|
Khin Myat Tun*, Sabai Nyi*, Thuzar Myint*, Than Htut**, Min Than Nyunt**, Myint Thein**, Yin Kyi Oo**, Than Tun Sein***
|
Abstract
A cross sectional survey was conducted to assess
the arsenic content of groundwater in Kyonpyaw and Thabaung townships,
Ayeyarwaddy Division in Myanmar during 2002. A survey covered 15 villages
in Thabaung and 10 villages in Kyonpyaw townships. A total of 99 water
samples either from tubewells or dug wells (sources) and 74 household-water
samples (actual sites of consumption) were collected. Arsenic content of
the water was determined by using atomic absorption spectrophotometry.
It was observed that 66.6% of the 99 collected
water samples from wells {83 arsenic-contaminated and three arsenic-free
shallow tubewells that had previously been identified by test kit together
with additional 13 wells which had not been tested before} had arsenic
levels of more than the national standard of 0.05 mg/l. However, only 36.5%
of the household water from drinking water pots had arsenic level of more
than 0.05 mg/l, indicating that the arsenic levels of water at the sites of
consumption were lower than at the water sources.
In addition, the exposed population in these
townships was assessed by examining any skin symptoms or other relevant
clinical manifestations for identification of cases with arsenicosis. Two
probable cases of arsenicosis were detected, which showed symptoms of
dermal changes likely to be the early stage of arsenical skin
manifestation. High arsenic content in their nail samples indicated the
evidence of exposure. Furthermore, the arsenic content of the water in the
tubewell which they had used, was eighteen times higher than the national
standard of 0.05 mg/L. In addition, arsenic content of the water from their
drinking water pots was six times higher than the national standard. After
six months of follow up assessment, it was observed that their skin
pigmentation became faded after stopping consumption of
arsenic-contaminated tubewell water.
Since this is the first health
survey done on arsenic contamination of groundwater and its impact on the
health of the population, further and thorough evaluation of the extent of
the arsenic problem in the potential areas should be considered.
|
Introduction
The provision of an adequate supply of safe water was
one of the eight components of primary health care identified by the International
Conference on Primary Health Care in Alma-Alta in 1978. The safe quality of
water supplied to communities is an important consideration in the protection
of human health and well-being.
Tubewells with hand pumps have proven effective in
providing bacterially safe water at a low cost and are widely accepted in the
developing world, including Myanmar. Although the great majority of
quality problems with community drinking water are related to faecal
contamination, a significant number of serious problems may occur as a result
of chemical contamination from a variety of natural and man-made sources.
Programmes to provide "safe" drinking water over the past 30 years
have helped to control water-borne diseases such as diarrhoea, dysentery, typhoid,
cholera and hepatitis. But in some areas, they have had the unexpected side
effect of exposing the population to another health problem – ‘arsenic’.
Natural contamination of groundwater by arsenic has
become a crucial water quality problem in many parts of the world,
particularly in the Bengal Delta (Bangladesh and West Bengal, India) (1-6).
Arsenic contamination of groundwater and other sources of drinking water have
also been documented in many countries, such as Thailand(7), Vietnam (8), Taiwan (9), Chile, USA, Mexico, Hungary, and China (10).
Arsenic contamination of groundwater in Myanmar first came to attention in the
year 2000. Since then, rapid field-testing for arsenic was conducted by the
Water Resources Utilization Department (WRUD) and the Department of
Development Affairs (DDA), Save the Children (UK) and UNDP/UNCHS. The test
results showed the presence of arsenic in varying degrees in different parts
of the country and in several water sources.
This prompted us to evaluate the arsenic field test kit
results of the tubewell water samples and detect the cases of arsenicosis in
the exposed population in selected villages in Thabaung and Kyonpyaw
townships in Ayeyarwaddy Division.
Objectives
The objectives of the survey were:
 To determine the arsenic levels of the dug
wells and shallow tubewells [previously detected and identified by field test
kits] by using Atomic Absorption Spectrophotometry (AAS);
To study and evaluate the cases of chronic
arsenic toxicity (arsenicosis) of the exposed population in the study area,
and
To compare the arsenic levels at the sources
and at the sites of the actual consumption.
