| At least 140 million people in 50 countries have been drinking watercontaining arsenic at levels above the World Health Organization guideline |
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A United Nations University study compares for
the first time the effectiveness and costs of many different technologies
designed to remove arsenic from groundwater – a health threat to at least 140
million people in 50 countries.
Released today by UNU’s Canadian-based
Institute for Water, Environment and Health, the report 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,” according to the report.
From 2014 to 2018, over 17,400 arsenic-related
publications were published and “there is a myriad of reportedly
‘low-cost’ technologies for treating arsenic-contaminated water. But the
specific costs associated with these technologies are rarely documented,”
says Duminda Perera, a Senior Researcher at UNU-INWEH and report
co-author.
The summary of costs and effectiveness of the
few dozen arsenic remediation technologies that are directly comparable in
those respects (table: http://bit.ly/2MpVWaa) can serve as a preliminary guideline for
selecting the most cost-effective option, he says. It may also serve as an
initial guideline (minimum standard) for summarising the results of future
studies describing arsenic remediation approaches.
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
µg/L – micrograms per litre), 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
says. “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.”
“This policy approach is not well-conceived
as it does not effectively resolve the issue.”
It is estimated that in Bangladesh, for
example, where the nationally-acceptable arsenic limit in water is set to 50
µg/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 µg/L or more.
Key findings:
UNU studied 23 technologies independently tested in
laboratory settings using groundwater from nine countries – Argentina,
Bangladesh, Cambodia, China, Guatemala, India, Thailand, the United
States, and Vietnam – and demonstrated efficiencies ranging from 50% to
~100%, with a majority reaching <90%. About half achieved the WHO standard
of 10 µg/L.
14 technologies tested in the field (at the household
or community level, in Argentina, Bangladesh, Chile, China, India, and
Nicaragua) achieved removal efficiency levels ranging from 60% to ~99%,
with 10 removing more than 90%. Only five reached established
the WHO standard.
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.
For lab tested technologies, the cost of treating one
cubic meter (m³) of water ranged from near-zero to ~US$93, except for
one technology which cost US$299 per m³. For field tested technologies, the
cost of treating 1m³ of water ranged from near-zero to ~US$70.
Key factors influencing removal efficiencies and
costs:
the arsenic concentration of the influent water
pH of the influent water
materials used
the energy required
absorption capacity
labour used
regeneration period and
geographical location
Remediation
technologies that demonstrate high arsenic removal efficiencies in a
laboratory setting need to be further assessed for their suitability for
larger-scale application, considering their high production and operational
costs.
Costs can be reduced
by using locally available materials and natural adsorbents, which provide
near zero-cost options and can have high arsenic removal efficiencies.
Leading authors Yina
Shan and Praem Mehta, who worked at UNU-INWEH and are now at McMaster
University, noted that exposure to arsenic can lead to severe health, social
and economic consequences, including arsenicosis (e.g. muscular weakness,
mild psychological effects), skin lesions and cancers (lung, liver, kidney,
bladder, and skin).
Social implications of
these health impacts include stigmatization, isolation, and social
instability, they added. 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 US$13.8 billion by around 2030.
Looking ahead, the
study identifies priority areas to assist in commercializing wide-scale
implementation of arsenic removal technologies.
“The main objective
of the report is to help accelerate the wide-scale implementation of
remediation solutions to alleviate, and ultimately eradicate, the problem of
arsenic-contaminated water consumption over the next decade and meet the
world’s Sustainable Development Goals,” says UNU-INWEH Director Vladimir
Smakhtin.
“This report aims
to inform decision-makers who face an arsenic public health challenge, of the
specific costs and effectiveness of technologies tested in laboratory or
field settings. It also urges researchers to present cost and effectiveness
data cohesively to better inform planners’ and policymakers’ choice of the
best arsenic remediation technologies.”
“Today, the
current science and knowledge on arsenic remediation technologies may be
mature enough to help significantly reduce the numbers of people affected by
this public health problem. However, the effective translation of research
evidence and laboratory-level successes into quantifiable and sustainable
impacts on the ground requires a concerted and sustained effort from
policymakers, engineers, healthcare providers, donors, and community
leaders.”
* * * * *
Authors
Yina Shan, UNU-INWEH, McMaster University
Praem Mehta, UNU-INWEH, McMaster University
Duminda Perera, Senior Researcher, UNU-INWEH
Yurissa Varela, UNU-INWEH, University of Ottawa
* * * * * Background High natural levels of inorganic arsenic exceeding the WHO limit are a characteristic feature of groundwater in many countries, including Bangladesh, India, Nepal, Mongolia, and the United States. Most arsenic-contaminated groundwater is caused naturally, some is caused by industry – mining, fertilizers / pesticides, waste disposal, and manufacturing. In nature, the poison can be released from arsenic-rich rocks by high acidity (pH) in oxygen-rich groundwater. Arsenic contamination is also mobilized by human interventions, such as. Globally, the primary route of human exposure to arsenic is contaminated drinking water; some is the result of irrigating crops with contaminated water. Sustainable Development Goal 3 (“good health and wellbeing”), adopted by UN Member States in 2015 for achievement by 2030, recognized the need to remove hazardous chemicals, including arsenic, from the world’s ecosystems. SDG 3.9 aims to “substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water, and soil pollution and contamination.” And SDG 6 (“Clean water and sanitation”) includes target 6.3, calling for an “improvement to water quality by reducing pollution, eliminating dumping and minimizing the release of hazardous chemicals and materials” (https://sustainabledevelopment.un.org). Estimated risks for arsenic contamination in drinking water based on hydrogeological conditions. (https://serc.carleton.edu/integrate/teaching_materials/water_science_society/student_materials/648) Schwarzenbach et al., 2010 * * * * * UNU-INWEH http://bit.ly/1vjfKAS The UNU Institute for Water, Environment and Health is a member of the United Nations University family of organizations. It is the UN Think Tank on Water created by the UNU Governing Council in 1996. Its mission is to help resolve pressing water challenges of concern to the UN, its Member States and their people, through knowledge- based synthesis of existing bodies of scientific discovery; cutting edge targeted research that identifies emerging policy issues; application of on-the-ground scalable solutions based on credible research; and relevant and targeted public outreach. |