Prevalence of skin lesions and exposure to arsenic in drinking water in Iran

Prevalence of skin lesions was investigated among 752 participants in eight villages in Kurdistan province in Iran with emphasis on total lifetime intake of arsenic from drinking water (TLIA). The participants were selected from eight villages with different exposure levels using a cluster-sampling technique. TLIA was calculated for each individual taking into account the type of water supply and their mean annual arsenic concentration. The study showed that 49 persons (6.5%) were suffering from hyperkeratosis and 20 persons (2.7%) from hyperpigmentation. The correlation between hyperkeratosis and hyperpigmentation was significant (R=0.325, p<0.01). Using the logistic regression model it was found that the relationship between TLIA and hyperkeratosis (OR=1.14, 95% CI=1.039-1.249), and hyperpigmentation (OR=1.254, 95% CI=1.112-1.416) was also significant. In conclusion, TLIA can be applied as a reliable indicator for the assessment of exposure.     

The association between arsenic exposure from drinking water and cerebrovascular disease mortality in Taiwan

Background

Chronic arsenic exposure is associated with a variety of diseases, including cancer, peripheral vascular disease, and diabetes. However, its association with cerebrovascular diseases (CVD) has not yet been resolved. The aim of this study is to explore this association in Taiwan using nation-wide data.

Materials and methods

We analyzed mortality data in Taiwan from 1971 to 2005 and choose two geographic areas with populations suffering from chronic exposure to arsenic in drinking water for study, the blackfoot disease endemic area (BFDEA) in the southwest and Lan-Yang Basin (LYB) in the northeast parts of Taiwan. The Chia-Yi and Tainan Counties, which surround the BFDEA, and the nation of Taiwan as a whole were used as reference populations. Direct standardized mortality rates and gender-specific indirect standardized mortality ratios (SMRs) were calculated for the four populations.

Results

The direct standardized mortality rate for CVD in Taiwan decreased from 2.46/10³ person-year in 1971 to 0.63/10³ person-year in 2005, and women had significantly lower mortality than men (SMR = 0.80; p < 0.05). The CVD mortality rates of populations with chronic arsenic exposure were significantly higher than the reference populations (SMR ranging from 1.06 to 1.09 in men and 1.12 to 1.14 in women; p < 0.05). The BFDEA had higher CVD mortality rates than the LYB, with SMR = 1.05 (p < 0.05) in men and SMR = 1.04 (p = 0.05) in women.

Conclusion

In Taiwan, while CVD mortality decreased in both genders between 1971 and 2005, chronic arsenic exposure from drinking water was associated with increased risks of CVD.     

Abiotic properties of landfill leachate controlling arsenic release from drinking water adsorbents

In this study, As leaching from five arsenic bearing solid residuals (ABSRs) comprised of the iron hydroxide adsorbent Bayoxide E33 used in long-term operations was evaluated in leaching trials using California Waste Extraction Test (CalWET) and Toxicity Characteristic Leaching Protocol (TCLP) leachate solutions, a landfill leachate (LL), and synthetic leachate (SL). The initial As loading of the media, which reflects the influence of source water chemistry and varying treatment conditions at the point of removal, strongly influenced the magnitude of As release. The chemical composition of the leachate also influenced As release and demonstrated the relative importance of different release mechanisms, namely media dissolution, pH-dependent sorption/desorption, and ion exchange. The CalWET solution, which partially dissolved the iron-based media, resulted in 100 times more As release than did the TCLP solution, which did not dissolve the media. The LL had a higher pH than the TCLP solution, and even though its organic carbon content was lower it tended to release more As. Tests with the SL were conducted to determine the influence of variations in leachate pH, phosphate, bicarbonate, sulfate, silicate, and natural organic matter (NOM). Release increased at high pH, in the presence of high concentrations of phosphate and bicarbonate, and in the presence of high NOM concentrations. For pH, this reflects the pH-dependence of sorption reactions, whereas for the anions and NOM, direct competition appeared important. Similar to the CalWET solution, excess NOM dissolved portions of the media thereby facilitating As release. In general, our results suggest that estimating As release into landfills will remain a challenge as it depends upon As loading, which reflects site-specific properties, and the composition of the leachate, which varies from landfill to landfill.     

