A rapid method for the selective analysis of total urinary metabolites of inorganic arsenic

Homicidal arsenic poisoning

The case of a 50-year-old man who died mysteriously after being admitted to hospital is reported. He had raised the possibility of being poisoned prior to his death. A Coroner’s post-mortem did not reveal the cause of death but this was subsequently established by post-mortem trace element analysis of liver, urine, blood and hair all of which revealed very high arsenic concentrations.

Urinary Arsenic Concentrations and their Associated Factors in Korean Adults

Arsenic (As) is a well-known human carcinogen and its dietary exposure has been found to be the major route of entry into general population. This study was performed to assess the body levels of As and their associated factors in Korean adults by analyzing total As in urine. Urine and blood samples were collected from 580 adults aged 20 years and older, who had not been exposed to As occupationally. Demographic information was collected with the help of a standard questionnaire, including age, smoking, alcohol intake, job profiles, and diet consumed in the last 24 hrs of the study. Total As, sum of As(III), As(V), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), in urine was determined using atomic absorption spectrometer involving hydride generation method. The geometric mean concentration of total As in urine was 7.10 μg/L. Urine As was significantly higher in men (7.63 μg/L) than in women (6.75 μg/ L). Age, smoking, alcohol consumption, and job profiles of study subjects did not significantly affect the concentration of As in urine. No significant relationship was observed between body mass index (BMI), Fe, and total cholesterol in serum and urinary As. Urine As level was positively correlated with seaweeds, fishes & shellfishes, and grain intake. A negative correlation between urinary As level and HDL-cholesterol in serum and meat intake was observed. Overall, these results suggest that urinary As concentration could be affected by seafood consumption. Therefore, people who frequently consume seafood and grain need to be monitored for chronic dietary As exposure.

Association of arsenic levels in soil and water with urinary arsenic concentration of residents in the vicinity of closed metal mines

Arsenic (As) pollution in the surroundings of metal mines has been observed, and may induce serious health problems, in particular cancer. Health hazard attributed to As in contaminated soil and water in the vicinity of closed or abandoned metal mines may be high. Little is known about how environmental exposure to As has affected the health of resident near closed metal mines. The objectives of this study were to compare the urinary level of As for those living near closed metal mines (the exposed group) with that of non-exposed group; and to investigate the correlation between As levels in soil (SoilAs) and water (WaterAs) and the urinary levels (UrineAs) of residents in the exposed group. Data for SoilAs and WaterAs were obtained from the national environmental survey performed between 2003 and 2005 by the Ministry of Environment in Korea. To measure UrineAs, 2674 and 237 subjects were selected from 67 closed metal mines (exposed areas) and two rural areas (non-exposed areas), respectively. Five milliliters of urine samples were taken, and graphite furnace atomic absorption spectrometry was used to analyze UrineAs. Of all the exposed areas, high SoilAs and WaterAs areas that exceed the Korean standards of As in soil (6 mg/kg-soil) and stream or groundwater (0.05 mg/l-water) were classified to evaluate the health risks in high polluted areas. Also, high UrineAs group was defined as 20 μg/g creatinine or more. Student's t-test was performed to compare the UrineAs level between the exposed and non-exposed groups. The odds ratio (OR) was calculated by a logistic analysis to evaluate the risk for high UrineAs level from high SoilAs and WaterAs areas. The mean of urinary As were 8.90 ± 8.34 μg/g-creatinine for the exposed group and 7.68 ± 4.98 μg/g creatinine for the non-exposed group, respectively; and the significant difference of urinary As level was observed between both groups (p<0.05). Moreover, the means for urinary As of people in areas with high As level in soil and water were significantly higher than that for the control areas (p<0.001), and these differences were more pronounced for the As level in water. The odds of subjects with high UrineAs were positively and significantly associated with living in the areas with high As level in soil (OR=1.62; 95% C.I.=1.13-2.31). These associations were much stronger for the areas with high WaterAs (OR=3.79; 95% C.I.=2.32-6.19). These results indicate that the high level of As in environment may increase the risk of having high urinary As level of people in the exposed areas.

