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MicroRNAs (miRNAs) play important roles in plant response to Cd stress. In our previous study, we observed significant differences in the expression levels of IamiR-4-3p between high-Cd and low-Cd cultivars of water spinach. The function of IamiR-4-3p was investigated by using wild type Arabidopsis (WT), Arabidopsis transfected with empty vector pCambia1302 (CK), and Arabidopsis transfected with IamiR-4-3p + vector pCambia1302 (p35S::miR-4-3p) in this study. In p35S::miR-4-3p Arabidopsis, the expression levels of GST3 and AWPM19-like were reduced by 20% and 24%. Under Cd treatment, higher root and shoot Cd concentrations were detected in the transgenic p35S::miR-4-3p Arabidopsis. MDA and H

To explore the possible roles of metallothioneins (MTs) played in cadmium (Cd) accumulation of water spinach, three IaMT genes, IaMT1, IaMT2 and IaMT3 in a high-shoot-Cd (T308) and a low-shoot-Cd accumulation cultivar (QLQ) were cloned, characterized, and quantitated. Gene expression analysis suggested that the expression of the IaMTs was differentially regulated by Cd stress in different cultivars, and T308 showed higher MTs expression overall. Furthermore, only shoot IaMT3 expression was cultivar dependent among the three IaMTs. Antioxidant analysis showed that the high production of IaMTs in T308 should be associated with its high oxidation resistance. The role of IaMTs in protecting against Cd toxicity was demonstrated in vitro via recombinant E. coli strains. The results showed that IaMT1 correlated with neither Cd tolerance nor Cd accumulation of E. coli, while IaMT2 conferred Cd tolerance in E. coli, IaMT2 and IaMT3 increased Cd accumulation in E. coli. These findings help to clarify the roles of IaMTs in Cd accumulation, and increase our understanding of the cultivar-dependent Cd accumulation in water spinach.

Breeding for pollution-safe cultivars (PSCs) can reduce pollutant accumulation in crops. However, the PSC breeding would face the risk of nutritional quality reduction, which is usually ignored in conventional breeding programs targeting to increase crop yield or nutritional quality. Thus, the doubt whether the risk would exist has to be clarified for supporting the PSC breeding. In the present study, a newly bred Cd/Pb-PSC of water spinach (Ipomoea aquatic Forsk.) and its parents (QLQ with low-Cd/Pb accumulation ability and T308 with high yield) of water spinach were employed to clarify the above-mentioned issue. Yields, and concentrations of Cd, Pb, nitrite, and organic and inorganic nutrients in shoots of the three experimental lines were determined. There were no significant differences in Cd/Pb concentration between the new PSC and QLQ, in nitrite content between the new PSC and its two parents and in yield between the new PSC and T308. It is decisively significant that shoot concentrations of organic and inorganic nutrients in the Cd/Pb-PSC were as high as those in one of its parents. It is affirmed that the breeding operations (crossing and consequently continuous selfing) for lowering Cd/Pb accumulation capacity of water spinach would not lower the nutritional values of the obtained Cd/Pb-PSCs from the breeding, which should be a pillar that supports the feasibility to minimize Cd/Pb pollution in vegetables using PSC-breeding method.

Brominated flame retardants (BFRs) and Dechlorane Plus (DP) were measured in both human hair and paired serum samples from a cohort of university students in South China. Segmental analysis was conducted to explore gender difference and the relationships between the hair and serum. The concentrations of total PBDEs in the hair and serum samples were in a range of 0.28-34.1ng/g dry weight (dw) and 0.16-156ng/g lipid weight (lw), respectively. Concentrations of ∑DPs (sum of the syn-DP and anti-DP isomers) in all hair samples ranged from nd-5.45ng/g dry weight. Concentrations of most PBDEs and decabromodiphenylethane (DBDPE) in distal segments (5-10cm from the scalp) were higher than those in the proximal segments (0-5cm from the scalp) (t-test, p < 0.05), which could be due to the longer exposure time of distal segments. The proximal segments exhibited a unique congener profile, more close to that in the serum rather than the distal segments of hair. An obvious gender difference was found in the levels of ∑PBDEs using integrated hair samples, while the difference disappeared when considering alone the proximal segments of hair (0-5cm from scalp) for both genders. This paper provides supplement to the current knowledge on sources of BFRs and DPs in hair and declares the importance of segmental analysis.

