Renal health and the environment: heavy metal nephrotoxicity

Uric acid mediates the relationship between mixed heavy metal exposure and renal function in older adult people

Background

Population aging is a pivotal trend observed globally, and the exposure to heavy metals can exacerbate the aging process and lead to kidney damage. However, the impact of combined heavy metal exposure on renal function among older individuals remains elusive. Our study employs machine learning techniques to delve into the effects and underlying mechanisms of mixed exposure to heavy metals on the renal function of the aging population.

Methods

This study extracted comprehensive data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2015 and 2020. A total of 3,175 participants aged 60 years and above, with complete information on six metals - lead, cadmium, manganese, cobalt, mercury, and selenium, along with relevant covariates, were included in the study. To assess the impact of single or mixed metal exposure on the renal function of older adult individuals, various statistical techniques were employed: multiple logistic regression, weighted quantitative sum (WQS) regression, Bayesian kernel machine regression (BKMR), and mediation effects analysis.

Results

Multiple logistic regression revealed that selenium and manganese were protective factors for chronic kidney disease (CKD). Cobalt was a risk factor for CKD. High concentrations of lead, cadmium, and cobalt were risk factors for urinary albumin creatinine ratio (ACR). WQS analyses revealed that mixed metal exposure was positively correlated with estimated glomerular filtration rate (eGFR) but negatively correlated with CKD. Selenium and manganese can neutralize the effects of other metals on eGFR. Mixed metal exposure was positively correlated with ACR, with lead and cadmium having a substantial effect. Mediation analysis showed that uric acid (UA) had a mediating effect of 9.7% and -19.7% in the association between mixed metals exposure and proteinuria and CKD, respectively.

Conclusion

The impact of heavy metals on renal function in the older adult differs from that of adolescents and adults. This study suggests that elevated levels of mixed metals exposure are linked to proteinuria and CKD, with UA serving as a mediating factor.

Multimetal exposure: Challenges in diagnostics, prevention, and treatment

Extensive use of heavy metals has posed a serious concern for ecosystem and human too. Heavy metals are toxic in nature and their accumulation in human body causes serious disorders such as neurological disease, cardiac disease, gastrointestinal problems, skin disorders, reproductive disease, lungs diseases, and so on. Furthermore, heavy metals not only affect the human health but also have a negative impact on the economy. In the current review, we have elaborated the impact of heavy metal exposure on human health and socioeconomics. We have discussed the molecular mechanism involved in the heavy metal-induced human disorders such as oxidative stress, neuroinflammation, and protein misfolding. Finally, we discussed the preventive measure and treatment strategy that could counter the negative effects of heavy metal intoxications. In conclusion, there is a substantial correlation between heavy metals and the onset and advancement of several health issues. Chelation treatment could be a useful tactic to lessen the toxic metal load and the difficulties that come with it.

Health of Holochilus chacarius (Rodentia: Cricetidae) in rice agroecosystem in a neotropical wetland assessed by histopathology

Small mammals have a short lifetime and are strictly associated with their environment. This work aimed to use histopathology to assess the health of Holochilus chacarius in a rice agroecosystem in the Pantanal of Mato Grosso do Sul. During necropsy, fragments of the lung, kidney, skin, liver, and reproductive system of 33 animals were collected and submitted to histological processing. Tissue damages were evaluated as mild, moderate, and severe and arranged in a matrix for further statistical analysis. Furthermore, we used generalized linear models to verify the influence of tissue changes on the body condition, obtained by a regression between body mass and length. In the lungs, we found an intense inflammatory infiltrate associated with anthracosis that had a negative influence on the body's condition. Also, we observed degenerative and inflammatory changes in the liver, kidneys, skin, and reproductive system that ranged from mild to moderate. The histopathological lesions observed in this study may be associated with environmental alterations of anthropic origin such as the exposure to soot from wildfires and heavy metals, evidenced by lesions in the lung, kidney, and liver. The present study provided a histopathological matrix as a new approach that allows to classify and quantify the tissue alterations. Tissue changes when associated with body condition demonstrated to be an effective tool to assess the health of small free-living mammals, showing that these animals can be used as bioindicators of environmental condition.

Effects of mixed heavy metals on kidney function in premenopausal and postmenopausal women

OBJECTIVE

To evaluate the relationships between heavy metals (cadmium, lead, and mercury) and their mixtures and estimated glomerular filtration rate (eGFR) in premenopausal and postmenopausal women.

METHODS

Using data from the Korean National Health and Nutrition Examination Survey (2009-2017), multivariate linear regression models, marginal effects, and weighted quantile sum regression, we assessed the associations between single heavy metals and their mixtures and eGFR among 5,372 women.

RESULTS

Risks of reduced eGFR, comorbidities, and heavy metal exposure were found to be higher in postmenopausal women than in premenopausal women. A negative association of cadmium ( β = -2.97; 95% CI, -5.10 to -0.85) and a positive association of mercury ( β = 2.97; 95% CI, 1.49 to 4.44), with eGFR in postmenopausal women. Inverse associations of lead with eGFR in both premenopausal women ( β = -4.75; 95% CI, -6.04 to -3.46) and postmenopausal women ( β = -4.54; 95% CI, -6.96 to -2.13). Interactions were identified between lead and mercury, as well as cadmium and lead for eGFR among premenopausal women ( β = -2.04; 95% CI, -2.98 to -1.10) and postmenopausal women ( β = -3.52; 95% CI, -6.04 to -1.01), respectively. There was a negative association between mixed heavy metals and eGFR in both premenopausal women ( β = -2.23; 95% CI, -3.51 to -0.96) and postmenopausal women ( β = -3.86; 95% CI, -6.89 to -0.83). Lead was found as a key chemical related to reduced eGFR. Cutoff values for each heavy metal concentration related to eGFR were provided.

CONCLUSION

Postmenopausal women were more influenced by mixed heavy metals' effects on kidney function than premenopausal women. Early interventions (eg, water filtering, heavy metal yearly screening) in women, especially postmenopausal women, are needed to reduce the incidence of chronic kidney disease.

