Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Inaccurate arsenic test kits jeopardize water safety in Bangladesh and India

19.11.2002


Thousands in southern Asia could be drinking arsenic-contaminated water from wells that are falsely labeled safe, while precious good water sits untapped in wells that are wrongly marked unsafe — a dire disparity for countries where water can be more valuable than gold.



A new study of wells in Bangladesh and West Bengal, India, suggests the arsenic test kits used by field workers are frequently inaccurate, producing scores of incorrectly labeled wells. The findings were published this month on the Web site of Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society, the world’s largest scientific society. The print version of the paper is scheduled for the Dec. 15 edition of the journal.

Researchers analyzed 2,866 water samples from wells that were previously labeled by field workers. They found that a large percentage of the wells were labeled erroneously.


Shallow wells, known as tubewells, are commonly used in Bangladesh and India to avoid the region’s surface water, much of which contains bacteria that can cause waterborne diseases like cholera. Beginning in the 1970s, international aid organizations dug millions of tubewells, and the program was basically successful in providing bacteria-free water. But officials soon found that the tubewells were reaching groundwater containing high levels of arsenic.

Arsenic is a slow poison; studies have linked long-term exposure to several types of cancer, according to the U.S. Environmental Protection Agency. The World Health Organization advocates a maximum arsenic level in water of 10 micrograms per liter — the standard currently used by the EPA — but many developing countries still use a standard of 50 micrograms per liter.

By 1993, the Bangladesh Department of Public Health Engineering had reported widespread signs of arsenic poisoning and blamed tubewell water. WHO called it the largest mass poisoning of a population in history. Similar problems have recently surfaced in other countries in the region, including India, Vietnam, Cambodia, Nepal and Myanmar (formerly Burma).

In 1997, the World Bank, WHO, UNICEF and other international organizations undertook a massive project to test every tubewell in Bangladesh and the surrounding area using field kits. Many wells were labeled with paint to indicate their viability: green for safe water (containing under 50 micrograms per liter of arsenic) and red for unsafe water.

"We have been surveying in arsenic-affected areas of Bangladesh since 1996," says Dipankar Chakraborti, Ph.D., head of the School of Environmental Studies at Jadavpur University in Calcutta, India, and lead author of the paper. He and his colleagues often heard stories from villagers about mislabeled wells. One villager reportedly brought two glasses of water for testing to field workers who had labeled the wells; one glass was declared safe by the workers and the other was declared unsafe. The villagers then proceeded to assault the workers, Chakraborti says. Both samples had apparently been taken from the same well.

The researchers began testing tubewells themselves with a technique called flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) — a fast and sensitive method performed in a laboratory setting. They found random errors in the labeling of tubewells, which led them to begin the systematic study reported in the current paper.

They found that nearly 50 percent of the wells painted red by field workers actually contained safe drinking water, according to their lab technique. Only 7.5 percent of the green wells turned out to be unsafe.

The point, the researchers emphasize, is that the field kits appear to be random and qualitative — not appropriate for large-scale testing initiatives with such important health, economic and environmental impacts.

The field kits are difficult to read with precision and often are not suitably accurate for this type of measurement — the majority of the analyses in Bangladesh were done before 2000, using a test kit with a minimum detection level of 100 micrograms per liter.

Chakraborti recommends using the FI-HG-AAS analysis because it not only provides more accurate readings, but there are also environmental impacts from the field kits that are not a concern in the lab. The field kits require relatively large quantities of toxic chemicals that must be disposed of, he says, but the lab technique uses a "micro-assay" technique with much less need for chemicals.

The lab technique can also be less expensive than the field kit method, Chakraborti says. "Cost is an important consideration but [it] requires comparison with the even higher cost of falsely labeling a well as unsafe," the researchers write. "Given the scarcity of uncontaminated water the mislabeling of 50 [percent] of safe wells has a major socioeconomic impact."

The School of Environmental Studies is a self-funded institute within Jadavpur University, which is operated solely on money earned from selling its expertise.

Beverly Hassell | EurekAlert!
Further information:
http://www.acs.org/
http://pubs.acs.org/estnews

More articles from Health and Medicine:

nachricht The FiTS app now offering cooking videos as it expands its concept for long-term behavior modification
18.09.2018 | vitaliberty GmbH

nachricht The microbiota in the intestines fuels tumour growth
18.09.2018 | Technische Universität München

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Patented nanostructure for solar cells: Rough optics, smooth surface

Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.

"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...

Im Focus: New soft coral species discovered in Panama

A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.

Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...

Im Focus: New devices based on rust could reduce excess heat in computers

Physicists explore long-distance information transmission in antiferromagnetic iron oxide

Scientists have succeeded in observing the first long-distance transfer of information in a magnetic group of materials known as antiferromagnets.

Im Focus: Finding Nemo's genes

An international team of researchers has mapped Nemo's genome

An international team of researchers has mapped Nemo's genome, providing the research community with an invaluable resource to decode the response of fish to...

Im Focus: Graphene enables clock rates in the terahertz range

Graphene is considered a promising candidate for the nanoelectronics of the future. In theory, it should allow clock rates up to a thousand times faster than today’s silicon-based electronics. Scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) and the University of Duisburg-Essen (UDE), in cooperation with the Max Planck Institute for Polymer Research (MPI-P), have now shown for the first time that graphene can actually convert electronic signals with frequencies in the gigahertz range – which correspond to today’s clock rates – extremely efficiently into signals with several times higher frequency. The researchers present their results in the scientific journal “Nature”.

Graphene – an ultrathin material consisting of a single layer of interlinked carbon atoms – is considered a promising candidate for the nanoelectronics of the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

One of the world’s most prominent strategic forums for global health held in Berlin in October 2018

03.09.2018 | Event News

4th Intelligent Materials - European Symposium on Intelligent Materials

27.08.2018 | Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

 
Latest News

Making better use of enzymes: a new research project at Jacobs University

19.09.2018 | Life Sciences

Light provides spin

19.09.2018 | Physics and Astronomy

Enjoying virtual-reality-entertainment without headache or motion sickness

19.09.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>