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Background and purpose: The Common Coot (Fulica atra) is an abundant aquatic bird in North of Iran and is anticipated to be a good indicator for metal pollution on north wetlands of Iran. The aim of this study was to determining metals concentration in water, sediment samples and two organs of Common coot (liver and kidney). Materials and methods: This study was tested on water, sediment and 30 Common coot samples, in winter 2009. The water and sediment samples were respectively collected by Rotner bottle and Ekman grab within six sites of Gomishan and Khalij Gorgan wetland. The concentration of heavy metals in samples (Bird tissues, water and sediment) was measured by GF-AAS and Flame-AAS. Results: The data indicated that maximum heavy metals concentration in water belongs to lead (0.154 ± 0.02 ppm) and in sediment to Zn (2.04 ± 0.42 ppm). There was a significantly high correlation among heavy metals in water and sediment samples (P<0.01). The metals (Cd, Pb, Zn) level in both water and sediment samples was below standard level, whereas Cr concentration in water sample was almost higher. The highest concentrations of cadmium and lead found in liver (2.2 , 9.1 µg/g) and kidney (2.1, 8.9 µg/g) of Common coots, respectivly. Among the metals, the highest concentration in liver was Zn element (14.9 ± 7.24 ppm) and the lowest level in kidney belongs to Cr (0.76 ± 0.56 ppm). Moreover, the data pshowed no any significant difference in both liver and kidney organs of both sexes. Conclusion: The result indicated that lead concentration in kidney and liver tissues of Common coot was at exposure level and cadmium found below toxicity level. Other elements were also below toxicity level.

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Background and purpose: This study aimed to determine the origin and distribution of lead, copper, zinc, nickel, chromium and vanadium in surface sediments of Mazandaran coastline (southeastern coast of the Caspian Sea). Materials and methods: Surface sediment samples were collected from four transects in Tonekabon, Noshahr, Babolsar and Amir abad port, at three different depths of 5, 15 and 30 m in July 2012. Metals concentration were determined by ICP - OES. Results: The metals in the studied areas were found to be from natural sources, probably due to weathering of rock and soils erosion transported by rivers into the sea. Significant difference was seen in the mean total concentration of metals along the four transect when the distance from the shore increased. The mean concentration of metals along the coast from east to west showed a significant increase. Among the metals, the highest concentrations was found for zinc (104 μg/g) at 30 m depth in Babolsar transect and the lowest concentration was found for copper (8.72 μg/g) at 5 m depth in Amir abad port transect. Conclusion: Total concentrations of metals were lower than standard levels (SQGs and NOAA). Moreover, the risk assessment code (the presence of metals in the exchangeable fraction) did not show any risk from copper, zinc, nickel, chromium and vanadium, but it showed only a low risk for lead. This study found that the studied metals have low-risk for local environment.

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Background and purpose: The pollution of aquatic ecosystems with heavy metals, have always been a major concern for aquatic organisms and human health. Contaminants such as heavy metals are accumulated along the food chain and then transmitted to human body. Levels of contaminants in fish are of particular interest because of the potential risk to humans. This study examined the levels of cadmium, lead, zinc and copper in muscle tissue of Esox lucius from the Anzali international wetland and then compared them with the standards established for human health. Materials and methods: This research was done on 26 Pike perch (Esox lucius) obtained from Anzali wetland by multimesh gill nets in September 2010. The samples were digested by concentrated nitric acid, and then were analyzed for Pb in a graphite furnace atomic absorption spectrophotometer and for Cd, Cu, and Zn in a flame atomic absorption spectrophotometer. Results: Mean concentration of Cd, Pb, Cu and Zn was 0.82 ± 0.06, 0.22 ± 0.02, 5.68 ± 0.31, 54.26 ± 0.87 (µg/g dry weight), respectively. The results showed no significant correlation between Pb, Cu and Zn concentrations with body weight and length but a significant negative correlation was observed between Cd concentration with body length (r= -0.88, P<0.05) and body weight (r= -0.9, P<0.05). Conclusion: The levels of Zn, Cu and Pb were lower than the standard levels established by WHO, FAO, and EPA but levels of Cd exceeded the standards of WHO and EPA. These results can be a warning for consumers of these fish. According to the daily intake of heavy metals consuming this fish on weekly basis is not prohibited.

