Urinary 8-hydroxy-2'-deoxyguanosine in inhabitants chronically exposed to arsenic in groundwater in Cambodia

Arsenic concentrations in hair and urine, and urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage, were examined for inhabitants of the Mekong Basin in Kratie Province, Cambodia. Also, the arsenic levels of tube-well water were determined. Total arsenic concentrations in tube-well water ranged from <1 to 886 microg L(-1), and 44.8% of these exceeded the WHO drinking water guideline of 10 microg L(-1). Elevated levels of arsenic were observed in the human hair and urine, and also a significant positive correlation was observed between the concentrations in hair and urine. These results suggest that the inhabitants are chronically exposed to arsenic through drinking the tube-well water. Levels of urinary 8-OHdG were higher for the subjects with higher arsenic levels in hair and urine, suggesting that induction of oxidative DNA damage was caused by chronic exposure to arsenic in tube-well water for the inhabitants in Kratie Province. To our knowledge, this is the first report on the oxidative DNA damage caused by chronic exposure to arsenic in groundwater for the inhabitants in Cambodia.     

Effect of fasting on the pattern of urinary arsenic excretion

Millions of people in some of the poorest regions of the world are exposed to high levels of arsenic through drinking contaminated water. It has been reported that development of cancer caused by arsenic exposure in such populations is dependent on dietary and nutritional factors which can modulate arsenic metabolism. Many people in arsenic exposed regions of Bangladesh and India practice fasting for at least one month every year when they refrain from consumption of food and fluid during daylight hours. How such practices may modulate arsenic metabolism has not been previously investigated. This study investigated this issue by determining total arsenic and its species in urine samples from a group of 29 unexposed volunteers at the beginning of the fasting and at the end of approximately 12 h of fasting period. Inductively coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography (HPLC) coupled with ICP-MS was used to measure the total arsenic and arsenic speciation in the urine samples, respectively. The mean total levels of arsenic at the beginning of fasting (18.3 microg g(-1) creatinine) and at the end of approximately 12 h of fasting (17.7 microg g(-1) creatinine) did not differ significantly (p > 0.05). However, the percentages of urinary arsenic as the methylated arsenic species methylarsonate (MA) were found to be significantly different (p < 0.05) and this species was observed more frequently at the end of fasting, although its overall concentration was similar. There were no significant differences (p > 0.05) in both the concentrations and percentages of other urinary arsenic species detected, namely arsenobetaine (AB) and dimethylarsinate (DMA). Arsenite (As(III)) and arsenate (As(V)) were also analyzed, but were not detected. We conclude that fasting for a period of 12 h results in a significant increase in the percentage of urinary arsenic as MA, and its frequency of detection in the volunteers at the end of the fasting period is almost nine fold higher. This suggests that metabolism of arsenic is altered by fasting.     

Arsenic speciation in human hair: a new perspective for epidemiological assessment in chronic arsenicism

The analysis for arsenic in hair is commonly used in epidemiological studies to assess exposure to this toxic element. However, poor correlation between total arsenic concentration in hair and water sources have been found in previous studies. Exclusive determination of endogenous arsenic in the hair, excluding external contamination has become an analytical challenge. Arsenic speciation in hair appears as a new possibility for analytical assessing in As-exposure studies. This study applied a relative simple method for arsenic speciation in human hair based on water extraction and HPLC-HG-ICP-MS. The concentration of arsenic species in human hair was assessed in chronically As(V)-exposed populations from two villages (Esqui?a and Illapata) of the Atacama Desert, Chile. The arsenic concentrations in drinking water are 0.075 and 1.25 mg L(-1), respectively, where As(V) represented between 92 and 99.5% of the total arsenic of the consumed waters. On average, the total arsenic concentrations in hair from individuals of Esqui?a and Illapata were 0.7 and 6.1 microg g(-1), respectively. Four arsenic species, As(III), DMA(V), MMA(V) and As(V), were detected and quantified in the hair extracts. Assuming the found species in extracts represent the species in hair, more than 98% of the total arsenic in hair corresponded to inorganic As. On average, As(III) concentrations in hair were 0.25 and 3.75 microg g(-1) in Esqui?a and Illapata, respectively; while, the As(V) average concentrations were 0.15 and 0.45 microg g(-1) in Esqui?a and Illapata, respectively. Methylated species represent less than 2% of the extracted As (DMA(V)+ MMA(V)) in both populations. As(III) in hair shows the best correlation with chronic exposure to As(V) in comparison to other species and total arsenic. In fact, concentrations of As(total), As(III) and As(V) in hair samples are correlated with the age of the exposed individuals from Illapata (R= 0.65, 0.69, 0.57, respectively) and with the time of residence in this village (R= 0.54, 0.71 and 0.58, respectively).     

