What do we know about exposure of Iranians to cadmium? Findings from a systematic review

Mechanism of cadmium-induced nephrotoxicity

Heavy metals are found naturally in our environment and have many uses and applications in daily life. However, high concentrations of metals may be a result of pollution due to industrialization. In particular, cadmium (Cd), a white metal abundantly distributed in the terrestrial crust, is found in mines together with zinc, which accumulates after volcanic eruption or is found naturally in the sea and earth. High levels of Cd have been associated with disease. In the human body, Cd accumulates in two ways: via inhalation or consumption, mainly of plants or fish contaminated with high concentrations. Several international organizations have been working to establish the limit values of heavy metals in food, water, and the environment to avoid their toxic effects. Increased Cd levels may induce kidney, liver, or neurological diseases. Cd mainly accumulates in the kidney, causing renal disease in people exposed to moderate to high levels, which leads to the development of end-stage chronic kidney disease or death. The aim of this review is to provide an overview of Cd-induced nephrotoxicity, the mechanisms of Cd damage, and the current treatments used to reduce the toxic effects of Cd exposure.

Cadmium Toxicity and Health Effects-A Brief Summary

Cadmium (Cd) is a ductile metal in the form of a blueish or silvery-white powder. It is naturally found in soil (about 0.2 mg/kg), minerals, and water. Cd belongs to the group of toxic, carcinogenic, and stimulating elements. Its biological half-life in the human body ranges from 16 to even 30 years on average. Some lung diseases (such as emphysema, asthma, and bronchitis) and high blood pressure are thought to be related to slow poisoning. The symptoms of cadmium poisoning may vary depending on the time of exposure, the type of diet, and the age and health status of the exposed people. For non-smokers and non-occupational exposures, the only source of exposure is diet. The FAO/WHO recommends that the tolerable cadmium intake for an adult is approximately 0.4-0.5 mg/week (60-70 µg per day). Cadmium is primarily absorbed through the respiratory system (about 13-19% of Cd from the air), but it can also enter through the digestive system (about 10-44%), when dust is mixed and swallowed with saliva. The amount of accumulated Cd ranges from 0.14 to 3.2 ppm in muscles, 1.8 ppm in bones, and 0.0052 ppm in the blood. People who are most frequently exposed to heavy metals should be continuously monitored in order to maintain a healthy lifestyle, as well as to implement effective preventive measures and improve public health.

The role of lead and cadmium in deciduous teeth and saliva on dental caries in children residing in Tehran, Iran

BACKGROUND

Lead (Pb) and Cadmium (Cd) are important environmental contaminants. There is no biological monitoring of exposure to these heavy metals and their potential effect on dental caries in children in Tehran, Iran, a polluted megacity. Therefore, the present study investigated the potential association between Pb and Cd levels in primary teeth and saliva and dental caries.

METHODS

In a cross-sectional design, 211 children aged 6-11 years referred to Tehran University of Medical Sciences, School of Dentistry and residing in Tehran were examined. Pb and Cd levels of exfoliated primary teeth and stimulated saliva were determined by atomic absorption spectrophotometry (AAS). Dental caries prevalence was evaluated according to WHO criteria. Socioeconomic status, oral hygiene behavior, snacking frequency and salivary pH data were acquired as confounding factors. Frequency and percentages were reported for categorical variables, mean and standard deviation (SD) for continuous variables, and geometric mean for skewed continuous variables. A simple linear regression and Pearson correlation tests were used for statistical analyses. P-values < 0.05 were considered as significant.

RESULT

The mean (95 % confidence interval) Pb and Cd levels in teeth were 213.26 ppb (164.29-274.84) and 23.75 ppb (20.86-27.05), respectively. The mean Pb and Cd levels in saliva were 11.83 ppb (10.71-13.06) and 3.18 ppb (2.69-3.75), respectively. Furthermore, Pb and Cd in primary teeth and saliva were not associated (p > 0.05) with socioeconomic status, oral hygiene behavior and snacking frequency CONCLUSION: This study showed no association between Pb and Cd concentrations in primary teeth and in saliva with dental caries prevalence.