Airway surface liquid (ASL) is one of the key factors affecting the respiratory system's physiological function. Abnormal ASL secretion can increase the incidence of various respiratory diseases. Lipopolysaccharide (LPS) stimulation can damage the airway epithelial barrier, affect the concentration of ASL contents, and down-regulate ion channel expression, which in turn causes abnormal ASL secretion. Naringenin, which exists in many Citrus foods, has the ability to promote airway surface liquid secretion. This work is designed to investigate the regulatory mechanism of naringenin on LPS-induced abnormal ASL secretion. The effects of naringenin and LPS on the viability of Calu-3 cells were measured by CellTiter 96® AQueous One Solution Cell Proliferation Assay (MTS). ASL secretion volume was measured by a micropipette on air–liquid interface cultured cells. The concentration of Cl−, Na+, lysozyme, and total protein in ASL were respectively measured by assay kits. The mRNA expressions were determined by quantitative real-time polymerase chain reaction, and proteins were measured by enzyme-linked immunosorbent assay. The results indicated that LPS could affect ASL secretion and regulate cystic fibrosis transmembrane conductance regulator (CFTR), aquaporin 1 (AQP1) and aquaporin 5 (AQP5) expression. Naringenin had the ability to regulate the ASL secretion by increasing secretion volume, and Cl− and Na+ concentrations, reducing lysozyme and total protein content, and regulating CFTR, AQP1, and AQP5 expression. This study indicated that naringenin had regulating effects to attenuate LPS-induced abnormal ASL secretion.

The concentrations of several organic contaminants (OCs) and heavy metals were measured in indoor dust from e-waste recycling, rural, and urban areas in South China to illustrate the spatial characteristics of these pollutants and to further evaluate human exposure risks. The median concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), and dechlorane plus (DPs) were 38.6-3560, 2360-30,100, 665-2720, and 19.5-1860ng/g, while the median concentrations of Cd, Pb, Cu, Cr, and Zn were 2.46-40.4, 206-1380, 217- 1200, 25.3-134, and 176-212μg/g in indoor dust. The levels of all pollutants, except Zn, in dust from the e-waste recycling area were significantly higher than those from the other areas. Cd, Pb, and most OCs exhibited similar pollution patterns in the three areas, indicating that e-waste recycling activities are the major pollution source. In contrast, Cu, Cr, Zn, and penta-BDE are likely derived from household products in the rural and urban areas. The highest estimated daily intakes (EDIs) of PCBs, PBDEs, DBDPE, and DPs were 0.15-163, 3.97-1470, 1.26-169, and 0.11-134ng/kg bw/day for toddlers and adults. The highest EDIs of BDE 209 and Pb in toddlers in the e-waste recycling area were 16% and 18 times higher than the reference doses, indicating the high exposure risk of these pollutants in the e-waste recycling area.

Heavy metals have serious health consequences and ecosystem impacts. A pot experiment was conducted to investigate the variation of cadmium (Cd) uptake and accumulation among 40 cultivars of radish (Raphanus sativus L.) at three Cd levels, including 0.31 (T1), 0.83 (T2), and 1.13 (T3) mg kg−1. Most of the tested cultivars had higher taproot biomass in the T3 treatment when compared to those in the T1 treatment, indicating a Cd stress-induced growth in radish. Taproot Cd concentrations in 95 and 5% of the tested cultivars were lower than 0.1 mg kg−1 (fresh weight, FW) in the T1 and T2 treatments, respectively; however, there was no cultivar suitable for safe consumption in the T3 treatment. Radish production showed potential risk of Cd pollution as high as some leafy vegetables when grown in the soils where Cd concentration exceeded 0.8 mg kg−1. When compared with Chinese heat-resisting or imported cultivars, Chinese common cultivars had significantly higher taproot Cd concentrations. Three low-Cd cultivars and five high-Cd cultivars were identified. Taproot Cd concentrations showed significant correlations between any two of the three treatments (p < 0.01), suggesting that Cd accumulation in taproot of radish was genotype-dependent.

