The Bengal Water Machine: Quantified freshwater capture in Bangladesh

Global food security depends on the sustainability of irrigated agriculture. Rising groundwater withdrawals from seasonally humid, alluvial plains across tropical Asia have enabled dry-season rice cultivation. This groundwater pumpage increases available subsurface storage that under favorable conditions amplifies groundwater replenishment during the subsequent monsoon. We empirically quantified this nature-based solution to seasonal freshwater storage capture described as the “Bengal Water Machine,” revealing its potential and limitations. On the basis of a million piezometric observations from 465 monitoring wells, we show that the collective operation of ~16 million smallholder farmers in the Bengal Basin of Bangladesh from 1988 to 2018 has induced cumulative freshwater capture that volumetrically (75 to 90 cubic kilometers) is equivalent to twice the reservoir capacity of the Three Gorges Dam.

Spatiotemporal distribution of boron in the groundwater and human health risk assessment from the coastal region of Bangladesh

High concentrations of naturally-occurring and man-accentuated boron in groundwater possess a potential threat to the health and well-being of humans worldwide. In Bangladesh, only a few studies focused on the health risks of boron-containing groundwater. Therefore, the present study investigated the spatiotemporal distribution of boron concentrations in groundwater and its associated health risks in the coastal districts of Bangladesh. A total of 268 samples from the shallow and deep wells during the wet and dry season (137 and 131 samples, respectively) were collected to determine the level of boron concentrations and health risk status. The groundwater boron concentrations ranged from 0 to 4.10 mg/L with an average concentration of 0.68 mg/L, which was much lower than the WHO and the values of Bangladesh drinking water standard guideline. The boron concentrations in the shallow wells override the deep ones with insignificant seasonal variation. Boron contamination affected 10% of the shallow wells in the wet season and only 6% of them in the dry season, whereas only 1% of deep wells exceeds the WHO guideline values of 2.40 mg/L during the wet and dry season, respectively. The human health risk of boron was determined by computing estimated daily intake (EDI) and hazard quotient (HQ) values for infants, children, teenagers, and adults. The average HQ value delimitated that children have high risk followed by teenagers, adults, and infants. About 90-95% of the studied samples were free from boron contamination because of having HQ values < 1 and the rest of the samples possess a high risk for children. For the overall study area, the deep wells were found safer than the shallow wells, which were more susceptible to boron contamination aided by localized freshwater inputs.

Abstract P224: Urinary Excretion of Sodium, Potassium, Calcium and Magnesium and Blood Pressure Among a Population of ≥ 20-Year-Olds: Evidence From Southwest Coastal Bangladesh

We analyzed data from a stepped wedge randomized trial to evaluate how urinary Na, K, Ca and Mg excretion are associated with the change in blood pressure (BP) among the adult population. We followed up a cohort of 1,191 participants (>20 years old) from 540 households in 16 communities of southwest coastal Bangladesh for five visits during December 2016 - April 2017 when they were exposed to high salinity drinking water. In all visits, we measured participants’ BP (N=5,746) and 24-hour urinary Na, K, Ca and Mg. We used multilevel linear regression models to determine the association among change in urinary excretion of Na, K, Ca and Mg with differences in mean systolic blood pressure (SBP) and diastolic blood pressure (DBP). Models included participant-, household-, and community-level random intercepts and were adjusted for age, sex, BMI, physical activity, smoking status, and household wealth. We restricted analysis among participants who had complete 24-hour urine collection based on measured versus expected urinary creatinine ratio of >=0.7 (N=5,103). The median urinary 24 hours Na excretion was 164 mmol, K was 34 mmol, Ca was 126 mg, and Mg was 83 mg in visit 1. The mean population SBP was 115.6 mmHg in visit 1 and 110.2 in visit 5, and the mean DBP was 68.9 mmHg in visit 1 and 65.9 in visit 5. Compared to visit 1, we found 85% higher urinary Ca in visit 3 and 57% higher urinary Mg in visit 5. We found 100 mmol per 24 hours increase in urinary Na was associated with 1.74 (95% CI: 0.85, 2.62) mmHg higher SBP and 0.51 (95% CI: -0.06, 1.08) mmHg higher DBP, and 50 mmol per 24 hours increase in urinary K was associated with 2.39 (95% CI: 0.84, 3.94) mmHg lower SBP and 0.79 (95% CI: -1.76, 0.17) mmHg lower DBP. We found 100 mg per 24 hours increase in urinary Ca was associated with 0.29 (95% CI: 0.02, 0.60) mmHg lower SBP and 0.32 (0.07, 0.57) mmHg lower DBP, and 100 mg per 24 hours increase in urinary Mg was associated with 1.09 (95% CI: 0.55, 1.64) mmHg lower SBP and 0.41 (0.07, 0.76) mmHg lower DBP. We found SBP lowering effect of urinary Mg increased if urinary Ca was lower (p = 0.048). We found urinary K, Ca, and Mg are associated with lower BP in coastal Bangladesh. Our results suggest a high intake of these beneficial minerals alongside Na reduction may successfully lower mean BP of the population.

Anemia and iron deficiency in rural Bangladeshi pregnant women living in areas of high and low iron in groundwater

BACKGROUND

Recent studies found a low rate of iron deficiency in Bangladeshi non-pregnant and non-lactating women. This was attributed to high iron concentrations in drinking water. However, there are limited data on iron deficiency among pregnant women in Bangladesh.

OBJECTIVES

Our aim was to investigate the prevalence of anemia, iron deficiency, and iron deficiency anemia (IDA) among rural pregnant women and explore the association of groundwater iron concentration with anemia and iron deficiency in this group.

METHODS

This study used data from a baseline assessment of an intervention study on rural pregnant women (n = 522), gestational age ≤20 wk, living in areas of low and high iron in groundwater.

RESULTS

Overall, 34.7% of the pregnant women had anemia, 27% had iron deficiency, and 13.4% had IDA. Prevalence of anemia, iron deficiency, and IDA among the pregnant women living in low-groundwater-iron areas was significantly higher than among the pregnant women from high-groundwater-iron areas. The odds of iron deficiency were significantly lower among pregnant women in the higher quartiles of daily iron intake from drinking water.

CONCLUSIONS

This study found a differential prevalence of anemia and iron deficiency among pregnant women living in areas of high and low groundwater iron. Iron status was independently associated with daily iron intake from drinking water. However, a significant proportion of the anemia could not be attributed to iron deficiency. Further research to identify other nutritional and non-nutritional contributors to anemia in Bangladesh is needed to formulate effective prevention and control programs for anemia.