Histopathological and health risk assessment of heavy metals in the straw-colored fruit bat, Eidolon helvum, in Nigeria

There is heightening concern regarding heavy metals environmental pollution requiring renewed global attention because of their bioaccumulation and toxicity at varying levels. The concern is most important in the highly migratory Eidolon helvum (E. helvum) that is very common and traverses wide geographical areas within the sub-Saharan Africa. The present study aimed to evaluate levels of cadmium (Cd), lead (Pb), and zinc (Zn) bioaccumulation in 24 E. helvum of both sexes from Nigeria to assess their indirect health risks to the human consumers of the bats in addition to their direct bioaccumulation and toxic damages in the bats themselves based on standard procedures. Lead, Zn, and Cd bioaccumulation concentrations were 2.83 ± 0.35, 0.42 ± 0.03, and 0.05 ± 0.01 mg/kg, respectively, with significant (p < 0.05) Pb bioaccumulation compared to either Cd or Zn in the affected bats. However, only Pb (markedly) and Cd (marginally) bioaccumulated above small mammals' critical threshold levels as there are no existing established threshold levels for bats. Sex played no major role in their bioaccumulation levels. The bioaccumulation levels posed no life-long non-carcinogenic nor carcinogenic risks to the human consumers of the bats at detected concentrations. The observed lungs, liver, and kidney histopathological changes suggested the possible direct effects of the metals in the bats. Nevertheless, other anthropogenic factors might be responsible as no significant (p > 0.05) correlation existed between cellular changes and the bioaccumulation levels. The presence of the heavy metals and their bioaccumulations above critical threshold levels suggested some levels of environmental contamination and pollution, which might have direct and indirect health implications to the bats and their human consumers.

Drinking Water Sources along the Banks of Buriganga River of Bangladesh are Polluted and Possess Serious Health Risks: A Comprehensive In Vivo Analysis

Background

The river Buriganga, one of the major dumping zones of industrial wastes in Bangladesh, is responsible for contaminating the drinking water sources along its length. This study aimed to assess the water quality from these sources by monitoring the changes in hematological, biochemical, and histological parameters caused in healthy rats due to their consumption.

Methods

Using ethylenediaminetetraacetic acid (EDTA) as an anticoagulant agent, hematological and biochemical analyses of Sprague-Dawley rat models were executed in this study. Following blood sampling, the rats were sacrificed, and the heart, lungs, kidneys, liver, and spleen were separated to carry out the histological analysis. Later, to perform the statistical analysis, SPSS, V.25.0 was utilized.

Results

A significant rise (p < 0.02) in body weight was recorded due to increased protein synthesis, inflammations; increased lymphocyte, white blood cell (WBC), and neutrophil count but hemoglobin (20.0 ± 1.39 g/dL vs. 15.25 ± 0.36 g/dL; p) and red blood cell (RBC) count ((6.24 ± 0.45) × 106/µL vs. (5.47 ± 0.34) × 106/µL)) decreased due to infections and hematopoietic stem cell poisoning by pathogens in water samples. Elevated (p < 0.01) serum urea, creatinine, alanine, and aspartate aminotransferase levels indicated kidney malfunction and hepatic tissue necrosis. Histological analysis revealed gross lesions, internal hemorrhages in the brain; inflammations, granulomas, migrating macrophages in the spleen; fibrosis (resulting in hypo-perfusion), and collagen formation in cardiac muscles.

Conclusions

The findings in this study provide comprehensive evidence, based on in vivo analysis, that the water bodies around the Buriganga river are likely to be contaminated with toxic chemicals and microbial entities making them unfit for human consumption.

Acute Oral Administration of Cerium Oxide Nanoparticles Suppresses Lead Acetate-Induced Genotoxicity, Inflammation, and ROS Generation in Mice Renal and Cardiac Tissues

Lead, a highly toxic pollutant, causes numerous health problems and affects nearly all biological systems thus arousing interest in using antioxidants to reduce its toxic effects. Therefore, the undertaken study estimated the influence of cerium oxide nanoparticles (CeO2-NPs) on the lead acetate-induced genotoxicity and inflammation in the kidney and heart tissues of mice. Twenty male mice were randomly divided into negative control and lead acetate and/or CeO2-NPs administrated groups. Comet and diphenylamine assays were conducted to assess the DNA damage and the expression of apoptosis-related genes and inflammatory cytokines were also measured in addition to the estimation of reactive oxygen species (ROS) level. Co-administration of CeO2-NPs significantly reduced the DNA damage and ROS generation caused by lead acetate in the kidney and heart tissues. The co-administration of CeO2-NPs also ameliorated the lead acetate-induced dysregulation in the expression levels of p53, K-ras, interleukin-6, and cyclooxygenase-2 in the kidney and heart. Conclusion: the co-administration of CeO2-NPs suppresses the genotoxicity, inflammation, and ROS generation resulting from lead acetate administration and restoring the genomic DNA integrity; thus, administration of CeO2-NPs is recommended to minimize the lead acetate-induced hazards.

Estimation of Ecological and Human Health Risks Posed by Heavy Metals in Street Dust of Madrid City (Spain)

In this work, sampling was carried out in the urban area of Madrid to analyze the content of total heavy metals (Zn, Pb, Cu, Cr, Ni, and Cd) in the street dust. Contamination was evaluated using various indices, such as the Contamination Factor (CF), Enrichment Factor (EF), Geo-accumulation Index (Igeo), Potential Ecological Risk Index (RI), Pollution Load Index (PLI), the Human Health Index Hazard Index (HI), and Cancer Risk (CR). Pollution indices were related to traffic density and color. Traffic density was the factor that most influenced the values of the pollution indexes, but no significant differences were found with the color of street dust. The concentration of heavy metals in the urban dust of Madrid had the following sequence: Zn (895) > Cu (411) > Pb (290) > Cr (100) > Ni (42) > Cd (1.25 mg kg−1). The pollution levels were high or very high in Pb, Zn, and Cd regarding the environmental pollution indexes. Ingestion was the main route of exposure to heavy metals contained in street dust. The CR for adults and children is less than 1 × 10−6, which means that there is no risk for the population. However, the HI was 10 times higher in children than in adults.