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Background and purpose: High concentrations of heavy metals in industrial and domestic wastewater cause adverse effects on the environment and human health. Therefore, removing heavy metals from water resources is considered as a positive step towards sustainable development. Today, application of artificial wetlands to remove pollutants such as heavy metals is increasing due to high costs of construction sites, low operation, maintenance, and energy needs. Materials and methods: This experiential research was carried out in a pilot scale in adjacent of wastewater treatment plant in the campus of Mazandaran University of Medical Sciences. The pilot was composed of four rectangular concrete reactors with 6 × 1.5 × 0.8 m length, width and affective depth. One reactor was used as control. The research was performed in five phases. Different hybrid systems of the reactors (combination of vertical and horizontal with parallel and series flow) were evaluated. The samples were digested using an acid digester and concentrations of lead and cadmium were analyzed using atomic absorption spectrophotometer. The data was analyzed using SPSS. Results: By increasing the hydraulic retention time (HRT) from 2 to 6 days, the mean percentage for removal of studied metals increased to 58 (which was 42 at the beginning). Among the different phases, phase four was more efficient which removed 54% of the heavy metals while the lowest removal percentage was detected in phase one. The average percentage removal of cell output for reed planting and the controls were 65% and 35%, respectively. These differences were statistically significant (P≤ 0.05). Conclusion: The findings of this research showed that combination of DF-UF (down flow-Up flow) reactors was the best condition for the removal of lead and cadmium from subsurface wetlands. The optimal hydraulic retention time was 4 to 6 days and 10 to 20 mm gravel could be more appropriate for the size of gravel in wetland.

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Background and purpose: Water and soil pollution with heavy metals are among serious ever-growing environmental problems. Human activity accounts for much of the poisonous metals and results in increases soil pollution. There are many factors related to soil and plants properties and environmental issues. Release of heavy metal into food chain in critical densities has harmful metabolic and physiologic effects on living creatures. Materials and methods: Three regions including Movaram Kola, Seyyed Mahalleh, Jouybar Mahalleh Kola located in Sari, Jouybar and Qaemshahr (central regions of Mazandaran province) were investigated to determine the concentrations of heavy metals in paddy fields irrigation and Tarom rice within 2010-2011 agricultural year. Sampling included samples of irrigation with water and rice, and field study for qualitative and quantitative properties of rice. Sampling and test method of heavy metals was in accordance with suggestive method of standard book of method. Finally density of heavy metals of samples was measured using atomic absorption machine. For statistical calculation and quantitative study of data Prism, Stata 11 and t-test were applied. Results: In the studied water samples, level of cadmium in Seyyed Mahalleh was higher than standard level which is worrying due to accumulative effect of cadmium. In addition, level of cadmium in rice samples of Jouybar (Mahalleh Kola) and Seyyed Mahalleh was higher than standard level. Levels of chrome in all studied areas were lower than standard levels. Conclusion: Accumulative effects of heavy metals and their harmful effects on human societies could endanger food safety, therefore, more precautions are needed to reduce such effects.

