Levels Of Arsenic In Water Research Articles

Quantitative health risk assessment in a historical contaminated area – exposure- and risk characterization

Introduction Production of glass has been going on since the 1800’s in Sweden, and several areas are contaminated by this industry. Environmental measurements show elevated levels of metals, arsenic, lead, cadmium and antimony in soil and water, and it is anticipated that the population living in those areas is highly exposed to metals in locally grown root crops, berries, etc. The aim of this study is to investigate the level of exposure and associated health risks in a population residing in a historically contaminated area. Methods We identified 34 271 individuals, who at some time between the years 1979-2004, had lived within 2 km radius of a glass works area. Information on the incidence of cancer diagnoses occurring among residents during the period 1979-2010 was obtained from the National Cancer Register. Information on dietary habits, lifestyle factors etc. were collected via questionnaires sent to all living cancer cases and to cancer-free controls from the same area. A subsample of them was asked to provide biological samples and metals were determined in blood and urine from approximately 800 individuals to assess exposure and body burdens. Preliminary results Cancer cases, residing for at least 10 years in the contaminated area, reported higher consumption of local root crops, fruit, berries and mushrooms than controls (p<0.05). Cancer cases had a longer period of residence in the area than the controls (46 and 35 years, resp.; p<0.01). Twelve % of the cancer cases and 9 % of the controls had worked in the glass production. Preliminary data based on 208 analyzed blood samples and evaluated by Principal Component Analysis, showed that metals co-varied with having a private well during childhood, long residence time in the glass works area, smoking and having a cancer diagnosis. Conclusions Preliminary data indicate an association between having a cancer diagnosis and the consumption of local food, residence time in the area and having had a private well.

Abstract 4299: Short telomeres are associated with increased risk for arsenic-related skin lesions in Bangladesh

Abstract Chronic exposure to arsenic, a human carcinogen, has been shown in epidemiologic studies to increase the risk of arsenical skin lesions (keratosis and melanosis) as well as cancer (including non-melanoma skin cancer). Recent studies suggest that the mechanism of arsenic's toxicity may be related to telomere dysfunction, including altered telomere length (TL), and differential expression of genes involved in telomere maintenance. However, prior studies of arsenic exposure, TL, and skin lesion tend to be small and cross-sectional in nature. In this study, we investigated the association between arsenic exposure and TL (measured by qPCR as T/S ratio), as well as TL and subsequent risk of skin lesion in individuals who are exposed to naturally contaminated drinking water with a wide range of arsenic levels in the Health Effects of Arsenic Longitudinal Study (HEALS) in Araihazar, Bangladesh (2000-2009). In all laboratory analyses, we attempted to randomize samples across plate positions, and in statistical analyses, we controlled for any residual confounding by plate or plate position. All TL data generated showed a strong inverse association with age. In a random sample of the baseline cohort (n = 649), we observed a positive association between water arsenic levels and TL (Ptrend = 0.035), with beta estimates of 0.001, 0.023, and 0.025 for water arsenic levels of 10.1-50ug/L, 50.1-150ug/L and 150+ug/L, respectively, compared to <10ug/L. However the association was not replicated in an independent random sample (n = 1181, Ptrend = 0.176) with beta estimates of 0.007, -0.004, and -0.017. In a nested case-control study comparing skin lesion incident cases diagnosed across a nine year period with sex- and age-matched controls (448 cases and 462 controls), we observed higher incident skin lesion risk with shorter TL (Ptrend = 4.6E-5), with odds ratios of 3.05, 1.30, and 1.21 for the first (shortest), second, and third TL quartiles compared to the longest. Our findings show that arsenic exposure is not strongly associated with TL, indicating that TL is likely not the main mode of action for arsenic's carcinogenic toxicity. However, TL is inversely associated with skin lesion risk, suggesting that short TL may be a biomarker of susceptibility for arsenical skin lesions independent of arsenic exposure. Citation Format: Chenan Zhang, Muhammad Kibriya, Farzana Jasmine, Shantanu Roy, Habibul Ahsan, Brandon L. Pierce. Short telomeres are associated with increased risk for arsenic-related skin lesions in Bangladesh. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4299.