Lead exposure-induced changes in hematology and biomarkers of hepatic injury: protective role of TrévoTM supplement

Lead exposure has been linked to health challenges involving multiple organ failure. More than fifty percent of lead present in the human body is accumulated in the liver causing hepatic injury. A major mechanism of lead toxicity is oxidative stress. TrévoTM is a nutritional supplement with numerous bioactive natural products with detoxifying and antioxidant properties. This study was designed to investigate the hepatoprotective effects of TrévoTM dietary supplements against lead-hepatotoxicity in male Wistar rats. Thirty-five healthy animals were divided into five groups of seven each as follows: Group I=control; II=15 mg/kg of lead acetate (PbA); III= 2 mL/kg of TrévoTM + PbA; IV= 5 mL/kg of TrévoTM + PbA;V=5 mL/kg of TrévoTM . Animals were orally treated with TrévoTM for two days before co-administration with PbA intraperitoneally for 12 consecutive days. Animals were sacrificed 24 h after the last administration and blood were collected via cardiac puncture and processed for hematological parameters and assessment of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and albumin (ALB). The liver was excised and processed for markers of oxidative stress and histopathological examination. Intraperitoneal administration of 15 mg/kg of PbA caused a significant increase in serum concentration of AST, ALT, while the concentration of ALB was significantly decreased (P<0.001). PbA caused a significant reduction in packed cell volume, hemoglobin while the total white blood cell count, neutrophils, lymphocytes, monocytes, eosinophils, and basophils were increased. Oxidative stress was significantly pronounced in the liver of rats exposed to PbA as observed in the high concentration of malonedialdehyde, decreased concentration of glutathione, the activity of catalase, superoxide dismutase, and glutathione-S-transferase. Pretreatment with TrévoTM was able to significantly prevent the anemic, oxidative damage, and hepatic injury initiated by PbA. Histological examination also corroborated the biochemical results. In conclusion, the study reveals that TrévoTM is effective in attenuating PbA-induced hepatotoxicity in male Wistar rats.

Effect of pre-treatment and drying methods on the content of minerals, B-group vitamins and tocopherols in kale (Brassica oleracea L. var. acephala) leaves

Dried vegetables are widely used in food production. Kale leaves, due to their high health-promoting properties, can be a valuable raw material for drying. The aim of the study was to evaluate the effect of blanching, drying methods (air-drying, freeze-drying), the time and temperature of storage on the content of ash, minerals, vitamins B₁, B₂, and tocopherols in dried kale products. The dried products were evaluated directly after processing and after 12 months of storage at ambient temperature, 18–20 °C and cold temperature, 8–10 °C. In 100 g dry matter from fresh raw material the dominant minerals were potassium (2613 mg), calcium (1346 mg), phosphorus (432 mg), magnesium (129 mg). Kale leaves had 0.828 mg vitamin B₁, 1.533 mg vitamin B₂ and 16.55 mg total tocopherols per 100 g of dry matter. Blanching, applied prior to drying, significantly reduced the levels of minerals (3–38%) and vitamins (8–45%), except for calcium, zinc and manganese. This pre-treatment had, however, a beneficial effect, especially on vitamin retention during the storage of dried products. After 12 month storage, the losses of vitamin B₁, B₂ and total tocopherols in dried, previously blanched, raw materials ranged from 3 to 10%, 1 to 4%, and 1 to 16%, respectively, depending on the type of sample. In the dried products obtained from unblanched raw material, the losses were larger and amounted to 10–17%, 8–16% and 4–17%, respectively. Throughout drying and storage, the minerals examined were fairly stable. Dried kale is generally a good source of minerals and vitamins. However, blanching before drying is recommended. In addition, freeze-drying and storage in cold temperature allows for higher vitamin preservation in dried kale.

Heavy Metal Accumulation in Rice and Aquatic Plants Used as Human Food: A General Review

Aquatic ecosystems are contaminated with heavy metals by natural and anthropogenic sources. Whilst some heavy metals are necessary for plants as micronutrients, others can be toxic to plants and humans even in trace concentrations. Among heavy metals, cadmium (Cd), arsenic (As), chromium (Cr), lead (Pb), and mercury (Hg) cause significant damage to aquatic ecosystems and can invariably affect human health. Rice, a staple diet of many nations, and other aquatic plants used as vegetables in many countries, can bioaccumulate heavy metals when they grow in contaminated aquatic environments. These metals can enter the human body through food chains, and the presence of heavy metals in food can lead to numerous human health consequences. Heavy metals in aquatic plants can affect plant physicochemical functions, growth, and crop yield. Various mitigation strategies are being continuously explored to avoid heavy metals entering aquatic ecosystems. Understanding the levels of heavy metals in rice and aquatic plants grown for food in contaminated aquatic environments is important. Further, it is imperative to adopt sustainable management approaches and mitigation mechanisms. Although narrowly focused reviews exist, this article provides novel information for improving our understanding about heavy metal accumulation in rice and aquatic plants, addressing the gaps in literature.

Synthetic Amphoteric Cryogels as an Antidote against Acute Heavy Metal Poisoning

The effectiveness of an amphoteric cryogel (AAC) as an oral sorbent (enerosorbent) for the treatment of acute poisoning of small animals (rats) with heavy metals (HMs) was studied in in vivo experiments. The morphological structure of the cryogel was examined using scanning electron microscopy/energy-dispersive X-ray analysis and confocal microscopy. The use of the cryogel in the treatment of rats administered an LD₅₀ dose of Cd(NO₃)₂, CsNO₃, Sr(NO₃)₂, or HgCl₂ in aqueous solution showed their high survival rate compared to the control group, which did not receive such treatment. The histological and chemical analysis of internal tissues and the biochemical analysis of the blood of the experimental animals showed the effectiveness of the cryogel in protecting the animals against the damaging effect of HMs on the organism comparable with unithiol, a chelating agent based on 2,3-dimercapto-1-propane sulfonic acid sodium salt (DMPS) approved for the treatment of acute poisoning with some heavy metals.

The Associations between Blood and Urinary Concentrations of Metal Metabolites, Obesity, Hypertension, Type 2 Diabetes, and Dyslipidemia among US Adults: NHANES 1999-2016

Background

Heavy metals are well known to be associated with cancer outcomes, but its association with obesity and cardiometabolic risk outcomes requires further study.

Methods

Adult data from the National Health and Examination Survey (NHANES Continuous 1999-2016, n = 12,636 to 32,012) with data for blood or urinary metals concentrations and body mass index were used. The study aim was twofold: (1) to determine the association between heavy metals and obesity and (2) to examine the influence of heavy metals on the relationship between obesity and hypertension, type 2 diabetes, and dyslipidemia. Logistic regression was used to examine the main effects and interaction effects of metals and obesity for the odds of prevalent hypertension, type 2 diabetes, and dyslipidemia. Models were adjusted for age, gender, ethnicity, smoking status, physical active status, and poverty-income ratio, with additional adjustment for creatinine in models with the urinary measures of heavy metals. High-low concentration categories were defined by grouping metal quintiles with the most similar associations with obesity.

