Quantification and characterization of recovered materials in the cycle of the informal household electronic waste dismantling in Buriram province, Thailand: A challenge towards sustainable management and circular economy.

The numerous amount of electronic waste (e-waste) has not been managed effectively resulting informal dismantling sites are being expanded in Thailand. The government attempts to improve the efficiency of an integrated e-waste management system, but baseline data of e-waste stream in informal sectors are insufficient. This research aimed to investigate the inflow and outflow of the materials throughout the informal e-waste dismantling processes at the well-known second-largest community in Buriram province during 2017-2018. To describe the quantities of dismantled materials, a material flow analysis was performed. The overall amount of e-waste taken to the community was estimated to be in the range of 1593-12,943 tonnes year-1. Valuable materials could be recovered at more than 90% (by mass) from fans, refrigerators, washing machines, microwaves and air conditioners. The amount of e-waste residue that the local administrative organization had to handle was up to 1144 tonnes year-1. The quantitative data retrieved from this study could provide a satisfactory equation for estimating the amount of separated valuable and non-valuable materials. Recyclable materials from dismantling have an economic incentive, e-waste dismantlers in a small and large household group that can earn approximately 798 and 1262 USD month-1 income, respectively. The notable e-waste characterization and quantification of recovered materials would be useful for improving the potential circular flow of e-waste in Thailand.

Health risk assessment of airborne Cd, Cu, Ni and Pb for electronic waste dismantling workers in Buriram Province, Thailand.

This study aimed to assess the risk levels of electronic waste dismantling workers in Buriram Province from exposure to cadmium (Cd), copper (Cu), nickel (Ni) and lead (Pb) via inhalation. The study area was Dang-Yai subdistrict, Baan Mai Chaiyapot district, Buriram province, Thailand. The sampling of particulate matter of less than 10 µm (PM10) was performed from 8 a.m. to 5 p.m. each day between 14th and 18th December 2015 inclusively. The PM10 was collected on a glass fiber filter using a nylon cyclone connected to a personal air pump with an air flow rate of 1.7 L/min. The samples were extracted by a microwave digester, and the metals were analyzed by inductively coupled plasma optical emission spectrometry. The average exposure concentrations of the workers to Cd, Cu, Ni and Pb were 0.0073 ±â€¯0.0084, 0.2083 ±â€¯0.6362, 0.3499 ±â€¯0.3738 and 0.1297 ±â€¯0.1746 µg/m3, respectively. The hazard quotients (HQs) of the non-carcinogenic effect of Cd, Cu and Ni, had 95% confidence intervals (CIs) of 0.067-0.167, 0.012-0.018 and 0.333-0.913, respectively. All HQs were less than 1, which indicated that there was no concern of increased non-carcinogenic health risks. The lifetime cancer risk (70 y) of the workers estimated for a 30-y exposure period showed 95% CIs of 7.55-18.6 × 10-5, 1.69-4.66 × 10-5 and 3.26-9.66 × 10-7 for Cd, Ni and Pb, respectively. Thus, the possible cancer risk levels from exposure to Cd and Ni for these workers were higher than the acceptable criterion of 10-6, which indicated that the workers have the potential to get cancer from electronic waste dismantling, due to cadmium and nickel exposure.

Relationship between PM10 and PM2.5 levels in high-traffic area determined using path analysis and linear regression.

The objective of this study was to determine the relationship between PM10 and PM2.5 levels as related to meteorological conditions and traffic flow using both a linear regression analysis and a path analysis. The Particulate matter (PM) samples were collected from Sukhumvit road, Bangkok, Thailand, at both open (104 samples) and covered (92 samples) areas along the road. Fifteen percent of all samples were separated before the statistical models were run and used for model validation. The results from the path analysis were more elaborate than those from the linear regression, thus indicating that meteorological conditions had a direct effect on the particulate levels and that the effects of traffic flow were more variable in open areas. The model also indicated that meteorological conditions had an indirect effect and that traffic flow had a direct effect on particulate levels in covered areas. The model validation results indicated that for open areas, the R2 values were not very different between the path analysis and the linear regression model, but that the path analysis was more accurate than the linear regression model at very low PM concentrations. At high PM concentrations, the path analysis model also had a better fit than did the linear regression, so the predictions from the path analysis model were more accurate than those from the linear regression.