Associations of micronutrients exposure with cadmium body burden among population: A systematic review

BACKGROUND

The absorption and accumulation of cadmium (Cd) within the human body can be influenced by the status of certain micronutrients, while available evidence for the association between micronutrient exposure and Cd body burden remains fragmented and inconsistent. To address this issue, this article reviews and synthesizes epidemiological studies that examine the association between micronutrient exposure and Cd burden in humans, to elucidate the potential association between micronutrient exposure and Cd body burden.

METHODS

We conducted a systematic review of epidemiologic studies reporting the association between micronutrient status and Cd body burden among the population. Relevant articles were selected based on predetermined criteria from PubMed, Web of Science, and Scopus databases published from 2000 to 2021. The exposures that were evaluated included micronutrients (zinc, selenium, iron, calcium, and vitamins) status or intakes of them. The outcome of interest was the Cd body burden as indicated by blood Cd or urinary Cd levels. The quality of included studies was assessed using The Joanna Briggs Institute critical appraisal tool. We extracted data from each article, including study design, study site, study population, micronutrient status, Cd body burden, and the correlations between micronutrient status and Cd body burden.

RESULTS

Our systematic search yielded 1660 articles. Of these, forty-four were selected for inclusion based on prespecified criteria. These selected articles evaluated the relationship between Cd body burden and seven different micronutrients, namely, selenium (Se), zinc (Zn), calcium (Ca), iron (Fe), vitamin A, vitamin B12, and vitamin D. The majority of studies (n = 41) were observational, while only three were randomized controlled trials. Among the seventeen studies assessing Zn status, ten reported a negative association between serum Zn levels or intake and urinary and blood Cd levels. Results were inconsistent among the ten studies examining the association between Se levels and Cd body burden. Six studies showed that Cd in blood and urine was negatively correlated with serum ferritin (SF), a biomarker of body Fe status. Two studies reported a negative correlation between Ca and blood Cd.

CONCLUSIONS

This synthesis of available evidence suggests that certain micronutrients, especially Zn and Fe, may play a role in reducing the Cd body burden among populations. The evidence strongly supports a negative association between Zn, Fe, and Cd body burden, whereas evidence for Se, Ca and vitamins is insufficient to draw definitive conclusions regarding their relationship with Cd body burden. In addition, observational studies limit the ability to infer a causal relationship between micronutrients and Cd body burden, highlighting the need for additional intervention studies. Our review may inform nutrient supplementation guidance, control of Cd body burden, and future research to mitigate the adverse health effects of Cd in the context of global Cd pollution.

Radiation-Grafting on Polypropylene Copolymer Membranes for Using in Cadmium Adsorption

Graft copolymerization has been a popular technique in recent years for adding different functional groups to polymers. In our research, polypropylene (PP) films are grafted with acrylonitrile (An) and acrylic acid (AAc) monomers to make them hydrophilic while retaining their mechanical qualities. Gamma radiation is used in this approach to establish active spots on an inert polymer that are appropriate for adding monomers radicals to form grafts, a procedure that is extremely difficult to perform using normal chemical processes. The graft parameters are investigated in order to acquire the highest percentage of graft. FTIR (Fourier transform infrared spectroscopy) spectra are used to analyze the grafting of AAc and An. SEM (scanning electron microscopy) and XRD (X-ray diffraction) micrographs are used to validate them. The specimens' tensile strength and hardness are measured and contrasted with blank PP films. Measurements are made of the effects of grafting on the tensile strength and elongation of the films, and a crucial grafting degree is established in order to preserve these properties. Water uptake is measured to adapt the copolymer to water treatment, and thermal behavior TGA (thermal gravimetric analysis) and DSC (diffraction scanning calorimeter) of the produced copolymer were performed. The elimination of cadmium was verified by an atomic absorption spectrophotometer (AAS) under different conditions of pH, time, and degree of grafting.