Results

Blood lead had a negative linear association with obesity (odds ratio (OR)  = 0.42, 95% confidence interval (CI) = 0.37-0.47). In those with obesity, high blood lead was associated with lower risk of prevalent dyslipidemia, while no association was found in those without obesity. The study observed a curvilinear relationship between urinary antimony and obesity with the moderate group having the highest odds of obesity (OR = 1.36, 1.16-1.59). However, the relationship between urinary antimony and prevalent hypertension and dyslipidemia risk was linear, positive, and independent of obesity. While not associated with prevalent obesity risk, high urinary uranium was associated with 30% (P=0.01) higher odds for prevalent type 2 diabetes.

Conclusions

The impact of environmental factors on obesity and health may be complex, and this study reinforces the heterogeneous relationship between various metals, obesity, and obesity-related metabolic diseases even at levels observed in the general population.

The Groundwater Geochemistry and the Human Health Risk Assessment of Drinking Water in an Area with a High Prevalence of Chronic Kidney Disease of Unknown Etiology (CKDu), Sri Lanka

Chronic kidney disease of unknown etiology (CKDu) has become an alarming health issue in Sri Lanka. The disease is more notable among farming communities and people who consume groundwater as their main source of drinking water. To assess the possible links between drinking water chemistry and expansion of CKDu, the study was compared with hydrogeochemical data of drinking water sources in a CKDu prevalent area (Girandurukotte GND, Badulla District) and a reference area (Dambethalawa GND, Ampara District) in Sri Lanka. Based on the results, nephrotoxic heavy metal (Cd, Cr, Pb, and As) concentrations were significantly higher in the CKDu prevalent site than the reference area, compromised the harmful consequences to the people in the CKDu hotspot. Results of the inverse distance weighted (IDW) interpolation tool indicated the nephrotoxic heavy metals contents including Cd, Pb, As, and Cr in CKDu hotspot were changed in the ranges of 9.78–187.25 μg/L, 0.08–0.66 μg/L, 20.76–103.30 μg/L, and 0.03–0.34 μg/L. The random distribution patterns were shown by the result in Moran’s index values. Noteworthy, the results have emphasized a strong association between fluoride and water hardness. The frequency of occurrence above the threshold limit of fluoride was 28% in non-CKDu water samples, while 81% in CKDu prevalent sites. The hardness values in the CKDu prevalent site indicated “moderately hard water,” while the non-CKDu area indicated the “soft water.” Furthermore, this paper quantified overall water quality and heavy metal contamination and assessed the human health risks associated with drinking water. According to the results of the water quality index, 90% of the samples in the CKDu prevalent area were classified as “poor water” and “very poor water” for drinking purposes, while 73.33% of the samples in the non-CKDu area were “good” and “excellent” for drinking usage. Calculated chronic daily intake (CDIoral) and hazard quotient (HQoral) of nephrotoxicants were higher in CKDu hotspot than the non-CKDu site. Besides, the hazard index (HI) values obtained for the CKDu prevalent area exceeding the acceptable limit (HI = 1) indicated potential health risks to the people in those areas. This study suggests that long-term exposure to nephrotoxic heavy metals, water hardness, and fluoride present in drinking water may threaten human health and affect kidney functions. Therefore, regular monitoring and better management of water supplies in CKDu prevalent areas are essential to determine the contamination load and reduce the health impacts due to excessive and long-term exposure to the nephrotoxicants.

Addressing the Challenge of Potentially Hazardous Elements in the Reduction of Hypertension, Diabetes and Chronic Kidney Disease in the Caribbean

BACKGROUND

Environmental surveys have characterized trace elements such as lead (Pb), cadmium (Cd) and arsenic (As) as potential risk factors for non-communicable diseases. There have been few studies conducted in the Caribbean region to explore, define or clarify such findings locally. Furthermore, local pollution control efforts are often juxtaposed against more seemingly immediate economic concerns in poor communities.

OBJECTIVES

The present commentary is a call to action for the evaluation of potentially hazardous elements as potential risk indicators and/or factors of common noncommunicable diseases in the Caribbean.

DISCUSSION

Findings from Jamaican studies have identified exposure to potentially hazardous elements (PHE) via water, food, and other anthropogenic activities to the detriment of the resident population. Several attempts have been made to abate toxic metal exposure in children with relative success. However, high levels of PHE have been noted in vulnerable populations such as patients with hypertension, diabetes mellitus and chronic kidney disease. Currently, there is low priority towards infrastructure building within the Caribbean region that would promote and sustain long term monitoring and better inform environmental polices impacting chronic diseases.

CONCLUSIONS

Further investigations are needed to clarify the role that PHE play in increasing the risk or progression of non-communicable diseases, especially in vulnerable groups.

COMPETING INTERESTS

The authors declare no competing financial interests.

Lead Exposure Influences Serum Biomarkers, Hepatocyte Survival, Bone Marrow Hematopoiesis, and the Reproductive Cycle in Japanese Quails

Lead toxicity has been a hallmark issue of toxicology over the last decades. However, predictive and non-robust models did not provide complete data on low-dose lead interaction with the organism at different functional levels (e.g., blood-serum-liver-bone marrow-bursa fabricii-reproductive system axis). Japanese quails are an animal model with a strong immune system, making them suitable for the thorough assessment of in vivo chronic lead toxicity. In this study, we have exposed Japanese quails via water ingestion to 0.25 and 0.5 μg/mL lead(II) chloride (PbCl₂) for 20 days and assessed blood cells, serum biomarkers, hepatocyte survival, bone marrow hematopoiesis, bursa fabricii, and lead accumulation in eggs. Blood cells passed through morphological alterations (loss and inversion of the erythrocyte nucleus, multiple erythrocyte and thrombocyte aggregation, lymphocyte degradation, and blast cell infiltration). In the serum, PbCl₂ increased the activity of creatine kinase (CK) and lactate dehydrogenase (LDH); increased the level of cholesterol, sodium, creatinine, and urea; and reduced the level of proteins, triglycerides, chloride, potassium, calcium, and alkaline phosphatase (ALP) activity (P < 0.05). Liver tissue of the exposed animals exhibited apparent death of hepatocytes. In the bone marrow, macrophages and heterophils contained a vast number of the infiltrated/uptaken granules upon PbCl₂ exposure. Ultimately, PbCl₂ exposure elicited a series of events observed first in the blood and serum parameters and later translated to the hematopoietic centers.