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Background and purpose: Heavy metals are non-degradable pollutants that could accumulate in marine animals including fish. The aim of this study was to determine the levels of six heavy metals (Zn, Cu, Ni, Pb, Cd and Hg) in edible tissue of Caspian carp (Cyprinus Carpio). We also studied the bioaccumulation factor (BFA) and target hazard quotients (THQ) of this fish in the southern Iranian Caspian Sea coast. Materials and methods: Twenty eight samples of fish were collected from seine and trawl during winter and spring 2010. Heavy metals were prepared (using Freeze dryer) by digestion and extraction process and then analyzed using atomic absorption equipped with flame, graphite and cold vapor system. Results: Results showed that Zinc (185±57) and Cu (3.68±0.30) µg/g.dw were seen more amongst the contaminants in the edible tissue of the Caspian carp. Concentration of Hg was 0.50±0.17 µg/g.dw and levels of Cd and Pb were below the limit of detection. BAF of metals were Zn> Cu> Hg. Conclusion: Ni, Cd and Pb in the Caspian carp muscle were lower that standard levels, but concentration of Hg was higher than the standard levels recommended by WHO, and ERL and ERM limits.

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Background and purpose: Heavy metal contamination of aquatic ecosystems is a major concern for animals and human health. Pollutants such as heavy metals accumulate the food chain and at the end, they transmit to the human body. In this research, the concentrations of nickel, lead and cadmium in Barbus grypus of Dez River, Iran, were determined and compared with international standards. Materials and methods: 30 Barbus grypus were caught from the central area of Dez River (city of Dezful). Then, the fishes were digested in concentrated nitric acid, and nickel, lead and cadmium concentrations were measured using graphite furnace device. Results: The concentrations of lead, cadmium and nickel in the gill tissues were 0.281 ± 0.013, 0.156 ± 0.009, and 0.315 ± 0.070 ppm, respectively. The concentrations of lead and cadmium were significantly higher in gill tissue compared to muscle (P < 0.05). Conclusion: The results indicate that the concentrations of nickel, lead and cadmium in Barbus grypus of Dez River were less than the World Health Organization standards.

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Background and purpose: The release of metals due to different natural and human activities, bioaccumulation, biological inseparability and toxicity, even in low densities, have caused serious threat to living creatures and human. This study evaluated the concentration of heavy metals including lead, cadmium, zinc and copper in edible tissues of Caspian Kutum (Rutilus frisii kutum) in Miankaleh International Wetland and the health risk resulted from consumption of this fish. Material and Methods: During fishing season, 20 White fishes were collected from Miankaleh International Wetland with the permission of Environmental Protection organization. The densities of heavy metals in skin and muscles were determined using atomic absorption (Scientific Equipment GBS). Data was analyzed using SPSS V.16. Results: The mean densities of lead, cadmium, zinc and copper in the skin were 3.4, 0.48, 40.55, and 3.3, respectively and 2.1, 0.39, 16.52, 4.5 microgram per gram of the wet weight in muscle tissues, respectively. A significant difference was seen in the concentration of heavy metals between the skin and the muscle tissue (p<0.01). The observed EDI and EWI were found lower than the guidelines recommended by WHO and FAO. Conclusion: According to this study the concentration of zinc and copper in whitefish were lower than the standard levels, so its consumption is not a threat to the health of consumers. However, the levels of cadmium and lead in edible tissues of whitefish were found higher than international levels. Hence, the pollutants of Miankaleh wetland (i.e. industrial and agricultural wastewater) should be highly controlled.

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Background and purpose: Heavy metals are released to the environment as a result of industrial, urban and agricultural sewages. They are usually resistant to chemical dissociation. They can easily contaminate aquatic animals especially fishes which are amongst the food chains of human. This study evaluated the concentration of heavy metals in the tissues of different types of Clupeonella cultriventris and Gasterosteus aculeatus in the waters of Caspian Sea in Mazandaran Province. Material and Methods: This cross-sectional descriptive study was performed on 50 Clupeonella cultriventris and 50 Gasterosteus aculeatus obtained from Mazandaran coastal by multi mesh gill nets in 2012. The samples were digested by concentrated 65% nitric acid, and were analyzed for Pb in a graphite furnace atomic absorption spectrophotometer and for Cd and Cr in a flame atomic absorption spectrophotometer. Results: Mean concentration of Pb, Cr and Cd in Gasterosteus aculeatus was 0.113, 5.28 and 0.046 and mean concentrations of Pb, Cr and Cd in Clupeonella cultriventris were 0.126, 4.29 and 0.096 (μg/g dry weight), respectively. The results showed no significant correlation between the concentrations of these metals and length of fish and different tissues of the fish. Conclusion: We found the concentration of heavy metals including Pb and Cr in both types of the fishes less than the amounts reported by WHO, so they do not bare considerable health risk. However, the concentration of Cd is more than the recommended consumption limit for human which could lead to many diseases. We believe that these fishes could be used as a bioindicator for assessing the pollution load of sea water and rivers.

