Daily intake of inorganic arsenic and some organic arsenic species of Japanese subjects

Spatiotemporal variation and toxicity of trace metals in commercially important fish of the tidal Pasur River in Bangladesh

The release of toxic metals in the water creates an adverse condition for the living organisms (e.g., fish). The aim of this research was to learn more about the spatiotemporal variations and toxicity of heavy metals (As, Cr, Cd, and Pb) among fish species that are economically important (Tenualosa ilisha, Gudusia chapra, Otolithoides pama, Setipinna phasa, Mystus vittatus, Glossogobius giuris, Harpadon nehereus, Pseudapocryptes elongatus, Polynemus paradiseus, and Sillaginopsis panijus) collected from Pasur River. Heavy metal (HMs) concentrations were evaluated using the atomic absorption spectrometry (AAS) technique. Most of the metals showed no significant variation spatiotemporally (p ˃ 0.05) except As and Cr showed substantial variation in terms of seasons (p ˂ 0.05). All fish species' Cr and Pb concentrations, as well as As and Cd values, were estimated to be greater than FAO/WHO tolerable concentrations, implying that these metals pose danger to humans. HM has a total hazard quotient (THQ) value in individual fish species reported to be greater than 1, whereas an individual metal, arsenic, exceeds the standard value (THQ > 1), causing a significant noncarcinogenic issue in the study region. The target hazard (TR) value for As and Pb exceeds the USEPA norm (10^-4) suggesting that long-term consumption of fish poses a chronic cancer risk to the people in the study field. According to the findings, the fish in the Pasur River are unfit for human consumption. The correlation matrix (CM) indicates that sources of metals are similar (e.g., industries, ships, agricultural inputs, etc.).

Arsenic compounds: The wide application and mechanisms applied in acute promyelocytic leukemia and carcinogenic toxicology

Arsenic (As), as well as its various compounds have been widely used for nearly 4000 years either as drugs or poisons. These compounds are valuable in the treatment of various diseases ranging from dermatosis to cancer, thereby emphasizing their important roles as therapeutic agents. The ability of As compounds, especially arsenic trioxide (ATO) in the treatment of acute promyelocytic leukemia (APL), has fundamentally altered people's understanding of the poison, and has become a major factor in the re-emergence of Western medicine candidates to treat leukemia and other solid tumors. However, long-term exposure to As has been correlated with numerous disadvantageous influences on health, particularly carcinogenesis. Importantly, accumulating evidence suggests that biotransformation of As, as a step to eliminate As from the human body, can induce alterations at the genetic and epigenetic levels, resulting in therapeutic effects or carcinogenesis. In this article, we aimed to provide a systematic overview of the primary contributions associated with As and its compounds, as well as the detailed mechanisms applied in APL cells and carcinogenic toxicology. This review may help to understand the underlying mechanisms and safe wide clinical applications of medicinal As along with its compounds.

Dietary intake and urinary excretion of methylated arsenicals of Japanese adults consuming marine foods and rice

Dietary intake and urinary excretion of monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine (AsB) were measured in 150 adult Japanese subjects. Duplicate diet (DD) samples and first void of urine on the next morning of DD sampling day were collected and analysed for arsenic species with liquid chromatography-ICP mass spectrometry. Median (min-max) intakes of MMA, DMA and AsB were <2.3 (<2.3-<2.3), 4.57 (<2.3-24.3), and 13.6 (<2.4-231) μg As/day, respectively, and median urinary concentrations were 1.90 (<0.37-26.), 21.9 (<0.27-141) and 19.6 (<0.37-1063) ng As/mg creatinine, respectively. Interrelationships between intake levels and urinary concentrations were mostly significant with positive coefficients indicating mutual association due to co-exposure, metabolism and/or dietary habit. Urinary concentrations and intake levels of AsB were also positively correlated confirming the applicability of urine analysis as biomarker of exposure. The present descriptive results provide with essential piece of information in assessing health risk of methylated arsenicals for population who consume marine products and rice.