Regulatory Role of Nano-Curcumin against Tartrazine-Induced Oxidative Stress, Apoptosis-Related Genes Expression, and Genotoxicity in Rats

The present study evaluates the regulatory effect of Nano-Curcumin (Nano-CUR) against tartrazine (TZ)-induced injuries on apoptosis-related gene expression (i.e., p53, CASP-3 and CASP-9), antioxidant status, and DNA damages in bone marrow in treated rats. Male rats were arbitrarily separated into five groups, and each group was comprised of 10 rats each. The 1st group served as control (G1). The 2nd group ingested 7.5 mg TZ/kg. b.w. (body weight). The 3rd group ingested Nano-CUR 1 g/kg b.w. The 4th and 5th groups were respectively administered with (1 g Nano-CUR + 7.5 mg TZ/kg. b.w.) and (2 g Nano-CUR + 7.5 mg TZ/kg. b.w.). At the end of the experiment, blood samples, livers, and kidneys were collected. Livers and kidneys were homogenized and used for the analysis of reduced glutathione, malonaldhyde, total antioxidant capacity, lipid peroxide antioxidant enzyme activities, apoptosis-related gene expression, and genotoxicity by comit test. The ingestion of TZ for 50 days resulted in significant decreases in body, and kidney weights in rats and a relative increase in the liver weight compared to control. In contrast, the ingestion of Nano-CUR with TZ remarkably upgraded the body weight and relative liver weight compared to the normal range in the control. Aditionally, TZ ingestion in rats increased the oxidative stress biomarkers lipid peroxide (LPO) and malonaldehyde (MDA) significantly, whereas it decreased the reduced glutathione (GSH) levels and total antioxidant capacity (TAC). Similarly, the levels of glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) significantly deteriorated in response to TZ ingestion. Moreover, the results revealed a remarkable up-regulation in the level of expression for the three examined genes, including p53, CASP-3, and CASP-9 in TZ-ingested rats compared to the control. On the other hand, the comet assay result indicates that the ingestion of TZ induced DNA damage in bone marrow. Notably, the administration of Nano-CUR protected the kidney and liver of TZ-ingested rats as evidenced by a significant elevation in all antioxidant activities of tested enzymes (i.e, SOD, GPx, and CAT), vital recovery in GSH and TAC levels, and a statistical decrease in LPO and MDA compared to TZ-ingested rats. Interestingly, the ingestion of rats with TZ modulates the observed up-regulation in the level of expression for the chosen genes, indicating the interfering role in the signaling transduction process of TZ-mediated poisoning. The results indicate that the administration of Nano-CUR may protect against TZ-induced DNA damage in bone marrow. According to the results, Nano-CUR exerted a potential protective effect against oxidative stress, DNA damage, and the up-regulation of apoptosis-related genes induced by TZ ingested to rats.

Bioaccumulation of Mineral Elements in Different Biological Substrates of Athletic Horse from Messina, Italy

The objective of this study was to evaluate the levels and the potential bioaccumulation of vanadium (V), chromium (Cr), cobalt (Co), copper (Cu), zinc (Zn), cadmium (Cd), lead (Pb), and bismuth (Bi) in horses from the industrial risk area of Sicily (Italy). Different biological substrates (whole blood, serum; tail and mane) and samples of hay, concentrate and water provided to the horses were processed by means of Thermo Scientific iCAP-Q ICP-MS spectrometer for mineral concentration. One-way analysis of variance (ANOVA) was applied to show the differences in various trace elements in the biological substrates. Pearson's test was applied to evaluate the correlation of mineral concentrations between whole blood and serum; and tail and mane. The results showed statistical differences of tested mineral elements among biological substrates; Cr whole blood concentrations were negatively correlated with serum concentrations and a positive correlation between whole blood and serum was observed for Cd and Bi. This latter also showed a positive correlation between mane and tail. The concentrations of V, Cr, and Pb in tail with serum and whole blood samples were negatively correlated, while the concentrations of Cd in tail and serum samples were positively correlated. Minerals had a non-homogenous distribution in the organism, showing different concentrations in the biological substrates.

Contamination of staple crops by heavy metals in Sibaté, Colombia

Heavy metal contamination in water resources, soil, and food sources is an issue that compromises food safety in Sibaté, Colombia. In the present study concentration of heavy metals [HMs], such as Cu, As, Pb, Cr, Zn, Co, Cd and Ni, present in vegetables included in the typical Colombian diet were measured. The study was conducted as follows: samples of parsley, artichoke and carrots produced in a location near the Muña dam were collected, where the Bogotá River water is treated for use as a water resource. To determine food safety, national and international [HMs] established limits were compared with quantified [HMs] in samples of different vegetable parts and of the surrounding soil. Fresh samples were separated in their respective parts for cold acid digestion with HCl and HNO₃ (1:1) for 15 days. Heavy metal mean ± standard error (SE) were as follows (mg/kg) As 2.36 ± 0.185, Cd 0.16 ± 0.009, Co 0.43 ± 0.019, Cr 12.1 ± 0.453, Cu 13.1 ± 1.68, Ni 0.00, Pb 7.07 ± 0.482 and Zn 3.976 ± 0.332. Cd, Cr, As, Co and Ni showed high transfer factor in Cynara scolymus. Moreover, high Pb, Cu and Zn transfer factor were present in Petroselinum crispum. Except for Daucus carota roots, there was a high metal transfer specifically in Petroselinum crispum leaves and other different plant parts, with high transfer factor for Cr, As, Co, Pb, Cu and Zn.

Silymarin protects the structure of kidney in the neonatal rats exposed to maternal cadmium toxicity: A stereological study

The present study aimed to investigate the protective effect of silymarin on maternal cadmium toxicity complications in the kidney of neonatal rats. Forty adults Wistar female rats were selected and placed with male rats for copulation. The pregnant animals were randomly divided into five groups (n = 8) including control, sham, silymarin, cadmium, and silymarin + cadmium. The animals received 400 mg L^-1 cadmium and 100 mg kg^-1 silymarin (sub-cutaneously, three days per week, three weeks). Two-day neonates were dissected and their right kidneys were fixed in 10.00% buffered formalin solution and processed by standard paraffin embedding. Tissue sections were stained by hematoxylin and eosin and analyzed histologically and stereologically. The data were statistically analyzed by SPSS using a one-way ANOVA test and Tukey's post-hoc. The results showed that silymarin significantly increased the neonatal rats' weight compared to the control group. Cadmium significantly decreased the weight of neonatal rats' kidneys. The results of histological studies indicated that cadmium caused subacute glomerulosclerosis, severe damage to urinary tubules such as tubular necrosis, and severe hyperemia in the medulla, but silymarin could preserve these complications. Stereological results revealed that cadmium decreased the total volume of kidney, medulla, and proximal and distal tubules and increased interstitial tissue and indicated the protective effects of silymarin on maternal cadmium toxicity complications in the kidney tissue of neonatal rats. It can be concluded that the administration of silymarin during pregnancy may be used as a useful and effective way of protecting the maternal cadmium toxicity complications in the kidney tissue of neonatal rats.