A study of factors influencing urinary arsenic excretion in exposed workers

This study was designed to evaluate the influence of occupational and non-occupational factors on urinary arsenic excretion in workers exposed to iAs (inorganic arsenic) in the dismantlement of a factory which once produced fertilisers. We measured iAs and its methylated metabolites in 108 urinary samples of workers exposed to iAs in July 2006. A total of 13.9% of the samples showed levels higher than the Biological Exposure Index (BEI) of 35 microg/l (mean value 23.9 microg/l). After the improvement of working conditions, in August-October 2006 we collected urinary samples from each of the 108 workers enrolled. We also administrated a questionnaire, in order to investigate the influence of occupational and non-occupational factors on the urinary arsenic excretion. A significant difference was observed in relation with seafood consumption and age stratification. We have found a significant reduction of urinary arsenic excretion between the two phases of biological monitoring, probably due to appropriate hygiene work-related interventions.

Human arsenic poisoning issues in central-east Indian locations: biomarkers and biochemical monitoring

The study reports the use of three biomarkers i.e. total arsenic in hair and nails, total arsenic in blood, and total arsenic in urine to identify or quantify arsenic exposure and concomitant health effects. The main source of arsenic was inorganic exposure through drinking water. The arsenic levels and the health effects were analyzed closely in a family having maximum symptoms of arsenic. Based on the result of this study it is reported that there exist a correlation between the clinically observable symptoms, the blood and urine arsenic level, and the arsenic intake through drinking water. An intensive study on the urinary arsenic levels was carried out in which the urine levels of arsenic and the urine sufficiency tests were performed. A composite picture of body burden of arsenic has been obtained by carrying out a complete biochemical analysis of a maximum affected family. This confirms pronounced chronic exposure of the arsenic to these people. A combined correlation study on the arsenic levels measured in whole blood, urine, hair, nails and age present a remarkable outcome. Accordingly, the arsenic levels in blood are negatively correlated with the urine arsenic levels, which indicate either the inadequacy of the renal system in cleaning the blood arsenic or a continuous recirculation of the accumulated arsenic. This is an important conclusion about arsenical metabolism in humans. The study also raises the issues of the prospects of complete elimination of the accumulated arsenic and the reversibility of the health effects. Based on the work in Kourikasa village we report that there are very remote chances of complete purging of arsenic and thus reversibility of the health effects owing to various factors. The paper also discusses the various issues concerning the chronic arsenic poisoning management in the affected locations.

Gender and age differences in the metabolism of inorganic arsenic in a highly exposed population in Bangladesh

Although genetic polymorphisms have been shown to explain some of the large variation observed in the metabolism of inorganic arsenic there may be several other factors playing an important role, e.g. nutrition. The objective of this study was to elucidate the influence of various factors on current arsenic exposure and metabolism in Matlab, a rural area in Bangladesh, where elevated water arsenic concentrations and malnutrition are prevalent. In total 1571 individuals, randomly selected from all inhabitants above 5 years of age, were investigated by measuring arsenic in urine and drinking water. In a subset of 526 randomly selected individuals, arsenic metabolites were speciated using HPLC coupled to inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS). A significant association was observed between arsenic in urine and drinking water (R2=0.41). The contribution to urinary arsenic from arsenic exposure from food and other water sources was calculated to be almost 50microg/L. The individuals in the present study had remarkably efficient methylation, in spite of high exposure and prevalence of malnutrition. Gender and age were major factors influencing arsenic metabolism in this population with a median of 77microg/L of arsenic in urine (range: 0.5-1994microg/L). Women had higher arsenic methylation efficiency than men, but only in childbearing age, supporting an influence of sex hormones. Overall, exposure level of arsenic, gender and age explained at most 30% of the variation in the present study, indicating that genetic polymorphisms are the most important factor influencing the metabolism of inorganic arsenic.

