Dietary exposure to PCBs based on food consumption survey and food basket analysis at Taizhou, China--the world's major site for recycling transformers

The levels of PCBs in different types of food (fish, shellfish, meat, rice, vegetables, and fruits) were analyzed to determine the dietary intake of 37 PCBs for local residents and e-waste workers (all lactating mothers) at Taizhou (China), a major electronic waste scrapping center, in particular for recycling transformers. The exposure to PCBs through dietary intake in Taizhou was estimated at 92.79 ngkg(-1)d(-1), contributed by consumption of freshwater fish (28%), rice (28%), meat (17%), shellfish (9%), vegetables (8%), egg (4%) and marine fish (2%). With regards to WHO-PCB-TEQ values, freshwater fish (40%), shellfish (24%), duck liver (18%) and rice (12%) were the main dietary sources with total daily intake (9.78 pg WHO-PCB-TEQ kg(-1)d(-1)), exceeding the FAO/WHO Tolerable Daily Intake (70 pg TEQkg(-1)body(-1)wt(-1)month(-1)).     

Root porosity and radial oxygen loss related to arsenic tolerance and uptake in wetland plants

The rates of radial oxygen loss (ROL), root porosity, concentrations of arsenic (As), iron (Fe) and manganese (Mn) in shoot and root tissues and on root surfaces, As tolerances, and their relationships in different wetland plants were investigated based on a hydroponic experiment (control, 0.8, 1.6 mg As L⁻¹) and a soil pot trail (control, 60 mg As kg⁻¹). The results revealed that wetland plants showed great differences in root porosity (9-64%), rates of ROL (55-1750 mmo1 O₂ kg⁻¹ root d.w. d⁻¹), As uptake (e.g., 8.8-151 mg kg⁻¹ in shoots in 0.8 mg As L⁻¹ treatment), translocation factor (2.1-47% in 0.8 mg As L⁻¹) and tolerance (29-106% in 0.8 mg As L⁻¹). Wetland plants with higher rates of ROL and root porosity tended to form more Fe/Mn plaque, possess higher As tolerance, higher concentrations of As on root surfaces and a lower As translocation factor so decreasing As toxicity.     

Chemical speciation and phytoavailability of Zn, Cu, Ni and Cd in soil amended with fly ash-stabilized sewage sludge

A sequential extraction method was used to determine chemical forms of Cu, Zn, Ni and Cd in fly ash-stabilized sludge. A loamy acid soil amended with fly ash-stabilized sludge was used to grow corn under greenhouse conditions. Sewage sludge amended with coal fly ash can reduce the availability of Cu, Zn, Ni and Cd in the sludge. Increasing fly ash amendment rate significantly reduced DTPA-extractable Cu, Zn, Ni and Cd concentrations. Percentages of Cu, Zn and Ni in residual fraction increased with an increase in fly ash amendment rates. Majority of Cu was associated with organic form, but Zn and Ni were associated with Fe-Mn oxide and residual forms. Addition of ash-amended sludge to soil significantly increased dry mass of corn. With coal fly ash amendment rate increasing, concentrations of Zn and Cu in shoot tissues of corn decreased significantly, but concentrations of Cd and Ni did not change significantly. Significant correlations were found between concentrations of Cu and Zn in corn shoot and oxide and total Cu fractions, and all chemical fractions of Zn in fly ash-stabilized sludge, respectively. Hence, ash amendment significantly reduced the availability of heavy metals by chemical modification of their chemical speciation into less available forms.     

Toxicity evaluation of sewage sludges in Hong Kong.

