Mitigating arsenic contamination in rice plants with an aquatic fern, Marsilea minuta.

Dangers of arsenic contamination are well known in human civilization. The threat increases when arsenic is accumulated in food and livestock through irrigated crops or animal food. Hence, it is important to mitigate the effects of arsenic as much as possible. This paper discusses a process for reducing the level of arsenic in different parts of rice plants with an aquatic fern, Marsilea minuta L. A pot experiment was done to study the possibility of using Marsilea minuta as a phytoremediator of arsenic. Rice and Marsilea minuta were allowed to grow together in soils. As a control, Marsilea minuta was also cultured alone in the presence and absence of arsenic (applied at 1 mg/L as irrigation water). We did not find any significant change in the growth of rice due to the association of Marsilea minuta, though it showed a reduction of approximately 58.64% arsenic accumulation in the roots of rice grown with the association of fern compared to that grown without fern. We measured a bioaccumulation factor (BF) of > 5.34, indicating that Marsilea minuta could be a good phytoremediator of arsenic in rice fields.

Comparative pharmacokinetic and relative bioavailability study of coated and uncoated azithromycin powder for suspension in healthy Bangladeshi male volunteers.

Azithromycin (AZT; CAS 83905-01-5) is an efficient antibiotic and is widely prescribed in Bangladesh. The taste of uncoated AZT suspension is bitter. Although several taste masked oral suspensions of AZT are available in Bangladesh, information regarding the bioavailability of these formulations in Bangladeshi population is unavailable. The purpose of this study was to compare the relative bioavailability and other pharmacokinetic properties of two oral formulation of AZT (200 mg/5 ml) suspensions, the uncoated reference product and coated test product (Tridosil 200 mg/5 ml) and to evaluate whether these formulations meet the FDA criteria to assume bioequivalence in Bangladeshi male volunteers. A randomized, single-dose, two-way cross-over, open-label pharmacokinetic study was conducted in 24 healthy male volunteers after administration of a single dose of 500 mg AZT suspension under fasting condition following a washout period of three weeks. Blood samples were collected in different time intervals and analyzed for serum AZT concentration using a validated LC/MS/MS method. The pharmacokinetic parameters were determined by the non-compartmental method. From serum data, the obtained values for test and reference products were 383.21 +/- 11.59 and 432.28 +/- 7.22 ng/ ml for Cmax; 5677.47 +/- 1229.53 and 6144.56 +/- 1098.70 h x ng/ml for AUC(0-120); and 6085.29 +/- 1267.53 and 6694.15 +/- 1222.50 h x ng/ml for AUC(0-infinity), respectively. On analysis of variance, no period or sequence effects were observed for any pharmacokinetic property; however, a significant formulation effect was observed for Cmax and AUMC(0-infinity). The 90% confidence intervals of the test formulation/reference mean ratios of the Intransformed Cmax, AUC(0-120) and AUC(0-infinity) mean values were found to be 87.89% to 89.36%, 87.96% to 95.71% and 86.77% to 94.29% respectively. In this single-dose study of AZT, it was found that the test formulation met the regulatory criteria for bioequivalence to the reference suspension formulation.

Groundwater chemistry and arsenic mobilization in the Holocene flood plains in south-central Bangladesh.

A comparative study of arsenic enrichment in the Bengal Delta (BD) was carried out in three alluvial aquifers in south-central Bangladesh. Investigated sites included Sonargaon in Narayanganj, Chandina in Comilla and Sirajdikhan in Munshiganj districts. At all sites samples from different depths were collected, and water chemistry and redox status vs. depth trends were determined. The concentrations of DOC and HCO(3)(-) were highest at Sirajdikhan site, while at the Sonargaon and Chandina sites the concentrations were lower. On the contrary, the NH(4)(+) concentration was high at the Chandina site as compared to the other sites. There was a good match between dissolved As and Fe at the Sirajdikhan and Sonargaon sites, but not at the Chandina site. The dissolved aqueous concentration of Mn was low at the Chandina site, which suggested that the Mn(IV) redox buffering step was missing. Speciation modeling indicated a possibility of siderite precipitation at all sites, but precipitation of rhodochrosite only at the Sonargaon and Sirajdikhan sites. At the Sirajdikhan site, the log P(CO2) values were very high (-1.37), which revealed the production of CO(2) in redox processes. Principal component analysis (PCA) indicated an impact of sea water and redox status of different samples. These results suggest that the dissolved As is de-coupled from dissolved Mn because when released, As is re-adsorbed onto the Fe(III) minerals in solid phase, as well as from dissolved Fe when precipitation of Fe(II) minerals controls the aqueous concentrations of Fe. In addition, several other concurrent redox processes may exert kinetic constraints depending on refractory characteristics of Fe(III) minerals.

Sorption and bioavailability of arsenic in selected Bangladesh soils.