Arsenic contamination of Ronphibun residents associated with uses of arsenic-contaminated shallow-well water other than drinking

High levels of urinary arsenic have been reported among residents of an area of southern Thailand where many households have shallow wells heavily contaminated with arsenic. However, the finding that very few of the residents in this area have used contaminated shallow-well water for drinking or cooking in the last 10 years prompted this investigation. The aim was to identify the uses of shallow-well water by adult residents that were related to a positive association between shallow-well water and urinary arsenic levels. Information on shallow-well water use for all personal and domestic purposes was obtained and arsenic levels of household shallow-well water and urine (after refraining from seafood for 2 days) were measured. Urinary and shallow-well water arsenic levels were strongly positively associated among residents who regularly used shallow-well water for bathing (including washing face, hair, hands and feet) but not among residents regularly using arsenic-safe water for bathing or regularly using shallow-well water for other purposes, such as brushing teeth, domestic cleaning or washing food and utensils. The findings suggest that appreciable transdermal absorption of arsenic is possible and that successful abatement of human contamination with arsenic may require the provision of arsenic-safe water, not only for consumption but also for personal hygiene purposes.

Evaluation of the three most commonly used analytical methods for determination of inorganic arsenic and its metabolites in urine

This work compares the three most common analytical methods for determination of inorganic arsenic and its metabolites in urine: high performance liquid chromatography coupled to either inductively coupled plasma mass spectrometry or atomic fluorescence spectrometry via hydride generation (high performance liquid chromatography-hydride generation-inductively coupled plasma mass spectrometry (HPLC-HG-ICPMS) and HPLC-HG-atomic fluorescence spectrometry (AFS), respectively) and atomic absorption spectrometry coupled to HG (HG-atomic absorption spectrometry (AAS)). This was done with the focus to find alternatives to ICPMS, the investment and running costs of which are rather high. Between-laboratory comparison of HPLC-HG-ICPMS and HPLC-HG-AFS showed good agreement for inorganic arsenic, methylarsonate (MA) and dimethylarsinate (DMA) (R(2)=0.91, R(2)=0.92 and R(2)=0.90, respectively, N=86). Within-laboratory comparisons of HPLC-HG-AFS, HPLC-HG-ICPMS and HG-AAS showed good agreement for all arsenic species and the sum of inorganic arsenic and its metabolites in urine (HPLC-HG-ICPMS versus HPLC-HG-AFS: R(2)=0.95; HG-AAS versus HPLC-HG-AFS: R(2)=0.95 and HPLC-HG-ICPMS versus HG-AAS: R(2)=0.97; N=89). HPLC-HG-AFS was found to be a simple, but high quality alternative to HPLC-HG-ICPMS for the speciation and quantification of inorganic arsenic and its metabolites in urine at arsenic concentrations above 10microgL(-1). Because of its considerably lower costs compared to HPLC-HG-ICPMS, it may be a good alternative in laboratories where the high cost of ICPMS is not justified in relation to the intended use of the instrument.

Comparison of atomic absorption and fluorescence spectroscopic methods for the routine determination of urinary arsenic

OBJECTIVE

Interpretation of urinary arsenic measurements is sometimes difficult because of the absorption of seafood that contains trimethylated arsenic forms (arsenobetaine and arsenocholine). The objective of this study was to develop a rapid and robust technique for the measurement of the sum of inorganic arsenic metabolites.

METHODS

Measurement of arsenic was performed in urine after hydride generation in acid medium. Using atomic fluorescence spectrometry (AFS) as the detection system, we developed a rapid (one determination in less than 2 min) technique using 50 microl urine without pre-treatment. Standardisation was done externally with a mixed standard solution containing inorganic trivalent arsenic (As(i) (III)), inorganic pentavalent arsenic (As(i) (V)), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) (15/15/12.5/57.5).

RESULTS

Samples distributed in the frame of an international comparison programme were used to assess accuracy of the AFS procedure, which gives a linear response up to 50 microg/l and proves more precise [coefficient of variation (CV)< 4% at 5 microg/l] and sensitive than the atomic absorption spectroscopy (AAS) technique using a quartz cell. An additional adaptation that allows the detection of non-directly reducible arsenic forms has also been validated for samples with high arsenic concentrations.