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Background and purpose: The chemical quality of feed water to dialysis instrument is very important, especially in terms of heavy metals which could cause serious health problems for dialysis patients. This study aimed to determine the concentration of selected heavy metals (lead, cadmium, chromium and zinc) in feed water to dialysis instrument and compared that with EPH and AAMI standards in hospitals of Kermanshah province in 2014. Materials and methods: A total of 42 samples of feed water, and 42 samples of permeate water (feed water to dialysis instrument) of reverse osmosis systems were collected from Kermanshah province hospitals. The collected samples were analyzed and the concentrations of lead, chromium, cadmium and zinc were determined using ICP (DV-Optima2100 model) according to standard methods. Then, the mean concentrations were compared with AAMI and EPH standards. Results: The mean concentration of lead, cadmium, chromium and zinc in permeate water of reverse osmosis system was 18.81± 14.32, 0.719± 0.53, 84.25 ± 2.46 and 43.39± 19.14 ppb, respectively. The efficiency of the settled reverse osmosis system before dialysis instrument was 61.5 and 2.1%, in removal of zinc and chromium, respectively. But this system was found inefficient in removal of lead and cadmium Conclusion: The mean concentrations of lead and chromium in the permeate water from the reverse osmosis system was higher than limited standards of AAMI and EPH, but the mean concentrations of chromium and zinc were lower than mentioned standards in all investigated hospitals. Therefore, the reverse osmosis system was able to decrease zinc in moderate and chromium in lower levels, but it was not effective in the removal of other heavy metals. So, periodic washing and cleaning or replacing the membrane of the reverse osmosis system is highly recommended.

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Background and purpose: Heavy metals due to non-biodegradability and having physiological effects on living organisms are particularly important. Due to the low mobility, these elements gradually accumulate in soil and eventually enter the food chain and threaten human and other organism’s health. Therefore, measurement and monitoring of heavy metal concentrations is necessary to . The aim of this study was to evaluate the concentration of lead in irrigation water, soil and vegetables in farmlands lands in Ahwaz (southwest of Iran) Materials and methods: The studied vegetables were basil, radish and purslane. The sampling was performed during June to August in 2013 on water, soil and vegetable in Ahwaz farmlands. Seventy samples of vegetables were collected and analyzed by furnace atomic absorption spectrophotometry according to standard methods. Also, samples of water and soil were analyzed according to standard methods. The concentration of lead in vegetables, soil and irrigation water were compared with the standard values recommended by WHO and FAO. Results: Themean concentration of lead in basil, radish and purslane were 9.7, 10.61, and11.13 mg/kg, respectively. Mean concentration of lead in water and soil were 0.47 and 10.19 mg/kg, respectively. The lead contents in vegetables were higher than standard values recommended by WHO/FAO. Conclusion: High concentration of lead in vegetables could be due to high accumulation of this metal in soil. Therefore, continues monitoring of heavy metals in soil and irrigation water of farmlands plays an important role in reducing the environmental risks threating human health.