Subsurface iron and arsenic removal for shallow tube well drinking water supply in rural Bangladesh

Subsurface iron and arsenic removal has the potential to be a cost-effective technology to provide safe drinking water in rural decentralized applications, using existing shallow tube wells. A community-scale test facility in Bangladesh was constructed for injection of aerated water (∼1 m³) into an anoxic aquifer with elevated iron (0.27 mmol L⁻¹) and arsenic (0.27 μmol L⁻¹) concentrations. The injection (oxidation) and abstraction (adsorption) cycles were monitored at the test facility and simultaneously simulated in the laboratory with anoxic column experiments.Dimensionless retardation factors (R) were determined to represent the delayed arrival of iron or arsenic in the well compared to the original groundwater. At the test facility the iron removal efficacies increased after every injection-abstraction cycle, with retardation factors (R_Fe) up to 17. These high removal efficacies could not be explained by the theory of adsorptive-catalytic oxidation, and therefore other ((a)biotic or transport) processes have contributed to the system’s efficacy. This finding was confirmed in the anoxic column experiments, since the mechanism of adsorptive-catalytic oxidation dominated in the columns and iron removal efficacies did not increase with every cycle (stable at R_Fe = ∼8). R_As did not increase after multiple cycles, it remained stable around 2, illustrating that the process which is responsible for the effective iron removal did not promote the co-removal of arsenic. The columns showed that subsurface arsenic removal was an adsorptive process and only the freshly oxidized adsorbed iron was available for the co-adsorption of arsenic. This indicates that arsenic adsorption during subsurface treatment is controlled by the amount of adsorbed iron that is oxidized, and not by the amount of removed iron. For operational purposes this is an important finding, since apparently the oxygen concentration of the injection water does not control the subsurface arsenic removal, but rather the injection volume. Additionally, no relation has been observed in this study between the amount of removed arsenic at different molar Fe:As ratios (28, 63, and 103) of the groundwater. It is proposed that the removal of arsenic was limited by the presence of other anions, such as phosphate, competing for the same adsorption sites.     

The correlation of arsenic levels in drinking water with the biological samples of skin disorders

Arsenic (As) poisoning has become a worldwide public health concern. The skin is quite sensitive to As and skin lesions are the most common and earliest nonmalignant effects associated to chronic As exposure. In 2005-2007, a survey was carried out on surface and groundwater arsenic contamination and relationships between As exposure via the drinking water and related adverse health effects (melanosis and keratosis) on villagers resides on the banks of Manchar lake, southern part of Sindh, Pakistan. We screened the population from arsenic-affected villages, 61 to 73% population were identified patients suffering from chronic arsenic toxicity. The effects of As toxicity via drinking water were estimated by biological samples (scalp hair and blood) of adults (males and females), have or have not skin problem (n = 187). The referent samples of both genders were also collected from the areas having low level of As (< 10 μg/L) in drinking water (n = 121). Arsenic concentration in drinking water and biological samples were analyzed using electrothermal atomic absorption spectrometry. The range of arsenic concentrations in lake surface water was 35.2-158 μg/L, which is 3-15 folds higher than World Health Organization [WHO, 2004. Guidelines for drinking-water quality third ed., WHO Geneva Switzerland.]. It was observed that As concentration in the scalp hair and blood samples were above the range of permissible values 0.034-0.319 μg As/g for hair and < 0.5-4.2 μg/L for blood. The linear regressions showed good correlations between arsenic concentrations in water versus hair and blood samples of exposed skin diseased subjects (R² = 0.852 and 0.718) as compared to non-diseased subjects (R² = 0.573 and 0.351), respectively.     