Arsenic exposure and risk of preeclampsia in a Mexican mestizo population.

BackgroundExposure to arsenic in drinking water has been associated with various complications of pregnancy including fetal loss, low birth weight, anemia, gestational diabetes and spontaneous abortion. However, to date, there are no studies evaluating its possible association with preeclampsia.MethodsThis case–control study involved 104 preeclamptic and 202 healthy pregnant women. The concentrations of arsenic in drinking water and urine were measured using a Microwave Plasma-Atomic Emission Spectrometer.ResultsWe found relatively low levels of arsenic in household tap water (range of 2.48–76.02 μg/L) and in the urine of the participants (7.1 μg/L vs 6.78 μg/L in cases and controls, respectively).ConclusionsThe analysis between groups showed for the first time that at these lower levels of exposure there is no association with preeclampsia.

Assessment of heavy metals concentration in water, soil sediment and biological tissues of the lesser flamingos in four eastern rift valley lakes

The term heavy metal refers to any metallic chemical element that has a relatively high density and is toxic at low concentrations. This study was conducted in four eastern Rift Valley lakes which included Lakes Oloidien, Crater, Elementaita and Nakuru, to determine the presence and levels of lead, arsenic, cadmium and chromium concentration in water, soil sediments and biological tissues of the Lesser Flamingos (Phoeniconaias minor) and compare with the set standards. As these lakes catchments fall directly within a combination of agricultural and industrial regions, the run-offs and the resulting effluents will make the waters highly prone to chemical contamination. The methodology involved collection of water samples (n=40), sediments samples (n=51) and the Lesser Flamingos (live n= 6; dead n=2) for qualitative and quantitative toxicological analysis. The analysis was done using Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS) model-Specter AA-10 Varian. Lead and arsenic were found to be in high concentration in soil sediments in all four lakes while chromium and cadmium were in low concentration. Soil sediments analysed from the inflow of the Nakuru sewerage drain (1754±22.81 ppb) and rivers to Lake Nakuru (1129±107 ppb) had the highest mean ± SD lead concentration. Arsenic, cadmium, chromium and lead were also observed in bird tissues. Metals in the Lesser Flamingo tissues were below the toxicological levels that are reported in literature to be harmful, except lead which was above the level recommended by the US Environmental Protection Agency. Key words: Heavy metals, lesser flamingo, environment.

Arsenic Pollution Study at Nitra-Krška Ny Location as an Example of Line Contamination

Abstract The aim of this article was to identify the level of arsenic in soils and water as a type of line contamination with widespread environmental impact. For this purpose, as the “model locality” was chosen the Nitra River (Krškany location situated around 80 km from the original source of contamination - Zemianske Kostoľany). EcaFlow 150 analyzer was used to identify the content of arsenic in water and soil samples, SEM and EDS were used to characterize morphology, surface area, and chemical composition of primary substrate. In Nitra-Krškany, significant values of arsenic concentrations were observed for surface water, 14.75 μg l-1, which exceeded the WHO international A limit 1.5 times, for filtered water from the sediment, 149.9 μg l-1, with the present exceedance in all categories (WHO international A limit 15 times), and for soil samples, 26.6 mg kg-1, which exceeded 2.6 times the Slovak soil legal limit (10 mg kg-1). Detection of arsenic confirmed line contamination in Nitra - Krškany. As the main source responsible for contamination there was evaluated coal combustion residuals that consist of spherical aggregates from 2 μm to 1 mm dimension, non-linear topography. This type of contamination has a long-term impact due to hazardous materials and non-stable reactive surface area.

