High Levels Of Cd Research Articles

Alleviation of cadmium toxicity in Zea mays L. through up-regulation of growth, antioxidant defense system and organic osmolytes under calcium supplementation.

Calcium (Ca) is a macronutrient and works as a modulator to mitigate oxidative stress induced by heavy metals. In this study, we investigated the role of Ca to ameliorate the Cd toxicity in Zea mays L. by modulating the growth, physio-biochemical traits, and cellular antioxidant defense system. Maize genotype Sahiwal-2002 was grown under a controlled glasshouse environment with a day/night temperature of 24 ± 4°C/14 ± 2°C in a complete randomized design with three replications and two Cd levels as (0 and 150 μM) and six regimes of Ca (0, 0.5, 1, 2.5, 5, and 10 mM). Maize seedlings exposed to Cd at 150 μM concentration showed a notable decrease in growth, biomass, anthocyanins, chlorophylls, and antioxidant enzymes activities. A higher level of Cd (150 μM) also caused an upsurge in oxidative damage observed as higher electrolyte leakage (increased membrane permeability), H2O2 production, and MDA accumulation. Supplementation of Ca notably improved growth traits, photosynthetic pigments, cellular antioxidants (APX, POD, and ascorbic acid), anthocyanins, and levels of osmolytes. The significant improvement in the osmolytes (proteins and amino acids), and enzymatic antioxidative defense system enhanced the membrane stability and mitigated the damaging effects of Cd. The present results concluded that exogenously applied Ca potentially improve growth by regulating antioxidants and enabling maize plants to withstand the Cd toxicity.

Effect of Treated Wastewater Irrigation on the Accumulation and Transfer of Heavy Metals in Lemon Trees Cultivated in Arid Environment

The Middle East is considered as one of the driest regions of the world and the use of municipal-treated wastewater (TWW) for agricultural purposes is needed. The aim of this study was to evaluate the effect of continuous irrigation of TWW in lemon orchards on the accumulation of heavy metals (HMs) in the soil, as well as their uptake and translocation to aerial parts of the trees. For this purpose, two lemon orchards were selected to be irrigated from two different water sources: TWW from a tertiary treatment plant and freshwater (SW) from Moses springs in Jordan. Continuous irrigation with TWW resulted in higher concentrations of nutrients and HM accumulation in the soil as compared to SW. However, HM accumulation in the soil was found to be within the acceptable range according to the standards of the WHO. On the contrary, the continuous irrigation with TWW resulted in the accumulation of HMs in plant parts when compared to SW irrigation; the fruits were clearly affected by the accumulation of high levels of Cd and Pb that exceed the maximum limits for the presence of HMs in plant tissues. The irrigation of lemon trees with TWW had a significant effect on the bioaccumulation factor and translocation factors (TF) of HMs into different lemon tree parts. Heavy metal accumulation coincided with high translocation rates to different tree parts, and this is considered to be a main challenge for long-term irrigation with TWW in arid environments.

Assessing Heavy Metal Pollution of the Largest Nature Reserve in Tianjin City, China.

Beidagang Wetland (BW) Nature Reserve is centrally situated in Tianjin City, experiencing an extreme industrial development. This study uses index characteristic analysis systems for assessing the individual and combined heavy metal pollution loading in the water during the spring and autumn seasons. By combining the pollution level of single pollutant, a more comprehensive evaluation of water quality in BW was achieved. Water quality was worst during autumn due to high level of Cd and Pb, which indicate the type of anthropogenic activities have a serious effect on heavy metal pollution in BW. In addition, high exchangeable amounts of Cd (> 40%) were found in the sediments of BW, indicating Cd pollution has emerged. There is a need for appropriate abatement actions curbing heavy metal loading and improving water quality of the BW Nature Reserve, thereby ensuring a sustainable management of its ecosystem services.

Assessment of trace element contamination in the historical nesting grounds of green sea turtle (Chelonia mydas) in Hainan Island, China.