Methodology
Study area and population
Cross-sectional survey for determination of arsenic
content in groundwater and case detection for chronic arsenic poisoning of
the exposed population was conducted in Thabaung and Kyonpyaw townships in
Ayeyarwaddy division, Myanmar.
Five village tracts in Kyonpyaw and six in ThabaungTownship, whose tubewells with arsenic
content of more than 0.05 mg/L, were selected on purpose. From these
respective village tracts, fifteen villages in Kyonpyaw and ten villages in
Thabaung townships were further selected for the study.
Active case detection for chronic arsenic poisoning of
the exposed population and water samples collection were carried out during
March 2002.
Sampling methods
A multistage sampling procedure was employed with the
following details.
Thabaung and Kyonpyaw
Townships were selected on
purpose, as it had been reported that groundwater arsenic content of many
tubewells in these townships were in excess of the proposed national standard
0.05 mg/L.
Village tracts in the above townships, whose
tubewells were previously reported as having arsenic contamination of >
0.05 mg/L were purposely selected.
Approximately 10% of contaminated tubewells
previously tested with field test kit by SC (UK) in each townships were
selected for validation of water arsenic level for this study. At least 30
wells in each township had to be tested. Random selection of tube wells as
well as dug wells serving as drinking water source for the community was
performed. Forty-five wells in Kyonpyaw and fifty-four in Thabaung townships
were tested for this study.
All households in the vicinity of these
selected arsenic contaminated tube-wells in Thabaung and Kyonpyaw townships
were eligible for the study. All households using water from the nearby
surrounding wells either for drinking or cooking purposes were selected; all
members from the selected households were chosen as exposed persons, and
clinical assessments were done for the evidence of chronic arsenic poisoning.
Methods of Data Collection
The survey consisted of two components: Collection of
water samples from selected shallow tubewells or dug wells along with
representative water samples from household drinking water pot for each well
from which it was fetched.
The other component was data collection by using
pre-tested structured questionnaire together with clinical assessment of the
study population. The health impact of chronic arsenic poisoning was assessed
through observation of dermal changes and physical examination of the
residents in the survey area.
Before the field survey, a series of training courses in
field data collection were conducted for interviewers. Trained interviewers
were allocated into three survey teams for collection of data and water
samples. The team leaders and members checked data quality every night of the
field survey.
During the home visits, face-to-face interviews were
conducted using a pretested structured questionnaire to obtain information on
sociodemography, life style factors and history of occupation and water use
as well as for tubewell characteristics.
The survey covered a total of 25 villages, 10 villages
in Kyonpyaw and 15 villages in ThabaungTownship. Number of households studied in
Kyonpyaw and Thabaung townships was 276 and 272 respectively. A total of
2 473 members from these households were studied and clinically assessed
for any evidence of arsenicosis and anthropometrics examination.
Water samples of forty-five wells (either tubewell or
dug well) from Kyonpyaw and fifty-four from ThabaungTownship were collected. In addition, 74
water samples from households were taken for determination of water arsenic
level. Water samples were stored in dry clean plastic containers and
acidified with 1% nitric acid (10 cc of nitric acid in 1 litre of water).
Arsenic content was determined at the Occupational Health laboratory in Yangon by using Atomic Absorption
Spectrophotometry (graphite furnace).
Data analysis
All data collected were computed by using Epi info
Version 6 (Centers for Disease Control, Atlanta, Georgia). Validity and consistency of
data were checked before performing analytical procedures. Stata version 6
statistical software (StataCorp, College Station, Texas) was used for data analysis.
Descriptive analyses were made using tabulation to obtain an overall view of
the data.
Results
Study population of 2473 for both townships consisted of
47.4% male and 52.6% female and the age ranged from 1 to 95 years. Ninety nine water
samples from wells and 74 water samples from households were assessed for
arsenic level.
Determination of the arsenic levels of the wells
Out of 99 wells tested in both townships, 90 are shallow
tubewells and nine are dug wells. All water samples from dug wells showed
that arsenic level was less than 0.05 mg/L.