An update on arsenic in rice, impact on dietary arsenic intakes and U.S. Department of Agriculture efforts at mitigation

Dietary arsenic from rice came to the attention of the public in 2012 following the release of analyses by Consumer Reports and Dr. Ozshowing levels of concern. Subsequently the U.S. Food and Drug Administration (USFDA) conducted their own analyses as well as a risk analysis for consumption of arsenic‐containing rice and rice foods (unreleased). Potentially high inorganic arsenic (iAs) levels previously have been reported in drinking water and apple juice. To understand the impact that rice consumption has on arsenic intake relative to other sources, an analysis was conducted using NHANES consumption data and USFDA data from analyses of arsenic in rice. These data show that water intake and arsenic levels in water are the primary determinants of iAs intake; however rice can be a significant source, especially among consumers of brown rice in areas where arsenic levels in wate rare low. The U.S. Department of Agriculture is committed to maintaining a safe and nutritious food supply and has put efforts into mitigating these problems. Agricultural Research Service projects include development of varieties of rice that take up less arsenic, agronomic techniques such as water management that reduce arsenic accumulation and methods of analysis that are quicker and cheaper and allow identification of arsenic content of harvested rice before mixing at grain elevators.Support or Funding InformationThis work was conducted by the U.S> Department of Agriculture, Agricultural Research Service

Arsenic Occurrence, Ecotoxicity and its Potential Remediation

Arsenic levels in water, sediments, and biota of the estuaries and coastal ecosystems have been well documented. Natural and anthropogenic activities such as industrial offshore oil spills and groundwater pollution have increased its levels in natural water systems. This brief review provides a clear view on arsenic occurrence, ecotoxicity and its potential remediation. Both humans and biota were affected from arsenic contamination. The development of substitute materials for arsenic applications in the agricultural and forestry industries and controls of arsenic emissions from the coal industry may be possible strategies to significantly decrease arsenic pollution sources and dissipation rates into the environment. At the same, to develop cost effective green remediation technology for cleaning As in water and soils is essential.

Enhanced Removal of Arsenite from Ground Water by Adsorption onto Heat-Treated Rice Husk

The effect of heat treatment for rice husk was investigated on the removal of arsenite in ground water by the adsorption onto the rice husk surface. The heat treatment was performed at the temperature from 80oC to 300oC in the closed system under anoxic environment. The continuous adsorption column method was applied for the removal of arsenite. The removal efficiency (75%) with rice husk treated at 150oC was better compared to those (54%) obtained with untreated rice husk. Therefore, the heat treatment of rice husk at relatively low temperature was effective for the enhancement of arsenic removal from water. The treatment conditions of As removal from aqueous solution were optimized. The developed treatment technique was applied into the real ground water sample in Bangladesh. The As concentration in sample water after treatment was approximately 18 and 8 μg/L, which was below the WHO guideline value of maximum admissible level of arsenic in ground water for Bangladesh (50 μg/L). The developed technique might become a potential avenue for simple and low cost arsenic removal methods.

Arsenic in Drinking Water and Lung Cancer Mortality in the United States: An Analysis Based on US Counties and 30 Years of Observation (1950–1979)

Background. To examine whether the US EPA (2010) lung cancer risk estimate derived from the high arsenic exposures (10–934 µg/L) in southwest Taiwan accurately predicts the US experience from low arsenic exposures (3–59 µg/L). Methods. Analyses have been limited to US counties solely dependent on underground sources for their drinking water supply with median arsenic levels of ≥3 µg/L. Results. Cancer risks (slopes) were found to be indistinguishable from zero for males and females. The addition of arsenic level did not significantly increase the explanatory power of the models. Stratified, or categorical, analysis yielded relative risks that hover about 1.00. The unit risk estimates were nonpositive and not significantly different from zero, and the maximum (95% UCL) unit risk estimates for lung cancer were lower than those in US EPA (2010). Conclusions. These data do not demonstrate an increased risk of lung cancer associated with median drinking water arsenic levels in the range of 3–59 µg/L. The upper-bound estimates of the risks are lower than the risks predicted from the SW Taiwan data and do not support those predictions. These results are consistent with a recent metaregression that indicated no increased lung cancer risk for arsenic exposures below 100–150 µg/L.

Arsenic from community water fluoridation: quantifying the effect.

