高效液相色谱-电感耦合等离子体质谱法同时测定海产品中6种砷形态的研究

目的建立高效液相色谱-电感耦合等离子体质谱联用(HPLC-ICP-MS)测定海产品中亚砷酸根As(Ⅲ)、砷酸根As(Ⅴ)、一甲基砷(MMA)、二甲基砷(DMA)、砷甜菜碱(AsB)和砷胆碱(AsC)6种砷形态的分析方法,了解海产品中砷的形态与含量。方法海产品经0.15mol/L硝酸溶液热提取后,高效液相色谱以色谱柱Dionex Ion Pac AS7(4mm×250mm,5μm)为分离柱,用碳酸铵为流动相进行梯度洗脱分离,用电感耦合等离子体质谱进行定量检测。结果 6种砷形态均达到良好分离,在2.5~150μg/L范围内有良好的线性关系,回收率82.0%~113.0%,相对标准偏差(RSD)5%;海产品中的砷主要以有机砷形式存在,砷甜菜碱含量较高。结论建立的砷形态分析方法简便、准确可靠,符合海产品砷形态检测的要求。     

高效液相色谱-动态反应池-电感耦合等离子体质谱法测定海产品中砷形态

目的 建立HPLC-DRC-ICP-MS法准确测定海产品中砷甜菜碱(AsB)、二甲基砷(DMA)、一甲基砷(MMA)和无机砷[As(Ⅲ)和As(V)]等砷形态的含量.方法 海产品经1％硝酸溶液提取和HLB固相萃取柱净化后,经HPLC-DRC-ICP-MS法测定海产品中的砷形态.结果 以Dionex IonPak AS1...     

食品中砷形态分析方法的研究

目的:针对动物类海产品、藻类样品,建立相应的砷形态分析方法。方法:针对动物性海产品、藻类样品(干样直接粉碎,湿样匀浆后冷冻干燥处理),以水作提取溶剂,70℃,涡漩混合,提取2 h,采用液相色谱-氢化物发生-原子荧光光谱法连用技术进行砷形态分析。结果:在最优实验条件下,仪器的检出限分别为:AsB:4.2μg/L;As(Ⅲ):8.5μg/L;DMA:2.4μg/L;MMA:3.5μg/L;As(Ⅴ):7.5μg/L;在10~100(μg/L)浓度范围中,5种不同砷形态的线性相关系数均大于0.999。采用砷形态混合标准溶液及不同种类样品进行了精密度测定,结果的相对标准偏差(n=6)均小于10%,5种不同砷形态加标回收率在81.7%~119.3%之间,回收率的RSD皆小于10%。结论:本方法切实可行、样品前处理简单、结果稳定性好,适用动物类海产品、海藻类样品中砷形态的分析。     

液相色谱-原子荧光联用测定海带和紫菜中的砷形态前处理方法比较

目的液相色谱-原子荧光联用测定海带和紫菜中的砷形态前处理方法比较。方法分别用稀酸水溶液提取法和湿法消解法处理样品后,用液相色谱-原子荧光联用仪测定样品中的砷形态。结果稀酸水溶液提取法测定砷的回收率为89.65%~97.53%,As(Ⅲ)、DMA、MMA、As(V)精密度(RSD)分别为0.59%、0.27%、1.20%和0.63%;湿法消解法测定DMA的率为79.0%~85.7%,DMA、MMA、As(V)精密度(RSD)分别为0.15%、0.95%和9.11%。结论用稀酸水溶液提取法处理样品更适合于海产品砷形态的分析。     