It was observed that 66.7% (66/99) of the 99 collected
water samples from wells had arsenic levels of more than 0.05 mg/L, among
which 24 wells (36%) had arsenic level of ł 0.1 mg/L (Table 1).
|
Arsenic level (mg/L)
|
Number and percentage of wells
|
Total
|
|
Kyonpyaw
|
Thabaung
|
|
No.
|
%
|
No.
|
%
|
No.
|
%
|
|
< 0.05
0.051-0.099
> 0.100
|
15
17
13
|
33.3
37.8
28.9
|
18
25
11
|
33.3
46.3
20.4
|
33
42
24
|
33.3
42.4
24.3
|
|
Total
|
45
|
100
|
54
|
100
|
99
|
100
|
Comparison of arsenic levels at the sources and at
the sites of consumption
Representative water samples were collected from 74
households and only 36.5% (27/74) of the household water from drinking water
pots had arsenic level of more than 0.05 mg/L, indicating that the arsenic
levels at the sites of consumption were lower than that of the water sources
from which these were collected (Fig 1). In these areas, people usually
treated the drinking water by one or more of the following methods: keeping
water overnight in a pot causing sedimentation effect; filtration by
cloth-filter; or treating with alum, which may have led to the reduction of
arsenic content in the water.
Identification of probable arsenicosis cases
In addition, probable cases with arsenicosis of the
exposed population in these townships were identified by examining any skin
symptoms or other relevant clinical manifestations. Two cases of arsenicosis
were identified during the field survey.
Case report (I)
The patient was Daw MK, 68 years old lady, who has lived
in Upper Thaung Ywa in KyonPyawTownship since her birth. She complained
of tingling and numbness of lower extremities for two years and darkening of
the skin over her lower chest and back for the same duration. She also gave
history of ischaemic heart disease (IHD) for six years but no history of
hypertension, diabetes mellitus, weakness/asthenia and brittleness of the
nails. Personal history revealed habit of smoking cheroots for thirty years’
duration with no history of consuming traditional medicine on a regular
basis. Physical examination showed pallor and low body mass index (BMI) of
17.57. Conjunctivitis and periorbital oedema were absent. There were multiple
spotted areas of melanosis over the lower chest and back, but no typical
pattern of hyperkeratosis of palms and soles. Her drinking water source was
the tubewell with water arsenic level of 0.942 mg/L, which is much higher
than the maximum permissible level of 0.05 mg/L. This tubewell had been dug
for three years and the depth was 142 feet. The household water sample from
drinking water pot had water arsenic level of 0.307 mg/L. For the
confirmation of chronic arsenic exposure, the nail sample was sent to the School of Environmental Studies, JadavpurUniversity laboratory in India. The method used for the test
was Flow injection-hydride generation-atomic absorption spectrometry
(FI-HG-AAS). Nail sample arsenic content was 1 950 µg/Kg, which was much
higher than the reference value. (Normal range for arsenic level in Nail = 430 –
1080 µg/Kg).
Case report (II)
The second case was of Daw OK, 63 years old lady, also a
resident of Upper Thaung Ywa in KyonpyawTownship. She developed a change in skin
colour (hyperpigmentation) of her trunk. There was no similar complaint in other
family members. The patient denied history of hypertension, IHD, diabetes
mellitus, tingling and numbness of the extremities, brittleness of nails,
nausea, vomiting and abdominal pain. She was a chronic smoker of twenty
years’ duration, with no history of consuming traditional medicine on a
regular basis.
During physical examination, pallor was present, but no
periorbital oedema and conjunctivitis. Her BMI was 15.78, which was quite
low. There were depigmented macules in hyperpigmented skin commonly referred
to as ‘raindrop pigmentation’ over her trunk, especially at the back
(leukomelanotic type). Other skin manifestations were absent.
Her dinking water source was the same as the above
patient as they were next-door-neighbours. Both the tubewell and household
water arsenic contents were above the normal limits (0.942 mg/L and 0.307
mg/L respectively). Diagnosis of arsenicosis was supported by high level of
nail sample arsenic content (1894 µg/kg), tested in the laboratory mentioned
above by FI-HG-AAS method.
Discussion
This is the first small-scale health survey conducted in
Myanmar with the aim to determine the
arsenic content of the wells in the selected areas that had previously been
tested with field test kit, integrated with detection of arsenicosis cases of
the exposed population.