Cadmium (Cd) is a highly toxic heavy metal and has spread widely in the environment in recent decades. This review summarizes current knowledge about Cd contamination of leafy vegetables, its toxicity, exposure, health risks, and approaches to reducing its toxicity in humans. Leafy vegetable consumption has been identified as a dominant exposure pathway of Cd in the human body. An overview of Cd pollution in leafy vegetables as well as the main sources of Cd is given. Notable estimated daily intakes and health risks of Cd exposure through vegetable consumption for humans are revealed in occupational exposure areas and even in some reference areas. Vegetable consumption is one of the most significant sources of exposure to Cd, particularly in occupational exposure regions. Therefore, numerous approaches have been developed to minimize the accumulation of Cd in leafy vegetables, among which the breeding of Cd pollution-safe cultivars is one of the most effective tools. Furthermore, dietary supplements from leafy vegetables perform positive roles in alleviating Cd toxicity in humans with regard to the effects of essential mineral elements, vitamins and phytochemicals taken into the human body via leafy vegetable consumption.

Cultivar-dependent cadmium (Cd) accumulation was principal in developing Cd-pollution safe cultivars (PSCs). Proteins related to different Cd accumulations of the low-Cd-accumulating (SJ19) and high-Cd-accumulating (CX4) cultivars were investigated by iTRAQ analysis. Higher Cd bioaccumulation factors and translocation factor in CX4 than in SJ19 were consistent with the cultivar-dependent Cd accumulations. The Cd uptake was promoted in CX4 due to its higher expression of Cd-binding proteins and the lower expression of Cd-efflux proteins in roots. What's more, significantly elevated thiol groups (PC2 and PC3) in CX4 under Cd stress might contribute to the high Cd accumulation in roots and the root-to-shoot translocation of Cd-PC complex. Up-regulated proteins involved in cellulose biosynthesis and pectin de-esterification in SJ19 enhanced the Cd sequestration of root cell walls, which was considered as the predominant strategy for reducing Cd accumulation in shoots. The present study provided novel insights in the cultivar-dependent Cd accumulation in shoots of B. parachinensis.

Brassica parachinensis L., a daily consumed leaf vegetable, is a high-Cd accumulator that substantially threatens human health. Screening and breeding Cd pollution-safe cultivars (Cd-PSCs) of crops is a low-cost strategy to restrict human Cd intake from contaminated soils via the food chain. However, little is known about the molecular mechanisms underlying the low-Cd-accumulating traits of B. parachinensis Cd-PSCs. In the current study, we analyzed the transcriptomes of the Cd-treated (5 μM) roots and shoots of a low-Cd-accumulating cultivar (SJ19) and a high-Cd-accumulating cultivar (CX4) of B. parachinensis to reveal the molecular mechanisms in response to Cd stress. Compared to CX4, many pathways involved in carbohydrate and amino acid metabolisms were exclusively up-regulated in SJ19 roots upon exposure to low Cd concentrations, which may produce more energy and metabolites for Cd detoxification. Antioxidant enzymes in the peroxisome were up-regulated in both SJ19 and CX4 roots in response to Cd, while glutathione biosynthesis was only activated in SJ19 roots. In SJ19 shoots, pathways of photosynthesis and cell growth were activated to mitigate Cd-induced damages. Furthermore, Cd transport genes, such as MTP1, HMA3 and CAX family genes, were highly induced by Cd stress in SJ19 roots in accordance with the high Cd concentration in roots, while genes involved in root-to-shoot Cd translocation such as FRD3 and CESA3 were suppressed, which may contribute to the low Cd concertation in edible part of SJ19. Our study provides a genetic basis for further Cd-PSCs screening and breeding.