Dietary exposure and biomarkers of arsenic in consumers of fish and shellfish from France

Seafood, especially fish, is considered as a major dietary source of arsenic (As). Seafood consumption is recommended for nutritional properties but contaminant exposure should be considered. The objectives were to assess As intake of frequent French seafood consumers and exposure via biomarkers. Consumptions of 996 high consumers (18 and over) of 4 coastal areas were assessed using a validated food frequency questionnaire. Seafood samples were collected according to a total diet study (TDS) sampling method and analyzed for total As, arsenite (AsIII), arsenate (AsV), arsenobetaïne (AsB), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The average As dietary exposure is 94.7 ± 67.5 μg/kg bw/week in females and 77.3 ± 54.6 μg/kg bw/week in males (p < 0.001) and the inorganic As dietary exposure is respectively 3.34 ± 2.06 μg/kg bw/week and 3.04 ± 1.86 μg/kg bw/week (p < 0.05).Urine samples were collected from 382 of the subjects. The average urinary As concentration is 94.8 ± 250 μg/g creatinine for females and 59.7 ± 81.8 μg/g for males (p < 0.001). Samples having an As concentration above 75 μg/g creatinine (n = 101) were analyzed for inorganic As (As(III), As(V), MMA(V) and DMA(V)) which was 24.6 ± 27.9 μg/g creatinine for males and 27.1 ±20.6 μg/g for females. Analyses do not show any correlation between dietary exposure and urinary As.These results show that biological results should be interpreted cautiously. Diet recording seems to be the best way to assess dietary As exposure. Seafood is a high source of As exposure but even among high consumers it is not the main source of toxic As. From a public health point of view these results should be interpreted carefully in the absence of international consensus on the health-based guidance value.     

Respiratory effects in people exposed to arsenic via the drinking water and tobacco smoking in southern part of Pakistan

In this study, a survey has been conducted during 2005-2007 on surface and groundwater arsenic (As) contamination and its impact on the health of local population, of villages located on the banks of Manchar lake, southern part of Sindh, Pakistan. We have also assessed the relationship between arsenic exposure through respiratory disorders in male subjects with drinking water and smoking cigarettes made from tobacco grown in agricultural land irrigated with As contaminated lake water. The biological samples (blood and scalp hair) were collected from As exposed subjects (100% smokers) and age matched healthy male subjects (40.2% smoker and 59.8% non smokers) belong to unexposed areas for comparison purposes. The As concentration in drinking water (surface and underground water), agricultural soil, cigarette tobacco and biological samples were determined by electrothermal atomic absorption spectrometry. The range of As concentrations in lake water was 35.2-158 µg/L (average 97.5 µg/L), which is 3-15 folds higher than permissible limit of World Health Organization (WHO, 2004). While the As level in local cigarette tobacco was found to be 3-6 folds higher than branded cigarettes (0.37-0.79 µg/g). Arsenic exposed subjects (with and without RD) had significantly elevated levels of As in their biological samples as compared to referent male subject of unexposed area. These respiratory effects were more pronounced in individuals who had also As induced skin lesions. The linear regressions showed good correlations between As concentrations in water versus hair and blood samples of exposed subjects with and without respiratory problems.     

Chemical reactions between arsenic and zero-valent iron in water

Batch experiments and X-ray photoelectron spectroscopic (XPS) analyses were performed to study the reactions between arsenate [As(V)], arsenite [As(III)] and zero-valent iron [Fe(0)]. The As(III) removal rate was higher than that for As(V) when iron filings (80-120 mesh) were mixed with arsenic solutions purged with nitrogen gas in the pH range of 4-7. XPS spectra of the reacted iron coupons showed the reduction of As(III) to As(0). Soluble As(III) was formed when As(V) reacted with Fe(0) under anoxic conditions. However, no As(0) was detected on the iron coupons after 5 days of reaction in the As(V)-Fe(0) system. The removal of the arsenic species by Fe(0) was attributed to electrochemical reduction of As(III) to sparsely soluble As(0) and adsorption of As(III) and As(V) to iron hydroxides formed on the Fe(0) surface under anoxic conditions. When the solutions were open to atmospheric air, the removal rates of As(V) and As(III) were much higher than under the anoxic conditions, and As(V) removal was faster than As(III). The rapid removal of As(III) and As(V) was caused by adsorption on ferric hydroxides formed readily through oxidation of Fe(0) by dissolved oxygen.     