Community water fluoridation is a WHO recommended strategy to prevent dental carries. One debated concern is that hydrofluorosilicic acid, used to fluoridate water, contains arsenic and poses a health risk. This study was undertaken to determine if fluoridation contributes to arsenic in drinking water, to estimate the amount of additional arsenic associated with fluoridation, and compare this to the National Sanitation Foundation/American National Standards Institute (NSF/ANSI) standard and estimates from other researchers. Using surveillance data from Ontario drinking water systems, mixed effects linear regression was performed to examine the effect of fluoridation status on the difference in arsenic concentration between raw water and treated water samples. On average, drinking water treatment was found to reduce arsenic levels in water in both fluoridated and non-fluoridated systems by 0.2 μg/L. However, fluoridated systems were associated with an additional 0.078 μg/L (95% CI 0.021, 0.136) of arsenic in water when compared to non-fluoridated systems (P = 0.008) while controlling for raw water arsenic concentrations, types of treatment processes, and source water type. Our estimate is consistent with concentrations expected from other research and is less than 10% of the NSF/ANSI standard of 1 μg/L arsenic in water. This study provides further information to inform decision-making regarding community water fluoridation.

Arsenic in African Waters: A Review

The review of studies on arsenic in African waters shows that arsenic can be found in high concentrations in both surface water and groundwater. Arsenic concentrations in African groundwater range between 0.02 and 1760 μg L−1, whilst the level of arsenic in surface water is ranged up to 10,000 μg L−1. This high level of arsenic in surface water is related to mining operations, agricultural drains, local sediments, disposal, and incineration of municipal and industrial wastes. However, mining activities remain the main source of surface water pollution. They have thereby a strong impact on the concentration of arsenic in the environment. As for groundwater, high levels of arsenic occur in natural conditions. It is due to the presence of iron oxides; sulphide minerals such as pyrite, arsenopyrite, and chalcopyrite; volcanic rocks; and geothermal waters. Few studies in Africa make the link between human health problems and high levels of arsenic in water. Only two articles were found dealing with arsenic remediation. This shows that arsenic, which constitutes a major public health issue in the world, has less interest in Africa although high concentrations of arsenic have been found in both surface water and groundwater in some African countries. Most of the studies carried out on arsenic issues in Africa are dedicated to the characterization and the quantification of the pollution, but studies on the risk to human health and treatment systems are limited. The arsenic issue in Africa needs special attention in order to avoid the problems experienced in some areas mainly in Asia.

Introduction: Legal Decision Making under Deep Uncertainty

How do we decide when we lack the information needed to have wellformed judgments, when we face what is alternatively called Knightian uncertainty, deep uncertainty, or ambiguity? Many decisions must be made under these conditions. Keynes (1937, p. 214) in a famous passage gave a number of examples of deep uncertainty: “The sense in which I am using the term [uncertainty] is that in which the prospect of a European war is uncertain, or the price of copper and the rate of interest twenty years hence, or the obsolescence of a new invention, or the position of private wealth owners in the social system in 1970. About these matters there is no scientific basis on which to form any calculable probability whatever. We simply do not know.” In all of these cases, society had to make choices in 1937 that were based on the likelihood of these events. Writing 65 years later, Sunstein (2002) posited as a prototypical case the problem of regulating arsenic. Below a certain threshold, we do not know the dose-response curve for arsenic. Because the sample size needed to get reasonable estimates is too large, we are not going to know. Yet the Environmental Protection Agency (EPA) must decide on a permissible level of arsenic in the water. If arsenic turns out to be toxic at low levels, the savings from restrictive regulations would be large and the regulations would pass a cost-benefit test. If arsenic turns out to be mostly harmless or even beneficial at low levels, would restrictive regulations fail a cost-benefit test? How should the EPA decide what to do? Another central case is the problem of climate change. As described in Greenstone, Kopits, and Wolverton (2013), in 2010 a group of agencies in the federal government convened to determine a unified value for the

Characteristics of arsenic-related bladder cancer: A study from Nationwide Cancer Registry Database in Taiwan