Ameliorative effect of curcumin against lead acetate-induced hemato-biochemical alterations, hepatotoxicity, and testicular oxidative damage in rats

Lead, toxic heavy metal of global concern, induces toxicity in various organs via oxidative stress. Thereby, in this study, the protective role of curcumin against lead acetate-induced toxicity was evaluated. Thirty-two male albino rats were allocated equally into four groups and orally administered with corn oil as a vehicle (Cont.), curcumin (CUR) (400 mg/kg bw), lead acetate (LA) (100 mg/kg bw), and lead acetate plus curcumin (LA + CUR). All rats had received their treatments daily for 4 weeks. The results revealed that LA toxicity induced normocytic normochromic anemia with significant leukocytosis and lymphocytosis. Moreover, LA-intoxicated rats showed a marked elevation in the liver enzyme activities, serum cholesterol, and triglyceride levels. In contrast, sero-immunological parameters, total protein, albumin, globulin, and testosterone levels were significantly reduced compared to the control rats. Additionally, LA-induced hepatic and testicular oxidative damage revealed by marked increased in MDA level with prominent reduction in the antioxidant system. The gene expression of the hepatic pro-inflammatory markers and testicular steroidogenic biomarkers including LHR and aromatase were significantly upregulated; meanwhile, the expressions of testicular StAR, CYP17a, 3B-HDS, SR-B1, and P450SCC were significantly downregulated in the LA-intoxicated group. Curcumin treatment could partially improve the hematological, biochemical, and histopathological alterations induced by LA. Also, it was observed that curcumin significantly restored hepatic pro-inflammatory markers and testicular steroidogenic enzymes. In conclusion, curcumin has antioxidant, anti-inflammatory, and immunomodulatory effects and is able to minimize the LA-induced oxidative damage in rats.

High Incidence of Moderately Reduced Renal Function and Lead Bioaccumulation in Agricultural Workers in Assin South District, Ghana: A Community-Based Case-Control Study

Background

The quest to enhance agricultural productivity and crop yields has led to increased use of agrochemicals on a global scale. Long-term use of these agrochemicals may be associated with adverse health implications.

Objective

To assess haematological indices, renal function, heavy metal bioaccumulation in farmers and sprayers, and their use of personal protective equipment (PPE).

Materials and Methods

This community-based case-control study was conducted from January 2018 to June 2018 in the Assin South District, Central Region, Ghana. A total of 144 participants were conveniently sampled: 83 agricultural workers (cases) and 61 indigenes with no direct exposure to agrochemicals (controls). Structured questionnaire was used to obtain demographic data as well as agricultural work practices followed by cases. Venous blood samples were drawn from participants and used for estimating full blood count and renal function (serum creatinine (CRE), blood-urea nitrogen (BUN), BUN : CRE ratio, and estimated GFR (eGFR)). Serum lead, arsenic, and cadmium levels were estimated using the Varian AA 240FS atomic spectrometer in an acetylene-air flame.

Results

The median RBC (4.49 vs. 4.92 × 10¹²/L), haemoglobin (12.50 vs. 13.70 g/dL), and platelet (220.00 vs. 268.00) counts were significantly lower in cases. A significantly higher proportion of cases were classified as anaemic or having microcytic cells compared to controls. Also, serum urea (4.08 vs. 3.41; p=0.0009), creatinine (108.10 vs. 101.10; p=0.0286), and BUN : CRE ratio (19.75 vs. 17.84) were significantly higher in cases. Additionally, 18.1% of cases were classified as having moderately reduced renal function compared to only 6.6% of controls. Moreover, a significantly higher proportion of cases had detectable serum lead (55.6% vs. 16.4%) and arsenic (53.1% vs. 9.8%) levels compared to controls. However, on average, 80% of agricultural workers did not use personal protective equipment (PPE) when applying agrochemicals; 84.3% of used agrochemical containments were discarded near the river/canal.

Conclusion

Neglect of the use of PPE may be predisposing the agrochemical workers and community to lead and arsenic bioaccumulation with a consequent reduced haematological and renal function.

Cell Death in the Kidney

Apoptotic cell death is usually a response to the cell's microenvironment. In the kidney, apoptosis contributes to parenchymal cell loss in the course of acute and chronic renal injury, but does not trigger an inflammatory response. What distinguishes necrosis from apoptosis is the rupture of the plasma membrane, so necrotic cell death is accompanied by the release of unprocessed intracellular content, including cellular organelles, which are highly immunogenic proteins. The relative contribution of apoptosis and necrosis to injury varies, depending on the severity of the insult. Regulated cell death may result from immunologically silent apoptosis or from immunogenic necrosis. Recent advances have enhanced the most revolutionary concept of regulated necrosis. Several modalities of regulated necrosis have been described, such as necroptosis, ferroptosis, pyroptosis, and mitochondrial permeability transition-dependent regulated necrosis. We review the different modalities of apoptosis, necrosis, and regulated necrosis in kidney injury, focusing particularly on evidence implicating cell death in ectopic renal calcification. We also review the evidence for the role of cell death in kidney injury, which may pave the way for new therapeutic opportunities.

Assessment of Heavy Metals and Color as Indicators of Contamination in Street Dust of a City in SE Spain: Influence of Traffic Intensity and Sampling Location

In the present work, a sampling grid of the urban core of the city of Murcia (South East Spain) was designed in order to analyze street dust, focusing on the contents of the heavy metals Cd, Cr, Cu, Ni, Pb, and Zn and their relationships with the color of the sample, the traffic pattern, and the location where they were sampled (sidewalks, ledges, and roads). The characterization of the samples was carried out by X-ray diffraction and scanning electron microscopy, whereas the heavy metals were extracted by acid digestion and determined by inductively coupled plasma mass spectrometry. The concentration (mg/kg) in urban dust of the city of Murcia was highest for Zn (653), followed by Cu (201) > Pb (177) > Cr (117) > Ni (51) >> Cd (0.5). The color expounded statistically significant differences with regard to the heavy metals, including the pollutant load. The same pattern was found when the classification variable was the traffic intensity, except in the case of Ni. The areas with a higher risk of contamination by heavy metals in the urban dust are the ledges of narrow city center streets with moderate traffic, where Zn and Pb seem to accumulate most greatly.

