Volatile organic compounds in an e-waste dismantling region: From spatial-seasonal variation to human health impact

doi:10.1016/j.chemosphere.2021.130022

Chemosphere

Volume 275, July 2021, 130022

https://doi.org/10.1016/j.chemosphere.2021.130022 Get rights and content

Highlights

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Ambient VOCs was studied in the e-waste dismantling region.
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BTEX in ambient air was found related with e-waste dismantling activity.
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The e-waste dismantling park is a hotspot of hazardous VOCs.
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The e-waste dismantling emission contributed 20% to total VOCs in adjacent ambient air.
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Higher inhalation health risks were found in the e-waste park than residential areas.

Abstract

The dismantling of electrical and electronic waste (e-waste) can release various Volatile organic compounds (VOCs), impacting the surrounding ambient environment. We investigated the spatio-temporal characteristics and health risks of the ambient VOCs emitted in a typical e-waste dismantling region by conducting multi-site sampling campaigns in four seasons. The pollution of benzene, toluene, ethylbenzene, and xylenes (BTEX) in the e-waste dismantling park has relation to e-waste dismantling by seasonal trend analysis. The highest concentrations of most VOCs occurred in winter and autumn, while the lowest levels were observed in summer and spring. The spatial distribution map revealed the e-waste dismantling park to be a hotspot of BTEX, 1,2-dichloropropane (1,2-DCP), and 1,2-dichloroethane (1,2-DCA), while two major residential areas were also the hotspots of BTEX. The e-waste emission source contributed 20.14% to the total VOCs in the e-waste dismantling park, while it was absent in the major residential and rural areas. The cancer risk assessment showed that six VOCs exceeded 1.0 × 10⁻⁶ in the e-waste dismantling park, while only three or four compounds exceeded this risk in other areas. The noncancer risks of all compounds were below the safety threshold. This study supplements the existing knowledge on VOC pollution from e-waste dismantling and expands the research scope of chemical pollution caused by e-waste.

Graphical abstract

Introduction

Electrical and electronic waste (e-waste), the fastest-growing solid waste worldwide, is estimated to increase at an annual rate of 3%–5% globally (Cucchiella et al., 2015; Singh et al., 2016). In 2016, roughly 45 million tons of e-waste was generated worldwide (Baldé et al., 2017). In 2019, this figure increased to 54 million tons (Forti et al., 2020). The main end-of-life treatment options of e-waste include recycling, incineration, and landfill (Tsydenova and Bengtsson, 2011). E-waste contains many valuable resources such as noble metals and is therefore considered an attractive secondary source (Kaya, 2016). E-waste dismantling can yield several economic benefits (Zhang et al., 2019; Zhao et al., 2019). However, various contaminants, including organic pollutants and heavy metals, are released during the e-waste dismantling process, which may threaten the health of the environment and human beings (Huang et al., 2019; Li et al., 2008, 2020a). For example, a study reported that the atmospheric polychlorinated biphenyls (PCBs) of Vietnam were mainly released from uncontrolled discarded e-waste (Wang et al., 2016b). In southeastern China, high concentrations of heavy metal observed in a river in an e-waste dismantling town were attributed to e-waste recycling (Guo et al., 2009). In Australia, the soil around two formal e-waste recycling facilities was reported to be contaminated with polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) originating from e-waste (McGrath et al., 2018).

Volatile organic compounds (VOCs) are one of the leading organic pollutants. They are ubiquitous pollutants affecting atmospheric chemistry and human health. The photochemical reactions and physical transformations of VOCs with oxides of nitrogen (NO_x = NO + NO₂) could contribute to the formation of tropospheric ozone (Edwards et al., 2014) and particulate matter (Ji et al., 2020; Lu et al., 2019), causing severe air quality problems (Ma et al., 2016; Shao et al., 2016; Wu and Xie, 2017; Wu et al., 2017). Furthermore, exposure to VOCs can directly affect human health, causing respiratory diseases, neurological symptoms, and even cancers (Amor-Carro et al., 2020; Chen et al., 2002; Kampa and Castanas, 2008; Wang et al., 2016a). The Shanghai Health Study reported that benzene exposure resulted in an increased risk of various blood and bone marrow abnormalities (Gross and Paustenbach, 2018). Ambient VOCs from gasoline emissions, architectural paints, and household products are positively linked to increased emergency hospital admissions for chronic obstructive pulmonary disease (Ran et al., 2020). Hydrocarbons, particularly alkenes and alkynes, are associated with cardiovascular diseases, emergency department visits, while VOCs with ketone groups are associated with asthma emergency department visits (Ye et al., 2017). It was also reported that exposure to VOCs in e-waste dismantlers is associated with carcinogenic and non-carcinogenic risks (An et al., 2014b).