Contamination of breast milk with lead, mercury, arsenic, and cadmium in Iran: a systematic review and meta-analysis

Breast milk is a complete food for the development of the newborn, but it can also be an important route for environmental pollutants transmission to the infants. This study was aimed to evaluate the status of heavy metals including lead (Pb), mercury (Hg), cadmium (Cd) and arsenic (As) in the breast milk of Iranian mothers. The international databases including Scopus, PubMed, Web of Science and the Persian electronic databases including Scientific Information Database, IranMedex and Magiran were examined to find relevant articles published until July 2021. A total of 23 studies examined the levels of toxic metals in Iranian breast milk samples. According to the findings, the pooled average concentrations (µg/L) of Pb, Cd, Hg and As were 25.61, 2.40, 1.29 and 1.16, respectively. The concentration of Hg and Pb in colostrum milk was more than twice of mature milk. The Hg mean concentration in the breast milk of mothers with at least one amalgam-filled tooth was approximately three times that of mothers without amalgam-filled teeth. Risk assessment analysis indicated that the intake of Pb and Hg by infants through breastfeeding can be considered a health concern in Iran. It seems necessary to reduce the Pb exposure of pregnant and lactating women in Iran. However, more extensive studies are needed to clarify the toxic metals' exposure status of infants through breast milk in other parts of the country.

Profile of Environmental Chemicals in the Korean Population-Results of the Korean National Environmental Health Survey (KoNEHS) Cycle 3, 2015-2017

The Korean National Environmental Health Survey (KoNEHS) program provides useful information on chemical exposure, serves as the basis for environmental health policies, and suggests appropriate measures to protect public health. Initiated on a three-year cycle in 2009, it reports the concentrations of major environmental chemicals among the representative Korean population. KoNEHS Cycle 3 introduced children and adolescents into the analysis, where the blood and urine samples of 6167 participants were measured for major metals, phthalates, phenolics, and other organic compounds. Lead, mercury, cadmium, metabolites of DEHP and DnBP, and 3-phenoxybenzoic acid levels of the Korean adult population tended to decrease compared to previous survey cycles but remained higher than those observed in the US or Canada. Both bisphenol A (BPA) and trans,trans-muconic acid concentrations have increased over time. Heavy metal concentrations (blood lead, and cadmium) in children and adolescents were approximately half that of adults, while some organic substances (e.g., phthalates and BPA) were high. BPA showed higher levels than in the US or Canada, whereas BPF and BPS showed lower detection rates in this cycle; however, as these are increasingly used as a substitute for BPA, further research is necessary. As environmental chemicals may affect childhood health and development, additional analyses should assess exposure sources and routes through continuous observations.

Fabrication and evaluation of slow-release lignin-based avermectin nano-delivery system with UV-shielding property

Nanopesticide is one of the best pesticide formulation technologies to overcome the disadvantages of traditional pesticides, which has received great attention from the international community. Using high-speed emulsification and ultrasonic dispersion technology, an avermectin nano-delivery system (Av-NDs) with a particle size of 80-150 nm was prepared through embedding the pesticide molecule utilizing the cross-linking reaction between sodium lignosulfonate and p-phenylenediamine diazonium salt. The formulation and composition of Av-NDs were optimized, the morphology of Av-NDs was analyzed by scanning electron microscope, transmission electron microscope and dynamic light scattering, and the structure of Av-NDs was characterized by UV, IR and ¹H NMR. Anti-photolysis and controlled-release tests show that the stability of Av-NDs is 3-4 times of the original avermectin (Av) and possesses the pH-responsive controlled release property. Furthermore, the insecticidal activity of Av-NDs is better than that of avermectin suspension concentrate (Av-SC). The Av-NDs with anti-photolysis and controlled-release characteristics is suitable for large-scale industrial production and is capable to be utilized as effective insecticide in the field.

RELATIONSHIP BETWEEN LEAD AND CADMIUM LEVELS IN BLOOD AND REFRACTORY CHRONIC CONSTIPATION AMONG IRANIAN CHILDREN

BACKGROUND

There is limited research examining reasons causing refractory chronic constipation (RCC) in children. The effects of lead (Pb) and cadmium (Cd) exposures on this condition have been even less clear. However, some related factors may contribute to evaluation of blood lead levels (BLLs) and blood cadmium levels (BCLs).

OBJECTIVE

The present study aimed to examine the relationship between Pb and Cd exposures and RCC in children living in the city of Ahvaz, Khuzestan Province, in Southwestern Iran.

METHODS

This study was performed on a total number of 48 children aged 2-13 years, including 36 medically-diagnosed RCC cases and 12 controls referring to a pediatric clinic in the city of Ahvaz. Their BLLs and BCLs were then determined using a graphite furnace atomic absorption spectrophotometer. The data from the researcher-designed questionnaire were also recoded and the related risk factors were analyzed through Spearman's correlation and logistic regression analysis.