Trace element pollution is a potential threat to the reproduction of sea turtles. Hainan Island was previously the most important nesting ground of green sea turtles in China before they disappeared approximately 36 years ago. The Chinese government has encouraged restoration work on historical nesting grounds, and it is necessary to evaluate the status of these sites before conducting habitat restoration. This study analyzed the concentrations of seven trace elements in the surface sediments of 13 historical nesting grounds in Hainan. The average concentrations were 19.47 (Cr), 4.67 (Ni), 6.99 (Cu), 0.08 (Cd), 16.68 (Pb), 0.02 (Hg), and 5.27 (As) mg/kg, which were lower than the first-grade limit values of the GB (18668-2002) national standard in China. The concentrations were close to the background value, except for the relatively high Cd value. The potential ecological risk was ranked as Cd > Hg > As > Cu > Pb > Cr. The spatial distribution of trace element contamination in Hainan was uneven, with high potential ecological risk levels of Cd and Hg contamination in Longwan'gang, Shimeiwan, Yazhou Qu, and Fushicun. Marine mariculture, wastewater discharge, and fishing boats are the main sources of trace element contamination in Hainan. We recommend strengthening the control of Hg and Cd contamination sources, monitoring trace elements in relevant/interest areas, and the environmental protection department should curb local residents from directly discharging mariculture wastewater and domestic sewage into the sea.

Elemental and isotopic compositions of New Zealand regional soils identifies human and climate-induced effects

A regional soil study of 61 sites from the Wairau and Awatere Valleys, Marlborough region, New Zealand characterised the geochemical baselines of different land-use types. The study used three stable isotopes (δ13C, δ15N, δ34S) and 65 elements to describe the influence of parent-rock geology, human and climate-induced effects and natural transport processes on the soil quality and soil health of this region. The temperate Marlborough region produces high quality wine and the elemental and isotopic composition of a subset of vineyard soils are examined in more detail to identify soil characteristics specific to this agriculturally productive region. Higher levels of Cd, K, N, P, S and Zn were found in vineyard soils compared to forested and rural soils, indicative of anthropogenic agricultural inputs. Stable isotopes in vineyard soils had higher δ13C and δ15N values and lower δ34S values than forested and rural soils, typical of more highly cultivated soils. The natural geogenic inputs from the ultra-mafic mountains enclosing the Wairau and Awatere Valleys were geochemically distinct from localised anthropogenic contaminants. Comparisons with a further 240 New Zealand urban (Dunedin) and rural (Southland-Otago region) soils suggests the elemental contaminants found in the Marlborough vineyard soils may be specific to high-yielding agricultural zones across New Zealand.

Cadmium Accumulation in the Goat Liver and Kidney Is Partially Promoted by the Upregulation of Metal Transporter Genes.

Simple SummaryThe pattern of cadmium (Cd) accumulation and the role of metal transport in tissues’ cadmium deposition using Cd from an organic source are not well-clarified in ruminants. The present study results clearly showed that dietary Cd exhibited different deposition rates between goat liver, kidney, and muscle. Cd concentration in the liver, kidney, and muscle of goats fed 1.07 mg Cd/kg of dry matter (DM) for 60 days remained within the scope of (1.0 mg/kg) the food safety standards of China (GB 2762-2017) and the European Commission Regulation 1881/2006 (amended by No. 629/2008). Dietary Cd promoted the expression of metal transporter genes in the liver and kidneys of goats. DMT1, ZIP8, and ZIP14 might play an imperative role in the uptake of Cd in the goat liver and kidney but not in the muscle.Metal transporters, including divalent metal-ion transporter-1 (DMT1), Zrt-/Irt-like protein 8 and 14 (ZIP8 and ZIP14), and ferroportin-1 (FPN1), reportedly participate in cellular cadmium (Cd) uptake, but those in farm animals remain unclarified. This study aimed to examine the growth, plasma biochemical indices, Cd accumulation, and expression of metal transporter genes in the liver, kidney, and muscle of goats exposed to rice paddies contaminated with different levels of Cd. Twenty-four goats were randomly assigned across three dietary treatments: 0.23, 0.63, and 1.07 mg of Cd/kg of dry matter (DM) for 60 days. The results showed that dietary Cd exposure increased (p < 0.05) both Cd accumulation and the mRNA expressions of metal transporter genes (DMT1, ZIP, and FPN1) in the liver and kidney but not in the muscle, suggesting dietary Cd exhibited different deposition rates between goat liver, kidney, and muscle. These outcomes suggest that high levels of dietary Cd stimulated the expression of metal transporter genes and thereby enhanced the uptake and accumulation of Cd in the goat liver and kidney. As such, higher Cd concentrations in the liver and kidney observed with Cd diets could be partly explained by upregulation of metal transport genes expression.

