Arsenic bioaccessibility in cooked rice as affected by arsenic in cooking water.

UNLABELLED: Rice can easily accumulate arsenic (As) into its grain and is known to be the highest As-containing cereal. In addition, the As burden in rice may increase during its processing (such as when cooking using As-polluted water). The health risk posed by the presence of As in cooked rice depends on its release from the matrix along the digestive system (bioaccessibility). Two types of white polished long-grain rice, namely, nonparboiled and parboiled (total As: 202 and 190 µg As kg(-1), respectively), were cooked in excess of water with different levels of As (0, 10, 47, 222, and 450 µg As L(-1)). The bioaccessibility of As from these cooked rice batches was evaluated with an in vitro dynamic digestion process. Rice cooked with water containing 0 and 10 µg As L(-1) showed lower As concentrations than the raw (uncooked) rice. However, cooking water with relatively high As content (≥ 47 µg As L(-1)) significantly increased the As concentration in the cooked rice up to 8- and 9-fold for the nonparboiled and parboiled rice, respectively. Parboiled rice, which is most widely consumed in South Asia, showed a higher percentage of As bioaccessibility (59% to 99%) than nonparboiled rice (36% to 69%) and most of the As bioaccessible in the cooked rice (80% to 99%) was released easily during the first 2 h of digestion. The estimation of the As intake through cooked rice based on the As bioaccessibility highlights that a few grams of cooked rice (less than 25 g dry weight per day) cooked with highly As contaminated water is equivalent to the amount of As from 2 L water containing the maximum permissible limit (10 µg As L(-1)). PRACTICAL APPLICATION: Studies on As bioaccessibility are needed for determining human As intake from rice for use in accurate risk assessments to establish updated legislation regarding maximum level of As in food. High As bioaccessibility from parboiled rice (consumed by the majority of the people in South Asia), and the findings of high As levels in discarded rice gruel (fed to livestock), has implications for human and animal health.

Betel quid chewing elevates human exposure to arsenic, cadmium and lead.

Several studies have reported increased skin lesions in betel quid (a mixture of Piper betel leaves, areca nut, tobacco/flavoured tobacco, lime) chewers compared to non-chewers, exposed to arsenic (As) contaminated drinking water in Bangladesh and India. The current study has determined As, cadmium (Cd) and lead (Pb) levels of betel quids and its components using inductively coupled plasma mass spectrometry (ICP-MS). The highest concentrations of As were found in slaked lime (4.56 mg kg(-1)) followed by Piper betel leaves (0.406 mg kg(-1)) and flavoured tobacco (zarda) (0.285 mg kg(-1)), with a mean concentrations of As in betel quids of 0.035 mg kg(-1) (SD 0.02 mg kg(-1)). Mean concentrations of Cd and Pb in ordinary quids were 0.028 (SD 0.07 mg kg(-1)) and 0.423 (SD 1.4 mg kg(-1)), respectively. We estimated that a daily intake of 6 betel quids could contribute 1.2, 1.9 and 8.5% of the provisional maximum tolerable daily intake (PMDTI) for As, Cd and Pb, respectively. Since betel quid chewing is most prevalent among women, our finding raises concern that women chewers - especially pregnant chewers - may be harming their health and that of their unborn babies through increased exposure to a mixture of toxic elements (As, Cd and Pb).

Betel quid chewing as a source of manganese exposure: total daily intake of manganese in a Bangladeshi population.