Evaluation of a novel hybrid inorganic/organic polymer type material in the arsenic removal process from drinking water

The objective of this paper is the evaluation of a hybrid inorganic/organic polymer type material based on hydrated ferric oxide (HFO), in the adsorption process of arsenic oxyanions from contaminated waters used as drinking water. The study includes rapid small-scale column tests conducted in continuous flow operation in order to assess the arsenic removal capacity in various conditions. Thus it was evaluated the influence of some competing ions like silicate and phosphate on As(V) adsorption and the influence of feed water pH in the removal process of As(V) and As(III) species. Based on the As/pH variation in time at different feed water pH (5, 7 and 9), a possible sorption mechanism that fits the experimental data was suggested. The regeneration and re-use of the hybrid adsorbent was studied in the presence and in the absence of the contaminant ions. The novel hybrid material is very selective towards arsenic oxyanions even though the presence of silica and phosphate reduces the adsorption capacity.     

Simultaneous removal of nitrate and arsenic from drinking water sources utilizing a fixed-bed bioreactor system

A novel bioreactor system, consisting of two biologically active carbon (BAC) reactors in series, was developed for the simultaneous removal of nitrate and arsenic from a synthetic groundwater supplemented with acetic acid. A mixed biofilm microbial community that developed on the BAC was capable of utilizing dissolved oxygen, nitrate, arsenate, and sulfate as the electron acceptors. Nitrate was removed from a concentration of approximately 50 mg/L in the influent to below the detection limit of 0.2 mg/L. Biologically generated sulfides resulted in the precipitation of the iron sulfides mackinawite and greigite, which concomitantly removed arsenic from an influent concentration of approximately 200 ug/L to below 20 ug/L through arsenic sulfide precipitation and surface precipitation on iron sulfides. This study showed for the first time that arsenic and nitrate can be simultaneously removed from drinking water sources utilizing a bioreactor system.     

Assessment of arsenic exposure from groundwater and rice in Bengal Delta Region, West Bengal, India

Arsenic (As) induced identifiable health outcomes are now spreading across Indian subcontinent with continuous discovery of high As concentrations in groundwater. This study deals with groundwater hydrochemistry vis-à-vis As exposure assessment among rural population in Chakdaha block, West Bengal, India. The water quality survey reveals that 96% of the tubewells exceed WHO guideline value (10 μg/L of As). The groundwaters are generally anoxic (−283 to −22 mV) with circum-neutral pH (6.3 to 7.8). The hydrochemistry is dominated by HCO₃⁻ (208 to 440 mg/L), Ca²⁺ (79 to 178 mg/L) and Mg²⁺ (17 to 45 mg/L) ions along with high concentrations of As_T (As total, below detection limit to 0.29 mg/L), Fe_T (Fe total, 1.2 to 16 mg/L), and Fe(II) (0.74 to 16 mg/L). The result demonstrates that Fe(II)-Fe(III) cycling is the dominant process for the release of As from aquifer sediments to groundwater (and vice versa), which is mainly controlled by the local biogeochemical conditions. The exposure scenario reveals that the consumption of groundwater and rice are the major pathways of As accumulation in human body, which is explained by the dietary habit of the surveyed population. Finally, regular awareness campaign is essential as part of the management and prevention of health outcomes.     