Recognition method for the health risks of potentially toxic elements in a headwater catchment

The spatial association of potentially toxic elements (PTEs) in soil–crop–groundwater systems is poorly recognised. In this study, the contents of arsenic (As), cadmium (Cd), copper (Cu) and lead (Pb) in paddy soils, rice and groundwater in the Xiancha River catchment were determined. The intrinsic effects of PTEs in soils on their spatial distribution in groundwater and rice were explored. Also, the potential sources and health risks of PTEs in multi-media were investigated. Results showed that the mean contents of As and Cd in soils were 23.86 and 0.26 mg kg−1, respectively. In groundwater, the maximum (average) content of As reached 6.55 (1.84) μg L−1. Moreover, As contents in soils and groundwater showed a sound spatial correlation (q = 0.81), and this is supported by the result of the soil column experiment, indicating homology and the strong vertical migration capacity of As. The non-homologous patterns of Pb, Cu and Cd contaminations in soil–groundwater system suggested that geogenic processes influenced the distribution of these PTEs. Cd presented a poor spatial correlation in soil–rice system, as multiple factors controlled its transfer process. Multivariate statistical analysis results demonstrated that As, Cu and Pb in soils mainly came from agricultural sources, whereas high Cd levels were from mining activities. Additionally, direct consumption of As-contaminated groundwater and Cd-contaminated rice posed significant health risks to local residents. This study, which proposes a risk recognition method used to investigate target PTEs in multi-media, may serve as a valuable reference for further research involving catchments.

Mitigating the accumulation of arsenic and cadmium in rice grain: A quantitative review of the role of water management

Arsenic exposure through rice consumption is a growing concern. Compared to Continuous Flooding (CF), irrigation practices that dry the soil at least once during the growing season [referred to here as Alternate Wetting and Drying (AWD)] can decrease As accumulation in grain; however, this can simultaneously increase grain Cd to potentially unsafe levels. We modelled grain As and Cd from field studies comparing AWD and CF to identify optimal AWD practices to minimize the accumulation of As and Cd in grain. The severity of soil drying during AWD drying event(s), quantified as soil water potential (SWP), was the main factor leading to a reduction in grain total As and inorganic As, compared to CF. However, lower SWP levels were necessary to decrease grain inorganic As, compared to total As. Therefore, if the goal is to decrease grain inorganic As, the soil needs to be dried further than it would for decreasing total As alone. The main factor driving grain Cd accumulation was when AWD was practiced during the season. Higher grain Cd levels were observed when AWD occurred during the early reproductive stage. Further, higher Cd levels were observed when AWD spanned multiple rice growth stages, compared to one stage. If Cd levels are concerning, the minimum trade-off between total As and Cd accumulation in rice grain occurred when AWD was implemented at a SWP of −47 kPa during one stage other than the early reproductive. While these results are not meant to be comprehensive of all the interactions affecting the As and Cd dynamics in rice systems, they can be used as a first guide for implementing AWD practices with the goal of minimizing the accumulation of As and Cd in rice grain.

One stone two birds: Bone char as a cost-effective material for stabilizing multiple heavy metals in soil and promoting crop growth

Remediation of farmland soils contaminated with high levels of multiple heavy metals near PbZn smeltery is still a great challenge. It is of great significance to find cost-effective green remediation technologies for stabilization of multiple heavy metals in soil and reduce metal accumulation in crops with ensured yield. In this study, we demonstrated that bone char (BC) is an effective heavy metal stabilizer which can substantially increase residual fractions of heavy metals and reduce metal accumulation in pea (Pisum sativum) with its enhanced growth. We chose the soils contaminated with high levels of Pb, Zn, Cu and Cd near the Baiyin PbZn smeltery as the tested soil. After 2 months of BC application, the relative mobile fractions (non-residual fractions) of Cu, Zn, Pb and Cd in the contaminated soil decreased while the residual fraction increased significantly. The leachability of Cu, Zn, Pb and Cd decreased by 91.2%, 38.6%, 67.6% and 54.3%, respectively compared with the control. BC application remarkably promoted pea growth and reduced accumulation of heavy metals in shoots. The mechanisms for stabilization of multiple heavy metals BC include ion exchange, surface complexation and subsequent mineralization, accompanied with release of Ca and phosphate. The immobilization of heavy metals led to their reduced toxicity to plant, and thus increased pea growth. The results show that BC is a cost-effective and sustainable heavy metal stabilizer with phosphate fertilization function. It can simultaneously immobilize multiple heavy metals in soil and facilitate crop production.