Attempt of Bayesian Estimation from Left-censored Data Using the Markov Chain Monte Carlo Method: Exploring Cr(VI) Concentrations in Mineral Water Products

Hexavalent chromium (Cr(VI)) is toxic, carcinogenic, and mutagenic substances. Oral exposure to Cr(VI) is thought to be primarily from drinking water. However, under the certain reporting limit (~0.1 µg/L), percentage of Cr(VI) concentration in mineral water products under the reporting limit were estimated higher than 50%. Data whose values are below certain limits and thus cannot be accurately determined are known as left-censored. The high censored percentage leads to estimation of Cr(VI) exposure uncertain. It is well known that conventional substitution method often used in food analytical science cause severe bias. To estimate appropriate summary statistics on Cr(VI) concentration in mineral water products, parameter estimation using the Markov chain Monte Carlo (MCMC) method under assumption of a lognormal distribution was performed. Stan, a probabilistic programming language, was used for MCMC. We evaluated the accuracy, coverage probability, and reliability of estimates with MCMC by comparison with other estimation methods (discard nondetects, substituting half of reporting limit, Kaplan-Meier, regression on order statistics, and maximum likelihood estimation) using 1000 randomly generated data subsets (n = 150) with the obtained parameters. The evaluation shows that MCMC is the best estimation method in this context with greater accuracy, coverage probability, and reliability over a censored percentage of 10-90%. The mean concentration, which was estimated with MCMC, was 0.289×10-3 mg/L and this value was sufficiently lower than the regulated value of 0.05 mg/L stipulated by the Food Sanitation Act.

Risk of exposure to total and inorganic arsenic by meat intake among different age groups from Brazil: a probabilistic assessment

Beef and poultry as well as cattle and chicken livers are staple food items for Brazilian population, and previous studies had detected arsenic levels in these foods. This study aims to evaluate the risk of exposure to total and inorganic arsenic by meat intake in three age groups from Brazil (11-16, 16-21, and > 21 years). Our hypotheses are (i) that there is differences in the risk of exposure between age groups and (ii) the older individuals (> 21 years) are under higher risk. To test these hypotheses, we calculated the probabilistic estimated daily intake of total As (TAs^EDI) from poultry, beef, cattle liver, and chicken liver, and the probabilistic estimated incremental lifetime skin, bladder, and lung cancer risk (ILCR) associated with inorganic As ingestion from poultry only. TAs^EDI and ILCR from poultry differed among groups which confirm the first hypothesis. However, TAs^EDI and ILCR results cannot support the second hypothesis. Even though the age groups are under a low risk of exposure to As by meat intake, the results indicate that bladder/lung cancer risk (from poultry intake) slightly exceeds the safe limits in the older population.

Variability and reliability of POP concentrations in multiple breast milk samples collected from the same mothers

Risk assessment of infant using a realistic persistent organic pollutant (POP) exposure through breast milk is essential to devise future regulation of POPs. However, recent investigations have demonstrated that POP levels in breast milk collected from the same mother showed a wide range of variation daily and monthly. To estimate the appropriate sample size of breast milk from the same mother to obtain reliable POP concentrations, breast milk samples were collected from five mothers living in Japan from 2006 to 2012. Milk samples from each mother were collected 3 to 6 times a day through 3 to 7 days consecutively. Food samples as the duplicated method were collected from two mothers during the period of breast milk sample collection. Those were employed for POP (PCBs, DDTs, chlordanes, and HCB) analysis. PCB concentrations detected in breast milk samples showed a wide range of variation which was maximum 63 and 60% of relative standard deviation (RSD) in lipid and wet weight basis, respectively. The time course trend of those variations among the mothers did not show any typical pattern. A larger amount of PCB intake through food seemed to affect 10 h after those concentrations in breast milk in lipid weight basis. Intraclass correlation coefficient (ICC) analyses indicated that the appropriate sample size for good reproducibility of POP concentrations in breast milk required at least two samples for lipid and wet weight basis.

Human exposure to dietary inorganic arsenic and other arsenic species: State of knowledge, gaps and uncertainties

Inorganic arsenic (iAs) is ubiquitous in the environment as arsenite (AsIII) and arsenate (AsV) compounds and biotransformation of these toxic chemicals leads to the extraordinary variety of organoarsenic species found in nature. Despite classification as a human carcinogen based on data from populations exposed through contaminated drinking water, only recently has a need for regulatory limits on iAs in food been recognized. The delay was due to the difficulty in risk assessment of dietary iAs, which critically relies on speciation analysis providing occurrence data for iAs in food - and not simply for total arsenic. In the present review the state of knowledge regarding arsenic speciation in food and diet is evaluated with focus on iAs and human exposure assessment through different dietary approaches including duplicate diet studies, market basket surveys, and total diet studies. The analytical requirements for obtaining reliable data for iAs in food are discussed and iAs levels in foods and beverages are summarized, along with information on other (potentially) toxic co-occurring organoarsenic compounds. Quantitative exposure assessment of iAs in food is addressed, focusing on the need of capturing variability and extent of exposure and identifying what dietary items drive very high exposure for certain population groups. Finally, gaps and uncertainties are discussed, including effect of processing and cooking, and iAs bioavailability.