离子色谱-电感耦合等离子体质谱法测定野生食用菌中6种砷形态

目的建立离子色谱-电感耦合等离子体质谱法(IC-ICP-MS)同时测定野生食用菌中砷甜菜碱(As B)、砷胆碱(As C)、二甲基砷(DMA)、一甲基砷(MMA)、亚砷酸As(Ⅲ)、砷酸As(Ⅴ)6种砷形态的方法。方法野生食用菌中砷形态用1%稀硝酸70℃超声提取1 h,离心后取上清液,残渣重复提取2次后合并上清液混匀,上清液经0.22μm滤膜过滤后通过阴离子色谱柱Dionex Ion Pac~(TM) AS7分离,2 mmol/L和100 mmol/L碳酸铵为流动相梯度洗脱,以电感耦合等离子质谱仪检测75As,外标法定量。结果 6种砷形态在0.5μg/L~50μg/L浓度线性关系良好,相关系数均为0.999 5,6种砷形态检出限为2μg/kg~8μg/kg,3个不同加标水平平均回收率为92.4%~109.1%,相对标准偏差7%。结论该方法具有灵敏度高、准确性好的特点,可用于野生食用菌中砷形态检测分析。     

加速溶剂萃取高效液相色谱-电感耦合等离子体质谱测定海产品中砷形态方法研究

目的建立加速溶剂萃取(PLE)与高效液相色谱-电感耦合等离子体质谱(HPLC-ICP MS)联用测定海产品中砷形态的方法,为食品安全风险监测提供参考方法。方法以50%甲醇-水为溶剂,采用快速溶剂萃取仪提取各形态的砷;利用阴离子交换柱分离,以O2为动态反应气消除质谱干扰,实现了As B、As(Ⅲ)、DMA、MMA、As(Ⅴ)5种形态砷的分离测定。结果 5种砷浓度在2.5μg/L~25μg/L时线性相关系数均≥0.999 0,检出限为0.1μg/L~0.2μg/L,相对标准偏差3.5%。实际样品加标回收率在80.1%~104.0%。结论方法具有快捷、准确、灵敏等优点,可分别用于无机砷、有机砷的测定,并可最大程度保留食品中砷的原始形态,便于进行形态分布研究。     

液相色谱-原子荧光联用法测定全血中砷形态化合物

采用液相色谱-原子荧光联用法测定全血中亚砷酸盐(As^Ⅲ)、二甲基砷酸(DMA)、一甲基砷酸(MMA)和砷酸盐(As^Ⅴ)。萃取后的上清液经阴离子交换色谱柱分离，原子荧光检测定量。四种砷形态化合物的线性范围为0～500μg/L,检出限为10.0μg/L,低、中、高三个浓度加标样品平均回收率为78.4%～105.0%,相对标准偏差(RSD)为3.20%～9.12%。本文所建立的全血中四种砷形态化合物的检测方法简单、灵敏、准确，可应用于实际接触人群中砷形态化合物的检测。     

LC—AFS测定湖南14个地级市大米的4种形态砷

目的：建立液相色谱—原子荧光光谱法(LC-AFS)测定大米中的4中砷形态含量的方法,并以此方法检测湖南省14个地级市的43份大米样品。方法：样品经0.15 mol/L硝酸溶液在90℃热浸提2.5 h,然后离心过滤,流动相选用磷酸氢二钠与磷酸二氢钾混合溶液,试样溶液中各砷形态经Hamilton PRP-X100阴离子交换柱分离,然后经原子荧光检测定量。结果：As(Ⅲ)、DMA、MMA、As(Ⅴ)在5～100μg/L浓度范围内线性良好,相关系数为0.9993～0.9998,检出限为0.003～0.008mg/kg,回收率为85.0%～107.0%。湖南43份大米样品As(Ⅲ)检出率为100%,DMA检出率93.0%,MMA与As(Ⅴ)则均未检出,As(Ⅲ)含量为0.036～0.168 mg/kg, DMA含量为ND～0.040 mg/kg,无机砷总量为0.036～0.168 mg/kg。结论：该方法操作简单,灵敏度高,准确性好,适合大米中4中砷形态检测。从实际样品检测结果来看,湖南各地区大米样品主要含有As(Ⅲ)、DMA两种形态,无机砷含量均未超过国家标准限量,合格率为100%。     

