Persistent organic pollutants (POPs) represent an important group of substances with the characteristics of high toxicity, persistence and bioaccumulation. Hexabromocyclododecane (HBCD) has been extensively used as a brominated flame retardant (BFR) for a long period of time in textiles, electronics, construction materials, thermal insulation materials, etc. γ-HBCD constitutes the main diastereoisomer of industrial HBCD, accounting for 75–89% of the overall weight, while α-HBCD (10–15%) and β-HBCD (1–12%) are two other diastereomers (Covaci et al., 2006). In 2011, about 31,000 tons of HBCD were produced worldwide (POPRC, 2011a, 2012). The Chinese HBCD production accounts for more than half of the global production (POPRC, 2012). Given the strong persistence, bioaccumulation, liver toxicity, neurotoxicity and immunotoxicity of HBCD (Tomy et al., 2008; Marvin et al., 2011; Zhu et al., 2016; Wang et al., 2016; Zhang et al., 2018), it was included in the list of POPs in 2013 (POPRC8.3, 2013). Besides, its production and utilization have been globally recommended to be banned since 2016. However, HBCD is still produced and applied in China, which allows its use in special building materials.
Additionally, HBCD is found in multiple environmental media, e.g., air, riverine water, sediments, sewage sludge and animal tissues (Ni et al., 2013; Feng et al., 2012; Gorga et al., 2013; Xia et al., 2018), as well as in humans (Kim et al., 2014) and biota in pristine regions, including the Antarctic Peninsula. Due to its low water solubility and high lipophilicity, HBCD can easily accumulate in aquatic organisms. Previous studies (Shi et al., 2009; Törnkvist et al., 2011; Barghi et al., 2016) demonstrated that HBCD levels are generally elevated in aquatic foods compared with other food products. Therefore, environmental pollution and human health problems caused by extensive application of HBCD have significantly attracted the attention of the international community.
Xiamen, in the southeast coast of China, currently undergoes rapid urbanization and industrialization; thus, seawater in this area tends to have poor quality. Furthermore, fish accounts for a great proportion of the dietary composition of Xiamen residents. This makes Xiamen residents even more vulnerable to exposure to persistent organic pollutants (POPs) via fish intake than inland inhabitants. Despite the importance of the abovementioned serious health problem in Xiamen, there are limited studies (Zhang et al., 2012; Qian et al., 2017) examining “classic” POPs, including DDT, HCH and PCB, in aquatic products in Xiamen, China. Hence, to date, data related to permissible levels of environmental exposure and associated risk factors in Xiamen are scarce.
No large-scale study focusing on HBCD quantitation in fish samples has been performed in Xiamen until now. Therefore, this work aimed to assess the contamination status of HBCD in fish collected from Xiamen, as well as species and regional distributions. Additionally, the related health risk for local residents consuming fish was estimated. We, for the first time, determined the estimated daily intake (EDI) of HBCD in Xiamen residents.