Evaluation of Risk Perception and Risk-Comparison Information Regarding Dietary Radionuclides after the 2011 Fukushima Nuclear Power Plant Accident

In the wake of the 2011 Fukushima Daiichi Nuclear Power Station accident, to facilitate evidence-based risk communication we need to understand radiation risk perception and the effectiveness of risk-comparison information. We measured and characterized perceptions of dread risks and unknown risks regarding dietary radionuclides in residents of Fukushima, Tokyo, and Osaka to identify the primary factors among location, evacuation experience, gender, age, employment status, absence/presence of spouse, children and grandchildren, educational background, humanities/science courses, smoking habits, and various types of trustworthy information sources. We then evaluated the effects of these factors and risk-comparison information on multiple outcomes, including subjective and objective understanding, perceived magnitude of risk, perceived accuracy of information, backlash against information, and risk acceptance. We also assessed how risk-comparison information affected these multiple outcomes for people with high risk perception. Online questionnaires were completed by people (n = 9249) aged from 20 to 69 years in the three prefectures approximately 5 years after the accident. We gave each participant one of 15 combinations of numerical risk data and risk-comparison information, including information on standards, smoking-associated risk, and cancer risk, in accordance with Covello’s guidelines. Dread-risk perception among Fukushima residents with no experience of evacuation was much lower than that in Osaka residents, whereas evacuees had strikingly higher dread-risk perception, irrespective of whether their evacuation had been compulsory or voluntary. We identified location (distance from the nuclear power station), evacuation experience, and trust of central government as primary factors. Location (including evacuation experience) and trust of central government were significantly associated with the multiple outcomes above. Only information on “cancer risk from radiation and smoking risk” enhanced both subjective and objective understanding without diminishing trust in all participants and in the high dread-risk perception group; use of other risk-comparison information could lead the public to overestimate risk.

A comprehensive assessment of arsenic in commonly consumed foodstuffs to evaluate the potential health risk in Bangladesh

Arsenic (As), particularly of its inorganic form (iAs) is highly toxic, and its presence in food composites is a matter of concern for the public health safety, specifically in Bangladesh which is regarded as the most arsenic affected country throughout the world. This study was carried out to investigate the levels of As in the composite samples of commonly consumed foodstuffs collected from 30 different agro-ecological zones for the first time in Bangladesh. Most of the individual food composites contain a considerable amount of As which was, as a whole, in the range of 0.077-1.5mg/kg fw which was lower than those reported from Spain, EU, France, Korea, whereas higher than those of Mexico, Chile, Japan, Cambodia, Hong Kong, Serbia, respectively. Cereals, vegetables, milk, and fish contribute about 90% to the daily intake of inorganic arsenic. Human health risk of dietary iAs was assessed separately for both the rural and urban adults. The estimated daily dietary intakes (EDI) of iAs for the exposed rural (3.5) and urban residents (3.2 μg/kg-BW/day) clearly exceeded the previous provisional tolerable daily intake (PTDI) value of 2.1 μg/kg-BW/day, recommended by the World Health Organization (WHO). From the health point of view, this study concluded that both the rural and urban residents of Bangladesh are exposed to carcinogenic and non-carcinogenic risks who consume As-contaminated water and foodstuffs.

Urinary inorganic arsenic concentrations and semen quality of male partners of subfertile couples in Tokyo

Inorganic arsenic (iAs) has been known as a testicular toxicant in experimental rodents. Possible association between iAs exposure and semen quality (semen volume, sperm concentration, and sperm motility) was explored in male partners of couples (n = 42) who visited a gynecology clinic in Tokyo for infertility consultation. Semen parameters were measured according to WHO guideline at the clinic, and urinary iAs and methylarsonic acid (MMA), and dimethylarsinic acid concentrations were determined by liquid chromatography-hydride generation-ICP mass spectrometry. Biological attributes, dietary habits, and exposure levels to other chemicals with known effects on semen parameters were taken into consideration as covariates. Multiple regression analyses and logistic regression analyses did not find iAs exposure as significant contributor to semen parameters. Lower exposure level of subjects (estimated to be 0.5 μg kg(-1) day(-1)) was considered a reason of the absence of adverse effects on semen parameters, which were seen in rodents dosed with 4-7.5 mg kg(-1).

