Elsevier

Environmental Pollution

Volume 286, 1 October 2021, 117561
Environmental Pollution

Urinary triclosan in south China adults and implications for human exposure

https://doi.org/10.1016/j.envpol.2021.117561Get rights and content

Highlights

  • Adults from South China were widely exposed to triclosan.

  • Marital status and age were found to positively influence urinary triclosan levels.

  • After adjustment for BMI, age was determined to be positively associated with triclosan concentrations.

  • Estimates of human intake indicated that the health risk of exposure to triclosan for adults in South China was very low.

Abstract

Triclosan (TCS) is widely applied in personal care products (PCPs) as an antimicrobial preservative. Due to its toxicity and potential risk to human health, TCS has attracted mounting concerns in recent years. However, biomonitoring of TCS in large human populations remains limited in China. In this study, 1163 adults in South China were recruited and urinary TCS concentrations were determined. TCS was detected in 99.5% of urine samples, indicating broad exposure in the study population. Urinary concentrations of TCS ranged from below the limit of detection (LOD) to 270 μg/L, with a median value of 3.67 μg/L. Urinary TCS concentrations from individuals were all lower than the Biomonitoring Equivalents reference dose, suggesting relatively low health risk in the participants. TCS concentrations did not differ significantly between sexes or education levels (p > 0.05). Nevertheless, marital status and age were found to be positively influence TCS levels (p < 0.001). After adjustment for body mass index (BMI), age was determined to be positively associated with TCS concentrations (p < 0.05), particularly in the age group from 31 to 51 years old. This study provides a baseline of urinary TCS exposure in South China general adult populations.

Introduction

Triclosan (TCS), a crystalline powder in whiteness, is easily resolved in alkali and organic solutions while irresolvable in water which has been extensively applied in personal care products (PCPs), detergents, daily necessities, medical disinfection and health care products, as well as the finishing of sanitary fabrics and anti-corrosion and treatment of plastics owing to its prominent property of wide-spectrum antisepsis (Rodricks et al., 2010; Zhu et al., 2016a). Besides, TCS with high purity is applied in toothpaste and mouthwash in the treatments of periodontitis or oral ulcers (Niederman, 2005; Prabin Shrestha et al., 2020). Hence, there are some pathways through which humans could expose to TCS like oral administration and cutaneous absorption. It has been frequently detected in biological specimens such as blood, urine and plasma (Geens et al., 2012; Wang and Tian, 2015). TCS could be metabolized via urine in the forms of glucuronic lactone or sulfuric acid conjugate with an excretion rate of 24–83% within four days and a short half-life within 24 h (Huang et al., 2016; Sandborgh-Englund et al., 2006).

TCS was found to be cytotoxic in PC12 cell derived from rat pheochromocytoma, leading to cell damage, reduction and inhibition of activation of AKT/mTOR and p38 pathways (Li et al., 2019). TCS exhibits a certain degree of reproductive toxicity and genotoxicity (Du et al., 2018; Lee et al., 2019). There are some adverse consequences caused by TCS exposure shown in previous studies like DNA damage, interference in endocrine activities and adverse birth outcomes (Etzel et al., 2017; Louis et al., 2017; Sun et al., 2019). TCS exposure could induce developmental abnormalities and epigenetic alterations in medaka (Oryzias latipes) embryos (Song et al., 2020). A recent study in flatfish suggested that TCS could induce early developmental malformation and growth retardation, especially in early larval stages and metamorphosis (Araújo et al., 2019). Female rats exposing to TCS in the period of pregnancy and lactation could lead to fetus growth obstruction, estrous cycle dysfunction and unexpected changes in uteri tissues of offspring (Bitencourt et al., 2019). Maternal rat exposing to TCS might increase the risk of autism spectrum disorders in future generations (Hao et al., 2019). It is also believed that TCS could interfere in thyroid hormone because of their similarity in chemical structures (Allmyr et al., 2009; Dann and Hontela, 2011). TCS has been revealed to be conducive to neurodevelopment in adversity through disrupting thyroid hormone homeostasis by both epidemiological and experimental studies conducted on animals (Johnson et al., 2016; Braun et al., 2017). Scorpion exposure to TCS at early development and metamorphosis could lead to changes in thyroid hormone levels which could delay the onset of metamorphosis subsequently (Schnitzler et al., 2016). Therefore, due to a variety of biological effects, human exposure to TCS has become a great public health concern (Johnson et al., 2016).

