Ingestion of drinking water is not the only elevated source of arsenic to the diet in the Bengal Delta. Even at background levels, the arsenic in rice contributes considerably to arsenic ingestion in subsistence rice diets. We set out to survey As speciation in different rice varieties from different parts of the globe to understand the contribution of rice to arsenic exposure. Pot experiments were utilized to ascertain whether growing rice on As contaminated soil affected speciation and whether genetic variation accounted for uptake and speciation. USA long grain rice had the highest mean arsenic level in the grain at 0.26 microg As g(-1) (n = 7), and the highest grain arsenic value of the survey at 0.40 microg As g(-1). The mean arsenic level of Bangladeshi rice was 0.13 microg As g(-1) (n = 15). The main As species detected in the rice extract were AsIII, DMAV, and AsV. In European, Bangladeshi, and Indian rice 64 +/- 1% (n = 7), 80 +/- 3% (n = 11), and 81 +/- 4% (n = 15), respectively, of the recovered arsenic was found to be inorganic. In contrast, DMAV was the predominant species in rice from the USA, with only 42 +/- 5% (n = 12) of the arsenic being inorganic. Pot experiments show that the proportions of DMAV in the grain are significantly dependent on rice cultivar (p = 0.026) and that plant nutrient status is effected by arsenic exposure.

An extensive data set of total arsenic analysis for 901 polished (white) grain samples, originating from 10 countries from 4 continents, was compiled. The samples represented the baseline (i.e., not specifically collected from arsenic contaminated areas), and all were for market sale in major conurbations. Median total arsenic contents of rice varied 7-fold, with Egypt (0.04 mg/kg) and India (0.07 mg/kg) having the lowest arsenic content while the U.S. (0.25 mg/kg) and France (0.28 mg/kg) had the highest content. Global distribution of total arsenic in rice was modeled by weighting each country's arsenic distribution by that country's contribution to global production. A subset of 63 samples from Bangladesh, China, India, Italy, and the U.S. was analyzed for arsenic species. The relationship between inorganic arsenic content versus total arsenic content significantly differed among countries, with Bangladesh and India having the steepest slope in linear regression, and the U.S. having the shallowest slope. Using country-specific rice consumption data, daily intake of inorganic arsenic was estimated and the associated internal cancer risk was calculated using the U.S.Environmental Protection Agency (EPA) cancer slope. Median excess internal cancer risks posed by inorganic arsenic ranged 30-fold for the 5 countries examined, being 0.7 per 10,000 for Italians to 22 per 10,000 for Bangladeshis, when a 60 kg person was considered.

Concern has been raised by Bangladeshi and international scientists about elevated levels of arsenic in Bengali food, particularly in rice grain. This is the first inclusive food market-basket survey from Bangladesh, which addresses the speciation and concentration of arsenic in rice, vegetables, pulses, and spices. Three hundred thirty aman and boro rice, 94 vegetables, and 50 pulse and spice samples were analyzed for total arsenic, using inductivity coupled plasma mass spectrometry (ICP-MS). The districts with the highest mean arsenic rice grain levels were all from southwestern Bangladesh: Faridpur (boro) 0.51 > Satkhira (boro) 0.38 > Satkhira (aman) 0.36 > Chuadanga (boro) 0.32 > Meherpur (boro) 0.29 µg As g -1 . The vast majority of food ingested arsenic in Bangladesh diets was found to be inorganic; with the predominant species detected in Bangladesh rice being arsenite (As III ) or arsenate (As V ) with dimethyl arsinic acid (DMA V ) being a minor component. Vegetables, pulses, and spices are less important to total arsenic intake than water and rice. Predicted inorganic arsenic intake from rice is modeled with the equivalent intake from drinking water for a typical Bangladesh diet. Daily consumption of rice with a total arsenic level of 0.08 µg As g -1 would be equivalent to a drinking water arsenic level of 10 µg L -1 .

