RESUMO
BACKGROUND: Rice grains are consumed by approximately half of the world's population. This cereal has higher arsenic (As) concentrations in grains than wheat or barley. Arsenic determination in food and/or in vitro studies are important for risk assessment; however, it is not enough to assess the real human exposure. METHOD: In vitro bioaccessibility was carried out in husked-rice using gastric and intestinal solutions similar to humans. Also, As naturally found in husked-rice was evaluated by in vivo bioavailability in humans. For this purpose, diets from the 1st and 2nd days were free of foods known to be high in As; 3rd and 4th days the diets were composed by rice and water and; 5th and 6th the diet was similar the 1st and 2nd days. During all experimentation, a representative aliquot of each meal, blood and urine were collected for total As (t-As) determination. Arsenic species were determined in the urine. RESULTS: t-As in husked rice varied from 157.3⯱â¯30.6 to 240.2⯱â¯85.2⯵g kg-1. The in vitrobioaccessible fractions ranged from 91 to 94%. Inorganic As (i-As) ranged from 99.7⯱â¯11.2 to 159.5⯱â¯29.4⯵g kg-1. For the in vivo assay, t-As concentrations in the woman and man blood were about 3⯵g mL-1 from the 1st to 6th day. Arsenic from the rice ingested was excreted by urine about 72â¯h after ingestion. The t-As and dimethyl As (DMA) in urine ranged from 3.59 to 47.17 and 1.02 to 2.55⯵gâ¯g-1 creatinine for the volunteers, indicating a two-fold DMA-increase in urine after ingestion of husked-rice. CONCLUSION: After rice ingestion, As was quickly metabolized. The higher As concentrations were found in urine 72â¯h after rice ingestion. The main As-specie found in urine was DMA, indicating that methylation of As from rice followed by urine excretion is the main biological pathway for As excretion.
Assuntos
Arsênio/análise , Bioensaio/métodos , Grão Comestível/química , Oryza/química , Adulto , Arsênio/sangue , Arsênio/urina , Arsenicais/sangue , Arsenicais/urina , Disponibilidade Biológica , Comportamento Alimentar , Feminino , Alimentos , Humanos , MasculinoRESUMO
Exposure to inorganic arsenic (iAs) remains a global public health problem. Urinary arsenicals are the current gold-standard for estimating both iAs exposure and iAs metabolism. However, the distribution of these arsenicals may differ between the urine and target organs. Instead, plasma arsenicals may better represent internal dose and capture target organ exposure to arsenicals. Drinking water iAs, plasma and urinary arsenicals were quantified in individuals living in the Zimapan and Lagunera regions of Mexico. The relationship between drinking water iAs and plasma arsenicals was examined using both Spearman correlations and multivariable linear regression models. In addition, the distribution of arsenicals in plasma and urine was examined and the association between plasma and urinary arsenicals was assessed using both Spearman correlations and multivariable linear regression models. Levels of iAs in drinking water were significantly associated with plasma arsenicals in unadjusted and adjusted analyses and the strength of these associations was similar to that of drinking water iAs and urinary arsenicals. These results suggest that plasma arsenicals are reliable biomarkers of iAs exposure via drinking water. However, there were notable differences between the profiles of arsenicals in the plasma and the urine. Key differences between the proportions of arsenicals in plasma and urine may indicate that urine and plasma arsenicals reflect different aspects of iAs toxicokinetics, including metabolism and excretion.
Assuntos
Arsenicais/sangue , Exposição Ambiental/análise , Intoxicação por Arsênico , Biomarcadores/metabolismo , Água Potável/análise , Feminino , Humanos , Modelos Lineares , Masculino , México , ToxicocinéticaRESUMO
Capillary electrophoresis coupled to inductively coupled plasma mass spectrometry was used in a speciation study on disodium monomethylarsonate (DS-MMA(V)) and its metabolites in horses, to which the drug was administered by intramuscular injection on five consecutive days at a single arsenic dosage of 270 mg day(-1). Samples of urine, whole blood, plasma, and mane hair were analyzed before, during, and after drug administration. The data show that blood clearing and urinary excretion of MMA is a fast process following first-order kinetics with biological half-lives of about 38 h and 44 h for urine and plasma, respectively. In the time period of 9 days studied, the only metabolite detected in urine was dimethylarsinic acid (DMA(V)), which 4 days after the last drug administration accounted for up to 75% of the total excreted arsenic species. This shows, for the first time, that biomethylation of MMA(V) to DMA(V) is the principal metabolic pathway of this drug in horses. Although DS-MMA(V) was administered only during a short 5-day period, an up to six fold increase of arsenic could be measured in the newly grown mane hair.
Assuntos
Arsenicais/sangue , Arsenicais/urina , Animais , Arsênio/administração & dosagem , Arsênio/análise , Arsenicais/metabolismo , Ácido Cacodílico/metabolismo , Ácido Cacodílico/urina , Eletroforese Capilar , Cabelo/química , Cavalos , Injeções Intramusculares , Espectrometria de Massas/métodos , Metilação , Sensibilidade e Especificidade , Fatores de TempoRESUMO
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.