Only five of the 14 technologies designed to remove arsenic from groundwater -- a health threat to at least 140 million people in 50 countries -- tested also in India reached levels of the World Health Organization (WHO) standard, a United Nations University study said on Thursday.
But all the 14 technologies achieved removal efficiency levels ranging from 60 to 99 per cent, with 10 removing more than 90 per cent.
This fact came to light in a report, "Cost and Efficiency of Arsenic Removal from Groundwater: A Review", by United Nations University's Canada-based Institute for Water, Environment and Health.
It said technologies that demonstrate high removal efficiencies when treating moderately arsenic-contaminated water may not be as efficient when treating highly contaminated water.
Also, the lifetime of the removal agents is a significant factor in determining their efficiency.
The 14 technologies tested in the field -- at the household or community level -- are in Argentina, Bangladesh, Chile, China, Nicaragua, besides India.
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It also studied 23 technologies independently tested in laboratory settings using groundwater from nine countries -- Argentina, Bangladesh, Cambodia, China, Guatemala, India, Thailand, the US and Vietnam -- and demonstrated efficiencies ranging from 50 to 100 per cent, with a majority reaching above 90 per cent.
About half of these technologies achieved the WHO standard of 10 Aug/L (micrograms per litre).
The study compares for the first time the effectiveness and costs of many different technologies designed to remove arsenic from groundwater.
It draws on 31 peer-reviewed, comparable research papers published between 1996 and 2018, each describing new technologies tested in laboratories and or in field studies.
And while no single technology offers a universal solution, the research helps point to remedies likely to prove most economical and efficient given the many variables present in different locations worldwide.
Serious health, social and economic losses are caused worldwide by arsenic-contaminated water and a wide range of technologies exists to remove it but "their widespread application remains limited", said the report.
From 2014 to 2018, over 17,400 arsenic-related publications were published and "there is a myriad of reportedly alow-cost' technologies for treating arsenic-contaminated water.
"But the specific costs associated with these technologies are rarely documented," said Duminda Perera, a Senior Researcher at Institute for Water, Environment and Health and report co-author.
The report notes that "arsenic-removal technology should only be seen as efficient if it can bring the water to the WHO standard"
In 2010, WHO's recommended a drinking water limit of 10 Aug/L, but countries with resource constraints or certain environmental circumstances e.g. typically high arsenic concentrations in groundwater have much higher, easier-to-reach concentration targets.
"While this may help national policymakers report better results for their national arsenic reduction efforts, it may have the opposite effect on public health," the report said.
"Higher thresholds will not help solve this public health crisis. On the contrary, if a country has a feeling that the arsenic situation is coming under control, this may reduce the sense of urgency in policy circles to eradicate the problem, while the population continues to suffer from arsenic poisoning."
It is estimated that in Bangladesh, for example, where the nationally-acceptable arsenic limit in water is set to 50 Aug/L, more than 20 million people consume water with arsenic levels even higher than the national standard.
And globally, despite international efforts, millions of people globally continue to be exposed to concentrations reaching 100 Aug/L or more.
Leading authors Yina Shan and Praem Mehta noted that exposure to arsenic can lead to severe health, social and economic consequences, including arsenicosis e.g. muscular weakness and mild psychological effects), skin lesions and cancers -- lung, liver, kidney, bladder and skin.
Arsenic-related health complications and mortality also lead to significant economic losses due to lost productivity.
The economic burden in Bangladesh is projected to reach $13.8 billion by around 2030.
--IANS
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