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Abstract Background and purpose: Heavy metals are the most important contaminants that enter the sea through rivers and shore zones and aggregate in the aquatic body through food chain. The purpose of this study was to compare the concentration of heavy metals (cadmium, copper, zinc, lead, and nickel) in the muscle tissue of Banana shrimp as the most abundant used species in Bandar Abbas, and also to compare these concentrations with global standards. Materials and methods: In this study, shrimp samples were obtained in October 2014 from daily hunting of fishermen in Bandar Abbas. After separating the muscle tissues they were dried in oven at 65 °C for 24 hours. Following acid digestion, the measurement of heavy metals concentration was performed by atomic absorption machine. Results: The samples’ mean concentration of zinc, copper, lead, cadmium, and nickel were 54.3, 18.3, 1.28, 1.02 and 0.2 ppm, respectively. The maximum and average concentrations were observed in zinc and the minimum level of contaminants was found in nickel. Conclusion: This study showed that the concentration of heavy metals including Zn,Cu and Pb in Banana shrimps were less than the amounts recommended by WHO, MAFF, USEPA, thereby not considered a health risk. However, the concentration of Ni and Cd were found to be almost harmful for human health, therefore, lower intake of Banana shrimp in this region is recommended.

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Background and purpose: Industrial effluent and sewage sludge are used as fertilizer since they contain high levels of nutrient. The main pollutant in industrial effluent is heavy metals. In this study an assessment was made on the impact of industrial wastewater effluent and sewage sludge on accumulation of heavy metals in agricultural soil at Agh ghallah industrial Estate. Materials and methods: In a descriptive-analytic study, 72 samples (sewage sludge, effluent and soil) were collected from the Industrial state. All sampling and tests were performed according to standard methods and concentration of heavy metals was determined using polarography method. To analyze the data, SPSS was used and 95% confidence intervals (P<0.05) were applied. Results: The mean concentrations of Cd, Cu. Pb and Zn in sewage sludge were 0.53, 15.9, 1.44 and 692.7 mg/kg dw, respectively which were found to be lower than EPA standard. The concentrations of investigated heavy metals were within normal range in wastewater effluent that was discharged into surface water. The mean concentrations of metals in soil irrigated by wastewater were higher than those of the control soil. In a 10-year period, the concentration of lead and zinc increased 130 and 4 fold and cadmium and copper concentrations increased less than two-fold. There was a significant correlation between Zn and Pb in soil, sewage sludge and control soil (P<0.05). However, the concentration of Cd and Cu were not affected (P> 0.05). Conclusion: The concentrations of heavy metal were found lower than the maximum allowable level. Therefore, in this area, wastewater and sewage sludge could be used to irrigate agricultural lands and greenspaces in shortage of water, however, environmental regulations should be taken into account.

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Abstract Background and purpose: Nowadays, tendency to consume bottled water shows significant growth due to increase of demand for safe drinking water, limited resources of fresh water and the public beliefs about the quality of bottled water. The aims of this study were to evaluate the microbial and physicochemical quality of bottled water in Mazandaran province and their heavy metal concentration. Materials and methods: This descriptive-cross sectional study was done in 60 types of 1.5 lit bottled water from 15 different brands which have been bottled in different seasons in Mazandaran province in 2012. We assessed 33 microbial and physicochemical characteristics and concentrations of heavy metals applying standard method and compared them with those recommended by WHO and Iran National Standard Organization. Results: The analyzed samples were 100% in the range of Iran National Standard regarding microbial and physicochemical quality. Among chemical parameters, fluorine (0.01 mg/l) was the least while nickel (0.08 mg/l) and boron (1 mg/l) were the most common. Compared to standard guidelines, among heavy metals, mercury, chrome and lead were found with maximum level (0.001, 0.01 and 0.05 mg/l, respectively). There was no significant difference between the measured and listed values on the labels of bottled water (P<0.05). Conclusion: Results showed that the values of all parameters except Nickel were acceptable and did not exceed the standard guidelines for bottled water quality. However, continuous monitoring of bottled water is necessary since there is an increasing trend in consumption of bottled water and new brands are being distributed in the market.