The bioavailability of arsenic (As) in the soil environment is largely governed by its adsorption-desorption reactions with soil constituents. We have investigated the sorption-desorption behaviour of As in four typical Bangladeshi soils subjected to irrigation with As-contaminated groundwater. The total As content of soils (160 samples) from the Laksham district ranged from <0.03 to approximately 43 mg kg(-1). Despite the low total soil As content, the concentration of As in the pore water of soils freshly irrigated with As-contaminated groundwater ranged from 0.01 to 0.1 mg l(-1). However, when these soils were allowed to dry, the concentration of As released in the pore water decreased to undetectable levels. Remoistening of soils to field moisture over a 10-day period resulted in a significant (up to 0.06 mg l(-1)) release of As in the pore water of soils containing >10 mg As kg(-1) soil, indicating the potential availability of As. In soils containing <5 mg As kg(-1), As was not detected in the pore water. A comparison of Bangladeshi soils with strongly weathered long-term As-contaminated soils from Queensland, Australia showed a much greater release of As in water extracts from the Australian soils. However, this was attributed to the much higher loading of As in these Australian soils. The correlation of pore water As with other inorganic ions (P, S) showed a strongly significant (P < 0.001) relationship with P, although there was no significant relationship between As and other inorganic cations, such as Fe and Mn. Batch sorption studies showed an appreciable capacity for both As(V) and As(III) sorption, with As(V) being retained in much greater concentrations than As(III).

Zinc, manganese, calcium, copper, and cadmium level in scalp hair samples of schizophrenic patients.

The purpose of the study was to determine the concentration of trace elements present in scalp hair sample of schizophrenic patients and to find out the relationship between trace elements level and nutritional status or socioeconomic factors. The study was conducted among 30 schizophrenic male patients and 30 healthy male volunteers. Patients were recruited from Bangabandhu Sheikh Mujib Medical University by random sampling. Hair trace element concentrations were determined by flame atomic absorption spectroscopy and analyzed by independent t test, Pearson's correlation analysis, regression analysis, and analysis of variance (ANOVA). Mn, Zn, Ca, Cu, and Cd concentrations of schizophrenic patients were 3.8 +/- 2.31 microg/gm, 171.6 +/- 59.04 microg/gm, 396.23 +/- 157.83 microg/gm, 15.40 +/- 5.68 microg/gm, and 1.14 +/- 0.89 microg/gm of hair sample, while those of control subjects were 4.4 +/- 2.32 microg/gm, 199.16 +/- 27.85 microg/gm, 620.9 +/- 181.55 microg/gm, 12.23 +/- 4.56 microg/gm, and 0.47 +/- 0.32 microg/gm of hair sample, respectively. The hair concentration of Zn and Ca decreased significantly (p = 0.024; p = 0.000, respectively) and the concentration of Cu and Cd increased significantly (p = 0.021; p = 0.000, respectively) in schizophrenic patients while the concentration of Mn (p = 0.321) remain unchanged. Socioeconomic data reveals that most of the patients were poor, middle-aged and divorced. Mean body mass indices (BMIs) of the control group (22.26 +/- 1.91 kg/m(2)) and the patient group (20.42 +/- 3.16 kg/m(2)) were within the normal range (18.5-25.0 kg/m(2)). Pearson's correlation analysis suggested that only Ca concentration of patients had a significant positive correlation with the BMI (r = 0.597; p = 0.000) which was further justified from the regression analysis (R (2) = 44%; t = 3.59; p = 0.002) and one-way ANOVA test (F = 3.62; p = 0.015). A significant decrease in the hair concentration of Zn and Ca as well as a significant increase in the hair concentration of Cu and Cd in schizophrenic patients than that of its control group was observed which may provide prognostic tool for the diagnosis and treatment of this disease. However, further work with larger population is suggested to examine the exact correlation between trace element level and the degree of disorder.

Arsenic contamination in food-chain: transfer of arsenic into food materials through groundwater irrigation.

Arsenic contamination in groundwater in Bangladesh has become an additional concern vis-à-vis its use for irrigation purposes. Even if arsenic-safe drinking-water is assured, the question of irrigating soils with arsenic-laden groundwater will continue for years to come. Immediate attention should be given to assess the possibility of accumulating arsenic in soils through irrigation-water and its subsequent entry into the food-chain through various food crops and fodders. With this possibility in mind, arsenic content of 2,500 water, soil and vegetable samples from arsenic-affected and arsenic-unaffected areas were analyzed during 1999-2004. Other sources of foods and fodders were also analyzed. Irrigating a rice field with groundwater containing 0.55 mg/L of arsenic with a water requirement of 1,000 mm results in an estimated addition of 5.5 kg of arsenic per ha per annum. Concentration of arsenic as high as 80 mg per kg of soil was found in an area receiving arsenic-contaminated irrigation. A comparison of results from affected and unaffected areas revealed that some commonly-grown vegetables, which would usually be suitable as good sources of nourishment, accumulate substantially-elevated amounts of arsenic. For example, more than 150 mg/kg of arsenic has been found to be accumulated in arum (kochu) vegetable. Implications of arsenic ingested in vegetables and other food materials are discussed in the paper.