不同砷化合物对血管内皮细胞毒性的研究

目的观察不同砷化合物对体外培养的牛主动脉血管内皮细胞(BAEC)的细胞毒性。方法培养的BAEC分别暴露于亚砷酸钠(NaAsO2,iAsⅢ0~50μmol/L)、砷酸钠(Na2HAsO4,iAsⅤ,0~10mmol/L)和甲基亚胂酸(CH3AsO,MMAⅢ,0~2μmol/L)24h,应用四甲基偶氮唑盐(MTT)法测定细胞生存率;诱导性偶联质谱分光光度(ICP-MS)法测定细胞内总砷(tAs)含量。结果不同剂量范围内的iAsⅢi、AsⅤ和MMAⅢ均能够显著降低BAEC的细胞生存率(P<0.01),且具有剂量-效应关系;iAsⅢi、AsⅤ和MMAⅢ暴露24h的BAEC细胞的50%生存率(IC50)经计算分别为24.1μmol/L、155.9μmol/L和1.7μmol/L,对BAEC的细胞毒性从大到小依次为:MMAⅢ>iAsⅢ>iAsⅤ;相同暴露剂量和时间下,BAEC对MMAⅢ暴露的砷摄取速度明显高于iAsⅢ暴露(P<0.01)。结论无机砷甲基化的活性中间产物MMAⅢ对BAEC的细胞毒性要明显强于无机砷化合物。     

液相色谱-原子荧光联用法测定食用菌中4种砷形态

目的 建立1种液相色谱-原子荧光联用法测定食用菌中4种砷形态的方法。方法 取处理后的干食用菌样品,加入硝酸溶液,放入恒温箱浸提后,取上清液,经0.45μm有机滤膜过滤后,进入液相色谱,以Princen砷形态快速分析柱为色谱柱,用梯度洗脱进行分离,分离出的As(Ⅲ)、As(Ⅴ)、一甲基砷(MMA)、二甲基砷(DMA)等4种砷形态成分进入原子荧光光谱仪检测,根据保留时间定性,峰面积定量。结果 本法在质量浓度1～100μg/L范围内线性良好,相关系数r>0.999。取样0.5 g,提取体积为20 ml时,As(Ⅲ)检出限为6.20μg/kg, As(Ⅴ)为7.92μg/kg, MMA为2.72μg/kg, DMA为2.32μg/kg,加标回收率为90.4%～102.5%,相对标准偏差(RSD)为0.9%～2.2%。结论 本方法前处理简单、检测速度快、检出限低、准确度和精密度较高,可用于食用菌中4种砷形态的测定。     

大米中无机砷测定方法的研究

目的通过比较不同浓度三氟乙酸(TFA)溶液和在不同提取时间下TFA对于标准参考物质(SRM1568a rice flour)中无机砷化合物的提取能力,优化TFA溶液的浓度和提取时间,提出大米中无机砷测定方法。同时采集不同原产地的大米样品,评价无机砷污染状况。方法加入TFA,热浸提后取上清液离心浓缩至干,以流动相超声复溶,过RP柱和滤膜后进样;1mmol/L磷酸二氢铵溶液(pH9.0)和20mmol/L磷酸二氢铵溶液(pH8.0)为流动相梯度洗脱,采用Hamilton PRPX-100阴离子交换柱分离,液相色谱-原子荧光光谱法(LC-AFS)测定。结果采用3%(V/V)TFA溶液对SRM1568a热浸提2h的样品前处理方法,其测定结果符合无机砷参考值。结论方法适用于大米中无机砷的测定。所采集大米样品的无机砷含量均未超出卫生标准。     

HPLC-ICP-MS speciation analysis of arsenic in urine of Japanese subjects without occupational exposure