The survey showed that about two third of the 99 wells
{83 arsenic-contaminated and three arsenic-free shallow tubewells that had
previously been identified with field test kit together with additional 13
wells which had not been tested before} determined by using AAS had arsenic
content of more than 0.05 mg/L. The highest concentration of arsenic content
in well water was detected in Thaung Ywa, KyonpyawTownship, the concentration of which was
eighteen times higher than the national standard 0.05 mg/L.
The two probable cases of arsenicosis, who were next
door neighbours, were detected in the vicinity of this high-arsenic
contaminated tubewell. They had collected drinking water from this tubewell,
as one of the various water sources available. This tubewell had been dug for
three years and was situated just in front of their houses, both households
collected the water from this well and used it for drinking and cooking
purposes since then. The arsenic content of their nail samples was also
higher than the reference normal range for arsenic level in nail. People in
these villages were informed of the facts about the arsenic contamination of
the tubewell and advised to stop drinking contaminated water. These two cases
were examined after six months and their skin pigmentation had faded to some
extent.
Arsenic is widely distributed in nature and has many
uses in industry, agriculture and also in some traditional medicine. Khay Mar
Yee et al. (1986) reported that 12 patients with vitiligo treated with
indigenous medicine had the characteristic skin manifestations of chronic
arsenic poisoning. The skin changes comprised palmo-plantar keratosis and
raindrop dermatosis (11). The amount of arsenic consumed could not
be established, but the duration of treatment in these patients varied from
two months to 13 years. However, in our study, both cases denied history of
taking traditional medicine or other western medicine on a regular basis and
there was no history of exposure to insecticides.
None of the family members from these households showed
any other signs of dermal changes or other clinical manifestations of
arsenicosis. The health outcomes of exposure to arsenic depend on the
modality and duration of exposure as well as the source and type of arsenic (12).
Toxicity of arsenic depends on its accumulation in the body. The time taken
to develop symptoms in the human body is believed to depend on the dose,
exposure, body defense mechanism, nutritional status, and other unknown predisposing
factors. It is thought that it may take 2-20 years to develop symptoms (13).
In these areas, due to the variety of water sources used
by people for different purposes at different times of the year, it is
difficult to estimate how many people use shallow tubewells for drinking
water and how much they consume. Availability of various water sources makes
it possible for people to take the drinking water from other sources apart
from the tubewell.
In this study, 44% of the wells were less than five
years old. The impact of arsenic pollution on human health – arsenicosis is
typically gradual. It was stated that the clinical symptoms of chronic
arsenic poisoning from ingestion of contaminated water were typically
observed after five years of exposure (14, 15), coupled with the
fact that various water sources were available in these areas, the likelihood
of detecting clinical symptoms in the vulnerable population at present
appeared to be quite low. Furthermore, the early manifestations were
difficult to diagnose, particularly in the absence of awareness of potential
problems (16). Detection of symptoms was presumed to be most
likely at locations where arsenic levels were the highest and where people
had depended substantially on such sources for many years.
There is no medicine yet known that can cure
arsenicosis. The best treatment is to drink arsenic-free water, which can
reverse the symptoms in the early stages of the disease.
Based on the cultural and societal norms of Myanmar, people do care for quality of
water. Priority is however, given only to such physical characteristics as
clarity, odour and taste, and not to the harmful effects due to, for example,
bacterial content or chemical contamination, which cannot be seen. Awareness
about chemical pollution in drinking water should be raised so that the users
(community) become well positioned to take initiatives for improving the
quality of the water they drink.
The arsenic problem and its impact on the health of the
population are relatively new to Myanmar. In our survey, only a fraction
of potentially contaminated wells had been validated by AAS. The full
magnitude and the scale of the problem are still unknown. To assess the
magnitude of the problem, it is crucial to confirm the arsenic field test kit
results by the gold standard method AAS in potentially contaminated areas.
It is suggested that much could be learned from others
working on the problem. It is necessary to recognize the importance of
finding a middle path between the two extremes of "condemning the
contaminated wells and creating panic in the community" and
"keeping quiet to avoid the scare". Considering the early stage of
knowledge about arsenic in Myanmar, it is recommended that further
and thorough evaluation of the extent of the arsenic contamination of
groundwater and public awareness mechanism be intensified in order to
mitigate the severity of exposure.