Direct analysis of ultra-trace semiconductor gas by inductively coupled plasma mass spectrometry coupled with gas to particle conversion-gas exchange technique

An inductively coupled plasma mass spectrometry (ICPMS) coupled with gas to particle conversion-gas exchange technique was applied to the direct analysis of ultra-trace semiconductor gas in ambient air. The ultra-trace semiconductor gases such as arsine (AsH3) and phosphine (PH3) were converted to particles by reaction with ozone (O3) and ammonia (NH3) gases within a gas to particle conversion device (GPD). The converted particles were directly introduced and measured by ICPMS through a gas exchange device (GED), which could penetrate the particles as well as exchange to Ar from either non-reacted gases such as an air or remaining gases of O3 and NH3. The particle size distribution of converted particles was measured by scanning mobility particle sizer (SMPS) and the results supported the elucidation of particle agglomeration between the particle converted from semiconductor gas and the particle of ammonium nitrate (NH4NO3) which was produced as major particle in GPD. Stable time-resolved signals from AsH3 and PH3 in air were obtained by GPD-GED-ICPMS with continuous gas introduction; however, the slightly larger fluctuation, which could be due to the ionization fluctuation of particles in ICP, was observed compared to that of metal carbonyl gas in Ar introduced directly into ICPMS. The linear regression lines were obtained and the limits of detection (LODs) of 1.5 pL L(-1) and 2.4 nL L(-1) for AsH3 and PH3, respectively, were estimated. Since these LODs revealed sufficiently lower values than the measurement concentrations required from semiconductor industry such as 0.5 nL L(-1) and 30 nL L(-1) for AsH3 and PH3, respectively, the GPD-GED-ICPMS could be useful for direct and high sensitive analysis of ultra-trace semiconductor gas in air.

Estimation of arsenic intake from drinking water and food (raw and cooked) in a rural village of northern Chile. Urine as a biomarker of recent exposure

The aim of this study was to estimate both the contribution of drinking water and food (raw and cooked) to the total (t-As) and inorganic (i-As) arsenic intake and the exposure of inhabitants of Socaire, a rural village in Chile´s Antofagasta Region, by using urine as biomarker. The i-As intake from food and water was estimated using samples collected between November 2008 and September 2009. A 24-hour dietary recall questionnaire was given to 20 participants. Drinking water, food (raw and cooked) and urine samples were collected directly from the homes where the interviewees lived. The percentage of i-As/t-As in the drinking water that contributed to the total intake was variable (26.8-92.9). Cereals and vegetables are the food groups that contain higher concentrations of i-As. All of the participants interviewed exceeded the reference intake FAO/OMS (149.8 µg∙i-As·day⁻¹) by approximately nine times. The concentration of t-As in urine in each individual ranged from 78 to 459 ng·mL⁻¹. Estimated As intake from drinking water and food was not associated with total urinary As concentration. The results show that both drinking water and food substantially contribute to i-As intake and an increased exposure risk to adult residents in contaminated areas.

Human health risk assessment of multiple contaminants due to consumption of animal-based foods available in the markets of Shanghai, China

To assess the health risks due to food consumption, the human daily intake and uptake of organochlorine pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, polycyclic aromatic hydrocarbons, and toxic trace elements (mercury, chromium, cadmium, lead, and arsenic) were estimated based on the animal-based foods collected from markets in Shanghai, China. The estimated daily intake and uptake considering the contaminant bioaccessibility via single food consumption were 9.4-399 and 4.2-282 ng/kg body weight/day for adults, and 10.8-458 and 4.8-323 ng/kg body weight/day for children, respectively. These values were 0.2-104 and 0.05-58.1, and 0.2-119 and 0.06-66.6 ng/kg body weight/day via multiple food consumption for adults and children, respectively. According to the United States Environmental Protection Agency risk assessment method, the non-cancer and cancer health risks posed by the contaminants were estimated using the hazard quotient and the lifetime cancer risk method, respectively. The results showed that the combined hazard quotient values for multiple contaminants via single or multiple food consumption were below 1, suggesting that the residents in Shanghai would not experience a significant non-cancer health risk. Among the contaminants investigated, the potential non-cancer risk of methylmercury was highest. However, the combined cancer risk posed by multiple contaminants in most foods exceeded the accepted risk level of 10(-6), and inorganic arsenic was the main contributor. The risks caused by polybrominated diphenyl ethers for cancer and non-cancer effects were negligible. The cancer risk of inorganic arsenic is a matter of concern in animal-based foods from Shanghai markets.