The toxicity and carcinogenicity of arsenic depend on its species. Individuals living in Japan consume much seafood that contains high levels of organoarsenics. Speciation analysis of urinary arsenic is required to clarify the health risks of arsenic intake. There has been no report of urinary arsenic analysis in Japan using high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). We performed speciation analysis of urinary arsenic for 210 Japanese male subjects without occupational exposure using HPLC-ICP-MS. The median values of urinary arsenics were as follows: sodium arsenite (AsIII), 3.5; sodium arsenate (AsV), 0.1; monomethylarsonic acid (MMA), 3.1; dimethylarsinic acid (DMA), 42.6; arsenobetaine (AsBe), 61.3; arsenocholine, trimethylarsine oxide, and unidentified arsenics (others), 5.2; and total arsenic (total As), 141.3 microgAs/l. The median creatinine-adjusted values were as follows: AsIII, 3.0; AsV, 0.1; MMA, 2.6; DMA, 35.9; AsBe, 52.1; others 3.5; and total As, 114.9 microgAs/g creatinine. Our findings indicate that DMA and AsBe levels in Japan are much higher than those found in Italian and American studies. It appears that the high levels of DMA and AsBe observed in Japan may be due in part to seafood intake. ACGIH and DFG set the BEI and BAT values for occupational arsenic exposure as 35 microgAs/l and 50 microgAs/l, respectively, using the sum of inorganic arsenic (iAs), MMA, and DMA. In the general Japanese population, the sums of these were above 50 microgAs/l in 115 (55%) samples. We therefore recommend excluding DMA concentration in monitoring of iAs exposure.     

Urinary arsenic species, toenail arsenic, and arsenic intake estimates in a Michigan population with low levels of arsenic in drinking water

The large disparity between arsenic concentrations in drinking water and urine remains unexplained. This study aims to evaluate predictors of urinary arsenic in a population exposed to low concentrations (≤50?μg/l) of arsenic in drinking water. Urine and drinking water samples were collected from a subsample (n=343) of a population enrolled in a bladder cancer case-control study in southeastern Michigan. Total arsenic in water and arsenic species in urine were determined using ICP-MS: arsenobetaine (AsB), arsenite (As[III]), arsenate (As[V]), methylarsenic acid (MMA[V]), and dimethylarsenic acid (DMA[V]). The sum of As[III], As[V], MMA[V], and DMA[V] was denoted as SumAs. Dietary information was obtained through a self-reported food intake questionnaire. Log(10)-transformed drinking water arsenic concentration at home was a significant (P<0.0001) predictor of SumAs (R(2)=0.18). Associations improved (R(2)=0.29, P<0.0001) when individuals with less than 1?μg/l of arsenic in drinking water were removed and further improved when analyses were applied to individuals who consumed amounts of home drinking water above the median volume (R(2)=0.40, P<0.0001). A separate analysis indicated that AsB and DMA[V] were significantly correlated with fish and shellfish consumption, which may suggest that seafood intake influences DMA[V] excretion. The Spearman correlation between arsenic concentration in toenails and SumAs was 0.36 and between arsenic concentration in toenails and arsenic concentration in water was 0.42. Results show that arsenic exposure from drinking water consumption is an important determinant of urinary arsenic concentrations, even in a population exposed to relatively low levels of arsenic in drinking water, and suggest that seafood intake may influence urinary DMA[V] concentrations.     

Occurrence,speciation analysis and health risk assessment of arsenic in Chinese mitten crabs (Eriocheir sinensis) collected from China