Effect of air-assisted backwashing on the performance of an anaerobic fixed-bed bioreactor that simultaneously removes nitrate and arsenic from drinking water sources

Contaminant removal from drinking water sources under reducing conditions conducive for the growth of denitrifying, arsenate reducing, and sulfate reducing microbes using a fixed-bed bioreactor may require oxygen-free gas (e.g., N₂ gas) during backwashing. However, the use of air-assisted backwashing has practical advantages, including simpler operation, improved safety, and lower cost. A study was conducted to evaluate whether replacing N₂ gas with air during backwashing would impact performance in a nitrate and arsenic removing anaerobic bioreactor system that consisted of two biologically active carbon reactors in series. Gas-assisted backwashing, comprised of 2 min of gas injection to fluidize the bed and dislodge biomass and solid phase products, was performed in the first reactor (reactor A) every two days. The second reactor (reactor B) was subjected to N₂ gas-assisted backwashing every 3-4 months. Complete removal of 50 mg/L NO₃⁻ was achieved in reactor A before and after the switch from N₂-assisted backwashing (NAB) to air-assisted backwashing (AAB). Substantial sulfate removal was achieved with both backwashing strategies. Prolonged practice of AAB (more than two months), however, diminished sulfate reduction in reactor B somewhat. Arsenic removal in reactor A was impacted slightly by long-term use of AAB, but arsenic removals achieved by the entire system during NAB and AAB periods were not significantly different (p > 0.05) and arsenic concentrations were reduced from approximately 200 μg/L to below 20 μg/L. These results indicate that AAB can be implemented in anaerobic nitrate and arsenic removal systems.     

Temperature-induced impacts on groundwater quality and arsenic mobility in anoxic aquifer sediments used for both drinking water and shallow geothermal energy production

Aquifers used for the production of drinking water are increasingly being used for the generation of shallow geothermal energy. This causes temperature perturbations far beyond the natural variations in aquifers and the effects of these temperature variations on groundwater quality, in particular trace elements, have not been investigated. Here, we report the results of column experiments to assess the impacts of temperature variations (5°C, 11°C, 25°C and 60°C) on groundwater quality in anoxic reactive unconsolidated sandy sediments derived from an aquifer system widely used for drinking water production in the Netherlands. Our results showed that at 5 °C no effects on water quality were observed compared to the reference of 11°C (in situ temperature). At 25°C, As concentrations were significantly increased and at 60 °C, significant increases were observed pH and DOC, P, K, Si, As, Mo, V, B, and F concentrations. These elements should therefore be considered for water quality monitoring programs of shallow geothermal energy projects. No consistent temperature effects were observed on Na, Ca, Mg, Sr, Fe, Mn, Al, Ba, Co, Cu, Ni, Pb, Zn, Eu, Ho, Sb, Sc, Yb, Ga, La, and Th concentrations, all of which were present in the sediment. The temperature-induced chemical effects were probably caused by (incongruent) dissolution of silicate minerals (K and Si), desorption from, and potentially reductive dissolution of, iron oxides (As, B, Mo, V, and possibly P and DOC), and mineralisation of sedimentary organic matter (DOC and P).     

A retrospective cohort study of trihalomethane exposure through drinking water and cancer mortality in northern Italy

A few epidemiologic studies have suggested that consumption of drinking water with high trihalomethane content increases the risk of cancer. We investigated the mortality of a cohort of 5144 residents in Guastalla, northern Italy, who were supplied tap water with high chloroform and trihalomethane content between 1965 and 1987. Using death rates of a nearby community as reference rates, the standardized mortality ratio from all cancers between 1987 and 1999 was slightly increased for both males (1.2, 95% confidence interval 1.1-1.4) and females (1.1, 95% confidence interval 1.0-1.3). This was mainly due to a higher mortality from stomach, liver, lung, prostate and bladder cancer in males and from stomach, pancreas, breast and ovarian cancer and lymphocytic leukemia in females. We also noted excess mortality from melanoma in both males and females. Overall, our findings were consistent with an association between trihalomethane exposure and increased cancer risk at some sites. However, the point estimates were statistically imprecise, due to the limited number of deaths for some site-specific cancers. In addition, we were unable to rule out the possibility of confounding due to smoking and other life-style factors with regard to some of the excess rates.     

