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Polybrominated diphenyl ethers (PBDEs) are widely used in many industrial and commercial materials as a class of brominated flame retardants (BFRs), and its related exposure threatens human health (1). Certain PBDEs have been banned worldwide, and the congeners in commercial penta-BDE mixtures, octa-BDE mixtures, and deca-BDE mixtures — including BDE-47, -99, -153, -154, -175, -183, and -209 — were listed as persistent organic pollutants (POPs) by the Stockholm Convention (2-3).
The details of the Total Diet Study (TDS) are described in the Foreword of this issue (4), and the measurement of PBDEs was detailed elsewhere (5-6). PBDEs were detectable in all samples. The concentrations of PBDEs varied greatly among various food groups as depicted in Table 1. The levels of ∑7PBDEs, the summation of 7 PBDE congeners, were dominated by aquatic products with 39.85±33.46 pg/g fresh weight (mean±standard deviation), followed by meats and eggs with concentrations of 29.75±32.73 pg/g fresh weight and 22.19±31.96 pg/g fresh weight, respectively. Lower concentrations were observed in dairy products and other plant origin food samples (P<0.05), which was consistent with other studies (7). Dietary intake of ∑7PBDEs for Chinese adults was 0.24±0.38 ng/kg body weight per day (mean±standard deviation) with a range of 0.02–1.96 ng/kg body weight per day, and the geometric mean was 0.13 ng/kg body weight per day. The dietary exposure varied greatly across all regions, as listed in Table 2. Adults from Zhejiang ingested the highest level of ∑7PBDEs at 1.96 ng/kg body weight per day, followed by those in Inner Mongolia, Guangxi, and Fujian with a dietary intake of 0.39, 0.38, and 0.36 ng/kg body weight per day, respectively. Generally, the dietary exposure levels in southeastern and southern coastal regions with more industrialization were relatively high, while the levels in central and western regions with typical agriculture and animal husbandry such as Ningxia, Qinghai, Shaanxi, and Shanxi were relatively low. Risk assessment was conducted using the margin of exposure (MOE) approach, and in this study, a conservative estimate was applied, calculated through dividing the levels of Σ7PBDEs by bench marker dose lower confidence limit 10% (BMDL10) of BDE-47, -99, and -153, respectively, applied by the European Food Safety Authority (EFSA). The large MOEs ranging 1.0×103–1.7×107 indicated a low health risk in China.
Food group N* Mean† Geometric mean§ Median Min Max Cereals 24 5.60±15.18 2.13 (0.45, 10.14) 2.30 0.13 102.76 Legumes 24 7.06±10.68 3.92 (1.22, 12.62) 3.96 0.78 44.85 Potatoes 24 9.12±24.06 3.78 (1.19, 12.02) 4.28 0.33 128.04 Meats 24 29.75±32.73 21.58 (9.28, 50.16) 19.59 4.70 165.14 Eggs 24 22.19±31.96 16.17 (6.50, 40.27) 15.74 3.82 206.63 Aquatic products 24 39.85±33.46 31.42 (13.61, 72.55) 31.99 3.05 163.81 Dairy products 24 4.17±6.12 2.53 (0.98, 6.53) 2.29 0.40 31.64 Vegetables 24 8.95±12.47 4.32 (1.03, 18.02) 5.34 0.09 60.95 Note: The unit of mean, GM, median, min, and max are pg/g fresh weight.
Abbreviations: PBDEs=polybrominated diphenyl ethers; TDS=Total Diet Study.
* Number of food composites of each food group.
† Data are mean ± standard deviation.
§ Data were geometric mean (+1 geometric standard deviation, -1 geometric standard deviation).Table 1. Concentrations of ∑7PBDEs in food categories from the Sixth TDS in China.
Dietary intake range of
PBDEs (ng/kg body weight per day)Regions (average dietary exposure to PBDEs) 0.01–0.09 Qinghai (0.09); Shanxi (0.09); Hubei (0.08); Shandong (0.07); Heilongjiang (0.04); Hebei (0.04); Henan (0.03); Ningxia (0.02); Shaanxi (0.02) 0.10–0.19 Beijing (0.18); Jiangsu (0.13); Jiangxi (0.10) 0.20–0.29 Guizhou (0.27); Jilin (0.26); Sichuan (0.25); Liaoning (0.22); Shanghai (0.21); Guangdong (0.20); Gansu (0.20); Hunan (0.20) 0.30–0.39 Inner Mongolia (0.39); Guangxi (0.38); Fujian (0.36) >0.39 Zhejiang (1.96) Abbreviations: PBDEs=polybrominated diphenyl ethers; TDS=Total Diet Study; PLADs=provincial-level administrative divisions. Table 2. Estimated dietary exposure to ∑7PBDEs from the Sixth TDS — 24 PLADs, China.
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The dietary exposure levels of PBDEs varied widely among countries and regions, ranging from 0.93 ng/kg body weight per day in Latvia to 2.9 ng/kg body weight per day in the United Kingdom (Supplementary Table S1). The dietary intake level in China was low in comparison to other countries in recent studies, which can be caused by differences in dietary study methods, the origin of samples, or dietary preference. For most regions, meat was the main source of dietary exposure to PBDEs, especially seafood (7). However, in China, the main food sources for PBDEs were meats, cereals, and vegetables contributing 24.4%, 23.4%, and 23.2%, followed by aquatic products contributing 12.7%. Plant foods including cereals, vegetables, potatoes, and legumes contributed 55.6%, as depicted in Supplementary Figure S1. The range of MOEs was notably higher than the threshold reference recommended by the EFSA, indicating very low health risk concern in China.
Figure 1 compares dietary exposures to PBDEs of the Fourth, Fifth, and Sixth TDSs during the period of 2007–2019. In the previous study, there was no statistical differences in dietary exposure between the Fourth and Fifth TDS (P>0.05). Whereas, in the Sixth TDS, the dietary intake level decreased sharply (P<0.05), which was reduced by 65.7% and 62.9% compared with the Fourth and Fifth TDS, respectively. In a study modeling of flame retardants in typical urban indoor environments in China during 2010−2030, Li et al. found that there will be a decline of human exposure to PBDEs after 2017 (8). The reduction of PBDEs exposure is likely related to contamination control by China authority. Referring to the list of POPs of Stockholm Convention, the Ministry of Ecology and Environment of the People’s Republic of China (MEP) in 2014 announced the ban of the import, export, production, and use of penta- and octa-BDE (9). In addition, there were only two areas, Zhejiang and Inner Mongolia Autonomous Region, where the dietary intakes were increased, especially in Zhejiang where it increased by 243.2%. In view of the large increase, it is necessary to follow-up with increased monitoring in Zhejiang. And, a limitation of this study is not paying attention to the potential health risk of dietary PBDEs of special populations. Moreover, considering the diverse possibilities of exposure for PBDEs — ranging from dust ingestion to dermal absorption to dietary intake — further studies should be conducted to investigate the current burden of PBDE exposure in populations.
Figure 1.Comparison of dietary exposures to ∑7PBDEs among the Fourth, Fifth, and Sixth TDS in China.
Abbreviations: PBDEs=polybrominated diphenyl ethers; TDS=Total Diet Sudy; PLADs=provincial-level administrative divisions.Based on the existing toxicological data, the current health risk caused by dietary exposure was still low. The dietary intake level decreased sharply compared with the Fourth and Fifth TDS, thus, continuous national monitoring is necessary to evaluate the time trends and support the legislation of POPs for China and from international conventions.
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The 24 provincial-level CDCs.
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No conflicts of interest.
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