Arsenic (As) is a major hazardous element in natural environments, and arsenic pollution is becoming an issue of concern worldwide. The more toxic inorganic arsenic, such as trivalent arsenite As(Ⅲ) and pentavalent arsenate As(Ⅴ), which normally can transform to organic arsenic compounds, such as arsenobetaine (AsB), arsenocholine (AsC), monomethyl arsenic acid (MMA), dimethyl arsenic acid (DMA), trimethyl arsenic acid (TMA), arsenosugars and arsenolipids. In this study, a total of 2130 individuals of Chinese mitten crabs were collected from seven locations and mixed to 71 samples. Total arsenic and six major species (AsC, AsB, DMA, MMA, As (Ⅲ), and As (Ⅴ)) were determined by inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS), respectively. The target hazard quotient (THQ) was utilized to evaluate the human health risk. The total arsenic concentration and totals for the six arsenic forms are 0.25–1.66 mg/kg and 0.05–1.19 mg/kg wet mass, respectively. Except for HH and LH, the six arsenic species concentrations accounted for more than 50.0 % of the total arsenic. The less toxic AsB is the most predominant in crabs, comprising 50.0 %–90.0 % of the sum of six types of arsenic. The more toxic inorganic arsenic only range from 0.01 to 0.21 mg/kg wet mass, much less than the limit content of 0.50 mg/kg inorganic As in crustacea. The THQ values of inorganic arsenic through the consumption of Chinese mitten crabs are estimated, and the values are all less than 1, indicating that intaking Chinese mitten crabs collected from China will not cause an appreciable hazard risk to human health.     

Assessing the measurement precision of various arsenic forms and arsenic exposure in the National Human Exposure Assessment Survey (NHEXAS)

Archived samples collected from 1995 to 1997 in the National Human Exposure Assessment Survey (NHEXAS) in U.S. Environmental Protection Agency Region 5 (R5) and the Children's Study (CS) in Minnesota were analyzed for total arsenic, arsenate [As(V)], arsenite, dimethyl arsenic acid (DMA), monomethyl arsenic acid (MMA), arsenobetaine (AsB), and arsenocholine. Samples for the CS included drinking water, urine, hair, and dust; both studies included food (duplicate plate, composited 4-day food samples from participants). Except for AsB and As(V), the levels for As species measured in the food and drinking water samples were very low or nonexistent. The analytical methods used for measuring As species were sensitive to < 1 ppb. During the analysis of food and drinking water samples, chromatographic peaks appeared that contained As, but they did not correspond to those being quantified. Thus, in some samples, the sum of the individual As species levels was less than the total As level measured because the unknown forms of As were not quantified. On the other hand, total As was detectable in almost all samples (> 90%) except for hair (47%), indicating that the analytical method was sufficiently sensitive. Population distributions of As concentrations measured in drinking water, food (duplicate plate), dust, urine, and hair were estimated. Exposures to total As in food for children in the CS were about twice as high as in the general R5 population (medians of 17.5 ppb and 7.72 ppb, respectively). In addition, AsB was the most frequently detected form of As in food eaten by the participants, while As(V) was only rarely detected. Thus, the predominant dietary exposure was from an organic form of As. The major form of As in drinking water was As(V). Spearman (rank) correlations and Pearson (log-concentration scale) correlations between the biomarkers (urine, hair) and the other measures (food, drinking water, dust) and urine versus hair were performed. In the NHEXAS CS, total As and AsB in the food eaten were significantly correlated with their levels in urine. Also, levels of As(V) in drinking water correlated with DMA and MMA in urine. Arsenic levels in dust did not show a relationship with urine or hair levels, and no relationship was observed for food, drinking water, and dust with hair. Urine samples were collected on days 3, 5, and 7 of participants' monitoring periods. Total As levels in urine were significantly associated across the three pairwise combinations--i.e., day 3 versus day 5, day 3 versus day 7, and day 5 versus day 7. Because the half-life of As in the body is approximately 3 days, this suggests that some exposure occurred continually from day to day. This trend was also observed for AsB, suggesting that food is primarily responsible for the continual exposure. DMA and MMA in urine were also significantly correlated but not in all combinations.     