Several existing studies have quantified the emission of VOCs during the e-waste dismantling process (Alston et al., 2011; Guo et al., 2020). Among them, benzene, toluene, ethylbenzene, and xylene isomers (BTEX) are important VOC species as they can cause severe health effects (Miri et al., 2016). For example, the pyrolysis of e-waste releases large quantities of methane, ethene, benzene, and toluene (Alston et al., 2011). An et al. detected high concentrations of aromatics in the rotary incinerator e-waste dismantling workshop, while equivalent amounts of aromatic and halogenated hydrocarbons were detected during the e-waste dismantling with electric heating furnaces (An et al., 2014b). These studies indicate that e-waste dismantling activity can lead to large-scale emission of VOCs. However, all these studies focused on the indoor dismantling process. Ambient VOC pollution due to the e-waste dismantling area has not been reported yet. The VOCs emitted from e-waste in rotary incinerators deserve urgent attention as they can pose cancer risk and noncancer risk to the exposed population (Chen et al., 2016). Since VOCs can easily diffuse from workshops to outdoors, it is crucial to study the outdoor VOCs pollution in the e-waste dismantling region.

In this study, we measured the ambient VOCs at multiple sites in four consecutive seasons in a small town famous for e-waste dismantling. This study aims to study the spatio-temporal variations of the VOCs in ambient air surrounding the e-waste dismantling area and its relationship with the dismantling activity. Factors considered in this study are: (1) the pollution profiles of main VOC species in the ambient air, (2) spatial and temporal characteristics of VOCs, (3) source identification and the source apportionment of ambient VOCs, (4) human cancer and noncancer risk assessment. This is the first study to comprehensively assess the ambient VOCs around the e-waste dismantling area, expanding the research scope of e-waste pollution.

Section snippets

Field sampling

Air samples were collected from an e-waste dismantling area during four grid-study campaigns in 2018 and 2019. The sampling was carried out on 28 December 2018 (11 °C–20 °C), 10 April 2019 (22 °C–31 °C), 16 July 2019 (28 °C–35 °C), and 31 October 2019 (21 °C–28 °C), representing the winter, spring, summer, and fall, respectively. Meteorological data were obtained from the meteorological information network of Guangdong province (Table S1) (https://www.gd121.cn/index.shtml). The e-waste

The dominant ambient VOC species

The annual average concentrations of tested VOCs are listed in Table S2. The most abundant VOCs (mean ± standard deviation) in the investigated areas were n-pentane (6.11 ± 13.50 μg m⁻³), isopentane (13.36 ± 38.65 μg m⁻³), benzene (3.75 ± 7.03 μg m⁻³), toluene (11.81 ± 24.24 μg m⁻³), ethylbenzene (2.31 ± 5.22 μg m⁻³), p-xylenes (4.96 ± 14.19 μg m⁻³), m-xylenes (2.22 ± 6.09 μg m⁻³), o-xylenes (2.73 ± 7.74 μg m⁻³), trichlorofluoromethane (CFC-11, 2.00 ± 1.09 μg m⁻³), dichlorodifluoromethane

Conclusions

Based on multi-site sampling, VOCs in a typical e-waste dismantling region in southeastern China were monitored during four seasons by grid-sampling. The dominant VOC species included n-pentane, isopentane, BTEX, CFCs, 1,2-DCA, and 1,2-DCP. Seasonal VOC trend analysis indicated seasonal pollution characteristics in different areas. VOC concentration was affected by meteorological conditions and emission sources, and long-range transport. VOC pollution was most severe in winter and autumn. The

Author statement

Daijin Chen: Methodology, Formal analysis, Writing-original draft. Ranran Liu: Methodology, Formal analysis. Qinhao Lin: Methodology, Formal analysis. Shengtao Ma: Methodology, Data curation. Guiying Li: Writing- Reviewing and Editing. Yingxin Yu: Visualization, Investigation. Chaosheng Zhang: Validation. Taicheng An: Conceptualization, 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.

Acknowledgements

This work was supported by National Natural Science Foundation of China (41731279), National key research and development project (2019YFC1804503), Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01Z032), The Innovation Team Project of Guangdong Provincial Department of Education, China (2017KCXTD012) and Leading Scientific, Technical and Innovation Talents of Guangdong special support program (2016TX03Z094).

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Volatile organic compounds in an e-waste dismantling region: From spatial-seasonal variation to human health impact

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Field sampling

The dominant ambient VOC species

Conclusions

Author statement

Declaration of competing interest

Acknowledgements

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