Plasticizer contamination in the urine and hair of preschool children, airborne particles in kindergartens, and drinking water in Hong Kong☆
Graphical abstract
Introduction
Over the past two decades, increasing evidence has indicated an association between a certain level of exposure to plasticizers and various long-term health problems, such as obesity, type 2 diabetes, thyroid disorders, neurodevelopmental delays, breast cancer, altered reproductive function in both sexes, and altered immune function (Karwacka et al., 2017; Nesan et al., 2018; Villanger et al., 2020; Wu et al., 2020). In this vein, a relatively large number of plasticizers have been defined as endocrine-disrupting chemicals (EDCs) (Gore et al., 2015).. (Fig. 1, Fig. 2)
Phthalates are a class of plasticizers that are mainly applied to the production of polyvinyl chloride, resins, and pharmaceutical products. Bisphenol A (BPA) is used widely in epoxy resins, food-packaging materials, and children’s toys, while many organophosphorus esters (OPEs) have been produced and used extensively as plasticizers and flame retardants (FRs) (de la Torre et al., 2020; Salthammer, 2020; Tsai, 2006; Wu et al., 2019). As many traditional plasticizers have proven to be toxic and consequently regulated, the increased industrial demand for plasticizers has led to the rapid development, production, and wide use of many alternatives [e.g., BPA analogs, the OPEs t-butylphenyl diphenyl phosphate (BPDP) and bisphenol A bis(diphenyl phosphate) (BDP)] (Tan et al., 2018; Zhang et al., 2020a). However, these new plasticizers also have adverse health effects. For example, BPA alternatives such as bisphenol AP (BPAP), bisphenol F (BPF), bisphenol B (BPB), and bisphenol S (BPS) have been reported to be as harmful as BPA; at low doses, these chemicals induce oxidative stress associated with endocrine disorders in humans, and disrupt daily sperm production (Ullah et al., 2019; Usman et al., 2019; Xiao et al., 2018).
Compared with adults, children are less able to metabolize and excrete plasticizers and are thus more vulnerable to the toxic effects (Braun, 2017; Kim and Lee, 2017; Schug et al., 2011). Certain plasticizers can alter brain development, affect pituitary and thyroid function, and perturb many other components of the human endocrine system, particularly during crucial developmental periods (Danielle et al., 2012; Miao et al., 2017). For example, experimental exposure to low concentrations of BPA and bisphenol analogs was shown to induce endocrine-disrupting effects in vitro and in vivo, and low-level exposure to BPA was reported to be related to obesity in school-children (Rochester, 2013; Ullah et al., 2018). In addition, the total exposure to various OPEs [tris(1,3-dichloro-2-propyl) phosphate (TDCPP), triphenylphosphate (TPP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(2-chloroethyl) phosphate (TCEP)] was found to be associated with poorer social skills in children (Lipscomb et al., 2017). Children may be exposed to these chemicals via multiple parallel pathways, as they are more likely than adults to eat and drink from containers containing plasticizers, place toys in their mouths, crawl or play on the ground, and intake plasticizer-containing dust and other particulates that settle on floors. Therefore, they may also be exposed more frequently to the associated health risks. To address these risks, commonly used plasticizers were replaced with chemicals previously considered less harmful (e.g., BPA analogs, new types of OPEs), which have been produced and used worldwide, leading to widespread pollution (Salthammer, 2020; Tan et al., 2018).
Children can be exposed to plasticizers via many pathways, e.g., food ingestion, water intake, dermal exposure to dust, or air inhalation (Tsai, 2006). As BPA is used widely in food packaging, dietary exposure has been reported as an important exposure pathway (Heras-Gonzalez et al., 2020). Indoor air and dust pollution are also important sources because many volatile plasticizers can easily be absorbed by airborne particles or settle in dust; for example, dust ingestion, rather than air, food, or water intake, was identified as the major exposure pathway of some types of OPEs (e.g., tris(2-butoxyethyl)phosphate (TBOEP) and TCEP) (de Boer et al., 2016). Considerable fractions of plasticizers are released into the environment and ultimately accumulate in drinking water, leading to the widespread presence of phthalates, BPA, TCEP, and TCPP in tap water (Li et al., 2019b; Radwan et al., 2020). Given this wide range of plasticizer exposure pathways and the associated adverse health effects, a better understanding of the incidence and pathways of exposure to plasticizers or their alternatives in Hong Kong is urgently needed. In particular, information is needed about the health risks of plasticizer exposure for children.