Human health risks derived from dietary exposure to toxic metals in Catalonia, Spain: temporal trend

The present study was aimed at estimating the current (2012) dietary intake of arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) by the population of Catalonia, Spain. The temporal trends with respect to previous surveys, performed in 2000, 2005, and 2008, were also determined. For that purpose, metal concentrations were analyzed in a number of widely consumed foodstuffs. A speciation study was also conducted by experimentally determining the levels of inorganic As (InAs) and methylmercury (MeHg) in the same food items. Furthermore, the dietary intake of those metals and species was calculated both deterministically and probabilistically by considering two food consumption surveys: ENCAT and ENIDE, representative of the Catalan and Spanish populations, respectively. An important temporal decrease of the dietary intake was noted for most elements, irrespective of the age-gender population group. Considering data for a male adult, the current dietary intake of As, InAs, Cd, Hg, MeHg, and Pb was estimated in 216, 2.6, 8.7, 10, 7.3, and 8.4 μg/day, respectively, being these values lower than the respective provisional tolerable weekly intakes (PTWIs) or benchmark dose lower confidence limits (BMDLs). Moreover, new calculations by means of ENIDE survey indicated similar results to those previously obtained by ENCAT, with the exception of MeHg, whose intake exceeded the maximum recommended values for some part of the population. Although our data are similar to those frequently found in other European countries, the important intake of MeHg, which is linked to the high consumption of fish and shellfish, deserves further investigation.

Estimated dietary intake of radionuclides and health risks for the citizens of Fukushima City, Tokyo, and Osaka after the 2011 nuclear accident

The radionuclides released from the Fukushima Daiichi nuclear power plant in 2011 pose a health risk. In this study, we estimated the 1st-year average doses resulting from the intake of iodine 131 (¹³¹I) and cesium 134 and 137 (¹³⁴Cs and ¹³⁷Cs) in drinking water and food ingested by citizens of Fukushima City (∼50 km from the nuclear power plant; outside the evacuation zone), Tokyo (∼230 km), and Osaka (∼580 km) after the accident. For citizens in Fukushima City, we considered two scenarios: Case 1, citizens consumed vegetables bought from markets; Case 2, citizens consumed vegetables grown locally (conservative scenario). The estimated effective doses of ¹³⁴Cs and ¹³⁷Cs agreed well with those estimated through market basket and food-duplicate surveys. The average thyroid equivalent doses due to ingestion of ¹³¹I for adults were 840 µSv (Case 1) and 2700 µSv (Case 2) in Fukushima City, 370 µSv in Tokyo, and 16 µSv in Osaka. The average effective doses due to ¹³⁴Cs and ¹³⁷Cs were 19, 120, 6.1, and 1.9 µSv, respectively. The doses estimated in this study were much lower than values reported by the World Health Organization and the United Nations Scientific Committee on the Effects of Atomic Radiation, whose assessments lacked validation and full consideration of regional trade in foods, highlighting the importance of including regional trade. The 95th percentile effective doses were 2–3 times the average values. Lifetime attributable risks (LARs) of thyroid cancers due to ingestion were 2.3–39×10⁻⁶ (Case 1) and 10–98×10⁻⁶ (Case 2) in Fukushima City, 0.95–14×10⁻⁶ in Tokyo, and 0.11–1.3×10⁻⁶ in Osaka. The contributions of LARs of thyroid cancers due to ingestion were 7.5%–12% of all exposure (Case 1) and 12%–30% (Case 2) in Fukushima City.

Pharmacokinetic properties of arsenic species after oral administration of Sargassum pallidum extract in rats using an HPLC-HG-AFS method

Sargassum pallidum is one of the Traditional Chinese Medicine widely used for phlegm elimination and detumescence. Arsenic is present in high concentration in seaweed belonging to the genus Sargassum. Therefore, the consumption of S. pallidum is a route of exposure to arsenic. Since the toxicity of arsenic is highly dependent on its chemical speciation, the determination of total arsenic is not adequate to assess the risks. Here, a high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) was developed for determination of the common arsenic species including arsenite [As(III)], dimethylarsinate (DMA), methylarsonate (MMA) and arsenate [As(V)] simultaneously. This method was applied to study the pharmacokinetic profile of these arsenic species in rats after oral administration of S. pallidum extract at different doses. The described assay was validated for limit of quantification, linearity, intra-day and inter-day precisions, accuracy, extraction recovery and stability according to the FDA validation guidelines. As(III) or MMA was not detected in any samples collected at all time points using the present HPLC-HG-AFS method. As(V) and DMA in the S. pallidum could be readily absorbed and eliminated in rats. A trend of dose-dependence was shown for DMA and As(V) in the drug concentration-time profiles. This study would be helpful for the apprehension of the action mechanism and clinical application of medicinal seaweeds.

