Ultraviolet (UV) radiation can cause aging of organic materials as well as human skin, posing a threat to both environment and human body (Correa et al., 2021; Zeng et al., 2018). As a result, UV stabilizers have been widely applied into industrial products and personal care products (PCPs). Among all UV stabilizers, benzotriazole ultraviolet stabilizers (BUVSs) have the largest output and most variety (Li and Li, 2007). BUVSs can absorb full spectrum of UV light from 280 to 400 nm (UV-A and UV-B), and they are widely used as additive in building materials, paint, plastics or sunscreens, creams and shampoos (Kim et al., 2011a; Nakata et al., 2009). Some BUVSs (like UV-234, UV-328, etc.) have been listed as High Production Volume Chemicals (HPVC) by the Organization for Economic Co-operation and Development (OECD) (OECD, 2017). BUVSs can be released into different environmental compartments, predominantly into aquatic system through various pathways, mainly via direct recreational activities such as bathing and swimming or indirect landfill leachate and sewage treatment plant effluents (Apel et al., 2018; Carpinteiro et al., 2010; Lu et al., 2017; Parajulee et al., 2018). And they can also be discharged into soils as a result of solid waste or emitted into air due to abrasion and volatilization (Carpinteiro et al., 2010; Xiong, 2017). Consequently, BUVSs have been detected in environmental matrices such as surface water (Parajulee et al., 2018), wastewater (Carpinteiro et al., 2010), sewage sludge (Lu et al., 2017), sediment (Nakata et al., 2009), soil (Lai et al., 2014), and indoor dust (Kim et al., 2012). Relatively few studies reported BUVSs in aquatic biota, mainly in marine invertebrates, fishes, coastal birds, and marine mammals (Hemalatha et al., 2020; Kim et al., 2012; Nakata et al., 2009), demonstrating their bioaccumulation potential. What’s more, it’s been reported that BUVSs are found in human urine and breast milk in recent years (Kim et al., 2019; Wang et al., 2013). Overall, these compounds are ubiquitous in the natural environment, human settlements and living organisms.
Considering the widespread presence of BUVSs, their adverse effects on organisms have been investigated. Hirata-Koizumi et al. (2009) found a gender-related hepatic peroxisome proliferative activity of HDBB in rats. And some BUVSs are proved to have partial estrogenic activity or to disturb thyroid hormone pathway, development, and locomotory activity of early-stage zebrafish (Feng et al., 2020; Liang et al., 2017). An activation of aryl hydrocarbon receptor pathway in zebrafish eleuthero-embryos was observed after their being exposed to BUVSs. Besides, these compounds are also reported to cause oxidative stress damages in Daphnia magna and zebrafish (Giraudo et al., 2017; Hemalatha et al., 2020). More recently, Li et al. (2019) and Li et al. (2020) revealed their inflammatory effects in fish, which was potentially caused through the AHR-IL17/IL22 pathways.
BUVSs have been considered to be persistent in environment (Nakata et al., 2010) and their lipophilicity/hydrophilicity (log Kow:4.31-8.28) property is the main factor governing their accumulation potential in aquatic organisms (Hemalatha et al., 2020; Xing et al., 2018). For instance, UV-327 showed a significant bioaccumulation property in marine mammals from the western North Pacific Ocean with a bioconcentration factor (BCF) value as high as that of persistent organochlorine pesticide, hexachlorocyclohexane (37 000) (Hemalatha et al., 2020). In addition, high bioaccumulation factor (BAF) of BUVSs were also observed in fresh water aquatic organisms from the Pearl River basin in China, and some of the BUVSs congeners showed trophic magnification behavior with trophic magnification factor (TMF) > 1 (Xiong, 2017). More recently, Zhang et al. (2021) investigated the accumulation and biotransformation of 6 BUVSs in zebrafish under controlled laboratory conditions and reported the BCF values at the range of 1.04-10400 in different fish tissues.
On the other hand, heavy metals such as Cd, Cr, Pb, Cu, Zn, etc., have been widely detected in environmental media including sediments, water, and soils (Li et al., 2015; Peng et al., 2022; Zhang et al., 2018). Among these heavy metals, copper draws a great concern. The average concentration of copper in China's major river basins ranged from 11.72 to 527.77 µg·L−1 in 2006-2017 (He et al., 2019). And the co-contamination by heavy metals and organic contaminants is attracting increasing attention, as they both can be persistent and bioaccumulative in environment (Zhao et al., 2018b). In previous studies, Zhao et al. (2018a) found that copper could increase the bioaccumulation of Fluoroquinolones (FQs) in zebrafish tissues. Recently, Zhang et al. (2021) reported a decline in the concentration of PFAAs (C2-C8) in wheat root by 6%-73% due to excessive Cu exposure, while the translocation of long-chain perଂuorooctanoic acid (PFOA) and perଂuorooctane sulfonic acid (PFOS) was promoted and positively associated with the Cu exposure levels. However, studies on the joint effect of copper and BUVSs are still lacking.
In present studies, combined effects of benzotriazole and copper on organisms have been evaluated, considering benzotriazole is widely used as corrosion inhibitor for copper and its alloy (Grillo et al., 2014; Xing et al., 2017; Xing et al., 2018). As a subgroup of benzotriazole with a phenolic group attaching to the benzotriazole structure, BUVSs are also widely used as additives in automobile components and some sports equipment etc (Nakata et al., 2009). Therefore, in this study, we investigated the bioconcentration and distribution pattern of BUVSs in different tissues (liver, kidney, muscle, and gill) of common carp (Cyprinus carpio) and evaluated the effect of copper on their bioaccumulation, which provided a first glimpse into the co-contamination by heavy metals and BUVSs.