs in seafood samples

(a) HBCDDs (Sample No.15); upper: Non-labeled, lower: ¹³C-labeled, (b) PBDEs (Sample No. 14); upper: Non-labeled, lower: ¹³C-labeled in each congener, (c) DRCs (Sample No.14); upper: Non-labeled, lower: 13C-labeled

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