CONCLUSIONS

The present study demonstrates the superiority of AFS over atomic absorption spectrometry (AAS) in arsenic determination and the interest of online mineralisation prior AFS detection for the determination of arsenic concentration in urine.

The Aral Sea disaster – human biomonitoring of Hg, As, HCB, DDE, and PCBs in children living in Aralsk and Akchi, Kazakhstan

Mercury and arsenic have been measured in urine samples and HCB, DDE and PCBs in blood samples of children from Aralsk and Akchi, Kazakhstan. Due to the special situation of Aralsk in the desert left by the drying out Aral Sea, environmental pollution with heavy metals and organic contaminants is believed to be higher than elsewhere in Kazakhstan. Aralsk was formerly located at the shore of the Aral Sea and is now far away from it. Akchi is a similar village and was included in this study as a Kazakh reference site. Urine concentrations of arsenic were higher in Akchi (9.4 microg/l) than in Aralsk (5.5 microg/l) and compared to children from Mannheim, Germany (4.25 microg/l; Median values). Regarding Hg, differences between children of Aralsk and Akchi were not significant and concentrations were lower than reference values from Germany. DDE contamination of children from Aralsk (2.48 microg/l) was significantly higher compared to Akchi (1.35 microg/l). DDE concentrations in blood samples from children in both cities were also significantly higher than the German reference value (0.7 microg/l). HCB and PCBs levels differed significantly between both Kazakh groups. However, concentrations of these compounds were lower than German reference values and there was no significant difference to samples from Mannheim children.

Determinants of inorganic arsenic methylation capability among residents of the Lanyang Basin, Taiwan: arsenic and selenium exposure and alcohol consumption

The objective of this study was to assess individual variation in inorganic arsenic methylation capability and the association between selenium levels in urine and blood, and inorganic arsenic methylation capability among residents of the Lanyang Basin who drank groundwater and were exposed to high concentrations of inorganic arsenic. According to the arsenic concentration of their drinking water, they were equally and randomly classified into four groups of 252 persons. It turned out that the higher the concentration of arsenic in well water was and thus the cumulative arsenic exposure, the higher the total inorganic arsenic metabolites in urine (total As(i)) and the overall inorganic and organic arsenic in urine (overall As(i+o)) were. The percentage of inorganic arsenic significantly decreased and the DMA percentage significantly increased as the concentration of urinary selenium and serum alpha-tocopherol increased. It appeared that urinary selenium levels increased the metabolism by methylation of arsenic, a finding that requires further investigation.

Laboratory case identification of arsenic in Ronpibul village, Thailand (2000-2002)

Ronpibul village dwellers in the southern part of Thailand have been exposed to arsenic in the water and the environment over three generations. Over the past decades, clean water supplies, utilization and consumption have been introduced to the area. The villagers still use and select rainwater to other forms of potable water. In 2000, the epidemiological survey by Siripitayakunkit (Siripitayakunkit, U. Survey of Chronic Arsenic Poisoning in Ronpiboon, Nakhon Si Thammarat, Thailand, 2000. Proc. 6th International Conference on the Biochemistry of Trace Elements, Guelph, Canada) showed prevalence rate at 24.7%, by using the skin lesion as selection criteria. In 2000-2002, attempt to initiate the local arsenic patient center, we investigated the population at risk in three villages. The laboratory analyses cover urine arsenic level, urine sugar screening and skin lesion classified by dermatologist. The result showed the prevalence of 5.99% of melanosis and 8.67% of hyperkeratosis, 3.84% of urine sugar > 100 mg/dL and 6.33% urine arsenic > 50 microg/g creatinine. There were low to negligible correlation between arsenic urine with urine sugar (r2 = 0.241) and arsenic urine with skin lesion (r2 = 0.058).

