PCDD/Fs in air and soil around an e-waste dismantling area with open burning of insulated wires in south China

Multi-media environmental fate of polychlorinated dibenzo-p-dioxins and dibenzofurans in China: A systematic review of emissions, presence, transport modeling and health risks

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are notorious persistent organic pollutants (POPs) with proven toxicity to human and ecosystems. This review critically evaluates existing research, emphasizing knowledge gaps regarding PCDD/F emissions, environmental behavior, human exposure, and associated risks in China. The current emission inventory of PCDD/Fs in China remains highly uncertain, both in terms of total emissions and emission trends. Moreover, existing monitoring data primarily focus on areas near pollution sources, limiting comprehensive understanding of the overall spatiotemporal characteristics of PCDD/F pollution. To address this, we propose a novel approach that integrates the Multi-media Urban Mode (MUM) model with an atmospheric chemical transport model that includes a dual adsorption model to capture gas-particle partitioning of PCDD/Fs in the atmosphere. This coupled model can simulate the transport and fate of PCDD/Fs in multi-media environments with high spatiotemporal resolution, facilitating a nuanced understanding of the impacts of emissions, climate, urbanization and other factors on PCDD/F pollution. Additionally, dietary ingestion, particularly from animal-derived foods, is identified as the predominant source (up to 98%) of human exposure to PCDD/Fs. While the changes in dietary structure, population distribution, and age structure can influence human exposure to PCDD/Fs, their impacts have not yet been quantified. The proposed model lays the foundation for a systematic assessment of health risks from PCDD/F exposure through various pathways by further incorporating a food chain model. Overall, this review offers a comprehensive strategy for assessing PCDD/F pollution, encompassing the entire continuum from emissions to environmental impacts.

Global occurrence, chemical properties, and ecological impacts of e-wastes (IUPAC Technical Report)

The waste stream of obsolete electronic equipment grows exponentially, creating a worldwide pollution and resource problem. Electrical and electronic waste (e-waste) comprises a heterogeneous mix of glass, plastics (including flame retardants and other additives), metals (including rare Earth elements), and metalloids. The e-waste issue is complex and multi-faceted. In examining the different aspects of e-waste, informal recycling in developing countries has been identified as a primary concern, due to widespread illegal shipments; weak environmental, as well as health and safety, regulations; lack of technology; and inadequate waste treatment structure. For example, Nigeria, Ghana, India, Pakistan, and China have all been identified as hotspots for the disposal of e-waste. This article presents a critical examination on the chemical nature of e-waste and the resulting environmental impacts on, for example, microbial biodiversity, flora, and fauna in e-waste recycling sites around the world. It highlights the different types of risk assessment approaches required when evaluating the ecological impact of e-waste. Additionally, it presents examples of chemistry playing a role in potential solutions. The information presented here will be informative to relevant stakeholders seeking to devise integrated management strategies to tackle this global environmental concern.

Severe dioxin-like compound (DLC) contamination in e-waste recycling areas: An under-recognized threat to local health

Electrical and electronic waste (e-waste) burning and recycling activities have become one of the main emission sources of dioxin-like compounds (DLCs). Workers involved in e-waste recycling operations and residents living near e-waste recycling sites (EWRS) are exposed to high levels of DLCs. Epidemiological and experimental in vivo studies have reported a range of interconnected responses in multiple systems with DLC exposure. However, due to the compositional complexity of DLCs and difficulties in assessing mixture effects of the complex mixture of e-waste-related contaminants, there are few studies concerning human health outcomes related to DLC exposure at informal EWRS. In this paper, we have reviewed the environmental levels and body burdens of DLCs at EWRS and compared them with the levels reported to be associated with observable adverse effects to assess the health risks of DLC exposure at EWRS. In general, DLC concentrations at EWRS of many countries have been decreasing in recent years due to stricter regulations on e-waste recycling activities, but the contamination status is still severe. Comparison with available data from industrial sites and well-known highly DLC contaminated areas shows that high levels of DLCs derived from crude e-waste recycling processes lead to elevated body burdens. The DLC levels in human blood and breast milk at EWRS are higher than those reported in some epidemiological studies that are related to various health impacts. The estimated total daily intakes of DLCs for people in EWRS far exceed the WHO recommended total daily intake limit. It can be inferred that people living in EWRS with high DLC contamination have higher health risks. Therefore, more well-designed epidemiological studies are urgently needed to focus on the health effects of DLC pollution in EWRS. Continuous monitoring of the temporal trends of DLC levels in EWRS after actions is of highest importance.