Association between cadmium and lead co-exposure, blood pressure, and hypertension: a cross-sectional study from northwest China

Cadmium (Cd) and lead (Pb) co-exposure have been inconsistently associated with blood pressure (BP) and hypertension (HTN). This cross-sectional study included 309 participants who completed a health examination and had blood Cd (Cd-B) and Pb (Pb-B) levels measured. The association between Cd, Pb, and their combined exposure levels, with systolic (SBP) and diastolic blood pressure (DBP) and HTN was evaluated using models which were stratified according to sex, age, BMI, and smoking habit categories. The results found both increasing Cd-B and Pb-B were associated with elevated SBP and DBP in the overall population. In addition, increases in Cd-B and Pb-B were also associated with increased risk of HTN in overall and stratified models. Moreover, compared with the low exposure group, co-exposure to high levels of Cd and Pb was associated with increased SBP (β = 10.95, 95% CI: 5.69, 16.21), increased DBP (β = 5.09, 95% CI: 1.53, 8.66), and increased HTN risk (OR = 2.45, 95% CI: 1.15, 5.21) in the overall model, and above results were different in the stratified model. This study provides evidence of an association between Cd and/or Pb exposure levels, BP, and HTN. However, the significance of this association differed according to sex, age, BMI, and smoking habit. Highlights Cadmium/lead exposure is associated with elevated blood pressure and hypertension. Cadmium and lead co-exposure increased blood pressure in a dose-dependent manner. Results revealed differences according to sex, age, BMI, and smoking habit category. Health oversight should be implemented for residents with high heavy metal exposure.

Bioaccumulation of total mercury, copper, cadmium, silver, and selenium in green turtles (Chelonia mydas) stranded along the Potiguar Basin, northeastern Brazil

Sea turtles face several threats and pollution has become a major concern for their conservation worldwide. We analyzed samples of the liver, muscles, and kidneys of 38 Chelonia mydas stranded along the Potiguar Basin, northeastern Brazil, between 2015 and 2018 to determine the total Hg concentration (THg), as well as the concentrations of Cu, Cd, Ag, and Se. The relation between turtle size and element concentrations revealed a negative correlation for THg and Se (liver, muscles, and kidneys), Cu and Cd (liver and kidneys) and a positive correlation for Ag in the three organs analyzed. Concentrations of THg, Cu, Ag, and Se were high in the liver, highlighting the Cu concentration (median = 25.1150 μg g−1 w.w.), while the kidneys had the highest Cd levels (median = 12.2200 μg g−1 w.w.). There was significant difference between element concentrations and the three organs analyzed, except for Ag and Se concentrations in the muscle and kidney samples. Our study showed that green turtles found in Potiguar Basin, northeastern Brasil, have bioaccumulated inorganic elements which indicate the need of further investigations on the environmental quality of the region.

Low-level exposure to lead, cadmium and mercury, and histopathological findings in kidney biopsies

BackgroundLead (Pb), cadmium (Cd) and mercury (Hg) are all nephrotoxic metals, and a large part of the body burden of Cd and Hg is found in the kidneys. There are, however, few studies on associations between exposure to these toxic metals and renal biopsy findings, and none at low-level exposure. AimTo examine the hypothesis that low-level concentration of Pb, Cd or Hg in the kidneys is associated with histopathological changes in the kidneys. MethodsWe determined concentrations of Pb, Cd and Hg in kidney, blood and urine in 109 healthy kidney donors, aged 24–70 years. The renal biopsies were scored according to the Banff classification regarding tubular atrophy, interstitial fibrosis, glomerulosclerosis, arteriosclerosis, and arteriolohyalinosis. Kidney function was assessed based on glomerular filtration rate (GFR) as well as urinary excretion of albumin, low molecular weight proteins, kidney injury molecule 1 and N-acetylglucose aminidase. Associations between metal concentrations and histopathological changes, were assessed in models also including age, sex and smoking. ResultsThe median kidney concentrations of Pb, Cd and Hg were 0.08, 13 and 0.21 μg/g, respectively. There were signs of tubular atrophy in 63%, interstitial fibrosis in 21%, glomerulosclerosis in 71%, arteriosclerosis in 47%, and arteriolohyalinosis in 36% of the donors, but, as could be expected, the histopathological findings were limited, mostly Banff grade 1. In models adjusted for age, sex and smoking, kidney Cd was positively associated with tubular atrophy (p = 0.03) and possibly with arteriolohyalinosis (p = 0.06). Kidney Hg was associated with arteriosclerosis (p = 0.004). Discussion and conclusionsThe results suggest that even low levels of Cd in the kidney can induce a mild degree of tubular atrophy. This is in line with previous findings at high-level Cd exposure. The association between kidney Hg and renal arteriosclerosis was unexpected, and may be a chance finding.