RESULTS

The findings revealed that the geometric means of Pb and Cd in blood samples in the control group were 58.95 µg/dL and 0.45 µg/dL; respectively. These values in the case group were equally 45.26 µg/dL and 0.26 µg/dL; respectively. A significant difference was additionally observed between BCLs in the case and control groups (P<0.01). All children in both groups also had BLLs greater than the permissible limit endorsed by the World Health Organization (WHO) (≤10 µg/dL). On the other hand, 8.3% of the individuals in the case group and 33.3% of those in the control group had BCLs higher than the acceptable range mentioned by WHO (≤0.5 µg/dL).

CONCLUSION

Pb and Cd exposures due to environmental pollution and susceptibility to heavy metals may not be associated with RCC in children living in the city of Ahvaz. Although this research was the first one providing data on BLLs and BCLs in children with RCC, the findings could be useful for designing future epidemiologic studies.

Microbial diversity in full-scale water supply systems through sequencing technology: a review

The prevalence of microorganisms in full-scale water supply systems raises concerns about their pathogenicity and threats to public health. Clean tap water is essential for public health safety. The conditions of the water treatment process from the source water to tap water, including source water quality, water treatment processes, the drinking water distribution system (DWDS), and building water supply systems (BWSSs) in buildings, greatly influence the bacterial community in tap water. Given the importance of drinking water biosafety, the study of microbial diversity from source water to tap water is essential. With the development of molecular biology methods and bioinformatics in recent years, sequencing technology has been applied to study bacterial communities in full-scale water supply systems. In this paper, changes in the bacterial community and the influence of each treatment stage on microbial diversity in full-scale water supply systems are classified and analyzed. Microbial traceability analysis and control are discussed, and suggestions for future drinking water biosafety research and its prospects are proposed.

A systematic review and meta-analysis of human biomonitoring studies on exposure to environmental pollutants in Iran

Population exposure to environmental contaminants can be precisely observed through human biomonitoring studies. The present study aimed to systematically review all the biomonitoring studies conducted in Iran on some selected carcinogen environmental pollutants. In this systematic review study, 11 carcinogen agents were selected including arsenic, cadmium, chromium, nickel, lindane, benzene, trichloroethylene (TCE), pentachlorophenol (PCP), radon-222, radium-224, - 226, - 228, and tobacco smoke. The Web of Science, PubMed, and Scopus databases were searched for peer-reviewed articles published in English. After several screening steps, data were extracted from the studies. Meta-analyses (a random-effect model using the DerSimonian-Laired method) were performed only for the biomarkers with more than three eligible articles, including cadmium in blood and breast milk, and arsenic in breast milk. Methodological quality of the studies was assessed using the Newcastle-Ottawa Quality Assessment Scale adapted for cross-sectional studies. Of the 610 articles found in the database search, 30 studies were eligible for qualitative review, and 13 were included in the meta-analysis (cadmium in blood (n = 3), cadmium in breast milk (n = 6), and arsenic in breast milk (n = 4)). The overall pooled average concentrations (95% CI) of cadmium in blood, cadmium in breast milk, and arsenic in breast milk were 0.11 (95% CI: 0.08, 0.14), 5.38 (95% CI: 3.60, 6.96), and 1.42 (95% CI: 1.02, 1.81) µg/L, respectively. These values were compared with the biomarker concentrations in other countries and health-based guideline values. This study showed that there is a need for comprehensive action plans to reduce the exposure of general population to these environmental contaminants.

Blood cadmium levels as a marker for early lung cancer detection

BACKGROUND

We assessed whether blood cadmium levels were associated with incident lung cancer and could be used in the context of a screening program for early-stage lung cancer.

MATERIAL AND METHODS

We measured blood cadmium levels among 205 lung cancer patients and 205 matched controls. Cases and controls were matched for sex, age and smoking history (total pack-years, years since cessation for former smokers).

RESULTS

The odds ratio for those in the highest quartile of cadmium level (versus lowest) was four-fold (OR = 4.41, 95 % CI:2.01-9.67, p < 0.01). The association was present in former smokers (OR = 16.8, 95 % CI:3.96-71.2, p < 0.01), but not in current smokers (OR = 1.23, 95 % CI: 0.34-4.38) or in never smokers (OR not defined). Among former smokers, the association was present in both early- and late-stage lung cancer.