Mapping polychlorinated dibenzo-p-dioxins/dibenzofurans in soils around Pugu municipal dump site in Dar es Salaam, Tanzania: Implications on dermal and soil ingestion exposure for people in the peripheral

Experimental data on the contribution of a dump site in Tanzania as a point source of the 17 possible congeners of PCDD/Fs to the environment is presented. Dry and wet season samples were collected around Pugu municipal dump site followed by GCxGC-TOFMS analysis. The dominant congeners were OctaCDD, 1,2,3,4,6,7,8-HepCDF; 1,2,3,4,6,7,8-HeptaCDD and 1,2,4,7-PeCDD. The concentrations of the congeners expressed as TEQ WHO₂₀₀₅ ranged from 11.69 to 48.97 pg/g with a mean of 29.44 pg/g for the dry season and TEQ WHO₂₀₀₅ 4.13-85.82 pg/g with a mean of 41.51 pg/g for the wet season. These levels were speculated high enough to accumulate in free-range chickens and cause harmful effects to humans that consumed them especially residents around Pugu dump site. Exposure of people to PCDD/Fs through dermal absorption and soil ingestion were estimated using the VLIER-HUMAAN Mathematical model. Exposure through dermal absorption was estimated to be 1.2 × 10^-4 and 9.8 × 10^-6 ng TEQ/kg day for children and adults respectively while through soil ingestion via consumption of contaminated foods and other sources was 0.0045 and 0.27 ng TEQ/kg day for children and adults respectively. These values however were well below the WHO tolerable daily intake. Generally, there was no significant variation for total PCDD/Fs in the dry and wet season (α = 0.08). Strong positive correlation (r = 0.94) between total PCDD/Fs and organic matter content was observed during the wet season.

A review of levels and profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans in different environmental media from China

This review provides a summary of the levels and profiles of PCDD/Fs throughout China, as reported in peer reviewed literatures since 1997. The literature shows that PCDD/Fs are widespread in various environmental media including air, water, sediment, and soil. PCDD/Fs concentrations in air were relatively low in most regions, with only a few areas considered polluted. Many studies reported seasonal trends, with higher and lower concentrations in winter and summer, respectively. We analyzed the factors affecting the concentrations of dioxins in air and summarized the causes of seasonal changes. As hydrophobic organic compounds, PCDD/Fs readily accumulate in sediments. The distribution of dioxins in sediment in Bohai Sea area was mainly introduced and the factors affecting concentrations of dioxins were studied. The levels of dioxins in soil in different regions varied greatly, with higher levels in areas close to pollution sources. We examined the dioxins concentrations in soil in places where the levels were very low (including the Tibet Plateau and other remote areas), contaminated areas, and other areas. Apart from the contaminated areas, the dioxins concentrations in soil were low. The results of the relatively low number of studies that have investigated PCDD/Fs in water have reported no obvious pollution in some waters, apart from Dongting Lake. PCDD/Fs levels across China are similar to those worldwide. Point sources, mainly related to local geographic, economic, and historical factors, were the most common source of contamination. E-waste dismantling and chemical production has the greatest impact on PCDD/Fs in different media.

Characterization and risk assessment of total suspended particles (TSP) and fine particles (PM2.5) in a rural transformational e-waste recycling region of Southern China

In 2016, total suspended particles (TSP) and fine particles (PM_2.5) were collected near four e-waste recycling parks in a region of Southern China. TSP and PM_2.5 levels and composition around these industrial activities were determined and the potential risks for human health due to the exposure to toxic elements contained on fine particles (PM_2.5) were evaluated. Levels of TSP and PM_2.5 were lower with advanced recycling methods than with small recycling e-waste workshops operating in the sampling region. The main trace elements in particles were Cu, Pb, and Ti, the same as those detected before the transition to advanced dismantling methods in e-waste recycling. Significantly higher levels of Cu, Pb, Sn, Te, Tl and NH₄⁺ in TSP and Cu and Te in PM_2.5 were found in e-waste recycling areas than in BG site. Taking Cu as the indicative element emitted from e-waste recycling activities, significant high positive correlations between Cu and W, and Cu and Te were found. These elements are present and can be released from electrical and electronical components during e-waste recycling processes. Exposure to elements for the population living near these e-waste recycling parks means carcinogenic risks above the acceptable threshold (>10^-5).

Air pollution and body burden of persistent organic pollutants at an electronic waste recycling area of China

This paper reviews the concentrations of persistent organic pollutants (POPs) in atmosphere of an electronic waste (e-waste) recycling town, Guiyu, in Southeast China, focusing on polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs). We assess the evidence for the association between air pollution and human body burden, to provide an indication of the severity of respiratory exposure. Compared with standards and available existing data for other areas, it clearly shows that four typical POPs, derived from recycling processes, lead to serious atmospheric pollution and heavy body burden. From published data, the estimated respiratory exposure doses of Guiyu adults and children, varied between 2.48-10.37 and 3.25-13.6 ng kg^-1 body weight (bw) day^-1 for PBDEs, 2.31-7.6 and 4.09-13.58 pg World Health Organization-Toxic Equivalent Quantity (WHO-TEQ) kg^-1 bw day^-1 for PCDD/Fs, 5.57 and 20.52 ng kg^-1 bw day^-1 for PCBs, and 8.59-50.01 and 31.64-184.14 ng kg^-1 bw day^-1 for PAHs, respectively. These results show that air pollution is more harmful to children. Furthermore, except for PBDEs, the hazard quotient (HQ) of the other three pollutants was rated more than 1 by respiratory exposure only, and all of them are at risk of carcinogenesis. So we speculate these pollutants enter the body mainly through air inhalation, making respiratory exposure may be more important than dietary exposure in the Guiyu e-waste recycling area. Effective management policies and remediation techniques are urgently needed to prevent the deterioration of ambient air quality in the e-waste recycling area.