Effects of heavy metals in acute ischemic stroke patients: A cross-sectional study.

Cerebrovascular disease is the second commonest cause of mortality globally and among the commonest causes of disability. However, research executed to probe the heavy metal exposure–stroke incidence relationship is scarce. Accordingly, we executed our study to probe the relationship of heavy metal concentrations (ie, concentrations of lead [Pb], mercury [Hg], cadmium [Cd], and arsenic) in the serum and urine of acute ischemic stroke (AIS) patients with several patient variables.For enrollment, we chose patients who had a first AIS within 7 days after the onset of a stroke. Thus, 33 newly diagnosed patients with AIS were recruited. We determined the aforementioned metals’ concentrations by executing inductively coupled plasma mass spectrometry. We also gauged the association between such metal concentrations and patient variables by employing Spearman correlation coefficient. To examine the differences in metal concentrations between the different variables, we implemented an independent Mann–Whitney U test.In our cohort analysis, we noted serum Pb and Cd concentrations to be positively correlated with serum creatinine and hemoglobin. Serum and urine Cd concentrations had a negative correlation with impaired HbA1c in AIS patients. Urine Hg had a positive correlation with C-reactive protein in the participants. Participants who smoked or consumed alcohol had significantly higher Pb and Cd levels in serum than did those who neither smoked nor drank. Patients with AIS who smoked or consumed alcohol had high levels of serum Pb and serum Cd than did those who did not. Patients with AIS who consumed alcohol had significantly higher Pb and Hg urine concentrations than did those who did not.Our study indicated that serum Cd and Pb elevation increased the AIS risk in southern Taiwan patients.

Heavy metal contamination of milk and milk Products produced in Boumerdes(Algeria)

Milk and its derivatives are major sources of micronutrients an overdose of these can be harmful. This study aimed to measure heavy metals concentration and its derivatives from the Factory LFB (Boudouaou Cheese Dairy) in Boumerdes, Algeria. The concentration were measured using a graphite furnace spectrophotometer, the all data processing was carried with XL-STAT 2014 software. The mean values (Cu, Zn, Fe, Mg, Cd, Cr and Pb) lie respectively between: (0.019-0.45), (0.29-7.24), (0.21- 0.56), (1.09-120.77), (0.012-0.41), (0.006-0.027), (0.086-0.72mg/L) Higher levels of Cd, Fe, Cr and Pb were observed in pasteurized milk and cheese, and higher levels of Zn and Cu in cheese than in other sampales, all exceeding World Health Organization (WHO) limits. The highest non-carcinogenic risk quotient (NCR) values were attributed to Pb and Cd in raw milk, pasteurized milk and cheese, which were above the values recommended by the Health Protection Agency United States Environment (USEPA) as for the carcinogenic risk factor (CR), desipite the low value found, consumption of milk and cheese over a long period of time does not exclude the risk of developing cancer.

Co-Selection of Heavy Metal and Antibiotic Resistance in Soil Bacteria from Agricultural Soils in New Zealand