Monitoring of arsenic exposure with speciated urinary inorganic arsenic metabolites for ion implanter maintenance engineers

For wafer fabrication in the semiconductor industry, maintenance engineers are potentially exposed to hazards during their work of disassembling machine components for cleanup. One special concern is the presence of arsenic or arsenic compounds in the working environment. This study analyzed speciated urinary inorganic arsenic metabolites of the maintenance engineers using high-performance liquid chromatography-hydride generation atomic absorption spectrometry to study the potential arsenic exposure during their maintenance work. In total, from six wafer fabrication facilities, 30 maintenance engineers were recruited as the exposed group and another 12 office-based engineers served as the control group. First morning-voided urine samples of each study subject were collected for 7 consecutive days. The levels of total urinary inorganic arsenic metabolites for the exposed group were 1.7+/-1.4, 1.4+/-1.1, 6.2+/-6.7, 20.2+/-14.1, and 29.5+/-17.2 micro g/L for As3+, As5+, monomethylarsonic acid, dimethylarsinic acid, and total inorganic arsenic, respectively. Both the concentration of monomethylarsonic acid and its percentage in total urinary inorganic arsenic metabolites showed significantly ascending trends for the control group, for the engineers without preventative maintenance work prior to their urine sampling, and for the engineers with such work prior to their urine sampling (P<0.05 and P<0.0005, respectively). The data also suggested that, at low-level occupational arsenic exposure, the concentration of total urinary inorganic arsenic metabolites might be misleading due to the confounding effect resulting from intake of seafood, such as arsenosuger. Nevertheless, monitoring of urinary arsenic species by using the percentage change of monomethylarsonic acid in total urinary inorganic arsenic metabolites as an indicator for the verification of arsenic exposure is helpful and appropriate in such cases.

Tetra-arsenic tetra-sulfide for the treatment of acute promyelocytic leukemia: a pilot report

In the past 6 years, we treated 129 patients who had acute promyelocytic leukemia (APL) with a new arsenic agent, oral tetra-arsenic tetra-sulfide (As(4)S(4)). Nineteen of the patients had newly diagnosed APL, 7 had first relapse, and 103 had hematologic complete remission (HCR). HCR was achieved in all patients with newly diagnosed APL and in all those with hematologic relapse. Of 16 patients with newly diagnosed disease and available cytogenetic and molecular analyses, 14 had cytogenetic and molecular complete remission (CR). Cytogenetic and molecular CR was also obtained in 5 of the 7 patients with hematologic relapse. In the HCR group, 35 of 44 patients positive for PML-RARalpha at baseline became negative. In the newly diagnosed group, estimated disease-free survival (DFS) rates for 1 and 3 years were 86.1% and 76.6%, respectively, with a median follow-up time of 13.5 months (range, 2-40 months). In the HCR group, DFS rates for 1 and 6 years were 96.7% and 87.4%, respectively, with a median follow-up of 23 months (range, 2-71 months). Treatment with As(4)S(4) was well tolerated, with only moderate side effects, including asymptomatic prolongation of corrected QT interval, transient elevation in liver enzyme levels, rash, and mild gastrointestinal discomfort; neither myelosuppression nor appreciable long-term side effects occurred. Degeneration or apoptosis of APL promyelocytes was observed during As(4)S(4) therapy. Pharmacokinetic studies showed that the agent was absorbed rapidly. Most urinary arsenic excretion occurred within the first 24 hours. Both blood and urinary arsenic levels declined after discontinuation of As(4)S(4). Our results show, for the first time, that As(4)S(4) treatment alone is highly effective and safe in both remission induction and maintenance therapy in patients with APL, regardless of disease stage.

Monitoring of low level arsenic exposure during maintenance of ion implanters

To delineate potential exposure in ion implanter maintenance, the authors recruited 21 maintenance engineers (exposed group) and 10 computer programmers (controls) at three semiconductor manufacturing facilities. Samples of air, wipes, and urine; used cleaning cloths; and used gloves were collected for the characterization of arsenic exposure. Arsenic levels were very low in environmental samples, but high arsenic levels were found in some wipe samples, used cleaning cloths, and gloves. The average baseline content of urinary arsenic measured for maintenance engineers was 3.6 microg/g creatinine. Maintenance engineers experienced an increase of 1.0-7.8 microg/g creatinine in urinary arsenic levels during ion implanter maintenance. Results of a mixed-model analysis indicated that urinary arsenic levels were associated significantly with time series (p = .0001), and the extent of association was different among the three facilities (p = .0226). The results of this study indicate that arsenic intake via ingestion, rather than through inhalation, might play a significant role in the elevation of urinary arsenic levels. However, a series of urine samples with self-reference continue to be a good approach for the monitoring of low-level arsenic exposure.