Differences in the subcellular distribution and chemical speciation of Cd between two Chinese flowering cabbage (Brassica parachinensis L.) cultivars, Lubao70 (LB70, low-Cd cultivar) and ChixinNO.4 (CX4, high-Cd cultivar) were investigated under various soil Cd and P treatments. Subcellular fractionation of Cd-containing tissues showed that a higher proportion of Cd was bound to the cell wall fraction of LB70 than that of CX4, indicating that Cd compartment functioned better in LB70. Compared to CX4, LB70 had lower proportions of Cd in inorganic form and water-soluble form, but higher proportions of Cd in proteins/pectates integrated form, implying that the low Cd accumulation in LB70 is associated with the low in vivo mobility of Cd. In both cultivars, shoot and root Cd concentration and translocation of Cd from the roots to the shoots obviously decreased with increasing soil P level. It was found that phosphorus (P) played important roles in Cd uptake and translocation via the processes involved in bonding Cd to the cell wall fraction and forming Cd-phosphate complexes. It is suggested that use of low-Cd cultivars in conjunction with P supply is a much useful way to reduce the pollution risk of Cd in the food chain.

To evaluate the biomagnification extent of polybrominated diphenyls ethers (PBDEs) and polychlorinated biphenyls (PCBs) in a highly contaminated freshwater food web from South China, trophic magnification factors (TMFs) for 18 PBDE congeners and 53 PCB congeners were calculated. The TMF values ranged 0.26-4.47 for PBDEs and 0.75-5.10 for PCBs. Forty-five of 53 PCBs and BDEs 47, 100 and 154 had TMFs greater than one, suggesting their biomagnification in the present food web. The TMFs for PBDEs were generally smaller than those for PCBs with the same degree of halogenation, indicating a lower biomagnification potential for PBDEs compared to PCBs. For PCBs, it followed a parabolic relationship between TMFs and logK(OW) (octanol-water partition coefficient). However, this relationship was not significant for PBDEs, possibly due to the more complex behaviors of PBDEs in the food web (e.g., metabolism), compared to that of PCBs.

In order to clarify how cadmium (Cd) chemical forms in planta relate to the genotype difference in Cd accumulation of spinach (Spinacia oleracea L.), two low-Cd and two high-Cd cultivars were compared under a hydroponic experiment with two concentrations of Cd (8.98 or 44.71 μmol Cd L(-1)). The concentrations of phosphorus in the hydroponic system were also adjusted to two levels (0.5 and 1.0 mmol L(-1)) to investigate the influence of phosphorus on the forms and accumulation of Cd in the tested cultivars. Average Cd concentrations in shoots were 8.50-10.06 mg kg(-1) for high-Cd cultivars and 6.11-6.64 mg kg(-1) for low-Cd cultivars a under lower Cd treatment and were as high as 24.41-31.35 mg kg(-1) and 19.65-25.76 mg kg(-1), respectively, under a higher treatment. Phosphorus significantly decreased Cd accumulation in the tested cultivars, and the effect had superiority over the cultivar alternation under higher Cd stress. Cadmium in the NaCl-extractable fraction of the plant tissues showed the greatest relationship to genotype difference of Cd accumulation. The difference in the capacity to binding Cd into F HAc, F HCl, or F Residue was another important mechanism involving in the genotype difference in Cd accumulation of spinach. Among them, average proportion of Cd in F HAc in low-Cd cultivars was higher than that in high-Cd cultivars in association with the effect of phosphorus.

Organophosphorus flame retardants (OPFRs) are important alternatives to brominated flame retardants (BFRs), but information on their contamination of the environment in China is rare. We examined the occurrence of 12 OPFRs in indoor dust in four microenvironments of southern China, including a rural electronic waste (e-waste) recycling area, a rural non-e-waste area, urban homes, and urban college dormitory rooms. The OPFR concentrations (with a median of 25.0 μg g−1) were highest in the e-waste area, and the concentrations in other three areas were lower and comparable (7.48–11.0 μg g−1). The levels of OPFRs in the present study were generally relatively lower than the levels of OPFRs found in Europe, Canada, and Japan because BFRs are still widely used as the major FRs in China. The composition profile of OPFRs in the e-waste area was dominated by tricresyl phosphate (TCP) (accounting for 40.7%, on average), while tris(2-chloroethyl) phosphate (TCEP) was the most abundant OPFR (64.4%) in the urban areas (homes and college dormitories). These two distribution patterns represent two OPFR sources (i.e., emissions from past e-waste and from current household products and building materials). The difference in the OPFR profiles in the rural area relative to the OPFR profiles in the urban and e-waste areas suggests that the occurrence of OPFRs is due mainly to emissions from characteristic household products in rural homes. Although human exposures to all the OPFRs were under the reference doses, the health risk for residents in the e-waste area is a concern, considering the poor sanitary conditions in this area and exposure from other sources.