Accumulation of trace elements (including heavy metals) in soil from usage of superphosphate fertilisers induces resistance of soil bacteria to trace elements of environmental concern (TEoEC) and may co-select for resistance to antibiotics (Ab). This study aimed to investigate selection of co-resistance of soil bacteria to Cd, Zn and Hg, and Ab in soils with varied management histories. Genetic diversity of these bacteria and horizontal transfer of Cd resistance genes (cadA and czcA) were also investigated. Soils with either pastoral and arable management histories and either high levels of Cd and Zn, or indigenous bush with background levels of these TEoEC from the Waikato region, New Zealand were sampled. Plate culturing with a range of TEoEC and Ab concentrations, Pollution Induced Community Tolerance (PICT) assay, antibiotic sensitivity, terminal restriction fragment length polymorphism (TRFLP) and horizontal gene transfer (HGT) analyses were employed to investigate co-selection of TEoEC and Ab resistance. Higher levels of bacterial resistance to TEoEC and Ab correlated with higher levels of TEoEC in soil. Bacterial community structures were altered in soils with high TEoEC levels. Cd resistance genes were transferred from donor bacterial isolates, to recipients and the transconjugants also had resistance to Zn and/or Hg and a range of Ab.

Urinary Cadmium Level Causing Impaired Kidney Function in Farmers in Gintungan Village, Bandungan District

Introduction: Farmers apply pesticides to control pests on vegetable farming in Semarang regency. One of the active ingredients of pesticides is cadmium (Cd), and exposure to cadmium in humans can interfere with kidney function. High exposure to Cd may cause the effects of chronic kidney failure. If there are a lot of free Cd ions in the body, the ability of the kidneys to produce metallothionein will be reduced. Thus, it may damage the kidney tubules as it results in high levels of urinary Cd which can be toxic. This study aimed to analyze an association between the levels of urinary Cd and impaired kidney function in farmers. Methods: This study was analytic observational and used design a cross-sectional study design. The population in this study was all farmers as many as 406 people in Gintungan village, Bandungan district, Semarang regency. There were 60 people selected as samples through purposive sampling. Results and Discussion: The level of urinary Cd in farmers on average was 0.958 µg/L with a standard deviation of 0.570 µg/L. The highest level of Cd was 5.390 µg/L and the lowest was &lt; 0.100 µg/L. The results of the statistical chi-square test showed there was an association between levels of urinary Cd and impaired kidney function (p = 0.041). Conclusion: Impaired kidney function in farmers in Gintungan might be caused by the level of urinary Cd. Further research should measure creatinine in the blood to ensure a decrease in the glomerular filtration rate in the kidneys of the farmers.

Effects of lead and cadmium co-exposure on liver function in residents near a mining and smelting area in northwestern China.

Chronic exposure to environmental cadmium (Cd) and lead (Pb) may have adverse effects on the human health. In this study, we aimed to determine the primary and interactive effects of Cd and Pb exposure on liver function in residents near a mining and smelting area in northwestern China. A total of 451 subjects were recruited, from which blood samples were collected to determine the levels of Cd, Pb, and liver function indices. Additionally, the association between the levels of exposure markers and liver function indices was analysed. Cd and Pb levels were significantly higher in subjects living in the polluted area than in those living in the non-polluted reference area. The liver function levels of subjects in the polluted area were poor compared with those in the reference area. In addition, Cd and Pb levels in the blood were positively associated with gamma glutamyl transpeptidase (GGT) levels and negatively associated with direct bilirubin (DBil) levels. Cd and Pb may be risk factors for abnormal liver function. The risk of abnormal liver function was higher in subjects with moderate Cd and Pb levels, high Cd levels, high Pb levels, and high Cd and Pb levels than in those with low Cd and Pb levels. Our data show that exposure to Cd and/or Pb can cause abnormal liver function. Cd and Pb may have an antagonistic effect on liver function, and high Cd exposure alone has a more profound effect on abnormal liver function compared with co-exposure to Pb and Cd.

Pb and Cd exposure linked with Il-10 and Il-13 gene polymorphisms in asthma risk relevant immunomodulation in children

