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What happens when exposed to arsenic?
Arsenicosis symptoms usually take six months
to years — from the time of exposure — to develop, depending on the exposure
level (the concentration of arsenic in water and food and its consumption by the
population) and the nutritional status of the community and individuals (see Box: Early
symptoms).
| Early symptoms |
| According to the World Health
Organization, intake of one milligramme of inorganic arsenic per day may give rise to skin
lesions within a few years.1 The early symptoms of arsenicosis — arsenic poisoning
— are manifested in the form of dark patches (melanosis) along with white patches
(leukomelanosis) on the skin (extremities), corn like lesions on palms and soles
(keratosis), increasing weakness and numbness of limbs (neurological manifestation) and
breathing problems (respiratory manifestation). |
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| Source: ATM. Farid et al
2003, A study of arsenic
contaminated irrigation water and its carried over effect[s] on vegetable[s], Fate of
Arsenic in the Environment, Proceedings of the BUET-UNU International Symposium, February
5-6, Dhaka, Bangladesh, mimeo. |
Prolonged exposure to arsenic may result in malignancy of skin, liver, kidney,
lungs and bladder. According to WHO, cancer risk (lifetime risk of dying from cancer) from
exposure to more than 0.05 milligramme arsenic per litre per day is 13/1,000. 6
Arsenic in food
Arsenic has not only infiltrated our drinking water sources, but also started impregnating our food chain with a vengeance. In 2003, Andrew
Meharg, a bio-geochemist at the University of Aberdeen in Scotland, and his team conducted
a study in Bangladesh to examine the arsenic assault on food chain. Soils in the regions
conspicuous with large number of irrigation pumps supplying arsenic-tainted water
contained high levels of arsenic. 7 A study conducted by Bangladesh University of
Engineering and Technology, Dhaka, has highlighted the fact that arsenic concentration in
the soil, particularly in the top layer, increases in direct proportion to the increase of
arsenic in irrigation water.
School of Environmental Studies (SOES) in Kolkata has come up with a calculation
that every year, 6.4 tonnes of arsenic is deposited on the agricultural fields of Deganga
Block of North 24-Parganas in West Bengal owing to the irrigation from the existing 3,200
irrigation tube-wells. Food crops grown on this arsenic-laden soil imbibe arsenic in
dangerous proportion. Rice samples tested in the contaminated regions have been reported
to contain arsenic at unsafe levels. The recommended daily safe levels of dietary intake
of arsenic (milligramme) for adults range between 0.171 and 0.189 and for children between
0.092 and
|
Arsenic diet
Arsenic levels (in milligramme per kilogramme (mg/kg)) in food items |
| Tuber |
150 |
| Tomato |
20.1 |
| Cabbage |
7.2 |
| Bean |
5.1 |
| Leafy vegetables |
4.5 |
| Cauliflower |
2.7 |
| Papaya |
1.1 |
| Vegetable curry |
0.81 |
| Rice |
0.35 |
| Spinach |
0.33 |
| Fish curry |
0.27 |
| Note:
Maximum permissible limit—0.2 mg/kg. Source: Andrew Meharg 2004, Arsenic in rice –
under-standing a new disaster for South East Asia, in Trends in Plant Science, Vol 20, No
20, pp 1-3. |
0.101. It is not only the raw food items that
are spiked with high concentration of
arsenic. Studies show that cooking doesn’t rid arsenic from our food, as cooked food
has also been reported to be high on arsenic (see Table: Arsenic diet). Various
studies conducted in West Bengal reveal the presence of arsenic in perilously high levels
in potato skin, vegetable leaves, arum leaf, papaya, rice, wheat, cumin, turmeric powder,
cereals, bakery food and spices.
According to Chakraborti, underground vegetables (roots, tubers and bulbs) contain
relatively higher concentration of arsenic. Adverse health implications due to arsenic
have been reported in animals as well. Presence of arsenic in rice straw — widely
used as fodder — can adversely affect cattle and, subsequently, human beings via the
plant-animal-human pathway. Elevated concentration of arsenic has been detected in the
hair and urine of cows and
buffaloes in the arsenic-affected villages. Local ice creams and cold drinks have
also been found to be laced with arsenic.
Nutrition has a say
Nutrition plays a decisive role in the prevention or the onset of arsenic-related
ailments. Low dietary intake of protein and micronutrients (calcium, selenium, vitamins)
increases vulnerability to arsenic-related diseases. The reason could be that nutrition
deficiency might result in slow elimination of arsenic from the body. Studies confirm that
people with poor nutrition develop skin manifestations after drinking water containing
arsenic at concentration 0.3 milligramme per litre. On the other hand, a healthy diet
offsets any such adverse impact. People with good nutrition were found to be in good
health even after drinking water containing arsenic at concentration 0.4 milligramme per
litre.
Strategies to combat arsenic
We must recognise that managing arsenic is more about effective water management
strategies and less about technologies to remove the toxin. The problem of arsenic
poisoning abounds because people residing in regions blessed with abundant surface water
increasingly depend on groundwater, especially for drinking purposes. This dependency can
be checked only by making available other safe drinking water options.