ObjectiveTo investigate the clinical and pathological characteristics of arsenic-related bladder cancer. MethodsFrom 2008 through 2011, data on 7699 patients with bladder cancer were extracted from the Taiwan Cancer Registry Database. A diagnosis of bladder cancer (International Statistical Classification of Diseases and Related Health Problems, 9th Revision: 188) was confirmed in all patients. Using birth residency codes, patients were divided into three groups: the core zone (CZ; an arsenic endemic area with well water arsenic levels of 350–1100 ng/mL); zone 1 (Z1; an area with well water arsenic levels of≥350 ng/mL but not a blackfoot disease-endemic area); and zone 2 (Z2; an area with well water arsenic levels of<350 ng/mL). Clinicopathological characteristics and survival outcomes were compared between the three groups. ResultsIn this cohort, 119 (1.5%), 1145 (14.9%), and 6435 (83.6%) patients were born in the CZ, Z1, and Z2, respectively. A higher proportion of female patients (35.3%, 31.4%, and 27.5%; p = 0.014) and lower smoking rates (29%, 34.8%, and 35.9%; p = 0.694) were noted in the CZ compared with Z1 and Z2. CZ patients had more high-grade differentiated (80.9%, 69.9%, and 63.0%; p < 0.001) and high clinical stage (stages II–IV, 52.8%, 38.1%, and 31.8%; p < 0.001) tumors compared with Z1 and Z2 patients. Radical cystectomy was infrequently performed for clinical stage II (19.6%) and stage III (25.2%) bladder cancer patients. CZ patients had significantly shorter overall and cancer-specific survival durations compared with Z1 and Z2 patients. Older age, female sex, higher tumor grade or stage, and higher arsenic levels were associated with both poorer overall and cancer-specific survival in a multivariate analysis with a Cox proportional model. ConclusionIn Taiwan, patients with arsenic-related bladder cancer may have poorer tumor characteristics and decreased overall and cancer-specific survival rates.

Assessment of arsenic levels in body samples and chronic exposure in people using water with a high concentration of arsenic: a field study in Kutahya.

This study aimed to evaluate the prevalence of skin lesions, which is a health effect of chronic arsenic (As) exposure, and determine the hair/blood arsenic concentrations of people living in Kutahya villages who are using and drinking tap water with a high concentration of arsenic. A total of 303 people were included in the present cross-sectional study. A prepared questionnaire form was used to collect the participants' information and environmental history. Skin examination was performed on all participants. Hair, blood and water samples were analyzed using atomic absorption spectroscopy. The cumulative arsenic index (CAI) was calculated for all participants. Villages were divided into two groups according to the arsenic level (<20 μg/L, Group I; >20 μg/L, Group II) in their water. The prevalence of skin lesions, hair and blood arsenic level, and CAI were found to be higher in the Group II participants. There was a positive association between body arsenic levels and CAI in the participants of each group. The number of skin lesions and arsenic concentrations in body samples were found to increase with the water arsenic level and exposure time. We hope that sharing this study's results with local administrators will help accelerate the rehabilitation of water sources in Kutahya.

Using an environmental public health tracking biomonitoring study to validate safe water restoration efforts in Florida.

Inorganic arsenic is a carcinogen when consumed over many years and is the type of arsenic that is associated with well water. Private wells in many central Florida counties have been found to contain levels of arsenic above 10 μg/L, which is the maximum contaminant level (MCL) established by the US Environmental Protection Agency. The purpose of this study was to test whether individuals living in homes with arsenic levels above the MCL who use bottled water or have a point of use (POU) filter on their main source of water in the house (eg, kitchen sink) are ingesting unsafe levels of arsenic through other unfiltered water sources in the home. Case-control study of residents with private wells above (case) and below (control) the MCL for arsenic in drinking water (10 μg/L) conducted between April and July 2013. Residents with private wells living in Hernando County, Florida, where nearly 400 unique wells of 1200 tested have been found to have elevated arsenic levels (targeted sampling). Participants with elevated water arsenic levels were referred to the Florida Safe Water Restoration Program for assistance in obtaining bottled water vouchers and/or POU filters. Creatinine-corrected total urinary arsenic levels and information on water use and consumption behaviors, dietary intake, and other possible exposure sources. Total urinary arsenic levels were similar for cases using POU filters or bottled water when compared with controls (geometric means of 7.17 and 7.19 μg/L, respectively). The current practice used by the Florida Safe Water Restoration Program of supplying POU filters or bottled water to households with arsenic levels in private wells between 10 and 50 μg/L appears to be sufficient to protect residents from arsenic exposure through tap water.