Genetic variants and environmental factor of heavy metal exposure accelerate the risk of immune-mediated respiratory diseases, including asthma in children. This study aims to investigate the effects and interaction of Pb, Cd exposure from e-waste and interleukin (IL)-10, IL-13 gene polymorphisms on interleukin expressions in children. Pb, Cd levels, Il-10 (rs1800871, rs1800872, rs1800896) and Il-13 (rs20541, rs1800925) polymorphisms were determined in blood or urine of 155 children (75 from e-waste-exposed area, Guiyu and 80 from reference area, Haojiang). Blood Pb and urine Cd levels of e-waste-exposed children were both higher (mean: 5.89 vs. 3.35 μg/dL; 6.04 vs. 1.82 μg/g, both P < 0.05). Exposed children had a larger proportion of high blood Pb level (> 5.00 μg/dL) (66.67% vs. 4.11%, P < 0.001), but they had no statistically different proportion of high urine Cd level (> 1.00 μg/g creatinine). Median levels of IL-13 decreased (3.674 vs. 4.410 ng/L, P < 0.01), but of IL-10 did not vary in serum of exposed children. The analyses revealed no significant associations of Pb or Cd with Il-10 or Il-13 gene polymorphisms. The high blood Pb and urine Cd level were respectively associated with the low IL-13 ( < 3.696 ng/L) and low IL-10 ( < 0.361 ng/L) level, after adjustment for children's age, gender, and BMI (both P ≤ 0.05). Children homozygous carrying major allele for Il-13 (rs20541 and rs1800925) had additive interactions with high blood Pb level on low IL-13 expression (OR = 5.37, 95% CI: 1.96, 14.73 and OR = 8.45, 95% CI: 2.61, 27.32; both P ≤ 0.001). In contrast, no interaction was observed amongst Pb or Cd with Il-10 gene polymorphisms on its expression. Our findings suggest that Pb exposure interacting with Il-13 gene polymorphisms negatively regulates IL-13 expression, which may pose a risk to abnormal asthma-relevant immunomodulation in preschool children.

Exogenous melatonin improves cadmium tolerance in Solanum nigrum L. without affecting its remediation potential

Although Solanum nigrum L. is a phytoremediator for different metals, its growth and physiology are still influenced by toxic levels of cadmium (Cd). Thus, the development of eco-friendly strategies to enhance its tolerance, maintaining remediation potential is of special interest. The present work aimed to evaluate the effects of exogenous application of melatonin (MT) in the physiological and biochemical responses of S. nigrum and remediation potential exposed to Cd. After 30 days of exposure, the results revealed that Cd-mediated inhibitory effects on biomass and photosynthetic pigment synthesis were efficiently mitigated upon application of melatonin, without affecting Cd accumulation. Higher levels of Cd were found in roots, regardless of the pretreatment with the melatonin. Foliar application of melatonin, however, induced distinctive effects, lowering malondialdehyde (MDA), relative electrical conductivity (REL), and proline levels in shoots. These changes contributed to improvements in the water status, photosynthetic pigment synthesis, and biomass production of S. nigrum under Cd stresses. Overall, our results indicate a protective effect of melatonin on S. nigrum response to excess Cd, contributing to a better tolerance and growth rate, without disturbing its phytoremediation potential. Novelty statement Although Solanum nigrum L. is a phytoremediator for different metals, its growth and physiology are still influenced by toxic levels of cadmium. This study evaluated the potential of melatonin to boost S. nigrum defence against Cd toward a better growth rate and remediation potential.

Microbial diversity in intensively farmed lake sediment contaminated by heavy metals and identification of microbial taxa bioindicators of environmental quality

The cumulative effects of anthropogenic stress on freshwater ecosystems are becoming increasingly evident and worrisome. In lake sediments contaminated by heavy metals, the composition and structure of microbial communities can change and affect nutrient transformation and biogeochemical cycling of sediments. In this study, bacterial and archaeal communities of lake sediments under fish pressure contaminated with heavy metals were investigated by the Illumina MiSeq platform. Despite the similar content of most of the heavy metals in the lagoon sediments, we found that their microbial communities were different in diversity and composition. This difference would be determined by the resilience or tolerance of the microbial communities to the heavy metal enrichment gradient. Thirty-two different phyla and 66 different microbial classes were identified in sediment from the three lagoons studied. The highest percentages of contribution in the differentiation of microbial communities were presented by the classes Alphaproteobacteria (19.08%), Cyanophyceae (14.96%), Betaproteobacteria (9.01%) y Actinobacteria (7.55%). The bacteria that predominated in sediments with high levels of Cd and As were Deltaproteobacteria, Actinobacteria, Coriobacteriia, Nitrososphaeria and Acidobacteria (Pomacocha), Alphaproteobacteria, Chitinophagia, Nitrospira and Clostridia (Tipicocha) and Betaproteobacteria (Tranca Grande). Finally, the results allow us to expand the current knowledge of microbial diversity in lake sediments contaminated with heavy metals and to identify bioindicators taxa of environmental quality that can be used in the monitoring and control of heavy metal contamination.