Relationship of urinary arsenic to intake estimates and a biomarker of effect, bladder cell micronuclei

The purpose of this study was to investigate methods for ascertaining arsenic exposure for use in biomarker studies. Urinary arsenic concentration is considered a good measure of recent arsenic exposure and is commonly used to monitor exposure in environmental and occupational settings. However, measurements reflect exposure only in the last few days. To cover longer time periods exposure can be estimated using arsenic intake data, calculated by combining measures of environmental arsenic and inhalation/ingestion rates. We compared these different exposure assessment approaches in a population chronically exposed to arsenic in drinking water in northern Chile. The study group consisted of 232 people, some drinking water low in arsenic (15 micrograms/l) and others drinking water with high arsenic concentrations (up to 670 micrograms/l). First morning urine samples and questionnaire data, including fluid intake information, were collected from all participants. Exfoliated bladder cells were collected from male participants for the bladder cell micronuclei assay. Eight different indices of exposure were generated, six based on urinary arsenic (microgram As/l urine; microgram As/g creatinine; microgram InAs/l urine; microgram MMA/l urine; microgram DMA/l urine; microgram As/h, excreted), and two on fluid intake data (microgram As/day, ingested; microgram As/l fluid ingested-day). The relationship between the different exposure indices was explored using correlation analysis. In men, exposure indices were also related to a biomarker of effect, bladder cell micronuclei. While creatinine-adjusted urinary arsenic concentrations had the strongest correlations with the two intake estimates (r = 0.76, r = 0.81), unadjusted urinary arsenic showed the strongest relationship with bladder cell micronuclei. These data suggest that, in the case of the bladder, unadjusted urinary arsenic concentrations better reflect the effective target organ dose compared to other exposure measures for biomarker studies.

Urinary arsenic excretion as a biomarker of arsenic exposure in children

Urinary arsenic concentration has been used generally for the determination of exposure, but much concern has been raised over the most appropriate expression for urinary arsenic levels. In this study, we examined the influence of various adjustments of expressing urinary arsenic data. All children who were less than 72 mo of age and who were potty trained were invited to participate in the present study. Urine, soil, and dust samples were collected, and arsenic measurements were made. The geometric mean of speciated urinary arsenic among children who provided first-voided urine samples on 2 consecutive mornings was 8.6 microg/l (geometric standard deviation = 1.7, n = 289). Speciated urinary arsenic was related significantly to soil arsenic in bare areas (p < .0005). Use of a single urine sample versus the average of two first-voided urine samples collected on 2 consecutive mornings did not significantly alter the relationship between environmental arsenic and urinary arsenic levels. Furthermore, none of the adjustments to urinary concentration improved the strength of correlation between urinary arsenic and soil arsenic levels. Concentration adjustments may not be necessary for urinary arsenic levels obtained from young children who provide first-void samples in the morning.

Environmental arsenic exposure of children around a former copper smelter site

Arsenic residues in the communities surrounding former smelters remain a public health concern, especially for infants and children. To evaluate environmental exposure among these children, a population-based cross-sectional study was conducted in the vicinity of a former copper smelter in Anaconda, Montana. A total of 414 children less than 72 months old were recruited. First morning voided urine samples and environmental samples were collected for arsenic measurements. The geometric mean of speciated urinary arsenic was 8.6 microg/liter (GSD = 1.7, N = 289). Average arsenic levels of different types of soil ranged from 121 to 236 microg/g and were significantly related to proximity and wind direction to the smelter site. The same significant relationship was observed for interior dust arsenic. Speciated urinary arsenic was found to be significantly related to soil arsenic in bare areas in residential yards (P < 0.0005). In general, elevated excretion of arsenic was demonstrable and warranted parents' attention to reduce exposure of their children to environmental arsenic.