Environmental toxin-induced acute kidney injury

Human beings are exposed to various potentially toxic agents and conditions in their natural and occupational environments. The kidney, due to its concentrating ability and excretory function, is highly vulnerable to the effects of environmental toxins. Identifying the precise cause and mechanisms of environmentally induced renal injury remains a challenge for which various scientific disciplines need to be involved. Investigations in this field are confronted with the apparent infinite types of toxins, their mutual interaction, handling/metabolization by the body, ways of exposure, etc. Although interdisciplinary efforts and persistence are required to identify, mechanistically unravel and tackle environmental toxin-induced pathologies, research eventually pays off in ameliorated working/living conditions and development of preventive/therapeutic strategies. This review was compiled to particularly emphasize the need for a maintained awareness of environmental threats in general and those targeting the kidney. Different mechanisms of renal toxicity are illustrated and discussed, thereby focusing on three types of environmental toxins, namely aristolochic acid, melamine and heavy metals.

Occupational exposure to respirable crystalline silica and chronic non-malignant renal disease: systematic review and meta-analysis

Background

While occupational exposure to respirable silica is known to lead to lung disease, most notably silicosis, its association with chronic kidney disease is unclear.

Objectives

This review explores the association between occupational exposure to respirable silica and chronic non-malignant renal disease such as glomerulonephritis. The evidence has been collected and compiled. Possible sources of bias are thoroughly discussed.

Methods

Cohort studies with silica exposure and case–control studies of renal disease were searched in PubMed until January 2015. Two authors independently abstracted data; any disagreement was resolved by consulting a third reviewer. A meta-analysis was performed to evaluate the association to silica exposure.

Results

A total of 23 cohort and four case–control studies were included in the analysis. The meta-analysis of cohort studies yielded elevated overall SMRs for renal disease. Some studies, however, included dose–response analyses, most of which did not show a positive trend. The approaches and results of the case–control studies were very heterogeneous.

Conclusions

While the studies of cohorts exposed to silica found elevated SMRs for renal disease, no clear evidence of a dose–response relationship emerged. The elevated risk may be attributed to diagnostic and methodological issues. In order to permit a reliable estimation of a possible causal link, exposed cohorts should be monitored for renal disease, as the information from mortality studies is hardly reliable in this field.

Electronic supplementary material

The online version of this article (doi:10.1007/s00420-017-1219-x) contains supplementary material, which is available to authorized users.

Physical Activity and Blood Lead Concentration in Korea: Study Using the Korea National Health and Nutrition Examination Survey (2008-2013)

Physical activity normally has a positive influence on health, however it can be detrimental in the presence of air pollution. Lead, a heavy metal with established adverse health effects, is a major air pollutant. We evaluated the correlation between blood lead concentration and physical activity using data collected from the Korea National Health and Nutrition Examination Survey. Multivariate logistic regression analysis was performed after dividing participants according to whether they were in the top 25% in the distribution of blood lead concentration (i.e., ≥ 2.76 µg/dL), with physical activity level as an independent variable and adjusting for factors such as age, sex, drinking, smoking, body mass index, region, and occupation. The high physical activity group had greater odds of having a blood lead concentration higher than 2.76 µg/dL (odds ratio 1.29, 95% CI 1.11-1.51) compared to the low physical activity group. Furthermore, blood lead concentration is correlated with increasing physical activity.

Cadmium Exposure and Potential Health Risk from Foods in Contaminated Area, Thailand

Man-made cadmium (Cd) emissions can be transported between environmental matrices and the food chain. Food is the primary source of Cd exposure among general population as a consequence of the bio-concentration of Cd from soil. Chronic Cd exposure has been reported to be associated with chronic kidney disease, osteoporosis, diabetes, cardiovascular disease and cancer. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) established the safe level of Cd intake as provisional tolerable monthly intake (PTMI) of 25 μg/kg bw in 2010. The major food groups that contribute to the most Cd exposure are rice and grains, shellfish and sea food, meat including edible offal, and vegetables. A number of studies reported the high Cd contaminated levels in foods from polluted areas in Thailand. The results are of high concern since the contaminations occur in foods that are major Cd contributors. Thus, in this review, the current situations of Cd contaminated foods in polluted areas of Thailand are summarized. In addition, the Cd intakes from selected scenarios are estimated to assess the potential health risk to consumers and the suggestions are also included.

Simultaneous exposure to multiple heavy metals and glyphosate may contribute to Sri Lankan agricultural nephropathy

BACKGROUND

Sri Lankan Agricultural Nephropathy (SAN), a new form of chronic kidney disease among paddy farmers was first reported in 1994. It has now become the most debilitating public health issue in the dry zone of Sri Lanka. Previous studies showed SAN is a tubulo-interstitial type nephropathy and exposure to arsenic and cadmium may play a role in pathogenesis of the disease.

METHODS

Urine samples of patients with SAN (N = 10) from Padavi-Sripura, a disease endemic area, and from two sets of controls, one from healthy participants (N = 10) from the same endemic area and the other from a non-endemic area (N = 10; Colombo district) were analyzed for 19 heavy metals and for the presence of the pesticide- glyphosate.

RESULTS

In both cases and the controls who live in the endemic region, median concentrations of urinary Sb, As, Cd, Co, Pb, Mn, Ni, Ti and V exceed the reference range. With the exception of Mo in patients and Al, Cu, Mo, Se, Ti and Zn in endemic controls, creatinine adjusted values of urinary heavy metals and glyphosate were significantly higher when compared to non-endemic controls. Creatinine unadjusted values were significant higher for 14 of the 20 chemicals studied in endemic controls and 7 in patients, compared to non-endemic controls. The highest urinary glyphosate concentration was recorded in SAN patients (range 61.0-195.1 μg/g creatinine).

CONCLUSIONS

People in disease endemic area exposed to multiple heavy metals and glyphosate. Results are supportive of toxicological origin of SAN that is confined to specific geographical areas. Although we could not localize a single nephrotoxin as the culprit for SAN, multiple heavy metals and glyphosates may play a role in the pathogenesis. Heavy metals excessively present in the urine samples of patients with SAN are capable of causing damage to kidneys. Synergistic effects of multiple heavy metals and agrochemicals may be nephrotoxic.