In neighbouring Bangladesh, for instance, mitigation
efforts include cleaning traditional ponds used to rear fish. As most of the
arsenic-affected regions receive abundant rainfall, rainwater harvesting could be a
feasible proposition in these areas. Collecting rainwater directly from the rooftops, or
channelling the rain into shallow bodies or even dug wells for household use is another
viable alternative. But it is essential to combine all these strategies with good
sanitation practices.
| Five-point programme |
| World Health Organization recommendations
to manage arsenicosis 1. Stop drinking
arsenic-contaminated water
2. Administration of specific drugs or nutrients (eating more of locally available fresh
vegetable and fruits) to hasten recovery or arrest further progression
3. Symptomatic management
4. Prevention of latent effects (for example, malignancy) through medical surveillance
5. Counselling and educating the affected persons and
family members |
| Source: WHO 2004. A
field guide for detection, management and surveillance of arsenicosis, WHO, New Delhi, pp
13-25. |
Management and surveillance
Arsenicosis can be successfully managed by surveillance and careful case management. The
primary objectives of the surveillance are to identify the disease in individuals within a
community, to monitor the trend of the disease and to follow up patients for clinical
management. Surveillance is essentially the responsibility of health department, public
health engineering department and state water and sanitation department.
Medicos can also play an important role in arsenicosis
surveillance by diagnosing the case clinically and looking for similar kind of symptoms in
patient’s family or locality. Generally, the practitioners are illequipped to
diagnose and treat this disease, as it doesn’t feature as a priority disease in the
medical curriculum. In order to rationalise the detection, management and reporting of
cases, WHO recommends two major diagnostic criteria: presence of pigmentation and
keratotic skin lesions, and evidence of exposure to arsenic by assessing arsenic
concentration in hair and nail (see Box: Five-point programme).
 |
| Arsenic has not only infiltrated our
drinking water sources, but also started impregnating our food chain with a vengeance |
The water and other biological samples (nail and hair of
clinically diagnosed patients) should be sent to the right authorities — like SOES,
Jadavpur University, Kolkata — for further examination. If the history on arsenic
concentration is unclear, an elevated concentration of arsenic in hair (>0.8
milligramme per kilogramme (kg)) or nail clippings (>1.3 milligrammes per kg) may serve
as a presumptive evidence of chronic exposure.
Any unhealed ulcer (suspected malignancy) in soles, palms
or any other part of the body ought to be diagnosed keeping the possibility of chronic
arsenicosis open.
There is no specific treatment for arsenicosis.
Nevertheless, there are some conflicting opinions on using chelating agents (Dimercaprol,
D-peni-cillamine) to eliminate arsenic from the body. But the results are not very
encouraging (as these medications can lead to some adverse side effects) and thus need
further evaluation. Moreover, these drugs are exclusive and expensive.
In West Bengal, the most prevalent practice for treating
keratotic lesions is the application of 5-10 per cent salicylic acid and 10-20 per cent
urea-based ointment.
How
effective are field kits?
To overcome the problem of long-distance transporting of water from far-off
arsenic-affected areas to high-tech laboratories, portable, reliable, sensitive and
user-friendly field kits were introduced. These offer instant results on the site itself
and thus can be used in remote areas where laboratory facilities are not available.8 UNICEF was the first agency to use these kits for testing arsenic
in the well water in mid-1997.
This encouraged a number of field kit
manufacturers to jump into the fray (see Table: Fielding kits). Majority of the
kits are based on colorimetric reactions in which inorganic arsenic is reduced to arsine
gas. The Industrial Toxicology Research Centre, Lucknow, is also in the process of
bringing out a field kit.9 It would be based on voltametric technology — the effect of
electrical conductivity on charged particles in water.
Fielding kits |
| Information on various field kits
available to test arsenic in water |
| Agency |
Cost |
Range (ppb) |
Availability |
Places they have been used |
| Hach |
Rs 7,678. Kit comes with reagents and
accessories to perform 100 tests |
0-500 ppb |
National Metallurgical Laboratory,
UNICEF, Bengal Engineering College, Punjab University |
Chennai, Kolkata, Delhi |
| NCL |
Kit — Rs 4,800, testing —
100 tests |
5-10 ppb |
Not widely marketed |
In parts of Jharkhand and Patna,
Bihar, primarily by UNICEF. |
| Development Alternatives |
Kit — Rs 2,500, testing — 50
samples for Rs 600 or Rs 12 per sample |
10-400 ppb |
NGOs and school groups |
Widely used by NGOs in parts of
Jharkhand, Orissa and Rajnandgaon in Chattisgarh |
| NEERI |
Kit — Rs 3,000, testing — Rs
3 per sample |
10-1,000 ppb |
Developed on behalf of WHO and ready
to be marketed |
Currently not in operation |
| Notes: UNICEF:
United Nations Children's Fund; WHO: World Health Organization, NGO: Non-governmental
Organisation, NCL: National Chemical Laboratory, NEERI: National Environmental Engineering
Research Institute; ppb: parts per billion Sources: 1. Hach undated, Hach EZ arsenic test
kit, HACH Company, Colorado, USA, p 3. 2.
O G B Nambiar 2004, Scientist, Chemincorp, Pune, October 14, personal communication.
3. Manoj Kumar 2004, Scientist, Tara
Environment Monitoring Facility, Development Alternatives, New Delhi, October 7, personal
communication.-----------------
4. S P Pande 2004, Head, R&D
Planning and Business Development Division, NEERI, October 11, personal communication. |
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