微波辅助提取-高效液相色谱-电感耦合等离子体质谱法测定干食用菌中6种砷形态

目的 建立干食用菌中砷胆碱（AsC）、砷甜菜碱（AsB）、亚砷酸根[As(III)]、二甲基砷（DMA）、一甲基砷（MMA）和砷酸根[As(V)]的微波辅助提取-高效液相色谱-电感耦合等离子体质谱测定方法。方法 经粉碎的干食用菌样品经1%硝酸为提取液，于100℃微波提取20 min，提取液离心、上清液经0.22 μm滤膜过滤后测定。采用Hamilton PRP - X100为分离柱，以0.1 mol/L碳酸铵(含2%甲醇）- 2%甲醇为流动相梯度洗脱。结果 方法检出限均低于0.3 μg/L，在0.5-100 μg/L范围内，线性相关系数（r）均大于0.999 5，加标回收率在97.4%～105%之间，RSD小于5%。结论 本法方法简便、快速，适用于食用菌中6种砷形态的分析。     

Seafood intake and urine concentrations of total arsenic, dimethylarsinate and arsenobetaine in the US population

Background

Seafood is the main source of organic arsenic exposure (arsenobetaine, arsenosugars and arsenolipids) in the population. Arsenosugars and arsenolipids are metabolized to several species including dimethylarsinate (DMA).

Objective

Evaluate the association of seafood intake with spot urine arsenic concentrations in the 2003–2006 National Health Nutrition and Examination Survey (NHANES).

Methods

We studied 4276 participants ≥6 years. Total arsenic was measured using inductively coupled plasma dynamic reaction cell mass spectrometry (ICPMS). Urine DMA and arsenobetaine were measured by high-performance liquid chromatography coupled with ICPMS.

Results

Participants reporting seafood in the past 24-h had higher urine concentrations of total arsenic (median 24.5 vs. 7.3 μg/L), DMA (6.0 vs. 3.5 μg/L), arsenobetaine (10.2 vs. 0.9 μg/L) and total arsenic minus arsenobetaine (11.0 vs. 5.5 μg/L). Participants reporting seafood ≥2/wk vs. never during the past year had 2.3 (95% confidence interval 1.9, 2.7), 1.4 (1.2, 1.6), 6.0 (4.6, 7.8) and 1.7 (1.4, 2.0) times higher (p-trend <0.001) concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine, respectively. In participants without detectable arsenobetaine and in analyses adjusted for arsenobetaine, seafood consumption in the past year was not associated with total arsenic or DMA concentrations in urine.

Conclusion

Seafood intake was a major determinant of increased urine concentrations of total arsenic, DMA, arsenobetaine and total arsenic minus arsenobetaine in the US population. Epidemiologic studies that use total arsenic, DMA, the sum of inorganic arsenic, methylarsonate and DMA, and total arsenic minus arsenobetaine as markers of inorganic arsenic exposure and/or metabolism need to address seafood intake.     

Bioaccumulation and biotransformation of arsenic in the Mediterranean polychaete Sabella spallanzanii: experimental observations

The Mediterranean fan worm Sabella spallanzanii is characterized by elevated basal levels of arsenic in branchial crowns (>1000 microg/g) and an unusual prevalence of dimethylarsinic acid (DMA), a relatively toxic compound with a possible antipredatory role. The aim of this work was to obtain further insights on the capability of this polychaete to accumulate arsenic from different compounds and to operate biotransformation reactions. Laboratory exposures to arsenate (As(V)), dimethylarsinic acid (DMA), trimethylarsine (TMA), and arsenobetaine (AsB) revealed significant differences among tissues and kind of experiments. The highest increases of arsenic content were observed in branchial crowns of organisms treated with arsenate, which can enter the cell through the phosphate carrier system; lower variations were measured with DMA and TMA, while not-significant changes of total As occurred after treatments with AsB. In body tissues, exposure to As(V), DMA, and TMA confirmed a progressively lower accumulation of total arsenic, while a marked increase was caused by AsB. Obtained results suggested that accumulated arsenic could be chemically transformed, thus explaining the elevated basal levels of DMA typical of S. spallanzanii; during all the experiments, DMA was the most accumulated molecule, suggesting that this species possesses the enzymatic pathways for methylation and demethylation reactions of inorganic and trimethylated arsenicals. Only arsenobetaine was not converted into DMA, which would confirm a microbial pathway for degradation for this molecule, particularly important in body tissues of S. spallanzanii for the presence of bacteria associated to digestive tracts. Overall, the present study suggests future investigations on the biological role of arsenic and DMA in S. spallanzanii as a potential adaptive mechanism against predation in more vulnerable tissues.     

