Accumulation of polychlorinated biphenyls and brominated flame retardants in breast milk from women living in Vietnamese e-waste recycling sites
Introduction
Waste electrical and electronic equipment, also known as e-waste, refers to end-of-life products encompassing information-communication devices, consumer electronics and household appliances. Owing to the short life span of devices such as computers, television sets, stereo systems, printers and cell phones, e-waste is generated in large amounts, with an annual volume of 20–50 million tonnes world-wide and increases rapidly at a rate of 3–5% per year (UNEP, 2005). The hazard of e-waste lies in the high content of many toxic substances (BAN and SVCT, 2002) including heavy metals (lead, mercury, cadmium, etc.) and persistent organohalogen compounds such as polychlorinated biphenyls (PCBs) and brominated flame retardants (BFRs). PCBs are present in older electrical capacitors and transformers as coolants and dielectrics whereas BFRs are additives found in most polymeric parts (printed circuit boards, cable coatings, plastic casings, etc.). There are increasing evidences that BFRs, such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs), exhibit a range of toxic effects similar to PCBs, including endocrine disruption as well as reproductive and neurodevelopmental toxicity (Legler and Brouwer, 2003, Birnbaum and Staskal, 2004).
Uncontrolled e-waste recycling has become a topic of serious concern in recent years. It is estimated that up to 80% of e-waste from industrialised countries is exported to Asian developing countries for recycling, exploiting the inexpensive cost of labour and weak enforcement of environmental laws (BAN and SVCT, 2002). Large scale waste processing operations employing primitive practices such as uncontrolled dismantling, acid stripping and open burning in Chinese e-waste recycling sites (EWRSs) have resulted in severe environmental contamination (Wong et al., 2007). The human exposure levels to PCBs in Taizhou region (Zhao et al., 2007) and to PBDEs in Guiyu town (Bi et al., 2007) are two of the highest ever reported. In other Asian developing countries such as Cambodia, India, Philippines and Viet Nam, although open waste disposal sites have been identified as potential sources of PCBs and dioxin-like compounds (Minh et al., 2003), information on EWRS are lacking. Available data, albeit limited, indicate that the levels of PCBs and BFRs in the general populations from these countries are lower than those from developed countries (Schecter et al., 2004, Sudaryanto et al., 2005, Sudaryanto et al., 2008a, Malarvannan et al., 2009); nevertheless EWRSs are suspected as potential hotspots of these contaminants. In this context, the present study was carried out to assess the human exposure to persistent organohalogen compounds related to e-waste recycling in Viet Nam. Breast milk was selected as bioindicator on account of the simple and non-invasive sampling, relatively high content of lipid and lipophilic contaminants, and relevance to infants' health. PCBs, PBDEs and HBCDs were determined in human breast milk collected from three EWRSs and a reference site in view of contamination levels, congener patterns, influence of lifestyle factors and potential health risk for breastfeeding infants.
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Study locations
End-of-life electrical and electronic equipment in Viet Nam are often picked up by scrap collectors, through purchase from their former owners or by scavenging domestic waste disposal sites. The wastes are then transported to trade villages specialised in recycling. The present study investigated three e-waste recycling sites located in the Red River delta region, in the northern part of the country; Dong Mai (DM, Hung Yen province, battery recycling), Trang Minh (TM, suburb of Hai Phong City,
Results
PCBs, PBDEs and HBCDs were detected in all the samples analysed (Table 2). In terms of total concentrations, PCBs were more abundant than PBDEs and HBCDs by one order of magnitude or higher in majority of the samples. However, PBDEs were more abundant than PCBs in three donors who were involved in the recycling of e-waste in BD.
Total PCB levels were statistically comparable among locations but significant differences were observed with individual PCB congeners. The residents of the three
Contamination levels
The similarity in PCB levels in the three Vietnamese e-waste recycling sites as also seen in the reference site indicates that the former were not major sources of PCBs. Total PCB levels in Vietnamese human breast milk were in comparable ranges with those reported in other Asian developing countries and lower than in developed nations (Table 4). The levels observed in this study were similar to the serum PCB levels in the residents of Guiyu (median 52 ng g− 1 lipid wt.), the largest recycling site
Conclusions
The present study found a significant accumulation of PBDEs in breast milk of women living in two Vietnamese e-waste dismantling sites, possibly through non-dietary intake by accidental ingestion/inhalation of dust. The highest PBDE levels were found in recyclers from the village Bui Dau, higher than the reference levels by two orders of magnitude and comparable to the highest levels reported in industrialised countries. PBDEs levels in these recyclers also exceeded those of legacy POPs such as
Acknowledgements
The authors thank Mr Bui Hong Nhat for coordinating the sampling survey. This study was partly supported by the grants-in-aid for scientific research (S) (no. 20221003) from Japan Society for the Promotion of Science (JSPS), the global environment research fund (RF-064) and the waste management research grants (K2062, K2129 and K2121) from the Ministry of the Environment, Japan, and grants from global COE program from the Japanese Ministry of Education, Culture, Sports, Science and Technology
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2021, Science of the Total Environment