Arsenic in Tubewell Water

Accordingly to the British Geological Survey, southeastern Bangladesh, where Matlab is located, is the part of the country with the most pronounced arsenic contamination of tube-well water. As a result, research into the health effects of arsenic was initiated.The project 'Arsenic in tube well water and health consequences' was begun in Matlab at 2001 with funding from Sida, WHO and USAID. Fieldwork included screening of the entire population of 220,000 for arsenic-induced skin lesions and measuring arsenic contamination by atomic absorption spectrophotometry (AAS) in all 13,286 functioning tube wells, as well as initiating mitigation activities in the entire area. An arsenic database has been added to the Matlab Health and Demographic Surveillance system including geographical coordinates of all tube wells, with information on their age, depth and arsenic content. The database also includes information about an individual’s skin lesions, and their water consumption pattern over the years.

The field research team is based in Matlab (photo) but the progamme includes collaborators at the Karolinska Institute Stockholm, International Maternal and Child Health, Uppsala University, Sweden, Mailman School of Public Health, Columbia University, University of California, Davis and the US Centers for Disease Control.

Arsenic contamination

In total, 16,461 tube wells were identified in Matlab. Water samples from 11,045 were analyzed by AAS and water samples from 2,689 by field-kits for arsenic content. The arsenic concentration ranged from 0.5 to 3,644 µg/L. Of the samples evaluated, 62% had arsenic levels of >50 µg/L. and 9% had arsenic levels of >500 µg/L. The sensitivity and specificity of the field kit was 98% and 86% respectively.

In total, 1,742 urine samples have so far been analyzed for arsenic. The average concentration is 137 µg/L, which is 10 times higher than in the

non-exposed populations. The findings demonstrate that the people are highly exposed to arsenic through drinking-water.

Arsenic and skin lesions

In all, 166,934 individuals were examined and interviewed, and the arsenic content of their drinking water measured. Among them, 504 arsenic-induced cases were identified.

Association of arsenic with maternal and cord blood

This project generated new and much needed knowledge on the association between arsenic exposure and the extent to which arsenic and other chemicals cross the placenta and are found in the blood of the newborn child. The study also examined the extent to which mothers and newborn infants can methylate arsenic and determined whether blood homocysteine, folate and vitamin B12 concentrations are related to arsenic methylation. This information may provide useful knowledge in taking appropriate measures to help reduce the harmful effects of arsenic exposure in pregnant women and neonates. So far, 52 mother-cord blood samples were analyzed. Preliminary analysis reveals that the relationship between maternal cord-blood arsenic and lead is significant compared to selenium and manganese (Fig. 2).

Arsenic mitigation

Several mitigation options have installed in Matlab. No single intervention is universally affordable and acceptable, but villagers are using several methods. The most popular household method is the Alcan filter. This method efficiently removes arsenic, but requires a replacement element after 2 years that costs money. The 30 pond-sand filters installed reached more people than all of household-level interventions combined. However, construction of a pond-sand filter does not guarantee that families will always collect their water from the pond-sand filter, rather than from their typically more conveniently-placed tube wells. Nevertheless, these data demonstrate that there are several potential strategies to reduce arsenic exposure among at-risk populations in Bangladesh. Further research is necessary to evaluate the most effective, sustainable approaches.

However, criteria for distribution of the safe water options are as follows:

r Willingness to bear 20% of the installation cost and 100% of the operational and maintenance costs

r Arsenic concentrations in water in the village

r Symptoms of arsenic toxicity in the village

r Poor socioeconomic conditions

The findings of this population-based study showed that more than half of the population in a rural area of Bangladesh has been drinking arsenic-contaminated water for many years. Hence, public health/ biomedical interventions for early diagnosis and treatment of arsenic-induced skin lesions are urgently required, among other steps, to make inroads into this massive public-health problem in Bangladesh.

A strong collaborative team has been formed between ICDDR,B and BRAC in Bangladesh and Metals and Health, Karolinska Institute and International Maternal and Child Health,  UppsalaUniversity,Sweden.

Two bangladeshi PhD candidates are working

• Dr Anisur Rahman is working on arsenic exposure in pregnancy and effects on foetus and child. Dr. Rahman is also affiliated to the Division of Metals & Health, Institute of Environmental Medicine; Karolinska Institutet, Stockholm.
• Md Jakariya is working on mitigation interventions and affiliated with Royal Techinical Institute, Stockholm, Sweden. Md Jakariya is also affiliated to the Division of Metals & Health, Institute of Environmental Medicine; Karolinska Institutet, Stockholm and IMCH, Uppsala University, Sweden.

Arsenic and flocculent-disinfectant

This study looks at the effectiveness of a point-of-use flocculent-disinfectant for arsenic mitigation and for improving the quality and microbial safety of surface water. The study enrolled 105 households for 12 weeks. One woman in each household was taught how to treat tubewell water. Drinking-water and spot-urine samples were collected at baseline and 2, 5, 9, and 12 weeks after the intervention. Water and urinary arsenic and its metabolites were measured at different weeks of the intervention. The mean baseline arsenic concentration in tubewell water was 162 mg/L (range 15-543). Following initiation of the intervention, arsenic concentrations in drinking-water decreased by an overall mean of 138 mg/L; 88% met the Bangladesh standard of <50< /FONT > mg/L. Urinary arsenic concentrations decreased by a mean of 160 m g/gcreatinine. The flocculent-disinfectant markedly reduced arsenic levels in tubewell water and, to a lesser extent, urinary arsenic in women who consumed treated water. All pre-treatment samples (n= 101) were non-potable and were contaminated with a mean of 2.9x104 CFU/100 mL faecal coliforms. Turbidity ranged from 6 to 92 NTU. Following treatment, 97 (96%) samples met the potability guideline. Treatment resulted in a mean reduction of 87% in turbidity (mean 4 NTU) with 93% of the samples meeting the WHO turbidity guideline of <5 NTU. Free chlorine was detected in 83% of the samples. Another 35 surface-water samples were collected and treated with the flocculent-disinfectant 3 times at one-month intervals and were analyzed for faecal coliforms. Following treatment with the flocculent-disinfectant, 96% of the surface-water samples met the WHO bacterial potability guideline. The samples showed markedly-improved clarity. This strategy may be useful in programmes for improving the quality and safety of drinking-water.

More information is provided in the Annual Report