Dechlorane Plus (DP) and a dechlorinated product of DP were measured in 34 matched human hair and serum samples (19 males and 15 females) collected from e-waste recycling workers in South China. The DP (sum of syn- and anti-DP) concentrations in hair and serum samples ranged from 6.3 to 1100 ng g(-1) dry weight and from 22 to 1400 ng g(-1) lipid weight (lw). The levels of anti-Cl11-DP ranged from 0.02 to 1.8 ng g(-1) in hair and from not detected to 7.9 ng g(-1) lw in serum. Significant positive correlations for both DP and anti-Cl11-DP concentrations between hair and serum samples were found (p0.05), indicating hair to be a suitable matrix for human DP exposure. However, a significant difference was found in the DP isomer composition between hair and serum, suggesting stereoselective bioaccumulation during the absorption of DP into hair. A sharp gender difference was found in the levels of DP in hair. Moreover, syn-DP, anti-DP and anti-Cl11-DP in hair significantly correlated with those in serum for male samples, but not for female samples. The observed gender differences in the present study may be, in part, ascribed to the much longer hair exposure time for females than males due to the difference in sampling distance from the scalp.

Maximum standardized uptake value (SUV(max)) is a marker of tumor glucose metabolism detected by [(18)F]-fluorodeoxyglucose ((18)F-FDG) PET/computed tomography (PET/CT) and reflects tumor aggressiveness. The aim of the study was to evaluate the value of SUV(max) in differentiating benign from malignant solitary pancreatic lesions and explore the correlation between SUV(max) and tumor proliferative activity.F-FDG PET/CT scans were performed in 80 patients with solitary pancreatic lesions who were scheduled for resective surgery. The relationships between SUV(max) and postoperative pathologic diagnosis, histologic grade, and Ki-67 proliferation index (PI) were analyzed.Of these 80 patients, 54 had malignant lesions. The SUV(max) of malignant tumors (6.3 ± 2.4) was significantly greater than that of benign lesions (2.9 ± 2.0) (P0.001). Receiver-operating characteristic curve analysis showed that the SUV(max) cutoff value of 3.5 had a high sensitivity (92.6%) and specificity (76.9%) for the diagnosis of malignancies. Among pancreatic cancers with low (Ki-675%), moderate (5% ≤ Ki-6750%), and high (Ki-67 ≥ 50%) PI, SUV(max) increased significantly from 4.2 ± 1.2, through 6.0 ± 1.7, to 8.6 ± 2.5 (P0.001). The SUV(max) had a positive correlation with Ki-67 PI (P0.001, r=0.60).The SUV(max) of F-FDG PET/CT can be used in the differential diagnosis of solitary pancreatic lesions and can also aid in the prediction of proliferative activity of pancreatic cancer.

Concentrations of heavy metals (Cd, Pb, Cu, Zn, and Ni) were measured in the foodstuffs, house dust, underground/drinking water, and soil from an electronic waste (e-waste) area in South China. Elevated concentrations of these potentially toxic metals were observed in the samples but not in drinking water. The health risks for metal exposure via food consumption, dust ingestion, and drinking water were evaluated for local residents. For the average residents in the e-waste area, the non-carcinogenic risks arise predominantly from rice (hazard index=3.3), vegetables (2.2), and house dust (1.9) for adults, while the risks for young children are dominated by house dust (15). Drinking water may provide a negligible contribution to risk. However, local residents who use groundwater as a water supply source are at high non-carcinogenic risk. The potential cancer risks from oral intake of Pb are 8×10(-5) and 3×10(-4) for average adults and children, and thus groundwater would have a great potential to induce cancer (5×10(-4) and 1×10(-3)) in a highly exposed population. The results also reveal that the risk from oral exposure is much higher than the risk from inhalation and dermal contact with house dust.