BACKGROUND: A relationship between betel quid chewing in Bangladeshi populations and the development of skin lesions and tremor has been previously reported, for people exposed to high levels of arsenic (As) through drinking contaminated groundwater. Exposure to manganese (Mn) is also known to induce neurotoxicity and levels of Mn in Bangladeshi groundwater are also high. The present study evaluates betel quid chewing as an overlooked source of Mn exposure in a Bangladeshi population. METHODS: Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine (1) urinary Mn levels for 15 chewers and 22 non-chewers from the ethnic Bangladeshi community in the United Kingdom, and (2) Mn levels in betel quids, its individual components and other Bangladeshi foods. RESULTS: Betel quid chewers displayed a significantly higher (P = 0.009) mean Mn concentration in urine (1.93 µg L(-1)) compared to non-chewers (0.62 µg L(-1)). High levels of Mn were detected in Piper betel leaves with an overall average of 135 mg kg(-1) (range 26 -518 mg kg(-1)). The mean concentration of Mn in betel quid was 41 mg kg(-1) (SD 27) and the daily intake of Mn in the Bangladeshi population was estimated to be 20.3 mg/day. Chewing six betel quids could contribute up to 18% of the maximum recommended daily intake of Mn. CONCLUSION: We have demonstrated that Mn in betel quids is an overlooked source of exposure to Mn in humans. Chewers display a 3.1 fold increased urinary Mn concentration compared to non-chewers. The practice of betel quid chewing contributes a high proportion of the maximum recommended daily intake of Mn, which could make chewers in Bangladesh more vulnerable to Mn neurotoxicity.

Risk of human exposure to arsenic and other toxic elements from geophagy: trace element analysis of baked clay using inductively coupled plasma mass spectrometry.

BACKGROUND: Geophagy or earth-eating is common amongst some Bangladeshi women, especially those who are pregnant, both in Bangladesh and in the United Kingdom. A large proportion of the population in Bangladesh is already exposed to high concentrations of arsenic (As) and other toxic elements from drinking contaminated groundwater. Additional exposure to As and other toxic elements from non-food sources has not been adequately addressed and here we present the first study to monitor As levels in baked clay (known as sikor). METHODS: Sikor samples originating from Bangladesh were digested using a microwave digester and analysed for their As, Pb, Cd, Mn, Fe and Zn levels using ICP-MS. Detailed As speciation analysis was performed using HPLC-ICP-MS. RESULTS: Of particular concern were the levels of As (3.8-13.1 mg kg(-1)), Cd (0.09-0.4 mg kg(-1)) and Pb (21-26.7 mg kg(-1)) present in the sikor samples and their possible impact on human health. Speciation analysis revealed that sikor samples contained mainly inorganic As. Modest consumption of 50 g of sikor is equivalent to ingesting 370 µg of As and 1235 µg of Pb per day, based on median concentration values. This level of sikor consumption exceeds the permitted maximum tolerable daily intake (PMTDI) of inorganic As by almost 2-fold. CONCLUSION: We conclude that sikor can be a significant source of As, Cd and Pb exposure for the Bangladeshi population consuming large quantities of this material. Of particular concern in this regard is geophagy practiced by pregnant women concurrently exposed to As contaminated drinking water. Future studies needs to evaluate the bioavailability of As and other elements from sikor and their impact on human health.

Biosorption of mercury from aqueous solutions by powdered leaves of castor tree (Ricinus communis L.).

A new biosorbent produced from castor leaves powder [Ricinus communis L.] was used to remove mercury(II) from aqueous solutions. The initial mercury concentrations, contact time and initial pH were evaluated. The ability of castor leaves to remove mercury at various pH (2-8) was studied. The maximum capacity (Qmax) of biomass was found to be 37.2mg Hg(II)/g at pH 5.5. Biosorption equilibrium was established in approximately 1h. The equilibrium data were described well by Langmuir and Freundlich models. The adsorbed mercury on biomass was desorbed using 10 ml of 4M HCl solution. The biomass could be reused for other biosorption assays. The ability of biomass to adsorb mercury(II) in a column was investigated. These studies consider the possibility of using leaves of castor tree as an inexpensive adsorbent for the removal of Hg(II) from contaminated chemical and mining industry wastewaters. It is also suggested that the dried biomass might be simply kept and used in a very low cost metal ion removal system.

A biomaterial based approach for arsenic removal from water.

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