Application of natural zeolites for preconcentration of arsenic species in water samples

Zeolites of the clinoptilolite type produced in Mexico and Hungary were investigated with respect to their sorption efficiency for various redox species of arsenic. Long-term experiments showed that arsenate remains stable for a long period in spiked deionised water and drinking water, as well as in the surface water of the Biela valley in Saxony, Germany. Both clinoptilolites are able to decrease the initial arsenic concentration of 200 microg l(-1) by more than 75% in deionised, drinking, ground and surface waters. In the case of the Mexican zeolite, both the arsenite and the arsenate concentrations (200 microg l(-1)) can be lowered from 200 microg l(-1) to 10 microg l(-1), which is the World Health Organisation's (WHO's) recommended maximum level. It was found that the presence of cations and anions in the natural waters of Biela, Germany, and Zimapán, Mexico, did not reduce the efficiency of the selected zeolites. The Hungarian zeolite removed 75% of the arsenate in the Zimapán water and only 50% when the sample was first acidified. This zeolite totally desorbed the fixed arsenic into a water volume that was half the volume in the adsorption experiment.     

Inorganic arsenic levels in rice milk exceed EU and US drinking water standards

Under EU legislation, total arsenic levels in drinking water should not exceed 10 microg l(-1), while in the US this figure is set at 10 microg l(-1) inorganic arsenic. All rice milk samples analysed in a supermarket survey (n = 19) would fail the EU limit with up to 3 times this concentration recorded, while out of the subset that had arsenic species determined (n = 15), 80% had inorganic arsenic levels above 10 microg l(-1), with the remaining 3 samples approaching this value. It is a point for discussion whether rice milk is seen as a water substitute or as a food, there are no EU or US food standards highlighting the disparity between water and food regulations in this respect.     

Speciation of arsenic using solid phase extraction cartridges

Various solid phase extraction (SPE) cartridges were investigated for speciation of arsenite [As(III)], arsenate [As(v)], monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Cartridges containing different types of sorbent materials were tested for arsenic retention and elution characteristics. Alumina cartridges were found to completely retain all the four target arsenic species, and are suitable for removal and preconcentration purposes. For speciation analysis, different arsenic species were separated on the basis of their selective retention on and elution from specific cartridges. DMA was retained on a resin-based strong cation exchange cartridge and eluted with 1.0 M HCl. MMA and As(v) were both retained on a silica-based strong anion exchange cartridge and sequentially eluted with 60 mM acetic acid (for MMA) and 1.0 M HCl [for As(v)]. As(III) was not retained on either cartridge and remained in solution. Arsenic species in solution and those eluted from the cartridges were subsequently quantified by using flow injection with hydride generation atomic fluorescence spectrometry (FI-HGAFS) and hydride generation atomic absorption spectrometry (FI-HGAAS). A detection limit of 0.05 microg L(-1) arsenic in water sample was achieved using HGAFS. An application of the method was demonstrated at a drinking water treatment facility. As(III) and As(v) species were determined in water at various stages of treatment. The method is suitable for routine determination of trace levels of arsenic in drinking water to comply with more stringent environmental regulations.     