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BackgroundAntibiotic self medication is highly prevalent in the developing countries due to easy availability and poor regulatory controls for selling these drugs. The purpose of this study was to evaluate the prevalence of self-medication with antibiotics for the treatment of various diseases by the peoples of Rajshahi city in Bangladesh.MethodsA cross-sectional survey was conducted to the patient’s (n = 1300) at eight locations of Rajshahi city in Bangladesh from March to April, 2014. The locations were selected by convenience and the study population within each study area was randomly selected. The survey was self-administered and included questions pertaining to self medicated drugs and antibiotic usage patterns as well. Data were analyzed using descriptive statistics.ResultsIt was found that 347 (26.69%) out of 1300 participants experienced self medication with antibiotics. Over fifty percent of the patients studied were between the ages of 21–30 years with 83.57% of them being males and 16.43% females. The highest percentage of self medicated antibiotics was metronidazole (50.43%) followed by azithromycin (20.75%), ciprofloxacin (11.53%), amoxicillin (10.37%) and tetracycline (7.49%) respectively. The key reasons for the self medication of antibiotics was the pre-experience (45.82%), suggestions from others (28.24%) and knowledgeable of the antibiotics (16.14%). The perceived symptoms to purchase the antibiotics independently was dysentery, diarrhea and food poisoning (36.02%), cold, cough and fever (28.24%), infection (12.97%), dental carries and toothache (9.22%), irritable bowel syndrome (3.46%), acne (4.32%), ear and throat pain (2.31%). The duration of maximum antibiotics usage was ranges between 0–10 years. Only 4.32% patient’s used self medicated antibiotics longer than 10 years. The patient’s compliance for self medication of antibiotics varies from excellent to no comments whereas only 6.92% patients reported side effects for the self medication of antibiotics.ConclusionsThe results of this study confirm that antibiotic self-medication is a relatively frequent problem in Bangladesh. Drug Administration of Bangladesh should implement the regulatory controls immediately on the distribution and selling of antibiotics in order to reduce the frequency of antibiotic misuse.

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We present data showing that arsenic (As) was codeposited with organic carbon (OC) in Bengal Delta sediments as As and OC concentrations are highly (p < 0.001) positively correlated in core profiles collected from widely dispersed geographical sites with different sedimentary depositional histories. Analysis of modern day depositional environments revealed that the As-OC correlations observed in cores are due to As retention and high OC inputs in vegetated zones of the deltaic environment. We hypothesize that elevated concentrations of As occur in vegetated wetland sediments due to concentration and retention of arsenate in aerated root zones and animal burrows where copious iron(III) oxides are deposited. On burial of the sediment, degradation of organic carbon from plant and animal biomass detritus provides the reducing conditions to dissolve iron(III) oxides and release arsenite into the porewater. As tubewell abstracted aquifer water is an invaluable resource on which much of Southeast Asia is now dependent, this increased understanding of the processes responsible for As buildup and release will identify, through knowledge of the palaeosedimentary environment, which sediments are at most risk of having high arsenic concentrations in porewater. Our data allow the development of a new unifying hypothesis of how As is mobilized into groundwaters in river flood plains and deltas of Southeast Asia, namely that in these highly biologically productive environments, As and OC are codeposited, and the codeposited OC drives As release from the sediments.

Summary• The genetics of arsenic tolerance in plants has not been extensively studied and no arsenic tolerance gene has been genetically mapped.• Screening 20 diverse genotypes of rice for reduced root growth in 13.3 µ M arsenate identified marked differences in tolerance. The most sensitive variety, Dawn, is known to be highly susceptible to straighthead, a condition linked to arsenic contamination of soil.• Screening 108 recombinant inbred lines of the Bala × Azucena mapping population revealed the presence of a major gene, AsTol , which mapped between markers RZ516 and RG213 on chromosome 6.• This gene is a good target for further characterisation. It should prove valuable for investigations into the physiological and molecular mechanism behind arsenic tolerance in plants and may lead to strategies aimed at breeding for arsenic contaminated regions. © New Phytologist (2004) 163 : 45 -49