CONCLUSION

Blood cadmium levels may be a marker to help with the early detection of lung cancer among former smokers.

Innovation and environmental total factor productivity in China: the moderating roles of economic policy uncertainty and marketization process

China's economic development practices are facing strict energy constraints and severe environmental pollution. Improvement of China's environmental total factor productivity (ETFP) through innovation is a major scientific focus of both policy-makers and academia. However, the boundary conditions where innovation affects ETFP are yet to be clarified. On this basis, the present study starts from two dimensions-policy context and market context, introduces economic policy uncertainty (EPU) and marketization process as moderating variables, and examines the impact mechanism of innovation on ETFP. The results show the following: (1) Innovation promotes ETFP. (2) Although EPU inhibits ETFP, it positively moderates the impact of innovation on ETFP. (3) The marketization process has an insignificant inhibitory effect on ETFP. Specifically, the development of product markets, the development of market intermediary organizations, and the legal system environment have a significant inhibitory effect on ETFP. In contrast, the marketization process positively moderates the impact of innovation on ETFP. (4) The impact of innovation on ETFP exhibits obvious regional heterogeneity. In regions with low pollution intensity, innovation and EPU promotes ETFP. The marketization process inhibits ETFP and shows a positive moderating effect. In regions with high pollution intensity, both innovation and EPU inhibits ETFP. Based on these conclusions, policy-makers should guide companies to increase investment in research and development, improve innovation capabilities, and focus on strengthening energy-saving and environmental protection technologies and process innovations. When formulating and adjusting economic policies, policy-makers should aim promote enterprise innovation and reduce the negative impact of economic policy uncertainty. Policies should fully utilize the decisive role of the market in the allocation of innovative factors and rely on market mechanisms to enhance the positive effect of innovation on regional ETFP.

Association between moderately cold temperature and mortality in China

Ambient air temperature is a key factor affecting human health. Adverse effects of extreme weather on mortality have been well explored and expounded in numerous epidemiological studies. The relationship between moderate temperature and mortality is, however, underexplored. This study quantitatively investigated the temperature-dependent mortality burden in China. Data on daily average temperature and mortality in 15 Chinese cities during 2010-2016 were collected for this study. The association between temperature and city-specific mortality was investigated with a quasi-Poisson regression combined with a distributed lag nonlinear model across lag 0-21 days. The results were then included in a multivariate meta-analysis to derive the pooled estimates of the effect of temperature on mortality at the multi-city level. Mortality fractions attributable to cold and heat (i.e., at temperatures below and above the minimum mortality temperature (MMT)) were calculated. Additionally, temperature ranges were further divided into 1 °C intervals of ambient temperature, and the attributable fractions were calculated for each range. The MMT varied from the 71th to 93th percentiles of temperature in the 15 Chinese cities, centering at the 78th percentile at the multi-city level. In total, 12.65% of non-accidental mortality was attributable to non-optimum temperature, of which cold and hot temperatures corresponded to attributable fractions of 11.38% and 1.27%, respectively. The results of temperature stratifications suggested that moderately cold temperatures provided the highest contribution to mortality caused by temperature. Specifically, the highest attributable fractions were at 7 °C, 7 °C, 8 °C, 8 °C, 4 °C, 4 °C, 5 °C, 7 °C, 7 °C, 4 °C, 5 °C, 5 °C, 6 °C, 11 °C, and 12 °C, for Harbin, Changchun, Shenyang, Urumqi, Beijing, Tianjin, Shijiazhuang, Xining, Lanzhou, Nanjing, Shanghai, Hefei, Chengdu, Kunming, and Guangzhou, respectively. Cold temperature was responsible for a higher proportion of deaths than heat. Moderate cold temperature contributed to most of the total health burden. Finally, the cumulative total counts of deaths caused by moderate cold were the largest. Although moderate cold conferred a slightly lower relative risk than extreme cold, it was more common than extreme cold. Taken together, our results show that the effects of moderate cold temperature on health should receive more attention. Furthermore, our findings could help improve the prediction of climate change effects on human health and support the development of response strategies for the changing climate.