The impact of a rice based diet on urinary arsenic

Rice is elevated in arsenic (As) compared to other staple grains. The Bangladeshi community living in the United Kingdom (UK) has a ca. 30-fold higher consumption of rice than white Caucasians. In order to assess the impact of this difference in rice consumption, urinary arsenicals of 49 volunteers in the UK (Bangladeshi n = 37; white Caucasians n = 12) were monitored along with dietary habits. Total urinary arsenic (As(t)) and speciation analysis for dimethylarsinic acid (DMA), monomethylarsonic acid (MA) and inorganic arsenic (iAs) was conducted. Although no significant difference was found for As(t) (median: Bangladeshis 28.4 μg L(-1)) and white Caucasians (20.6 μg L(-1)), the sum of medians of DMA, MA and iAs for the Bangladeshi group was found to be over 3-fold higher (17.9 μg L(-1)) than for the Caucasians (3.50 μg L(-1)). Urinary DMA was significantly higher (p < 0.001) in the UK Bangladeshis (median: 16.9 μg DMA L(-1)) than in the white Caucasians (3.16 μg DMA L(-1)) as well as iAs (p < 0.001) with a median of 0.630 μg iAs L(-1) for Bangladeshi and 0.250 μg iAs L(-1) for Caucasians. Cationic compounds were significantly lower in the Bangladeshis (2.93 μg L(-1)) than in Caucasians (14.9 μg L(-1)). The higher DMA and iAs levels in the Bangladeshis are mainly the result of higher rice consumption: arsenic is speciated in rice as both iAs and DMA, and iAs can be metabolized, through MA, to DMA by humans. This study shows that a higher dietary intake of DMA alters the DMA/MA ratio in urine. Consequently, DMA/MA ratio as an indication of methylation capacity in populations consuming large quantities of rice should be applied with caution since variation in the quantity and type of rice eaten may alter this ratio.     

A biomaterial based approach for arsenic removal from water

We demonstrate that the non-living, dried roots of the water hyacinth plant [Eichhornia crassipes(Mart.) Solms] can rapidly remove arsenic from water. Atomic absorption spectrometry was used to demonstrate that more than 93% of arsenite (As(iii)) and 95% of arsenate (As(v)) were removed from a solution containing 200 microg As l(-1) within 60 minutes of exposure to a powder produced from dried roots. No difference in removal efficiency was observed between the two oxidation states of As studied. The amount of arsenic remaining in solution was found to be less than 10 microg l(-1) which is the WHO guideline limit value for As in drinking water. The presence of arsenic in drinking water in a number of countries in the developing world has been found to be much higher than the WHO level, affecting the health of millions of people. In this paper, we show that a biomaterial produced from dried water hyacinth roots, a plant that is found in abundant supply in many parts of the world, can provide a simple, effective and yet cheap method for removing arsenic from contaminated water.     

Arsenic and Other Metal Contamination of Groundwaters in the Industrial Area of Thessaloniki, Northern Greece

In groundwater, used for drinking water supply in the greater industrial area of Thessaloniki, in Northern Greece, concentrations of total arsenic exceeded the WHO provisional guideline value and the EU maximum contaminant level (MCL) of 10 μg/L. The concentration of total arsenic was in the range between 4–130 μg/L, whereas the median value was 36 μg/L and the average concentration 46 μg/L. Nine out of the eleven wells contained total arsenic at concentration higher than 10 μg/L and it should be stressed that 6 of them contain arsenic at concentrations between 10 (new MCL) and 50 μg/L (previous MCL). The examined groundwaters were found to contain elevated concentrations of manganese and phosphate. Arsenic had a positive correlation with the pH, indicating the possible effect of pH on arsenic mobilisation. These findings emerge the problem of contamination from arsenic, since, according to the EU directive 98/83, all drinking water sources within the European Union should have achieved compliance with the new limits by 12/2003, implying that the situation requires urgent remedial action.     

垃圾填埋场地下水污染对居民健康的风险评价

调查了某垃圾填埋场地下水和周边居民饮用水中的As、Hg等重金属和挥发酚等有机物的污染状况，运用美国环保局的健康风险计算模型，评估了该垃圾填埋场地下水对周边居民的潜在健康风险。结果表明，各类人群对4种有阈化合物的饮食和皮肤暴露的终身健康危险度在8．2×10^-11～1．3×10^-10之间，均低于可以接受的风险水平10^-6；对As的终身超额健康危险度在3．1×10^-7～4．9×10^-7之间，表明地下水中砷污染对居民潜在的致癌风险不明显。各类人群通过皮肤对Hg、As、Cd和挥发酚的暴露剂量比通过饮水暴露的剂量高0．7倍～14．5倍，皮肤暴露将是地下水影响人体健康并构成潜在风险的重要途径。     

Population-based biomonitoring in the Czech Republic: urinary arsenic

The method of Guo et aL (AnaL Chim. Acta, 1997, 349, 313-318) for the determination of the toxicologically relevant arsenic in urine was verified and then used for the determination of arsenic in urine of the Czech population for monitoring purposes. Statistical evaluation at the level alpha = 0.05 did not prove any significant differences between industrial and agricultural regions, between males and females and smokers and nonsmokers. Likewise no differences were found among children in all the regions monitored. In the adult population small differences were found between some regions but these differences were not dependent on industrial pollution. The values of toxicologically relevant arsenic are low for all regions. The summarised value of the median for all groups together is 3.5 microg (g creatinine)(-1).     