Concentrations of six heavy metals (Cu, Ni, Zn, Cd, Cr, and Pb) in sediments and fine roots, thick roots, branches, and leaves of six mangrove plant species collected from the Futian mangrove forest, South China were measured. The results show that both the sediments and plants in Futian mangrove ecosystem are moderately contaminated by heavy metals, with the main contaminants being Zn and Cu. All investigated metals showed very similar distribution patterns in the sediments, implying that they had the same anthropogenic source(s). High accumulations of the heavy metals were observed in the root tissues, especially the fine roots, and much lower concentrations in the other organs. This indicates that the roots strongly immobilize the heavy metals and (hence) that mangrove plants possess mechanisms that limit the upward transport of heavy metals and exclude them from sensitive tissues. The growth performance of propagules and 6-month-old seedlings of Bruguiera gymnorhiza in the presence of contaminating Cu and Cd was also examined. The results show that this plant is not sufficiently sensitive to heavy metals after its propagule stage for its regeneration and growth to be significantly affected by heavy metal contamination in the Futian mangrove ecosystem. However, older mangrove seedlings appeared to be more metal-tolerant than the younger seedlings due to their more efficient exclusion mechanism. Thus, the effects of metal contamination on young seedlings should be assessed when evaluating the risks posed by heavy metals in an ecosystem.

OBJECTIVE To evaluate the clinical value of F-fluorodeoxyglucose positron emission tomography and computed tomography (¹⁸F-FDG PET/CT) in postoperative patients with gastrointestinal mucinous adenocarcinoma. METHODS From July 2007 to March 2009, 30 patients who had previous surgical resection of histopathologically diagnosed gastrointestinal mucinous adenocarcinoma underwent ¹⁸F-FDG PET/CT scans in our center. The standard of reference for tumor recurrence, regional lymph node (LN) metastasis, peritoneal and distant metastasis consisted of histopathologic confirmation or clinical follow-up information for at least 6 months after PET/CT examinations. RESULTS With final diagnosis, tumor recurrences were confirmed in eight of the 30 patients (26.7%). If a maximum standardized uptake value (SUVmax) of 2.5 or more was used as a cut-off point, the sensitivity, specificity, and accuracy of PET/CT were 87.5, 77.3, and 80.0%, respectively. However, if an SUVmax of 4.0 or more was the criterion, the sensitivity, specificity, and accuracy were 25.0, 86.4, and 70.0%, respectively. A cut-off point of 2.5 showed a higher sensitivity (P=0.041), and there was no statistical difference in the specificity and the accuracy of these two criteria. For the diagnosis of metastasis in regional LNs and peritoneum, the detection rate was 95.2 and 86.4%, respectively. In addition, we followed up 20 patients with 26 suspicious distant lesions. The sensitivity, specificity, and accuracy were 58.3, 92.9, and 76.9%, respectively. CONCLUSION ¹⁸F-FDG PET/CT may be effective to discriminate tumor recurrence, and to detect regional LNs, peritoneal and distant metastasis in postoperative patients with gastrointestinal mucinous adenocarcinoma.

(R)-Ethyl-3-hydroxyglutarate, (R)-3, is an intermediate in the synthesis of the statin side chain. Here, a new two-step, indirect biotransformation pathway involving the formation of ethyl (R)-4-carbamoyl-3-hydroxybutanoate, (R)-2, as an intermediate for (R)-3 production was developed using Rhodococcus boritolerans with ethyl (R)-4-cyano-3-hydroxybutyate, (R)-1, as substrate. Maximum conversion was with 10 g (R)-1/l, 7 g cells/l (dry wt), pH 7.5 and 25°C. A yield of 98 ± 0.5% (w/w) was attained within 8 h.