National surveillance of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins/furans in soil in Taiwan

In this study, the polychlorinated dibenzo-p-dioxin/furan (PCDD/F) levels in 381 soil samples coming from different background areas (n = 238) and contaminated areas (n = 143) in Taiwan were investigated from 2011 to 2015 using high resolution gas chromatograph/high resolution mass spectrometry (HRGC/HRMS). The contaminated areas showed higher PCDD/F contamination as compared to the background areas (1230 vs 749 pg/g dry weight (dw)); 14.0 vs 6.25 pg WHO₂₀₀₅-TEQ/g dw). The lowest levels were recorded in the outlying islands (1.28 pg WHO₂₀₀₅-TEQ/g dw). PCDD/F congener distribution profiles in the background and contaminated areas as well as on the islands varied. OCDD was the dominant congener in almost all locations, including the northern background (87.7%) and central contaminated (74.2%) areas. Other dominant species included OCDF and 1,2,3,4,6,7,8-HpCDD. Levels of PCDD/F-TEQs in Taiwanese soils, including the background areas, were higher than in some developing countries and regions with global background levels due to high industrialization except for the contaminated areas. Geographic differences in dioxin-contaminated soils were also shown in this study. Higher soil dioxin-TEQs were observed in locations with high populations and population densities. Despite the limitations, the economic status of Taiwan represented by the annual averaged family income (AAFI) was positively correlated to soil dioxin-TEQs.

Airborne PCDD/Fs in two e-waste recycling regions after stricter environmental regulations

Since the 2010s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) after stricter environmental regulations. PM_2.5 and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32pgTEQ/(kg•day), which far exceeded the tolerable daily intake (TDI) limit (1-4pgTEQ/(kg•day). Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.

Occurrence, profiles, and toxic equivalents of chlorinated and brominated polycyclic aromatic hydrocarbons in E-waste open burning soils

We conducted this study to assess the occurrence, profiles, and toxicity of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) and brominated polycyclic aromatic hydrocarbons (Br-PAHs) in e-waste open burning soils (EOBS). In this study, concentrations of 15 PAHs, 26 Cl-PAHs and 14 Br-PAHs were analyzed in EOBS samples. We found that e-waste open burning is an important emission source of Cl-PAHs and Br-PAHs as well as PAHs. Concentrations of total Cl-PAHs and Br-PAHs in e-waste open burning soil samples ranged from 21 to 2800 ng/g and from 5.8 to 520 ng/g, respectively. Compared with previous studies, the mean of total Cl-PAH concentrations of the EOBS samples in this study was higher than that of electronic shredder waste, that of bottom ash, and comparable to fly ash from waste incinerators in Korea and Japan. The mean of total Br-PAH concentrations of the EOBS samples was generally three to four orders of magnitude higher than those in incinerator bottom ash and comparable to incinerator fly ash, although the number of Br-PAH congeners measured differed among studies. We also found that the Cl-PAH and Br-PAH profiles were similar among all e-waste open burning soil samples but differed from those in waste incinerator fly ash. The profiles and principal component analysis results suggested a unique mechanism of Cl-PAH and Br-PAH formation in EOBS. In addition, the Cl-PAHs and Br-PAHs showed high toxicities equivalent to PCDD/Fs measured in same EOBS samples when calculated based on their relative potencies to benzo[a]pyrene. Along with chlorinated and brominated dioxins and PAHs, Cl-PAHs and Br-PAHs are important environmental pollutants to investigate in EOBS.

Environmental pollution of electronic waste recycling in India: A critical review

The rapid growth of the production of electrical and electronic products has meant an equally rapid growth in the amount of electronic waste (e-waste), much of which is illegally imported to India, for disposal presenting a serious environmental challenge. The environmental impact during e-waste recycling was investigated and metal as well as other pollutants [e.g. polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs)] were found in excessive levels in soil, water and other habitats. The most e-waste is dealt with as general or crudely often by open burning, acid baths, with recovery of only a few materials of value. As resulted of these process; dioxins, furans, and heavy metals are released and harmful to the surrounding environment, engaged workers, and also residents inhabiting near the sites. The informal e-waste sectors are growing rapidly in the developing countries over than in the developed countries because of cheapest labor cost and week legislations systems. It has been confirmed that contaminates are moving through the food chain via root plant translocation system, to the human body thereby threatening human health. We have suggested some possible solution toward in which plants and microbes combine to remediate highly contaminated sites.