AMBIENT PM10 AND PM2.5 CONCENTRATIONS AT DIFFERENT HIGH TRAFFIC-RELATED STREET CONFIGURATIONS IN BANGKOK, THAILAND.

This study investigated the potential exposure levels of PM10 and PM2.5 at two different road configuration sites in Bangkok, Thailand: covered and open roadside areas. One hundred samples were collected together with the meteorological data: temperature, relative humidity, wind speeds, and solar radiation. Spearman rank correlation was used to analyze the relationships between these factors, and PM10 and PM2.5 levels at different roadside areas. The PM10 and PM2.5 levels at the covered area were 1.72 and 1.60 times more than those levels at open area were. The mean levels were found to be 154.59 and 94.42 µg/m³ at the covered areas, and 89.43 and 58.69 µg/m³ at the open areas. These results suggested that a higher potential risk for workers, such as street vendors, was the exposure to particulate matters at the covered areas compared to open areas. Wind speeds and relative humidity were significantly negative-related influencing factors on PM10 and PM2.5 levels at the open area, but not significantly related for the covered areas.

Vitamin D3 regulates PM-driven primary human neutrophil inflammatory responses.

Recent evidence has demonstrated that both acute and chronic exposure to particulate air pollution are risk factors for respiratory tract infections and increased mortality from sepsis. There is therefore an urgent need to establish the impact of ambient particulate matter (PM) on innate immune cells and to establish potential strategies to mitigate against adverse effects. PM has previously been reported to have potential adverse effects on neutrophil function. In the present study, we investigated the impact of standard urban PM (SRM1648a, NIST) and PM2.5 collected from Chiang Mai, Thailand, on human peripheral blood neutrophil functions, including LPS-induced migration, IL-8 production, and bacterial killing. Both NIST and the PM2.5, being collected in Chiang Mai, Thailand, increased IL-8 production, but reduced CXCR2 expression and migration of human primary neutrophils stimulated with Escherichia coli LPS. Moreover, PM-pretreated neutrophils from vitamin D-insufficient participants showed reduced E. coli-killing activity. Furthermore, in vitro vitamin D3 supplementation attenuated IL-8 production and improved bacterial killing by cells from vitamin D-insufficient participants. Our findings suggest that provision of vitamin D to individuals with insufficiency may attenuate adverse acute neutrophilic responses to ambient PM.

Standardized Thunbergia laurifolia Extract Inhibits PM2.5-Induced Oxidative Stress by Regulating p62-KEAP1-NRF2 Signaling Pathway.

BACKGROUND/AIM: Fine particulate matter (PM2.5) in air pollution causes skin damage through the induction of oxidative stress in the epidermis. Antioxidants help counteract cellular oxidant species and maintain cell homeostasis. This study aimed to examine the protective effect of standardized ethanolic extract of Thunbergia laurifolia leaves on PM2.5-mediated oxidative stress in epidermal keratinocytes. MATERIALS AND METHODS: The extract was standardized with rosmarinic acid. Effects of standardized T. laurifolia extract (STLE) (0-400 µg/ml) and PM2.5 (0-32 µg/ml) on cell viability after 24 h of treatment were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. PM2.5 (0-32 µg/ml) induction of intracellular reactive oxygen species (ROS) at 6 h was monitored using 2',7'-dichlorodihydrofluorescein diacetate. Cells were co-treated for 6 h with PM2.5 (32 µg/ml) and STLE (25-100 µg/ml) and monitored for oxidative stress inhibition. Proteins related to cellular antioxidant defense system were examined by western blot analysis, after co-treatment and STLE treatment for 6 h and 24 h, respectively. Nuclear expression of nuclear factor erythroid 2-related factor (NRF2) and p62 were determined by immunofluorescence after co-treatment of 6 h. RESULTS: PM2.5 (32 µg/ml) remarkably induced ROS production within 6 h. The co-treatment dramatically inhibited PM2.5-induced oxidative stress at 6 h. In addition, STLE enhanced cellular defense system by increasing the levels of p62, NRF2 and superoxide dismutase 1 proteins. STLE stimulated nuclear localization and function of NRF2 and p62 proteins, while suppressing Kelch-like ECH-associated protein 1. CONCLUSION: STLE exhibits promising natural antioxidant activity against oxidative stress induced by PM2.5 in keratinocytes.