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Background and purpose: Aquatic ecosystems are important sources of food for human which are sometimes highlycontaminated. It is important to determine their levels of contaminations, so, in this study, theconcentrations of lead, cadmium and nickel was investigated in the gills and musclesof Barbusxanthopterus captured from Dez River, Iran. Materials and methods: Thirty samples of Barbusxanthopterus were captured from the central basin of Dez River using gillnet. The tissues were isolated, and the samples were digested. The concentrations of lead, cadmium and nickel were measured using a PE-4100 graphite furnace atomic absorption spectrometer. Results: The levels of lead, cadmium and nickel in gills were 0.322 ± 0.006, 0.182 ±0.006, and 0.004 ± 0.219, respectively. The concentration of these metals in muscle were 0.277 ± 0.014, 0.005 ± 0.0146, and 0.013 ± 0.165, respectively. Higher concentrations of heavy metals were found in gills. T-test revealed significant differences in the levels of nickel, lead, and cadmium between the gills and muscle. Conclusion: According to thisresearchthe concentrations of studied metals were lower than the WHO standards.

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Background and purpose: Sewage sludge can contain heavy metals. This study aimed at investigating the effect of cow manure as bulking agent on concentration of heavy metals (cadmium, chromium, copper and lead) during municipal sewage sludge vermicomposting and compares that with standard levels. Materials and methods: In an experimental research, vermicompost was produced by mixing sewage sludge and cow manure using earthworms (Eisenia Foetida species). Composting process was conducted in 27 pilots for three months. The heavy metals concentrations were measured by atomic absorption spectroscopy in the vermicomposting process. Then, data was analyzed by descriptive statistics and statistical test of Repeated Measured ANOVA. Results: In all pilots the heavy metals concentration decreased with increasing vermicomposting time. Reduction in Cd, Cr, Cu and Pb concentration values in the vermicompost produced from mixture of sewage sludge and cow manure was found 50% higher than other pilots. The concentration of heavy metals of in terms of kind of composted material decreased significantly in all pilots (P<0.05). Concentration of heavy metals for the number of worms also decreased in all pilots but this decrease was not found to be significant (P>0.05). Therefore, a compost produced by a mixture of 50% sewage sludge, 50% cow manure and 40 Eisenia Foetida in 1.2 Kg could have a higher quality in terms of heavy metals. Conclusion: The concentration of heavy metals was lower than the standard levels set by Iranian national (class I and II), WHO and US Environmental Protection Agency. The use of cow dung as a cheap and available bulking agent is recommended in vermicomposting of sewage sludge.

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Background and purpose: In recent years, dust storms have affected many regions in Iran including Kurdistan province. Along with dust other pollutants such as heavy metals may also be transferred which pose a risk to human health. The purpose of this study was to determine heavy metals concentrations in atmospheric PM₁₀ in Sanandaj, Iran and also assessing their health risk on the staff and students in Kurdistan University of Medical Sciences (KUMS).

Materials and methods: KUMS was chosen as the sampling site and the samples were taken every six days and also on dusty days. Omni air sampler was used to determine the concentration of heavy metals, including arsenic, cadmium, chromium, cobalt, zinc, iron, copper, manganese, and nickel in PM10, from April to September 2013. Health risk assessment of cancerous and noncancerous diseases caused by these heavy metals was carried out using the guideline of United States Environmental Protection Agency (USEPA) for three groups including the staff, students using KUMS accommodation and students resident in other places.

Results: The heavy metal with highest concentration was iron which was seen in both dusty and ordinary days. In dusty and ordinary days cadmium was found to have the least concentration in May and September, respectively. The overall risk of cancer for all the studied metals and for the three groups in dusty days was higher than non-dusty days (less than two per one million). Acute and chronic non-cancer risks of studied metals for the three studied groups were less than one.

Conclusion: According to the baseline values of cancerous and noncancerous risks provided by the USEPA, it seems that, during the investigation period, the studied metals do not increase the risk of cancer and non-cancer diseases among individuals working and studying in KUMS.