Human hair and indoor dust from urban, e-waste, and rural areas in south China were collected and analyzed for brominated flame retardants (BFRs). BFRs concentrations in hair from occupational e-waste recycling workers were higher than those from non-occupational exposed residents in other sampling areas. Polybrominated diphenyl ethers (PBDEs) and decabromodiphenyl ethane (DBDPE) are two major BFRs in hair samples. The PBDE congener profiles in hair from the e-waste area are different from those from urban and rural areas with relatively higher contribution of lower brominated congeners. DBDPE, instead of BDE209, has become the major BFR in non-e-waste recycling areas. Significant correlations were found between hair level and dust level for DBDPE and BTBPE but not for PBDEs. The different PBDE congener profiles between dust and hair may suggest that exogenous exposure to the PBDE adsorbed on dust is not a major source of hair PBDEs.

Heavy metals were measured in hair from occupationally and nonoccupationally exposed populations in an e-waste recycling area and from residents from a control rural town. The levels of five heavy metals were in the following order of Zn > Pb, Cu > Cd > Ni, with the highest levels found in the occupationally exposed workers. The levels of Cd, Pb, and Cu were significantly higher in residents from the e-waste recycling area than in the control area. Elevated Cd, Pb, and Cu contents along with significant positive correlations between them in hair from the e-waste recycling area indicated that these metals were likely to have originated from the e-waste recycling activities. The similarity in heavy metal pattern between children and occupationally exposed workers indicated that children are particularly vulnerable to heavy metal pollution caused by e-waste recycling activities. The increased Cu exposure might be a benefit for the insufficient intake of Cu in the studied area. However, the elevated hair Cd and Pb levels implied that the residents in the e-waste area might be at high risk of toxic metal, especially for children and occupationally exposed workers.

Phytochelatins (PCs) play an important role in detoxification of heavy metals in plants. PCs are synthesized from glutathione by phytochelatin synthase (PCS), a dipeptidyltransferase. Sesbania rostrata is a tropical legume plant that can tolerate high concentrations of Cd and Zn. In this study, the S. rostrata PCS gene (SrPCS) and cDNAs were isolated and characterized. Southern blot and sequence analysis revealed that a single copy of the SrPCS gene occurs in the S. rostrata genome, and produces four different SrPCS mRNAs and proteins, SrPCS1-SrPCS4, by alternative splicing of the SrPCS pre-mRNA. The SrPCS1 and SrPCS3 proteins conferred Cd tolerance when expressed in yeast cells, whereas the SrPCS2 and SrPCS4 proteins, which lack the catalytic triad and the N-terminal domains, did not. These results suggested that SrPCS1 and SrPCS3 have potential applications in genetic engineering of plants for enhancing heavy metal tolerance and phytoremediation of contaminated soils.

Contents of trace elements (Cd, Pb, Cu, Zn and Ni) in sediments of river bed and bankside and adjacent agricultural soils along the Zhongxin River, Guangdong, China, were determined to investigate the metal distribution and assess ecological risk of trace element contamination. The results show that Cd and Zn are the two major metal elements contaminating the sediments and riverine farmlands. Geo-accumulation index (I(geo)) also revealed that the river sediments were polluted by Cd at levels from moderate to extreme, and by Zn at levels from moderate to high in most cases. Agricultural soils were generally moderately or highly polluted by Cd, and were unpolluted by Zn in most cases. The trace element contents of the river sediments in the upper and middle reaches of the river were much higher than in the downstream reaches. Agricultural soils in site S3 at Zhongxin Town had the highest amount of all the tested trace elements. Although the contents of the trace elements generally decreased from the upper and middle reaches to the downstream river, there was no obvious trend found for agricultural soils. The trace element contents were less influenced by pH and TOC in the sediments as well as in the soils. Storage in river alluvium and dilution by downstream clean sediments were the main mechanisms responsible for the decrease of the metal contents in the river sediments. The linear fit model depicts the risk of transportation of polluted sediments to Xinfengjiang Reservoir, the largest protection zone for sources of drinking water in Guangdong Province. Torpedo grass and rice plant showed the potential to be used in biomonitoring of metal contamination, however, further investigations are needed before using them in practice.