A unique metabolism of inorganic arsenic in native Andean women

The metabolism of inorganic arsenic (As) in native women in four Andean villages in north-western Argentina with elevated levels of As in the drinking water (2.5, 14, 31, and 200 micrograms/1, respectively) has been investigated. Collected foods contained 9-427 micrograms As/kg wet weight, with the highest concentrations in soup. Total As concentrations in blood were markedly elevated (median 7.6 micrograms/1) only in the village with the highest concentration in the drinking water. Group median concentrations of metabolites of inorganic As (inorganic As, methylarsonic acid (MMA) and dimethylarsinic acid (DMA)) in the urine varied between 14 and 256 micrograms/1. Urinary concentrations of total As were only slightly higher (18-258 micrograms/1), indicating that inorganic As was the main form of As ingested. In contrast to all other populations studied so far, arsenic was excreted in the urine mainly as inorganic As and DMA. There was very little MMA in the urine (overall median 2.2%, range 0.0-11%), which should be compared to 10-20% of the urinary arsenic in all other populations studied. This may indicate the existence of genetic polymorphism in the control of the methyltransferase activity involved in the methylation of As. Furthermore, the percentage of DMA in the urine was significantly higher in the village with 200 micrograms As/1 in the water, indicating an induction of the formation of DMA. Such an effect has not been observed in other studies on human subjects with elevated exposure to arsenic.

Assessment of exposure to inorganic arsenic by determining the arsenic species excreted in urine

Urinary concentrations of inorganic arsenic metabolites (AsIII, AsV, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)) and occupational exposure to arsenic were measured in 24 copper smelter and arsenic trioxide refinery workers during a study period consisting of 2 pairs of work days and the 6 (partly 4) days off between them. The correlations between the time-weighted average (TWA) concentrations of arsenic in air (0.8-45 micrograms/m3) and the concentrations of arsenic species in urine 0, 0-8, 8-16 and 16-20 h after the exposure were calculated. The best correlation (r = 0.78, P = 0.0001) was found for the sum of AsIII and AsV concentration in urine collected between 0 and 8 h after the exposure. The DMA concentrations at any time in urine correlated only poorly to the exposure. A reason for this was obviously an increased urinary excretion of DMA due to the ingestion of DMA in the diet. An 8-h TWA exposure of 10 micrograms As/m3 was calculated to lead to an inorganic arsenic concentration of 5 micrograms/l in urine.

Effect of seafood consumption on the urinary level of total hydride-generating arsenic compounds. Instability of arsenobetaine and arsenocholine

Arsenobetaine and arsenocholine are considered to be non-toxic and are present as a relatively large proportion of total arsenic in seafoods, and they do not respond to hydride generation. The present study describes the effect of seafood consumption on the urinary concentration of hydride-generating arsenic compounds measured by a newly developed flow injection atomic absorption spectrometric (FI-AAS) method. Consumption of plaice, pighvar and tunny resulted in a 2-fold increase, and consumption of mussels produced a 6-fold increase in the urinary level of hydride-generating arsenic compounds. Hence, a person who has consumed mussels may be suspected of being occupationally or environmentally exposed, if the level of consumption of this seafood is unknown. As the FI-AAS method cannot be used to detect arsenobetaine and arsenocholine, the observed increase in urinary concentration of hydride-generating arsenic compounds after consumption of seafood must originate either from hydride-generating arsenic compounds in the seafood or from degraded arsenobetaine or arsenocholine. The present study has demonstrated that both arsenobetaine and arsenocholine are unstable when incubated in daylight in the presence of hydrogen peroxide, i.e., an oxidizing environment. Hence, it is tempting to speculate that arsenobetaine could be converted into hydride-generating arsenic compounds during storage or cooking of seafood. The feasibility of speciation methods based on high-performance liquid chromatographic (HPLC) separation and on-line analysis by inductively coupled plasma atomic emission spectrometry (ICP-AES) and FI-AAS was also investigated. The FI-AAS system is approximately 35 times more sensitive to the hydride-generating arsenic species than the ICP-AES system.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of occupational exposure to inorganic arsenic based on urinary concentrations and speciation of arsenic