Acknowledgements
The investigators would like to acknowledge their
sincere thanks to Professor Paing Soe, Director-General, Department of
Medical Research (Lower Myanmar) and Dr. U Wan Maung Director-General, Department of
Health for their permission to conduct this study.
We also wish to express our gratitude to Dr U Than Aung
(Divisional Health Director, Ayeyarwaddy Division), Dr U Aye Maung (Township
Medical Officer, Kyonpyaw), Dr U Kyaw Yin (Township Medical Officer,
Thabaung), and basic health staff from study villages in Kyonpyaw and
Thabaung townships, Ayeyarwaddy Division for their cooperation and help
during the study period.
We are grateful to UNICEF for providing financial
support for the study.
References
1. Nickson,
R, McArthur, J, Burgess, W, Ahmed, K M, Ravenscroft, P, Rahman, M, Arsenic
poisoning of ground water Nature 1998, 395; 338.
2. McArthur,
JM, Arsenic poisoning in the Ganges delta Nature 1999,
401; 546-547.
3. Acharyya,
SK, Chakraborty, P, Lahiri, S, Raymahas
hay, BC,Guha, S, Bhowmik, A; Arsenic poisoning in the Ganges
delta Nature 1999, 401 (6753): 545; discussion 546-547.
4. Chowdhury,
TR, Basu, GK, Mandal, BK, Biswas, BK, Samanta, G, Chowdhury,
UK, et al Arsenic
poisoning in the Ganges delta Nature 1999, 401-546.
5. Arsenic
contamination of groundwater in Bangladesh Final Report summary: Kinniburgh,
DG, Smedley, PL, Eds; Bangladesh Department for Public Health Engineering,
British Geological Survey: Keyworth, UK,
2000.
6. McArthur,
JM; Ravenscroft, P; Safiulla, S; Thiriwall, MF Water Resources Research,2001,
37; 109-117.
7. Foy-HM;
Tarmapai-s, Eamchan-P, Metdilagkul-O. Chronic arsenic poisoning from well
water in a mining area in Thailand Asia-Pacific Journal of Public Health
1992-93, 6(3); 150-2.
8. Michal
B, Hong Con Tran, Thi Chuyen Nguyen et al Arsenic contamination of
groundwater and drinking water in Viet Nam; A Human Health threat
Environmental Science and Technology, 2001, 35(13); 2621-2626.
9. Smith
AH, Hopenhayn-Rich C, Bates MN, Goeden Hm, Hertz-Picciotto I, Duggan HM, Wood
R, Kosnett MJ, Smith MT Cancer risks from arsenic in drinking water
Environmental Health Perspectives, 1992 July, 97; 259-267.
10. DPHE,
(1999) Groundwater studies for arsenic contamination in Bangladesh,
Rapid Investigation Phase, Final Report prepared for the Department of Public
Health Engineering by Mott Macdonald Ltd and the British Geological Survey
under assignment from the Department for International Development (UK).
11. Khay
Mar Yee, Khin Maung Kyaw, Hnin Yee, Khin Nu Nu & Aye Nyein (1986) Paper
presented in Research Paper Reading Session, Medical Science Division,
Yangon, Myanmar.
12. Regional
Committee, Fifty-fourth Session Arsenic contamination in groundwater
affecting some countries in the South-East Asia Region Provisional Agenda
item 9 SEA/RC54/8, 3 July 2001,
3-4.
13. Ranjit
Kumar Dey Arsenic health problem In: An outcome of the International workshop
on Arsenic mitigation in Bangladesh,
Dhaka, 14-16 January, 2002, 59-78.
14. National
Research Council Arsenic in drinking water National Academic Press: Washington
DC, 1999.
15. Arsenic
exposure and health effects: Chappell WR, Abernathy CO, Calderon RL, Eds:
Elsevier Science: Kidlington, Oxford, UK,
1999.
16. Saha
JC, Dikshit AK, Bandyopadhyay M, Saha KC, A review of arsenic poisoning and
its effects on human health Critical Reviews in Environmental Science and
Technology 1999, 29; 281-313. * Clinical Research Division,
Department of Medical Research (Lower Myanmar) ** Occupational Health Division,
Department of Health *** Director, Department of Medical
Research (Lower
Myanmar)
|