Determination of arsenic species in fish, crustacean and sediment samples from Thailand using high performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS)

Suitable techniques have been developed for the extraction of arsenic species in a variety of biological and environmental samples from the Pak Pa-Nang Estuary and catchment, located in Southern Thailand, and for their determination using HPLC directly coupled with ICP-MS. The estuary catchment comprises a tin mining area and inhabitants of the region can suffer from various stages of arsenic poisoning. The important arsenic species, AsB, DMA, MMA, and inorganic arsenic (As III and V) have been determined in fish and crustacean samples to provide toxicological information on those fauna which contribute to the local diet. A Hamilton PRP-X100 anion-exchange HPLC system employing a step elution has been used successfully to achieve separation of the arsenic species. A nitric acid microwave digestion procedure, followed by carrier gas nitrogen addition- (N2)-ICP-MS analysis was used to measure total arsenic in sample digests and extracts. The arsenic speciation of the biological samples was preserved using a Trypsin enzymatic extraction procedure. Extraction efficiencies were high, with values of 82-102%(As) for fish and crustacean samples. Validation for these procedures was carried out using certified reference materials. Fish and crustacean samples from the Pak Pa-Nang Estuary showed a range for total arsenic concentration, up to 17 microg g(-1) dry mass. The major species of arsenic in all fauna samples taken was AsB, together with smaller quantities of DMA and, more importantly, inorganic As. For sediment samples, arsenic species were determined following phosphoric acid (1 M H3PO4) extraction in an open focused microwave system. A phosphate-based eluant, pH 6-7.5, with anion exchange HPLC coupled with ICP-MS was used for separation and detection of AsIII, AsV, MMA and DMA. The optimum conditions, identified using an estuarine sediment reference material (LGC), were achieved using 45 W power and a 20 minute heating period for extraction of 0.5 g sediment. The stability and recovery of arsenic species under the extraction conditions were also determined by a spiking procedure which included the estuarine sediment reference material. The results show good stability for all species after extraction with a variability of less than 10%. Total concentrations of arsenic in the sediments from the Pak Pa-Nang river catchment and the estuary covered the ranges 7-269 microg g(-1)and 4-20 [micro sign]g g(-1)(dry weight), respectively. AsV was the major species found in all the sediment samples with smaller quantities of AsIII. The presence of the more toxic inorganic forms of arsenic in both sediments and biota samples has implications for human health, particularly as they are readily 'available'.     

Seasonal perspective of dietary arsenic consumption and urine arsenic in an endemic population

Exposure to arsenic in arsenic endemic areas is most remarkable environmental health challenges. Although effects of arsenic contamination are well established, reports are unavailable on probable seasonal variation due to changes of food habit depending on winter and summer seasons, especially for endemic regions of Nadia district, West Bengal. Complete 24-h diets, drinking–cooking water, first morning voided urine samples, and diet history were analyzed on 25 volunteers in arsenic endemic Chakdah block of Nadia district, once in summer followed by once in winter from the same participants. Results depicted no seasonal variation of body weight and body mass index. Arsenic concentration of source drinking and cooking water decreased (p?=?0.04) from 26 μg L^?1 in summer to 6 μg L^?1 in winter season. We recorded a seasonal decrease of water intake in male (3.8 and 2.5 L day ^?1) and female (2.6 and 1.2 L day^?1) participants from summer to winter. Arsenic intake through drinking water decreased (p?=?0.04) in winter (29 μg day^?1) than in summer (100 μg day^?1), and urinary arsenic concentration decreased (p?=?0.018) in winter (41 μg L^?1) than in summer (69 μg L^?1). Dietary arsenic intake remained unchanged (p?=?0.24) over the seasons. Hence, we can infer that human health risk assessment from arsenic needs an insight over temporal scale.     

