The State of Arsenic in Nepal - 2003 - Harvard University ...

3 . Arsenic in groundwater in East and South Asia
Arsenic contamination in groundwater has been reported in
more than 20 different countries around the world.
Environmental health crises related to arsenic presently are
present in Bangladesh, West-Bengal, India, China (including
Inner Mongolia), and Taiwan. During the past two-three
years arsenic contamination has also been reported in Laos,
Vietnam, Cambodia, Myanmar, Pakistan, and Nepal
(Chakraborti et. al, 2001).
Taiwan: Arsenic contamination in groundwater in Taiwan
was first identified in the year 1960. The well-known black
foot disease was observed in this country, where arsenic
concentration in groundwater was found as high as
1,800 µg/l (Smedley et. al, 2001).
Thailand: Arsenic contamination in groundwater was
identified in Ron Phibun District in Nakhon Si Thammarat of
southern Thailand in 1987, and is one of the worst case of
arsenic poisoning related to mining activity. Arsenic
concentrations up to 5,000 µg/l were found in shallow ground
waters. By the late 1990s, around 1,000 people had been
diagnosed with arsenic related skin disorder. Maximum
average arsenic concentration in stream water related to
mining was 1,000 µg/l during 1992-1997, and then decreased
to 590 µg/l in 1998 and 290 µg/l in 1999 (Buapeng et. al,
2001).
Vietnam: A comprehensive survey on arsenic in
groundwater and drinking water in the city of Hanoi and of
the surrounding rural districts in Red River Delta of northern
Vietnam revealed arsenic concentrations in the groundwater
ranging from 1–3,050 µg/l. The initial survey showed that
48% of the tested groundwater samples exceeded the national
standard of 50 µg/l and 72% exceeded the WHO guideline
value of 10 µg/l. Arsenic concentration in the tap water of
Hanoi city ranged from 25–91 µg/l. The population
consuming water with arsenic concentrations more than 50
µg/l is estimated to be greater than one million (Smedley et.
al, 2001).
3
India: Arsenic contamination in groundwater and noncirrhotic
portal hypertension due to chronic arsenic intake
was first reported in India from Chandigarh, Punjab in 1976.
In West Bengal, it was reported for the first time in 1983,
when 22 villages from 12 blocks in 5 districts were identified.
The population, drinking water with arsenic concentrations
greater than 50 µg/l (as high as 3,200 µg/l) is estimated to be
about 6 million covering an area of 23,000 km 2 . Out of the
101,934 tube wells water samples tested, 52% and 25% of
the tubewells contain arsenic concentration above the WHO
guideline value of 10 µg/l and national Indian standard of 50
µg/l respectively. Recently analyzed the arsenic content of
206 tubewells in the Semria Ojha Patti village in the Middle
Ganga Plain of Bihar and found 56.8% samples exceeded 50
µg/l (Chakraborti et. al., 2003).
Pakistan: Using Merck field test kits in the Punjab, Sindh
and Baluchistan, 8,777 water samples were tested in Pakistan.
The water testing shows that district of Multan and Rahim
Yar Khan in Punjab, and Dadu and Khairpur in Sindh are
found to have highest number of wells with arsenic exceeding
the national standard of 50 µg/l. All districts in Punjab and
Sindh have arsenic in the range of 10–50 µg/l. There were
777 groundwater samples (about 9%) found above 10 µg/l
and 58 samples (less than 1%) have arsenic concentrations
greater than 50 µg/l. Water samples from 11 districts were
found to have arsenic concentrations exceeding 50 µg/l
(Memon et. al, 2002).
Bangladesh: Arsenic contamination in groundwater in
Bangladesh was not reported until 1993. An estimated 30-45
million people are exposed to drinking water with arsenic
concentration greater than the national standard of 50 µg/l
(as high as 2,500 µg/l) on the delta of the Ganges,
Brahmaputra, and Meghna rivers. The affected aquifers are
generally shallow, with a depth of 15-60 m. Out of 64 districts
in the country, 60 districts are reported to have naturally
occurring arsenic in groundwater (Biswas et. al, 2003). A
national survey by the British Geological Survey for the
DPHE shows that 27% of the shallow tube wells exceeded
50 µg/l and 46% exceeded 10 µg/l (BGS and DPHE, 2001).
Less than 1% of the tested tube wells deeper than 150 m
exceed 50 µg/l and 5% exceed 10 µg/l (Burgess, et. al, 2001).