Anaerobically digested sewage sludges collected from four wastewater treatment plants located in Sha Tin, Tai Po, Yuen Long, and Shek Wu Hui in Hong Kong were subjected to chemical characterization and toxicity testing to provide preliminary assessment of their suitability for land application. All sewage sludges were slightly alkaline with pH range of 8.3-8.7. Electrical conductivity (EC; 0.69 dS m(-1)) and soluble NH4-N content (996 mg kg(-1)) of sewage sludge from Yuen Long were lower than that of other plants. Concentrations of heavy metals were determined as total, extractable, and water-soluble fraction using mixed acid digestion, DTPA (pH 7.3), and distilled water, respectively. Yuen Long sludge was most polluted with Zn and Cr higher than the pollutant concentration limits listed in Part 503 of USEPA, owing to the effluent coming from the tannery industry. High concentration of Ni was found in sludge from Sha Tin that originated mainly from the electroplating industry. DTPA-extractable Zn contents were high in sludges from Yuen Long (1247 mg kg(-1)) and Shek Wu Hui (892 mg kg(-1)), while 3.7 mg kg(-1) of DTPA-extractable Cr was found in Yuen Long sludge. Metal speciation of sludges showed that Pb was major in residual phase while Cu, Cr, and Ni in organic and residual phases, and Zn did not show any dominant chemical phase. The sludge extracts did not exert significant adverse effect on seed germination of Brassica chinensis (Chinese cabbage), but Yuen Long sludge caused a reduction in root growth. In view of its lower EC and soluble ammonia contents, the high concentration of Zn and Cr in Yuen Long sludge would likely be responsible for this adverse effect on root growth. Therefore, Yuen Long sludge would likely have a more serious impact on soil quality and plant growth as compared to other sludges. This would require further verification from greenhouse and field experiments.     

Uptake and accumulation of arsenic by 11 Pteris taxa from southern China

A field survey was conducted at a deserted arsenic (As) mine in Guangxi Province, China to explore new potential As hyperaccumulators. In addition, young plants of 11 Pteris taxa were grown in glasshouse conditions for 12 weeks on As-amended soils with 0, 50 and 200 mg As kg(-1). Results of the field survey showed that the fern Pteris fauriei accumulated over 1000 mg As kg(-1) in its fronds. Of the 11 Pteris taxa, Pteris aspericaulis, Pteris cretica var. nervosa, P. fauriei, Pteris multifida, P. multifida f. serrulata, and Pteris oshimensis were all found to hyperaccumulate As in addition to P. cretica 'Albo-Lineata' and Pteris vittata (already reported as As hyperaccumulators). However, Pteris ensiformis, Pteris semipinnata and Pteris setuloso-costulata showed no evidence of As hyperaccumulation. Results also revealed a constitutive property of As hyperaccumulation in different populations of P. cretica var. nervosa, P. multifida, P. oshimensis and P. vittata.     

Trace metal contamination of sediments in an e-waste processing village in China

This study examined trace metal contamination of sediments in Guiyu, China where primitive e-waste processing activities have been carried out. It was found that some river sediments in Guiyu were contaminated with Cd (n.d.-10.3mg/kg), Cu (17.0-4540mg/kg), Ni (12.4-543mg/kg), Pb (28.6-590mg/kg), and Zn (51.3-324mg/kg). The (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of the Pb-contaminated sediments of Lianjiang (1.1787+/-0.0057 and 2.4531+/-0.0095, respectively) were lower than those of Nanyang River (1.1996+/-0.0059 and 2.4855+/-0.0082, respectively), indicating a significant input of non-indigenous Pb with low (206)Pb/(207)Pb and (208)Pb/(207)Pb ratios. Copper, Pb and Zn in the non-residual fractions noticeably increased in the contaminated sediments compared to those in the uncontaminated sediments. A genuine concern is associated with potential transport of the contaminated sediments downstream and enhanced solubility and mobility of trace metals in the non-residual fractions.     

Evidence of excessive releases of metals from primitive e-waste processing in Guiyu, China

Guiyu, China is infamous for its involvement in primitive e-waste processing and recycling activities. Freshwater samples were collected in and outside of Guiyu for dissolved metal analysis. It was found that dissolved metal concentrations were higher in Lianjiang and Nanyang River within Guiyu than the reservoir outside of Guiyu. Lianjiang was enriched with dissolved As, Cr, Li, Mo, Sb and Se, while Nanyang River had elevated dissolved Ag, Be, Cd, Co, Cu, Ni, Pb and Zn. Temporal distributions of the metals suggested recent discharges of metals attributable to a strong acid leaching operation of e-waste, where dissolved Ag, Cd, Cu and Ni (0.344+/-0.014, 0.547+/-0.074, 87.6+/-3.0 and 93.0+/-1.4 microg/L, respectively) were significantly elevated. Pb isotopic composition of dissolved Pb confirmed that more than one non-indigenous Pb were present in Lianjiang and Nanyang River. In summary, it was evident that the riverine environment of Guiyu was heavily impacted by e-waste related activities.     