Investigation of sequential and enzymatic extraction of arsenic from drinking water distribution solids using ICP-MS

A sequential extraction approach was utilized to estimate the distribution of arsenite [As(iii)] and arsenate [As(v)] on iron oxide/hydroxide solids obtained from drinking water distribution systems. The arsenic (As) associated with these solids can be segregated into three operationally defined categories (exchangeable, amorphous and crystalline) according to the sequential extraction literature. The exchangeable As, for the six drinking water solids evaluated, was estimated using 10 mM MgCl(2) and 10 mM NaH(2)PO(4) and represented between 5-34% of the total As available from the solid. The amorphously bound As was estimated using 10 mM (NH(4))(2)C(2)O(4) and represented between 57-124% of the As available from the respective solid. Finally, the crystalline bound As was estimated using titanium citrate and this represented less than 1.5% of the As associated with the solids. A synthetic stomach/intestine extraction approach was also applied to the distribution solids. The stomach fluid was found to extract between 0.5-33.3 microg g(-1) As and 120-2,360 microg g(-1) iron (Fe). The As concentrations in the intestine fluid were between 0.02-0.04 microg g(-1) while the Fe concentration ranged from 0.06-0.7 microg g(-1) for the first six drinking water distribution solids. The elevated Fe levels associated with the stomach fluid were found to produce Fe based precipitates when the intestinal treatment was applied. Preliminary observations indicate that most of the aqueous Fe in the stomach fluid is ferric ion and the observed precipitate produced in the intestine fluid is consistent with the decreased solubility of ferric ion at the pH associated with the intestine.     

The health hazards of potentially toxic metals in the daily diets of adults and children from a mining and smelting region (Hezhang County) in southwestern China

Toxic metals accumulated in the human body are predominantly absorbed by the digestive tract in non-occupationally exposed populations. In the current study, we collected plowed soil samples, and investigated the varied food compositions in a mining and smelting area in southwestern China, to measure the concentrations of ten potentially toxic metals—As, Ba, Cd, Cr, Cu, Mn, Ni, Pb, Sr, and Zn. We collected information on the daily intakes of these metals to assess the health risks associated with their exposure among children and adults. The urine concentrations of the metals were also measured to obtain data on the amounts present in the body. The results showed that the hazard indexes (HIs) of As, Ba, Cd, Cr, Ni, Pb, and Sr were all larger than 1, for both adults and children; the Zn and Cu values were comparatively higher in children. The intake of staple foods of the region posed the greatest health risk, while drinking water only posed risks clearly associated with As exposure. The urine samples of local residents contained larger amounts of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn, confirming the hazards in the health risk assessment. Obvious differences in the urine metal concentrations between men and women were confirmed. In conclusion, higher concentrations of metals in the surface soil and rain water were the predominant cause of elevated exposure through home-grown crops and produce to accumulate in local residents’ bodies.     

Arsenic concentration and speciation in five freshwater fish species from Back Bay near Yellowknife, NT, CANADA

The concentration of total arsenic and five different arsenic species [As(III), As(V), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), and arsenobetaine (AsB)], were measured in the muscle, liver and gastrointestinal tract (GIT) of five different fish species [lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum), northern pike (Esox lucius), white sucker (Catostomus commersoni) and longnose sucker (Catostomus catostomus)] from Back Bay, Great Slave Lake, near the city of Yellowknife, NT, Canada. The total concentration (dry weight) of arsenic in muscle ranged from 0.57 to 1.15 mg/kg, in the liver from 0.42 to 2.52 mg/kg and in the GIT from 1.48 to 8.92 mg/kg. Among fish species, C. commersoni had significantly higher total arsenic concentrations in the GIT than S. vitreum, E. lucius and C. clupeaformis, and higher total arsenic concentrations in the liver than C. clupeaformis. The mean concentration of As(III) and As(V) in the muscle of all fish ranged from < or =0.01 to 0.05 mg/kg and < or =0.01 to 0.02 mg/kg, respectively, and together comprised < or =7.5% of the total arsenic measured in muscle. The concentrations of MMA were below detection in the muscle of all five fish species. However, AsB and DMA were measured in all fish species and nearly all fish tissues. The concentrations of AsB ranged from 0.01 to 0.13 mg/kg and the concentrations of DMA ranged from <0.02 to 0.45 mg/kg. The majority (>50%) of organic arsenic in almost all of the tissues from fish caught in Back Bay was not directly identified. Evidence from the literature suggests that most of these other organic arsenic species were likely trimethylated arsenic compounds, however, further analytical work would need to be performed to verify this hypothesis.     