Recent monitoring studies and our previous work suggest that OPEs, BPA, and phthalates are widespread in the air, dust, marine sediment, and surface water in Hong Kong (Deng et al., 2018; Fei et al., 2014; Li et al., 2019c; Peng et al., 2012; Xu et al., 2016a). However, few studies have explored the environmental distributions of new alternative plasticizers (e.g., bisphenol analogs and new OPEs) or the extent of exposure to these chemicals and the accompanying health risks in children. Hong Kong is one of the most densely populated areas in the world and one of the most economically developed regions in China. Plasticizers in the environment may pose risks to the population of Hong Kong. One study determined that OPEs were more readily distributed into the air during warmer summer months, leading to increased inhalation exposure during these periods (Xu et al., 2016b). Hong Kong has a warm climate year-round, and children remain indoors for long periods of time. Accordingly, their levels of exposure to plasticizers might be even more serious than those of children in other areas of the world.
Accordingly, in this study, we sought to better understand the species of plasticizers and the magnitude of the plasticizer burden affecting children in Hong Kong. We quantified common plasticizers (phthalates) and their metabolites and new alternative plasticizers (bisphenol analogs, BPDP, and BDP) in urine and hair samples collected from children in Hong Kong, in drinking water (tap water and bottled water) samples, and airborne particulate samples via high-performance liquid chromatography–electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). We also performed a children’s health risk-assessment.
Section snippets
Chemicals
BPDP (≥99%), BDP (≥99%), bisphenol Z (BPZ, ≥99%), BPAP (≥98%), bisphenol AF (BPAF, ≥99%), bisphenol P (BPP, ≥99%), bisphenol M (BPM, ≥99%), BPS (≥99%), BPF (≥99%), tetrabromobisphenol A (TBBPA, ≥98%), monobutyl phthalate (MBP, ≥98%), monoethylhexyl phthalate (MEHP, ≥98%) monobenzyl phthalate (MBZP, ≥98%), monoethyl phthalate (MEP, ≥98%), monomethyl phthalate (MMP, ≥98%), dimethyl phthalate (DMP, ≥98%), diethyl phthalate (DEP, ≥98%), dibutyl phthalate (DBP, ≥98%), butyl benzyl phthalate (BBP,
Bisphenol analogs in samples of urine, hair, drinking water, and airborne particles
The DFs and concentrations of bisphenol analogs in samples of urine, hair, airborne particles, and drinking water were calculated and are listed in Table 1, Table 2, Table 3, Table 4, and the corresponding spatial distribution profiles are shown in the Supporting Information (Fig. S1–S4). In the urine samples, eight target bisphenol analogs were detected at DFs ranging from 15% (BPZ) to 64% (BPS), and their geometric mean (GM) concentrations ranged from 5.26 (BPAF) to 98.1 ng/L (BPF). The
Discussion
Plasticizers such as phthalates, BP analogs, and OPEs are widely used as additives in building materials, furniture, electronic equipment, and children’s toys. Because these compounds are not chemically bonded to those host materials, they can migrate easily into the environment (Guerra et al., 2011). We found that all of the participating children in our study had been exposed to various plasticizers, and that both common plasticizers and new alternatives were ubiquitous in the residential
Conclusions
The findings of this investigation suggest that children in Hong Kong are exposed to various forms of plasticizers (phthalates, bisphenol analogs, BPDP, and BDP). These target plasticizers were detected ubiquitously in samples of the children’s hair and urine, in tap water and bottled water, and airborne particles collected from kindergartens in Hong Kong. To the best of our knowledge, we are the first research group to detect BPDP and BDP in so many matrixes (air, tap water, bottled water, and
Authors statement
Na Li, Conceptualization, Writing – original draft. Wen-Jing Deng, Funding acquisition, Supervision, Writing – review & editing. Guang-Guo Ying, Writing – review & editing. Hua-Chang Hong, Writing – review & editing. Eric Po Keung Tsang, Writing – review & editing.
Declaration of competing interest
The authors declared that we have no conflict of interest to this work.
Acknowledgments
This research was financially supported by General Research Fund of Hong Kong (No.18300919), FLASS Dean’s Research Fund (04424&04389, 04547&04535) and Internal Teaching Development Grant (0300P&T0221) of The Education University of Hong Kong.
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This paper has been recommended for acceptance by Jörg Rinklebe.