A comparative study of exposure levels and risk of endocrine disrupting chemicals among children in Hong Kong and southwest China /

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Student Theses

2022

Li, Ziying

Thesis

In recent years, many chemicals commonly used in our daily life have been shown to be endocrine disrupting chemicals (EDCs), which can alter the normal function of the endocrine system in humans and wildlife. Nowadays, people are exposed to EDCs daily through drinking, eating, breathing, or contacting with EDC-contaminated materials. As a result, EDCs can now be widely detected in the human body, especially in blood and urine, which has raised considerable health concerns. Many researchers have suggested that contaminated consumer products are the primary sources of human exposure, and various exposure routes have been identified. In this thesis, analytical methods and standard operation procedures for seven EDCs, namely 2,4- dibromophenol (2,4-DBP), 2,4,5-tribromophenol (2,4,5-TBP), 2,4,6-tribromophenol (2,4,6-TBP), triclosan (TCS), bisphenol A (BPA), diethylstilbestrol (DES), and 17α- ethynylestradiol (EE2), are developed, after which by a systematic comparative study of the exposure, level, and risk of these EDCs to children in Hong Kong and southwest China is performed. Biomonitoring of EDCs and their metabolites in urine serves as a useful tool to assess exposure and the resulting risks. Correspondingly, we optimised a sensitive and specific method to determine seven EDCs listed above in urine samples, using enzymatic hydrolysis, liquid-liquid extraction, solid-phase extraction, derivatisation, followed by gas chromatography-tandem mass spectrometry (GCMS/MS). Levels of EDCs were then normalised as ug/g creatinine, with linearity > 0.995, recoveries between 80% and 120%, and repeatability < 20%, on both artificial and real samples. Despite the fact that humans are constantly exposed to a variety of EDCs, nowadays, information concerning EDC exposure in children in developed and rapid developing areas remains very limited. In this study, urine samples were collected from parents (n = 44) and children (n = 63) in Hong Kong, as well as children in Guiyang, southwest China (n = 128) to study the EDC levels among parent-child pairs and to assess and compare their exposure routes and the risk posed by the seven EDCs listed above. The results showed that levels of 2,4,6-TBP and BPA were significantly higher in the urine samples of mothers and fathers, and levels of 2,4,5-TBP were significantly higher in the urine samples of mother. Among the selected EDCs, TCS was predominant EDC in Hong Kong with geometric mean of 1.71 μg/g creatinine and BPA was prominent EDC in Guiyang with geometric mean of 1.83 μg/g creatinine. The results indicate that children in Hong Kong have relatively low exposure and risk. However, children in Guiyang face a relatively high risk of BPA, DES and EE2. Questionnaire surveys were administered to reveal children’s lifestyle and dietary habits with the aim of elucidating relationships between EDC biomarker levels in urine with probable exposure sources. Statistical analyses further showed that urinary EDC levels were significantly associated with BMI in children and level of parental knowledge of EDCs. The EDC exposure routes examined included parental smoking, finger sucking, type and frequency of personal care products used, water bottle and tableware materials used, and consumption of canned food. For the first time, this study showed that children in Hong Kong and Guiyang, southwest China are exposed to a wide range of different EDCs through different exposure sources and routes

LG51.H43 Dr 2022eb Liz

https://educoll.lib.eduhk.hk/records/fapYGA5Z