Shaban W. Al-Rmalli

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

BackgroundGeophagy 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).MethodsSikor 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.ResultsOf 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.ConclusionWe 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.

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).

Dietary Intake of Cadmium from Bangladeshi Foods

UNLABELLED Human exposure to cadmium (Cd) is associated with various diseases and high levels of Cd have been detected in Bangladeshi population warranting further research to identify the source of this exposure. In this study, Cd levels in 327 and 94 samples of Bangladeshi food and non-food samples, respectively, were determined using inductively coupled plasma mass spectrometry. This is the largest number of Bangladeshi food and nonfood samples investigated for their Cd content. High Cd levels were detected in leafy vegetables (mean 31 [SD 29]μg/kg). Of these vegetables, lal shak (Amaranthus tricolor) contained the highest Cd level (303 μg/kg [wet weight]; mean 100.5 [SD 95]μg/kg). Bangladeshi rice also showed significant concentration of Cd (mean 37.2 [SD 30]μg/kg). Of particular concern is the very high level of Cd detected in some puffed rice, which we attribute to the illegal practice of using urea for whitening the puffed rice. Tobacco leaves, which are commonly consumed during betel quid chewing by Bangladeshis, contain significant levels of Cd (mean 95 [SD 87]μg/kg). The total daily intake (TDI) of Cd from foods for Bangladeshis was estimated to be 34.55 μg/d. This is rather high when compared to the TDI of Cd for other populations. Our analysis reveals that this is mainly due to the very high intake of rice and vegetables, and lower consumption of animal products (which are low in Cd), by the Bangladeshis. We also determined the provisional maximum tolerable daily intake and target hazard quotients values for Cd. Clearly a more balanced diet is necessary to reduce the Cd intake in the Bangladeshi population, especially by reducing the very high intake of rice and certain leafy vegetables. Food manufacturing and agricultural practices needs to be altered to reduce the entry of Cd into the food chain. PRACTICAL APPLICATION Exposure to high levels of Cd can be harmful to human health and this study provides a comprehensive analysis of Cd levels in a variety of food items from Bangladesh. The findings are of particular importance to consumers of Bangladeshi foods in both Bangladesh and in other countries. Data obtained will be valuable resources for food safety and regulatory bodies as our study suggests entry of Cd in foods through use of illegal chemicals in food manufacturing processes.

Reducing human exposure to arsenic, and simultaneously increasing selenium and zinc intake, by substituting non-aromatic rice with aromatic rice in the diet

Hundreds of millions of people world-wide are exposed to high concentrations of the toxic element arsenic (As) through drinking water and consumption of certain foods, especially rice. In this study Inductively Coupled Plasma Mass Spec- troscopy (ICP-MS) was used to analyse rice from the greater Sylhet region of Bangladesh which has relatively lower ground- water As concentrations. Different varieties of rice were analysed for inorganic-As (i-As) and other elements (Cd, Mn, Pb, Se and Zn) in order to identify rice with low As content and higher essential element (Zn and Se) content. Sylheti non-aromatic rice showed lower As concentration (27.1-174.1 µg/kg) compared to non-aromatic rice from other regions of Bangladesh. Fur- thermore, aromatic rice from Sylhet had the lowest As content (10.1 µg/kg) and the highest Se content (341 µg/kg) compared to non-aromatic rice. Approximately 70% of the total As in Sylheti rice was i-As and parboiled rice contained the highest i-As (90%) compared to other rice varieties. Aromatic rice generally contained lower concentrations of toxic elements (As, Cd, Pb) and higher concentrations of essential elements (Se, Zn) compared to non-aromatic rice. For someone consuming 500 g of non-aromatic or aromatic rice from Sylhet, the daily intake of As from consumption of rice would be reduced by approximately 48% and 69%, respectively, compared to non-aromatic rice from other parts of Bangladesh thus far investigated. Also the daily intake of As from consumption of aromatic rice is 40% lower compared to non-aromatic rice sourced from the Sylhet region. The daily intake of Se and Zn from consumption of rice would be increased by 46% and 23%, respectively, for someone con- suming aromatic rice instead of non-aromatic rice from Sylhet. This study reveals that consuming certain types of aromatic rice can potentially not only reduce exposure to As but also increase the daily intake of Se and Zn in Bangladeshis. This type of rice could also be used in infant foods instead of rice with higher As concentration.

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

BackgroundA 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.MethodsInductively 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.ResultsBetel 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.ConclusionWe 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.

Intake of Arsenic and Selenium in a Bangladeshi population investigated using Inductively Coupled Plasma Mass Spectrometry

Millions of people in Bangladesh are exposed to high concentration of the toxic element arsenic (As) through drinking water and consumption of foods. It has also been reported that Bangladeshis have a low intake of the essential element selenium (Se), which is known to be important as an antioxidant and has been suggested to counteract the toxicity of As. We report here on total intake of As and Se in a Bangladeshi population, based on inductively coupled plasma mass spectrometric (ICP-MS) analysis of a range of Bangladeshi foods. The total daily intake of As and Se from foods was estimated to be 74.2 and 87.7 μg/day, respectively. If As from water, used for drinking and cooking rice, is included the TDI increases to 385 μg of total As per day. An important finding of our study, contrary to suggestions given in other reports, is that the Bangladeshi diet does not appear to be deficient in Se and this may explain why the blood Se concentrations in Bangladeshis is similar to the USA population. This requires further investigation and detailed dietary and human biomonitoring studies on the Bangladeshi population should be conducted. Rice and fish were the main sources of dietary As and Se for Bangladeshis. Leafy vegetables could also be a significant contributor of high concentration of As in the Bangladeshi diet. The flesh and eggs of Hilsha (Tenualosa ilisha) species of fish were found to contain particularly high levels of total arsenic (range 0.77–6.15 mg/kg) although this is likely to be dominated by the non-toxic organoarsenic species.