Is a long term work in automotive industry a risk factor for renal dysfunction?

Background:

Disorders of renal system can cause renal failure; therefore screening is necessary especially in workers who are exposed to harmful materials. Hypertension, diabetes mellitus, and hazardous exposures are non-occupational and occupational risk factors for renal diseases.

Aim:

The objective of this study was to determine the effects of working in automotive industry on renal function in Iran.

Subjects and Methods:

In a historical cohort study, workers of automotive industry who worked in production and had low exposure to metal fumes were selected and divided to three groups with 5–10, 11–20, and 21–30 years work duration. risk factors for renal diseases were collected and analyzed with SPSS using one-way ANOVA, correlation coefficient and with P < 0.05 and relative risk with a confidence interval (CI).

Results:

The means of work duration in Groups (A), (B) and (C) were 9.8 (0.6), 13.8 (2.0), 22.3 (1.6) years respectively with ANOVA (F) =187.864 and P < 0.01. Glomerular filtration rate (GFR) was 59.75 (0.70), 59.16 (1.52) and 59.10 (2.23) in Groups (A), (B), and (C) respectfully The relative risk of creatinine clearance, uric acid and mean blood pressure were the highest in Group (B); 1.970 - CI, 0.541–7.169, 1.571 95% CI: 0.198–12.470, and 1.519 95% CI: 0.425–5.426, but the differences were not significant.

Conclusion:

GFRs were decreased with work duration, but the differences were not significant. Working in automotive Industry with low exposure to toxic metals and solvents has no significant effect on GFR, creatinine clearance, uric acid, and mean blood pressure.

Study on the in vivo toxic mechanism of xixin based on trace elements determination by inductively coupled plasma-mass spectrometry

Background:

Xixin has been widely used as a traditional Chinese medicine for headache, toothache and inflammatory diseases. Clinical investigation indicated that adverse drug reactions occurred with an overdose of xixin, but the toxic mechanism of xixin in vivo based on trace elements has not been researched yet.

Objective:

To explore the in vivo toxic mechanism of xixin induced by trace elements.

Materials and Methods:

The contents of trace elements in the serum and liver of mice were determined by inductively coupled plasma-mass spectrometry (ICP-MS) after obtaining xixin extracts. Principal component analysis (PCA) and cluster analysis (CA) were performed between the trace elements’ content and dosage using the software GeneSpring 12.1 to analyze the main toxic elements in vivo.

Results:

Trace elements’ contents were obviously raised after xixin extracts were taken as a dosage of 150 mg/mL and 50 mg/mL, respectively. Na, Ca, Cu and Cd in serum and Ca and Zn in liver were the main trace elements inducing the toxic reaction of xixin.

Conclusion:

Xixin possesses the potential function of indirectly upregulating trace elements in vivo. This study, for the first time, elucidated the in vivo toxic mechanism of xixin based on trace elements. This method could also be utilized in the research of corresponding aspects.

Glyphosate, hard water and nephrotoxic metals: are they the culprits behind the epidemic of chronic kidney disease of unknown etiology in Sri Lanka?

The current chronic kidney disease epidemic, the major health issue in the rice paddy farming areas in Sri Lanka has been the subject of many scientific and political debates over the last decade. Although there is no agreement among scientists about the etiology of the disease, a majority of them has concluded that this is a toxic nephropathy. None of the hypotheses put forward so far could explain coherently the totality of clinical, biochemical, histopathological findings, and the unique geographical distribution of the disease and its appearance in the mid-1990s. A strong association between the consumption of hard water and the occurrence of this special kidney disease has been observed, but the relationship has not been explained consistently. Here, we have hypothesized the association of using glyphosate, the most widely used herbicide in the disease endemic area and its unique metal chelating properties. The possible role played by glyphosate-metal complexes in this epidemic has not been given any serious consideration by investigators for the last two decades. Furthermore, it may explain similar kidney disease epidemics observed in Andra Pradesh (India) and Central America. Although glyphosate alone does not cause an epidemic of chronic kidney disease, it seems to have acquired the ability to destroy the renal tissues of thousands of farmers when it forms complexes with a localized geo environmental factor (hardness) and nephrotoxic metals.

Cadmium toxicity and treatment

Cadmium is a heavy metal of considerable toxicity with destructive impact on most organ systems. It is widely distributed in humans, the chief sources of contamination being cigarette smoke, welding, and contaminated food and beverages. Toxic impacts are discussed and appear to be proportional to body burden of cadmium. Detoxification of cadmium with EDTA and other chelators is possible and has been shown to be therapeutically beneficial in humans and animals when done using established protocols.

Involvement of TRPA1 activation in acute pain induced by cadmium in mice

Background

Cadmium (Cd) is an environmental pollutant and acute exposure to it causes symptoms related to pain and inflammation in the airway and gastrointestinal tract, but the underlying mechanisms are still unclear. TRPA1 is a nonselective cation channel expressed in sensory neurons and acts as a nociceptive receptor. Some metal ions such as Ca, Mg, Ba and Zn are reported to modulate TRPA1 channel activity. In the present study, we investigated the effect of Cd on cultured mouse dorsal root ganglion neurons and a heterologous expression system to analyze the effect of Cd at the molecular level. In addition, we examined whether Cd caused acute pain in vivo.

Results

In wild-type mouse sensory neurons, Cd evoked an elevation of the intracellular Ca concentration ([Ca²⁺]_i) that was inhibited by external Ca removal and TRPA1 blockers. Most of the Cd-sensitive neurons were also sensitive to cinnamaldehyde (a TRPA1 agonist) and [Ca²⁺]_i responses to Cd were absent in TRPA1(−/−) mouse neurons. Heterologous expression of TRPA1 mutant channels that were less sensitive to Zn showed attenuation of Cd sensitivity. Intracellular Cd imaging revealed that Cd entered sensory neurons through TRPA1. The stimulatory effects of Cd were confirmed in TRPA1-expressing rat pancreatic cancer cells (RIN-14B). Intraplantar injection of Cd induced pain-related behaviors that were largely attenuated in TRPA1(−/−) mice.

Conclusions

Cd excites sensory neurons via activation of TRPA1 and causes acute pain, the mechanism of which may be similar to that of Zn. The present results indicate that TRPA1 is involved in the nociceptive or inflammatory effects of Cd.