Occurrence, oral exposure and risk assessment of volatile organic compounds in drinking water for Izmir

Concentrations of volatile organic compounds (VOCs) were measured in the drinking water in Province of Izmir, Turkey, and associated health risks due to ingestion of these compounds were investigated using population weighted random samples. A total of 100 houses were visited in different districts of Izmir and drinking water samples were collected from consumers' drinking water source. Questionnaires were administered to one participant in each house to determine demographics and drinking water consumption rates. Oral exposure and risks were estimated for each participant and Izmir population by deterministic and probabilistic approaches, respectively. The four trihalomethane (THM) species (i.e., chloroform, bromodichloromethane, dibromochloromethane, and bromoform), benzene, toluene, p-xylene, and naphthalene were the most frequently detected VOCs with concentrations ranging from below detection limit to 35 microg/l. The risk estimates were found to be less than the values reported in the literature with few exceptions. Noncarcinogenic risks attributable to ingestion of VOCs for Izmir population were negligible, whereas the mean carcinogenic risk estimates for bromodichloromethane and dibromochloromethane were above the de minimis level of one in a million (10(-6)). For all VOCs, the concentrations measured in metropolitan area were greater than those in other districts. All THM species were detected in higher concentrations in tap water, whereas nontap water contained more benzene, toluene, p-xylene, and naphthalene. Therefore, the concentrations of the latter four compounds and associated risks increased with increasing income and education level since bottled water was used in larger proportions within these subgroups. The results of this study showed that oral exposure to drinking water contaminants and associated risks may be higher than the acceptable levels even if the concentrations fall below the standards.     

Relationship between intensity, concentration, and temperature for drinking water odorants

Odor analyses experiments indicated that, for the concentrations and temperatures tested, odor intensity was a function of both aqueous concentration and water temperature for water containing 1-butanol, free available chlorine, geosmin, n-hexanal, 2-methylisoborneol, and trans-2, cis-6 nonadienal. At weak odorant concentrations (approximately 4 on the flavor profile rating scale) the perceived odor intensity of these six chemicals was greater when the temperature was 45 degrees C than was 25 degrees C. Both of these temperatures are commonly encountered by consumers when they use tap water. Odor response to water containing isobutanal was affected by concentration but not water temperature. Experiments also revealed that reduction in aqueous concentration did not consistently reduce odor intensity; for some aqueous concentrations and chemicals an increase in odor intensity occurred at lower concentrations.     

Formation and removal of genotoxic activity during UV/H2O2-GAC treatment of drinking water

The objective of this study was to determine the genotoxic activity of water after UV/H₂O₂ oxidation and GAC filtration. Pre-treated surface water from three locations was treated with UV/H₂O₂ with medium pressure (MP) lamps and passed through granulated activated carbon (GAC). Samples taken before and after each treatment step were extracted and concentrated by solid phase extraction (SPE) and analyzed for genotoxicity using the Comet assay with HepG2 cells and the Ames II assay.The Comet assay showed no genotoxic response in any of the samples. In the Ames II, no genotoxic response was obtained with the TAMix (a mix of six strains), but the TA98 strain showed an increase in genotoxic activity after MP-UV/H₂O₂ for all three locations. GAC post treatment effectively reduced the activities to control levels at two of the three locations and to below the level of the pre-treated water at one site. The results indicate that UV/H₂O₂ treatment may lead to the formation of genotoxic by-products, which can be removed by subsequent GAC filtration.     

Studies on vinyl chloride migrating into drinking water from polyvinyl chloride pipe and reaction between vinyl chloride and chlorine

To determine the conditions for the migration of vinyl chloride monomer (VCM) into water from polyvinyl chloride (PVC) pipes and to examine the reaction between VCM and the chlorine present in drinking water, we studied the migration of VCM into water. It was found that migration of VCM into water from PVC pipes (containing 29.5 ppm VCM) could only be detected by using an apparatus that prevented volatilization of VCM and increasing the surface area of the pipe wall in contact with the water. The amount of VCM which could undergo action of the chlorine in the water decreased markedly with the age of the pipes and when the pH was lowered. VCM occurred in the water was converted to chloroacetaldehyde, chloroacetic acid, etc., by its reaction with chlorine, while the amounts of these reactants varied with pH of the solution was changed.