The geomorphology and ecosystem service economic value baselines of tributary watersheds in Malaysia

Environment, Development and Sustainability - This study presents how a cluster of tributary watersheds was evaluated for geomorphology and ecosystem service economic value baselines. Tributary...     

Stability of the conjugated species of environmental phenols and parabens in human serum

In humans, the metabolism of environmental phenols may include the formation of conjugated species (e.g., glucuronides and sulfates), but the free species—not the conjugated forms—are considered biologically active. Therefore, information on the concentration of these free species in blood or urine could be helpful for risk assessment. Because conjugates could hydrolyze to their corresponding free forms during collection, handling, and storage of biological specimens, information on the temporal stability of the conjugates is of interest. Previously, we reported the temporal stability of urinary conjugates of several environmental phenols, but data on the stability of phenols' conjugated species in serum, albeit critical if concentrations of free and conjugated species are compared, are largely unknown. In the present study, we investigate the stability of the conjugates of four phenols—bisphenol A, benzophenone-3, triclosan, and 2,5-dichlorophenol—and two parabens—methyl paraben and propyl paraben—in 16 human serum samples for 30 days at above-freezing temperature storage conditions (4 °C, room temperature, and 37 °C). These conditions reflect the worst-case scenarios that could occur during the short-term storage of biological samples before their long-term storage at controlled subfreezing temperatures. We found that the percentage of the conjugated species of the four detected compounds (2,5-dichlorophenol, triclosan, and methyl and propyl parabens) in these serum specimens even when stored at 37 °C for at least 30 days did not vary significantly. These preliminary data suggest that the phenols' serum conjugates appear to be more stable than their corresponding urinary conjugates, some of which started to hydrolyze within 24 h under similar storage conditions. The reported stability of these conjugated species in human serum also suggests that the free species are unlikely to have resulted from the hydrolysis of their corresponding conjugates. This information could be important for interpreting the low concentrations of free phenol species detected in serum samples of nonoccupationally exposed populations. To our knowledge, this is the first study to report on the stability of conjugated species in serum, and as such requires replication.     

Mutagenicity, genotoxicity and carcinogenic risk assessment of indoor dust from three major cities around the Pearl River Delta

The mutagenicity and genotoxicity of workplace dust including commercial office, secondary school, shopping mall, hospital, electronics factory and manufacturing plant in Hong Kong and settled house dust from Hong Kong, Shenzhen and Guangzhou were measured. Results indicated that indoor dust contained both frameshift and base pair substitution mutagens. Dust from manufacturing plant showed highest mutagenic potency on TA98±S9 and TA100±S9 activation, whereas, electronics factory showed highest genotoxicity with and without S9 activation. TA100 (-S9) mutagenic potency was significantly correlated with genotoxicity expressed as SOSIP (-S9) of workplace dust (r(2)=0.37, p<0.01). The total PAHs concentration of settled house dust from PRD ranged from 1.63 to 29.2μg/g. Linear regression analyses indicated that the PAHs likely accounted for about 45% of the TA98 with S9 mutagenic activity of workplace dust. TA98 (-S9) mutagenicity (r(2)=0.27, p<0.05) and SOSIP (-S9) of house dust (r(2)=0.41, p<0.01) were both significantly correlated with the number of inhabitants in the house. To achieve a more accurate cancer risk assessment, the oral bioaccessibility of B(a)A, Chry, B(b+k)F, B(a)P, D(ah)A and I(cd)P in different dust ranging from 1.3% to 17% was taken into account. Risk assessments indicated that about 26% of house dust samples resulted in unacceptable cancer risk (>1×10(-6)) for preschool children.