An analytical speciation method, capable of separating inorganic arsenic (As (V), As (III] and its methylated metabolites (MMAA, DMAA) from common, inert, dietary organoarsenicals, was applied to the determination of arsenic in urine from a variety of workers occupationally exposed to inorganic arsenic compounds. Mean urinary arsenic (As (V) + As (III) + MMAA + DMAA) concentrations ranged from 4.4 micrograms/g creatinine for controls to less than 10 micrograms/g for those in the electronics industry, 47.9 micrograms/g for timber treatment workers applying arsenical wood preservatives, 79.4 micrograms/g for a group of glassworkers using arsenic trioxide, and 245 micrograms/g for chemical workers engaged in manufacturing and handling inorganic arsenicals. The maximum recorded concentration was 956 micrograms/g. For the most exposed groups, the ranges in the average urinary arsenic speciation pattern were 1-6% As (V), 11-14% As (III), 14-18% MMAA, and 63-70% DMAA. The highly raised urinary arsenic concentrations for the chemical workers, in particular, and some glassworkers are shown to correspond to possible atmospheric concentrations in the workplace and intakes in excess of, or close to, recommended and statutory limits and those associated with inorganic arsenic related diseases.

Airborne arsenic and urinary excretion of metabolites of inorganic arsenic among smelter workers

The relationship between airborne concentrations of arsenic and the urinary excretion of inorganic arsenic metabolites (inorganic arsenic + methylarsonic acid + dimethylarsinic acid) have been studied among smelter workers exposed to arsenic trioxide. The urinary concentrations of arsenic metabolites were found to increase steadily during the first day of the working week (after 2-3 d off from work), whereafter they reached a steady state. The concentration in the late evening after a day of exposure was very similar to that in the early morning after. Both were well correlated to the total daily excretion. In the second part of the study, comprising 18 subjects, the first-void morning urine of each participant was collected for 2 to 3 d during the steady-state phase. Total concentration of arsenic in the breathing zones was measured by personal air samplers. Airborne arsenic (8-h values) varied between 1 and 194 micrograms As/m3, and urinary arsenic between 16 and 328 micrograms As/g creatinine. With the urinary arsenic concentrations (mean values of 2-3 d for each subject) plotted against the corresponding airborne arsenic concentrations, the best fit was obtained by a power curve with the equation y = 17 X X0.56. However, four of the participants were found to excrete far more (105-260%) arsenic in the urine than possibly could have been inhaled, most likely due to oral intake of arsenic via contaminated hands, cigarettes or snuff. If these four were excluded, the best fit was obtained by a straight regression line with the slope 2.0 and the intercept 29 micrograms As/g creatinine (coefficient of correlation 0.92; P less than 0.001).

Metabolism of arsenobetaine in mice, rats and rabbits

The distribution, retention and biotransformation of arsenobetaine, the most common organic arsenic compound in fish and crustacea, have been studied in mice, rats and rabbits by use of synthesized 73As-labelled arsenobetaine. Orally administered arsenobetaine was almost completely absorbed from the gastro-intestinal tract in mice. The urinary excretion for 3 days following intravenous injection was about 75% of the dose in the rabbits and more than 98% in the mice and rats. The rate of excretion in mice was independent of the dose level in the range 4 to 400 mg As/kg body weight. In both animal species the tissue distribution differed widely from that observed following exposure to inorganic arsenic. The clearance of arsenobetaine from plasma and most tissues was fast (somewhat faster in mice than in rabbits) and seemed to follow first-order kinetics. The clearance from cartilage, testes, epididymis, and in the rabbits also the muscles, was slower and consisted of more than one phase. 73As-arsenobetaine was the only labelled arsenic compound detected in urine and soluble extract of tissues, indicating that no biotransformation occurred.