Urine Arsenic Concentrations and Species Excretion Patterns in American Indian Communities Over a 10-year Period: The Strong Heart Study

Background

Arsenic exposure in drinking water disproportionately affects small communities in some U.S. regions, including American Indian communities. In U.S. adults with no seafood intake, median total urine arsenic is 3.4 μg/L.

Objective

We evaluated arsenic exposure and excretion patterns using urine samples collected over 10 years in a random sample of American Indians from Arizona, Oklahoma, and North and South Dakota who participated in a cohort study from 1989 to 1999.

Methods

We measured total urine arsenic and arsenic species [inorganic arsenic (arsenite and arsenate), methylarsonate (MA), dimethylarsinate (DMA), and arsenobetaine] concentrations in 60 participants (three urine samples each, for a total of 180 urine samples) using inductively coupled plasma/mass spectrometry (ICPMS) and high-performance liquid chromatography/ICPMS, respectively.

Results

Median (10th, 90th percentiles) urine concentration for the sum of inorganic arsenic, MA, and DMA at baseline was 7.2 (3.1, 16.9) μg/g creatinine; the median was higher in Arizona (12.5 μg/g), intermediate in the Dakotas (9.1 μg/g), and lower in Oklahoma (4.4 μg/g). The mean percentage distribution of arsenic species over the sum of inorganic and methylated species was 10.6% for inorganic arsenic, 18.4% for MA, and 70.9% for DMA. The intraclass correlation coefficient for three repeated arsenic measurements over a 10-year period was 0.80 for the sum of inorganic and methylated species and 0.64, 0.80, and 0.77 for percent inorganic arsenic, percent MA, and percent DMA, respectively.

Conclusions

This study found low to moderate inorganic arsenic exposure and confirmed long-term constancy in arsenic exposure and urine excretion patterns in American Indians from three U.S. regions over a 10-year period. Our findings support the feasibility of analyzing arsenic species in large population-based studies with stored urine samples.     

Arsenic drinking water exposure and urinary excretion among adults in the Yaqui Valley, Sonora, Mexico

The objective of this study was to determine arsenic exposure via drinking water and to characterize urinary arsenic excretion among adults in the Yaqui Valley, Sonora, Mexico. A cross-sectional study was conducted from July 2001 to May 2002. Study subjects were from the Yaqui Valley, Sonora, Mexico, residents of four towns with different arsenic concentrations in their drinking water. Arsenic exposure was estimated through water intake over 24 h. Arsenic excretion was assessed in the first morning void urine. Total arsenic concentrations and their species arsenate (As V), arsenite (As III), monomethyl arsenic (MMA), and dimethyl arsenic (DMA) were determined by HPLC/ICP-MS. The town of Esperanza with the highest arsenic concentration in water had the highest daily mean intake of arsenic through drinking water, the mean value was 65.5 microg/day. Positive correlation between total arsenic intake by drinking water/day and the total arsenic concentration in urine (r = 0.50, P < 0.001) was found. Arsenic excreted in urine ranged from 18.9 to 93.8 microg/L. The people from Esperanza had the highest geometric mean value of arsenic in urine, 65.1 microg/L, and it was statistically significantly different from those of the other towns (P < 0.005). DMA was the major arsenic species in urine (47.7-67.1%), followed by inorganic arsenic (16.4-25.4%), and MMA (7.5-15%). In comparison with other reports the DMA and MMA distribution was low, 47.7-55.6% and 7.5-9.7%, respectively, in the urine from the Yaqui Valley population (except the town of Cocorit). The difference in the proportion of urinary arsenic metabolites in those towns may be due to genetic polymorphisms in the As methylating enzymes of these populations.