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Background and purpose: Exposure to heavy metals can cause neurological, respiratory and cardiovascular disorders, imbalance of hormones, hair loss, infertility, and abortion. Kohl containing heavy metals can lead to such complications due to long-term contact with the lining of the eye. The aim of this study was to investigate the contamination level of Kohl by heavy metals (cadmium, zinc, nickel, chrome, lead, and copper) used in some Iranian cities.

Materials and methods: Thirty samples of Kohl were prepared from 10 brands available in Iran’s market. The samples were digested by perchloric and nitric acid. Concentration of heavy metals were measured using atomic absorption spectrophotometer.

Results: The highest concentrations measured in samples from Kohl with mean ± SD included: cadmium  2350 ± 20, chrome 2270 ± 240, lead 61900 ± 1900, nickel 3380 ± 210, zink 16190 ± 120, copper 36240 ± 250  (ng per gram) in Kohl samples. The lowest concentrations were observed with cadmium (2 ± 0.002), chrome (2 ± 0.002), lead (341 ± 0.8), nickel (3 ± 0.4), zink (1100 ± 40), and copper (9 ± 0.8 ng per gram) in all samples. The concentrations of cadmium, zinc, nickel, chrome, lead, and copper in all samples were within the range suggested by WHO.

Conclusion: High levels of heavy metals in noncertified Kohl are a warning. Therefore, constant vigilance is needed to ensure that allowable level of heavy metals is used in this product. Therefore, heavy metals concentration in Kohl should be determined before entering the market.

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Background and purpose: Rice is one of the most widely consumed cereal, and one of the major components of the food basket of approximately 2.4 billion people in the world. In Iran it is the second staple crop after wheat. This study aimed at investigating the level of different heavy metals (cadmium, arsenic, and lead) in rice consumed in Hormozgan province, 2014.

Materials and methods: An analytical cross-sectional study that was carried out in 75 samples of Iranian, Pakistani, and Indian rice consumed in Hormozgan province in 2014. The samples were randomly selected and analyzed.

Results: The mean concentrations of arsenic, lead and cadmium were 0.045, 0.057 and 0.022 mg/kg, respectively. The maximum level of arsenic was found in unauthorized Indian rice (0.033 mg/kg) and the maximum lead content was observed in unauthorized Pakistani rice (0.070 mg/kg).

Conclusion: Due to the high consumption of rice in the country and contamination of rice with heavy metals, it is important to choose safe products to avoid accumulative effect of these metals on human health.

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Background and purpose: Presence of heavy metals in water resources is of great concerns due to adverse effects on human health. The aims of this study were to evaluate the efficiency of coagulation process using Polyaluminum Silicate Chloride (PASiC) in removal of hexavalent chromium and Cadmium from aqueous solutions and comparing that to the standards.

Materials and methods: Experiments were carried out by Jar test using PASiC coagulant. The applied pH range in this study was 4 to 11, and different PASiC dosage (15 to 187.5 mg/l), heavy metal concentrations (5 to 100 mg/l), and settling times (10 to 90 minutes) were investigated. All experiments were repeated three times for accuracy and precision.

Results: The optimum conditions for chromium removal was in PASiC dose of 150 mg/l, pH= 5, and settling time= 45 minutes, which decreased the chromium concentration (from 10 mg/l initial concentration) to 3.118 ± 0.29 mg/l and this was more than the standard levels of wastewater discharge into receiving water. The PASiC in 75 mg/l could reduce the cadmium level to 0.019 ± 0.01 mg/l (from 5 mg/l) in optimum condition (pH= 8 and settling time= 30 minutes). This level of cadmium removal was less than the standard levels of wastewater discharge into the receiving water.

Conclusion: The PASiC coagulant was found to be more effective in removing cadmium than chromium from aqueous solutions and could be applied for cadmium removal from water and wastewater.