Ecological risk assessment of arsenic, cadmium, copper, and lead contamination in soil in e-waste separating household area, Buriram province, Thailand.

This study aimed to determine the arsenic (As), copper (Cu), cadmium (Cd), and lead (Pb) concentrations in the soil at e-waste separating houses in Buriram province. Soil samples were collected from five e-waste separating and five non-separating houses in each of two neighboring communities and from six reference houses located approximately 4 km away from the e-waste community. At each selected house, the surface (0-15-cm depth) and the subsurface (15-30-cm depths) soils were taken to be digested by a microwave digester and then analyzed for the heavy metal contents by atomic absorption spectrophotometry. The As, Pb, and Cd levels in the e-waste separating sites ranged from < 0.012 to 1.380, 0.110 to 15.283, and < 0.014 to 0.284 mg/kg, respectively, which were not in excess of the Thai standard level for residential soil (As = 3.9, Pb = 400, and Cd = 37 mg/kg), while Cu ranged from 1.180 to 380.413 mg/kg and exceeded the intervention value (190 mg/kg) of contaminated soil at three sites from a total of ten sampling sites. The physical e-waste dismantling activity enhanced the As, Cd, and Cu contamination levels in the surface soils. Ecological risk assessment revealed that the risk posed by the heavy metals in soils was higher at the e-waste separating houses than those at the non-separating sites and was mainly attributed to the levels of Cu > As > Cd > Pb for the surface soils and Cd > Cu > As > Pb for the subsurface soil. The association of the heavy metal soil levels with e-waste activity showed that if the e-waste activities were continuously operated, the As and Cu levels in the surface soil were more likely to exceed those levels in the reference houses. A good procedure for e-waste dismantling is necessary to be developed and implemented to prevent soil contamination and other related environmental problems.

Isovitexin Increases Stem Cell Properties and Protects Against PM2.5 in Keratinocytes.

Background/Aim: Fine airborne particles of Particular Matter of less than 2.5 micrometers (PM 2.5 ) have been recognized as a dominant air contamination causing critical health concerns. Herein, we determined whether isovitexin, a natural plant-derived compound could protect PM2.5-mediated oxidative stress and induce stemness in epidermal cells. Materials and Methods: Cell viability was detected by the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. Reactive oxygen species (ROS) were determined by flow cytometry with 2',7'-dichlorofluorescin diacetate (DCFH-DA). Protein hallmarks of stem cells were examined by western blot analysis. Results: PM2.5 treatment for 30 min increased the levels of intracellular ROS. Pre-treatment of cells with 10-50 µM of isovitexin dramatically inhibited the ROS induced by PM2.5. Antioxidant efficacy of isovitexin was also determined by the ROS scavenging activity against 2,2-diphenyl-2-picrylhydrazyl (DPPH), ABTS and superoxide anion radicals. In addition, we found that isovitexin enhanced the stem cell properties of keratinocytes, indicated by the significant increase in the levels of stem cell proteins. Conclusion: Isovitexin can be potentially used as an effective compound for preventing skin damage.