Nephroprotective effect of astaxanthin against trivalent inorganic arsenic-induced renal injury in wistar rats

Inorganic arsenic (iAs) is a toxic metalloid found ubiquitously in the environment. In humans, exposure to iAs can result in toxicity and cause toxicological manifestations. Arsenic trioxide (As₂O₃) has been used in the treatment for acute promyelocytic leukemia. The kidney is the critical target organ of trivalent inorganic As (iAs^III) toxicity. We examine if oral administration of astaxanthin (AST) has protective effects on nephrotoxicity and oxidative stress induced by As₂O₃ exposure (via intraperitoneal injection) in rats. Markers of renal function, histopathological changes, Na⁺-K⁺ ATPase, sulfydryl, oxidative stress, and As accumulation in kidneys were evaluated as indicators of As₂O₃ exposure. AST showed a significant protective effect against As₂O₃-induced nephrotoxicity. These results suggest that the mechanisms of action, by which AST reduces nephrotoxicity, may include antioxidant protection against oxidative injury and reduction of As accumulation. These findings might be of therapeutic benefit in humans or animals suffering from exposure to iAs^III from natural sources or cancer therapy.

Inorganic arsenic in the Japanese diet: daily intake and source

The concentrations of arsenic (As) species in 19 food composites prepared from 159 food items purchased in Shizuoka city, Japan, were determined (1) to estimate total daily intake of inorganic As (InAs) and some organic As species and (2) to determine food contributing to total daily InAs intake. As analysis included extraction of As species with a synthetic gastric juice (0.07 mol/L HCl + 0.01 % pepsin) from food composite and high-performance liquid chromatography-high efficiency photo-oxidation-hydride generation-inductively coupled plasma mass spectrometry. InAs was detected in 9 of 19 food composites at a concentration of 0.423-450 ng As/g fresh-weight. Daily intake of InAs from cereals was greatest (13 μg/person/day) followed by algae (5.7 μg/person/day), and the intake from the two categories constituted 90 % of the total daily InAs intake of adults (21 μg/person/day on a bioaccessible-fraction basis and 24 μg/person/day on a content basis). Analysis of individual food items showed that rice and hijiki contributed virtually 100 % of InAs from cereals and algae, respectively. The present survey indicated that InAs from rice and hijiki consumption contributed to total daily InAs intake and consequently to significant cancer risk of the general Japanese population. Daily intake of some organic forms of As and their contributing food categories was also estimated.

[Daily inorganic arsenic intake of the Japanese estimated by a probabilistic approach]

OBJECTIVE

The objective was to estimate the inorganic arsenic (iAs) intake of the general Japanese adult population by a probabilistic approach.

METHODS

Bioaccessible iAs concentrations in rice (n=56) and hijiki (n=32), the two food items that are the major iAs sources for the Japanese, were measured by liquid chromatography-ICP mass spectrometry. The concentration in cooked rice was estimated from the measured concentration in a raw rice sample while taking into consideration the loss of iAs during cooking. The iAs concentration in hijiki was measured using soaked hijiki samples. The daily consumption of cooked rice and soaked hijiki was taken from published data. The distribution profile of daily iAs intake was estimated by multiplying the bioaccesible iAs concentration in cooked rice and soaked hijiki samples by the amount of these samples consumed daily, which were randomly extracted according to the respective distributions. This process was repeated 10,000 times.

RESULTS

The distribution profiles of iAs concentration in rice and hijiki were normal and log-normal, respectively, and those of the amount of cooked rice and soaked hijiki consumed were beta and log-normal, respectively. The daily bioaccessible iAs intake values were estimated to be 19 and 59 μg/day at 50 and 95 percentile. At 50 percentile iAs intake, the contributions from rice and hijiki were estimated to be equal, whereas the contribution from hijiki increased with the estimated total daily iAs intake.

CONCLUSIONS

The iAs intakes of Japanese subjects estimated in previous duplicated portion studies were fairly consistent with the present estimation. Moreover, it was confirmed that the cancer risk derived from dietary iAs intake of the general Japanese population was not negligible.