The Effects of Cadmium Toxicity

Cadmium (Cd) is a toxic non-essential transition metal that poses a health risk for both humans and animals. It is naturally occurring in the environment as a pollutant that is derived from agricultural and industrial sources. Exposure to cadmium primarily occurs through the ingestion of contaminated food and water and, to a significant extent, through inhalation and cigarette smoking. Cadmium accumulates in plants and animals with a long half-life of about 25-30 years. Epidemiological data suggest that occupational and environmental cadmium exposure may be related to various types of cancer, including breast, lung, prostate, nasopharynx, pancreas, and kidney cancers. It has been also demonstrated that environmental cadmium may be a risk factor for osteoporosis. The liver and kidneys are extremely sensitive to cadmium's toxic effects. This may be due to the ability of these tissues to synthesize metallothioneins (MT), which are Cd-inducible proteins that protect the cell by tightly binding the toxic cadmium ions. The oxidative stress induced by this xenobiotic may be one of the mechanisms responsible for several liver and kidney diseases. Mitochondria damage is highly plausible given that these organelles play a crucial role in the formation of ROS (reactive oxygen species) and are known to be among the key intracellular targets for cadmium. When mitochondria become dysfunctional after exposure to Cd, they produce less energy (ATP) and more ROS. Recent studies show that cadmium induces various epigenetic changes in mammalian cells, both in vivo and in vitro, causing pathogenic risks and the development of various types of cancers. The epigenetics present themselves as chemical modifications of DNA and histones that alter the chromatin without changing the sequence of the DNA nucleotide. DNA methyltransferase, histone acetyltransferase, histone deacetylase and histone methyltransferase, and micro RNA are involved in the epigenetic changes. Recently, investigations of the capability of sunflower (Helianthus annuus L.), Indian mustard (Brassica juncea), and river red gum (Eucalyptus camaldulensis) to remove cadmium from polluted soil and water have been carried out. Moreover, nanoparticles of TiO2 and Al2O3 have been used to efficiently remove cadmium from wastewater and soil. Finally, microbial fermentation has been studied as a promising method for removing cadmium from food. This review provides an update on the effects of Cd exposure on human health, focusing on the cellular and molecular alterations involved.

Association Among Sources Exposure of Cadmium in the Adult Non-smoking General Population of Tehran

Acute and chronic exposure to cadmium can cause numerous health effects including poisoning, as well as, bone, liver, and kidney diseases. Cadmium competes with iron absorption in blood and can induce anemia. Cadmium body burden can be measured through urine and blood samples. Urine reflects chronic and blood indicates recent and cumulative exposures to cadmium. Dietary is considered as the main source of exposure to cadmium in non-smoking general population. The study was conducted to determine cadmium level in blood, urine, and in diet of 120 non-smoking adults in Tehran. Dietary components and consumption pattern of participants estimated by a food frequency questionnaire. Next, the correlation investigated between them. Moreover, serum ferritin measured as a marker of iron storage in blood to determine its association with cadmium. The prediction of cadmium fate in the body is determined by toxicokinetic models. This study tried to evaluate one of these models' validity which is developed to predict urinary cadmium from dietary. Afterwards, the predicted urinary compared with the measured urinary cadmium. The correlation coefficient between dietary and blood cadmium equaled 0.66 which was statically significant, but the correlation between dietary and urinary cadmium was minimal and not statically significant (p > 0.05). An inverse and negative correlation was found between serum ferritin and blood cadmium. The mean predicted urinary cadmium calculated by the model was 2.5-fold higher than the measured value in the total population. Results of the present study revealed that blood cadmium reflected mainly acute exposure. There was no correlation between chronic and acute exposures to cadmium. The low serum ferritin level increased cadmium amount in blood. Moreover, the mean predicted urinary cadmium by the model was greater than the measured value. It can because of characteristics of populations and type of dietary exposure. Thus, it is suggested that the model coefficients are determined in each society based on their characteristics.