Previous studies on human exposure to TCS mainly focused on two aspects, one is the TCS exposure level in females and corresponding impact on offspring, the other is the correlation between TCS exposure in males and sperm quality (Jurewicz et al., 2018; Nassan et al., 2019). It was reported that TCS concentrations detected in urine in American children were significantly associated with reductions in scores measured from cognition test of 8-year-old children (Jackson-Browne et al., 2018). A recent cross-sectional study found that urinary TCS concentrations in 317 women were inversely associated with specific serum thyroid function biomarkers, suggesting that TCS might affect thyroid homeostasis and autoimmunity (Skarha et al., 2019). A cohort study, which was conducted prospectively in Shanghai, has found that elevated levels of TCS in mother urine during pregnancy were in association with levels of neonatal thyroid in decrease (Wang et al., 2017) The relationships between TCS exposure and ovarian reserve were investigated in women aged 25–39 in Lodz, Poland and a negative impact was found on female antral follicle count, which was a hallmark of ovarian reserve (Jurewicz et al., 2019). Similar results were found in women aged 18–45 years in Massachusetts, United States (US) (Mínguez-Alarcón et al., 2017). A recent epidemiological survey found that TCS levels in urine correlated with bone mineral density negatively in adult females in America while with the prevalence of osteoporosis positively (Cai et al., 2019). In addition, studies which were conducted in males between 18 and 55 years old in Massachusetts, US, discovered the inverse correlation between TCS concentrations obtained in urine and sperm quality detected in corresponding subjects (Nassan et al., 2019). TCS exposure reduced testes and other sexual organs, thereby reducing male sperm density and sperm quality (Kumar et al., 2009). In addition, human exposure to TCS might be related to overweight and obesity. It was reported that high level of TCS exposure was inversely correlated with body mass index (BMI) and abdomen circumference among general adults in US (Li et al., 2015a). However, biomonitoring of TCS from large sizes of populations remains very limited in China.

Therefore, our study aimed to: (1) determine urinary concentrations of TCS in 1163 adults from South China, (2) explore the factors influencing urinary TCS levels and potential sources. To our knowledge, this is the largest scale biomonitoring studies of urinary TCS in Chinese populations, which may provide a baseline for future investigation of human exposure to TCS and related health effects.

Section snippets

Chemicals and reagents

Both reference standards of TCS and that of D3-TCS (98% purity) were made acquisition from CDN Isotopes (Quebec, Canada). β-Glucuronidase/arylsulfatase, which were 85,000 units/mL and 7500 units/mL, respectively, were gained from Anple (Shanghai, China). Chromatographic grade methanol and acetonitrile were purchased from Merck (Darmstadt, Germany). Sodium acetate, ammonium acetate and acetic acid were obtained from Fisher Scientific (Houston, TX, USA). Water for experiments was produced by

Description of study subjects and urinary concentrations of TCS

General information of the participants was summarized in Table 1. Among the 1163 participants, 1138 were males and 25 were females. Participants were mainly 21–61 years old and most of them were married (66.5%). Ninety percent of them had college or university education. Most of the participants (54.3%) had a BMI between 18.5 and 23.9 kg/m2. TCS was detected in 1158 urine samples with a frequency of 99.5%, suggesting that South China adults were widely exposed to TCS. It was noteworthy that

Conclusions

In the present study, urinary TCS was determined in South China adults. High detection frequency suggested broad exposure in the studied population. Urinary levels of TCS in South China adults were relatively higher compared with those reported in other countries and regions. Marital status and age, but not sex and education levels, were found to be associated with urinary TCS. BMI and TCS concentrations were positively correlated in participants aged 32–41 years. Estimation of human intake and

Credit authorship statement

Dongfeng Yang: Methodology, Writing - review & editing; Sifang Kong: Formal analysis, Writing - review & editing; Feng Wang: Supervision; Lap Ah Tse: Supervision; Zhi Tang: Investigation; Yang Zhao: Methodology; Chun Li: Investigation; Minhui Li: Formal analysis; Shaoyou Lu: Supervision.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This study was supported by the National Natural Science Foundation of China (No. 42077385), the Fundamental Research Funds for the Central Universities of China (No. 20ykpy87) and the 100 Top Talent Programs of Sun Yat-sen University.

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