The contribution of drinking water to exposure to toxic substances in Canada

Factors influencing the contribution made by drinking water to an individual's exposure to chemical contaminants are reviewed. Deficiencies inherent in simple computational procedures (such as those which rely on the impact of average values to estimate the relative importance of air, food and water and other vehicles by which man is exposed to contaminants) are examined. An alternative approach is described in which a mathematical model incorporating a probabilistic approach is used to predict the distribution of the total exposure of a population. Values of the means and standard deviations for various quantities including contaminant concentrations and food and drinking water intake are used as inputs to the model. The model enables estimations to be made of the proportion of individuals whose exposure exceeds a certain critical value and the relative contribution each exposure pathway makes to the overall distribution of exposure; its versatility is illustrated utilizing data available for lead. The paper also includes a critical assessment of the value of various techniques employed for monitoring drinking water supplies in providing data suitable for exposure assessment and summarizes conclusions from a recent survey of Canadian drinking water consumption habits.     

Air concentrations and urinary metabolites of polycyclic aromatic hydrocarbons among paving and remixing workers

The exposure of paving workers to polycyclic aromatic hydrocarbons (PAH) during stone mastic asphalt (SMA) paving and remixing was evaluated. The effects on the workers' PAH exposure were also evaluated during the use of an industrial by-product, coal fly ash (CFA), instead of limestone as the filler in the SMA. The PAH exposure was measured by personal air sampling and by analysing the levels of urinary naphthols, phenanthrols and 1-hydroxypyrene (1-OHP) in the workers' pre- and post-shift urine samples. The respiratory PAH exposure of the paving workers (geometric mean (GM) 5.7 microg m(-3)) was about ten-fold that of the traffic controllers (GM 0.43 microg m(-3)). The levels of PAH metabolites were significantly higher (p < 0.05) in the post-shift urine samples than in the pre-shift urine samples, and the levels of metabolites in the post-shift urine of paving workers were significantly higher than in that of the controls (p < 0.01). Urinary 1-naphthol correlated well with the airborne concentrations of the two- to three-ring PAHs (r = 0.544, p = 0.003) and naphthalene (r = 0.655, p < 0.001), when non-smoking paving workers were tested. A good correlation was observed between urinary 1-OHP and the airborne concentrations of the four- to six-ring PAHs (r = 0.524, p = 0.003) as well as total PAHs (r = 0.575, p = 0.001). The concentrations of 1-OHP and phenanthrols in the urine of the pavers were significantly higher (p < 0.01) during remixing than during SMA paving. The CFA in the asphalt had no effect on the airborne PAH exposure or on the concentrations of the PAH metabolites in the paving workers' urine.     

Statistical analysis of arsenic contamination in drinking water in a city of Iran and its modeling using GIS

In this research, probable arsenic contamination in drinking water in the city of Ardabil was studied in 163 samples during four seasons. In each season, sampling was carried out randomly in the study area. Results were analyzed statistically applying SPSS 19 software, and the data was also modeled by Arc GIS 10.1 software. The maximum permissible arsenic concentration in drinking water defined by the World Health Organization and Iranian national standard is 10 μg/L. Statistical analysis showed 75, 88, 47, and 69% of samples in autumn, winter, spring, and summer, respectively, had concentrations higher than the national standard. The mean concentrations of arsenic in autumn, winter, spring, and summer were 19.89, 15.9, 10.87, and 14.6 μg/L, respectively, and the overall average in all samples through the year was 15.32 μg/L. Although GIS outputs indicated that the concentration distribution profiles changed in four consecutive seasons, variance analysis of the results showed that statistically there is no significant difference in arsenic levels in four seasons.     

Potential health risk of arsenic and cadmium in groundwater near Xiangjiang River, China: a case study for risk assessment and management of toxic substances

As part of our efforts to find effective methods to the drinking water risk management, the health risk assessment of arsenic and cadmium in groundwater near Xiangjiang River was analyzed. The results suggest that although the arsenic and cadmium concentrations in 97% of groundwater sources are less than the requirement of Water Quality Standards for Drinking Water (GB5749-2006) in China, the residents served by almost all of the investigated centralized drinking water sources have a significant potential health risk by consumption, especially cancer risk. It is justified through analyses that risk assessment is an effective tool for risk management, and the maximum permissible concentration of arsenic and cadmium in drinking water (0.01 and 0.005?mg L^-1, respectively) is suitable for China at present, considering the current economic status of China. Risk managers develop cleanup standards designed to protect against all possible adverse effects, which should take into account highly exposed individuals, effects of mixtures of toxic substances, attendant uncertainties, and other factors such as site-specific (or generic) criteria, technical feasibility, cost?Cbenefit analyses, and sociopolitical concerns.