Determining additional risk of carcinogenicity and non-carcinogenicity of heavy metals (lead and arsenic) in raw and as-consumed samples of imported rice in Tehran, Iran

Rice is considered the most main food in Iranian diet. Its chemical contamination with heavy metals can lead to adverse effects to human health. In the present study, 60 imported rice samples from 20 different brands were collected and examined in terms of lead and arsenic levels in Tehran. Besides, point estimation and uncertainty analysis were used to determine the additional risk of carcinogenicity and non-carcinogenicity in raw and as-consumed rice. The results showed that the means of lead and arsenic (mg/kg fresh weight) in raw sampled rice were 0.0352 ± 0.0398 and 0.106 ± 0.049, respectively, and they were 0.0226 ± 0.0360 and 0.0689 ± 0.046 in as-consumed rice, respectively. Additionally, lead and arsenic amounts were 5% and 15% higher than the value set by Institute of Standards and Industrial Research of Iran respectively, while assessment of the non-carcinogenicity risk of lead and arsenic in point estimation and uncertainty analysis showed the hazard quotient and hazard index values were less than 1 and in safe ranges in both raw and as-consumed rice and were not considered a threat to the public health. The additional risk of arsenic carcinogenicity in point estimation and uncertainty analysis in raw and as-consumed rice samples found higher than the 1E-06 EPA's acceptable level of risk. So, these results could be applicable and encourage researchers to perform more detailed studies with more samples for considering by food authorities.

Effects of sub-chronic, low-dose cadmium exposure on kidney damage and potential mechanisms

Background

The present study was to investigate the potential mechanisms underlying the sub-chronic low-dose cadmium (Cd) exposure induced renal injury in rats.

Methods

Totally 40 male adult SD rats were randomly divided into four groups: control group, low-dose Cd group (1 mg/kg CdCl₂), moderate-dose Cd group (2.5 mg/kg) and high-dose Cd group (5 mg/kg).

Results

From the 3^rd week, the body weight of rats in moderate-dose and high-dose declined significantly as compared to the control group (P<0.05); the liver to body weight ratio increased, the volumes of 24-hour urine and drinking-water decreased markedly (P<0.05), the BUN, SCr and β₂-MG increased significantly, but the Fe²⁺ concentration decreased markedly as compared to the control group (P<0.05); the serum MDA and SOD₁ content contents increased, but the serum SOD₂ and CAT contents decreased significantly in Cd-treated groups (P<0.05); Renal injury deteriorated with the increase in Cd dose; swelling glomeruli showed stenotic renal-tubules, and epithelial-cell-necrosis, shedding and accumulation in the lumen, massive infiltrated inflammatory cells and interstitial hyperaemia were observed; The mitochondria in renal-tubular-epithelial-cells displayed swelling, deformation and vacuolation; the renal ROS content increased in Cd-exposure-groups; the renal SOD₁ expression increased but the expression of SOD₂ and CAT decreased (P<0.05). The Bcl-2 expression decreased, but Bax expression and Bax/Bcl-2 ratio increased significantly in a Cd-dose dependent manner.

Conclusions

Cd may cause renal injury in a dose dependent manner, which may be ascribed to the disordered Fe²⁺ absorption, redox imbalance and apoptosis in the kidney.

Contamination and Prevalence of Histamine in Canned Tuna from Iran: A Systematic Review, Meta-Analysis, and Health Risk Assessment

Histamine is one of the most important health issues associated with consumption of canned tuna because of possible allergic and anaphylactic reactions in consumers. Although the concentrations of histamine in tuna in Iran have been investigated in several studies, definitive conclusions are elusive. This study was undertaken as a systematic review and meta-analysis of the concentration and prevalence of histamine in Iranian canned tuna, and the related health risk was assessed. An extensive search of articles in the databases Scopus, PubMed, and Scientific Information Database resulted in 11 articles and a total of 693 samples for inclusion in this review. The minimum and maximum concentrations of histamine were determined as 8.59 ± 14.24 and 160.52 ± 87.59 mg kg⁻¹, respectively. The mean concentration was calculated as 77.86 mg kg⁻¹ (95% confidence interval [CI], 47.51 to 108.21 mg kg⁻¹), which was lower than the 200 mg kg⁻¹ recommended limit by the U.S. Food and Drug Administration (FDA). The mean prevalence of histamine was 9.19% (95%; CI, 6.88 to 11.5%). The 95% value of the target hazard quotient for adult consumers was calculated as 0.10. In all studies performed in Iran, the concentration of histamine in canned tuna was lower than FDA standard. Health risk assessment indicated low histamine risk (target hazard quotient < 1) for adults in Iran from consumption of canned tuna.