Transfer of Arsenic from Groundwater and Paddy Soil to Rice (Oryza sativa L.) Grain: A Micro Level Study in Chandina, Comilla

Rice (Oryza sativa L.) is one of the major food crops in many countries. As the cultivation of rice requires huge volume of water, long term use of Arsenic contaminated groundwater for irrigation may result in the increase of arsenic concentration in the agricultural soil and eventually accumulation in rice grains. A micro level study was conducted to investigate the transfer of arsenic from irrigation water and soil to rice plants in the arsenic affected 8 unions of Chandina upazilla, Comilla district. The level of arsenic in irrigation water (0.12±0.08 and 0.67±0.07 mg l-1) was much above the WHO permissible limit of 0.01 mg l-1 for drinking water and FAO permissible limit of 0.10 mg l-1 for irrigation water. The total soil arsenic concentrations ranged from 3.21±0.80 to 8.74±2.83 mg kg-1 dry weight of soil, which was below the maximum acceptable limit for agricultural soil of 20.0 mg kg-1 as recommended by the European Community. The accumulation of arsenic in the grain ranged from 0.12±0.04 to 0.58±0.06 mg kg-1 in Boro and 0.16±0.04 to 1.06±0.20 mg kg-1 in T. Aman. Except grain sample (T. Aman) of one union, the grains in both Boro and T. Aman of all unions did not exceed 1.0 mg kg-1 dry weight of arsenic (the permissible limit of arsenic in rice according to WHO recommendation). Thus, till now rice has remained harmless for consumption in the study area. The results clearly showed that the arsenic content in the grains of Boro rice is correlated to the intensity of arsenic contamination of irrigation water and soil. The Agriculturists 2014; 12(2) 74-82

Elevated levels of plasma uric acid and its relation to hypertension in arsenic-endemic human individuals in Bangladesh

Blood uric acid has been recognized as a putative marker for cardiovascular diseases (CVDs). CVDs are the major causes of arsenic-related morbidity and mortality. However, the association of arsenic exposure with plasma uric acid (PUA) levels in relation to CVDs has not yet been explored. This study for the first time demonstrated the associations of arsenic exposure with PUA levels and its relationship with hypertension. A total of 483 subjects, 322 from arsenic-endemic and 161 from non-endemic areas in Bangladesh were recruited as study subjects. Arsenic concentrations in the drinking water, hair and nails of the study subjects were measured by inductively coupled plasma mass spectroscopy. PUA levels were measured using a colorimetric method. We found that PUA levels were significantly (p<0.001) higher in males and females living in arsenic-endemic areas than those in non-endemic area. Arsenic exposure (water, hair and nail arsenic) levels showed significant positive correlations with PUA levels. In multiple regression analyses, arsenic exposure levels were found to be the most significant contributors on PUA levels among the other variables that included age, body mass index, blood urea nitrogen, and smoking. There were dose–response relationships between arsenic exposure and PUA levels. Furthermore, diastolic and systolic blood pressure showed significant positive correlations with PUA levels. Finally, the average PUA levels were significantly higher in the hypertensive group than those in the normotensive group in both males and females living in arsenic-endemic areas. These results suggest that arsenic exposure-related elevation of PUA levels may be implicated in arsenic-induced CVDs.

Discontinuity in the cancer slope factor as it passes from high to low exposure levels--arsenic in the BFD-endemic area.

The ingestion of inorganic arsenic causes bladder and lung cancers demonstrably at >400-500ug/L but questionably below 100-200ug/L. Using the standard 42-village cancer mortality dataset from the Blackfoot-disease (BFD) endemic area of southwest Taiwan (Wu et al., 1989), we examined the risk from low exposures by excluding the high exposures. Poisson regression analyses with the sequential removal of the highest exposure village have been performed using the median, mean, or maximum village well water arsenic level and demonstrated graphically. Risk estimates are positive when villages with exposures of 200-400ug/L are included and significantly so when villages with >400ug/L are included. Risk estimates for exposures below 100ug/L are negative but rarely significantly so. The inflection point where the slope is no longer positive occurs in the range of 100-200ug/L, depending upon whether the exposure metric used is the median, the mean or the maximum. There is a discontinuity in the cancer slope factor or risk from arsenic exposure that occurs in the range of 100-200ug/L. Above these levels, there are significantly positive risks, while below these levels there are not. The analysis reveals within this dataset an intrinsic non-linearity in the cancer risk. The literature speaks to this discontinuity, but this is the first demonstration within a single dataset that shows the discontinuity across the full exposure range and where the low-dose data are not compromised with high-dose data.

Spatial distribution of mercury and arsenic levels in water, soil and cassava plants in a community with long history of gold mining in Tanzania.

This study examined the spatial distribution of total mercury (THg) and total arsenic (TAs) in water, soil and cassava (Manihot esculenta) (leaves and roots) samples taken from areas in Rwamagasa village in northwestern Tanzania where daily living activities occur in close proximity to extensive artisanal and small scale gold mining. Results indicated that 33.3 % of the water sources had THg levels above the WHO guideline of 1.0 µg/L for safe drinking water, and 12.5 % had TAs levels above 10 µg/L. Cassava leaves were found to have higher THg (ranging from 8.3 to 167 µg/kg) and TAs (ranging from 60 to 1,120 µg/kg) levels than cassava roots, which ranged between 1.2-8.3 µg/kg for THg and 25-310 µg/kg for TAs. Concentrations of THg and TAs in soil samples ranged between 5.8-1,759 and 183-20,298 µg/kg, respectively. Both THg and TAs were found to be distributed throughout Rwamagasa village.

Arsenic in drinking water and urinary tract cancers: a systematic review of 30years of epidemiological evidence.

BackgroundArsenic in drinking water is a public health issue affecting hundreds of millions of people worldwide. This review summarizes 30 years of epidemiological studies on arsenic exposure in drinking water and the risk of bladder or kidney cancer, quantifying these risks using a meta-analytical framework.MethodsForty studies met the selection criteria. Seventeen provided point estimates of arsenic concentrations in drinking water and were used in a meta-analysis of bladder cancer incidence (7 studies) and mortality (10 studies) and kidney cancer mortality (2 studies). Risk estimates for incidence and mortality were analyzed separately using Generalized Linear Models. Predicted risks for bladder cancer incidence were estimated at 10, 50 and 150 μg/L arsenic in drinking water. Bootstrap randomizations were used to assess robustness of effect size.ResultsTwenty-eight studies observed an association between arsenic in drinking water and bladder cancer. Ten studies showed an association with kidney cancer, although of lower magnitude than that for bladder cancer. The meta-analyses showed the predicted risks for bladder cancer incidence were 2.7 [1.2–4.1]; 4.2 [2.1–6.3] and; 5.8 [2.9–8.7] for drinking water arsenic levels of 10, 50, and 150 μg/L, respectively. Bootstrapped randomizations confirmed this increased risk, but, lowering the effect size to 1.4 [0.35–4.0], 2.3 [0.59–6.4], and 3.1 [0.80–8.9]. The latter suggests that with exposures to 50 μg/L, there was an 83% probability for elevated incidence of bladder cancer; and a 74% probability for elevated mortality. For both bladder and kidney cancers, mortality rates at 150 ug/L were about 30% greater than those at 10 μg/L.ConclusionArsenic in drinking water is associated with an increased risk of bladder and kidney cancers, although at lower levels (<150 μg/L), there is uncertainty due to the increased likelihood of exposure misclassification at the lower end of the exposure curve. Meta-analyses suggest exposure to 10 μg/L of arsenic in drinking water may double the risk of bladder cancer, or at the very least, increase it by about 40%. With the large number of people exposed to these arsenic concentrations worldwide the public health consequences of arsenic in drinking water are substantial.