F.A.Q. on Arsenic
1. What is arsenic?
Ans: Arsenic (As) is a metalloid widely distributed in the earth’s crust. Elemental arsenic is a
member of Group VA of the periodic table, with nitrogen, phosphorus, antimony and bismuth. It
has an atomic number of 33 and an atomic mass of 74..91.
2. What are the different valence states of arsenic?
Ans: It can exist in four valence states: -3, 0, +3 and +5. Under reducing conditions, arsenite [As
(III)] is the dominant form; arsenate [As(V)] is generally the stable form in oxygenated
environments.
3. What are the forms of arsenic available in nature?
Ans: Arsenic and its compounds occur in crystalline, powder, and amorphous or vitreous forms. It
usually occurs in trace quantities in all rock, soil, water and air. It is the 26th abundant element in the
earth crust.
4. Which form of arsenic is most toxic?
Ans: Arsenite [As (III)] is most toxic form of arsenic if considering acute toxicity. It is
considered that for chronic toxicity As (III) and As (V) has similar toxicity. Previously it was
known that methylated forms of arsenic [MMA (V), DMA (V)] are less toxic, now it has been
reported that MMA (III) and DMA (III) are highly toxic.
5. What are the different exposure sources of arsenic?
Ans: The exposure sources of arsenic in the environment include natural and anthropogenic
sources.
Natural: Leaching of ambient arsenic in groundwater from sediments containing arsenic bearing
minerals; leaching and percolation of arsenic in soils.
Anthropogenic: Agrochemicals, wood preservatives, industrial sources, mineral processing, acid
mine drainage, burning of fossil fuels etc.
6. What are the toxic effects of arsenic?
Ans: Arsenic causes or increases the risk of numerous illnesses. Examples are skin damage
including keratosis and skin cancer, internal cancers such as lung and bladder, and diseases of the
vascular system. Other health problems, such as diabetes, cancers of the other organs and adverse
reproductive outcomes have been observed, but the evidence is not yet conclusive, although it
keeps increasing.
7. Will all be affected and show arsenical skin lessions drinking high arsenic contaminated
water?
Ans: Our field experience shows usually people drinking arsenic contaminated water for couple
of years may show arsenical skin lessions. But for > 500 μg/l the chance is more. However one
have found in some families all are affected except one. We do not know the exact reason.
8. Is there any treatment of arsenic?
Ans: Till date there is no claim for a successful treatment of arsenic poisoning. There are several
trials using chelation therapy using chelating agents like BAL (British Anti Luecent), DMPS (Di
mercipto Phenyl succinate), DMSA (Di mercipto phenyl succinic acid) etc. But the chelating
agents may work may work for acute toxicity. For chronic toxicity their effect has not been
proved yet. Arsenic safe water and nutritious food are best medicine for chronic arsenic
treatment.
9. What is the source of arsenic in GMB Plain?
Ans: The flood plains of many rivers originating from the Himalaya Mountains and the Tibetan
plateau are affected. The Ganga plain foreland basin is a repository of sediments derived from
Himalaya and peninsular croton. The weathered material brought from the Himalaya is deposited
in the alluvial plain where they undergo further chemical weathering mobilizing several anions
and cations. In Ganga river sediments As, Cr, Cu, Pb, U, Th, W etc. are concentrated
significantly.
10. How many states in India is arsenic affected?
Ans: Till date 8 states, West Bengal, Bihar, Uttar Pradesh, Jharkhand, Chhattisgarh, Assam,
Nagaland, Manipur, Tripura, Arunachal Pradesh are found to be arsenic affected. Major
contamination is in West Bengal, Bihar, Uttar Pradesh and Jharkhand.
11. What is the magnitude of groundwater arsenic contamination in GMB Plain?
Ans: According to our latest estimates, parts of all the states and countries surveyed in the
Ganga-Meghna-Brahmaputra (GMB) plain, which has an area of approximately 500,000 km2 and
a population over 500 million, are at risk from groundwater arsenic contamination.
12. What are the alternative options of arsenic free water?
Ans: The alternate sources may be dugwell, surface water, deep tubewell tapping arsenic free
aquifer, rainwater. The option is location specific. Except deep tubewells there is possibility of
bacterial contamination to other sources. Now technologies are available to clean water from
bacterial contamination.
13. Why some of the dugwells are arsenic contaminated?
Ans: Usually dugwell water is under oxidation condition and if dugwell water contains enough
iron and not in reducing condition dugwells is expected to be arsenic free.
14. How arsenic is being released to groundwater from sediment in deltaic region of West Bengal
and Bangladesh?
Ans: There are various theories considered for leaching of arsenic from sediment to groundwater.
It is expected that arsenic adsorbed on iron oxyhydroxide is released under reducing aquifer
condition along with Fe2+. It is also considered that due to carbon flow and also microbial action
arsenic is released from sediment.
15. Can one use surface water and rainwater and dugwell water as an arsenic free drinking water
source? How?
Ans: These sources can be used for drinking purpose after proper treatment against bacterial
contamination and other toxins. Most of the dugwells are arsenic safe but some of the dugwells
could be arsenic contaminated. Surface water is not usually arsenic contaminated.
16. What are the arsenic removal technologies available?
Ans: Mainly there is four different treatment technology mentioned below:
(a) Precipitative processes, (b) Adsorption processes, (c) Ion exchange processes, and (d)
Membrane Separation processes.
17. What could be most simple method to remove arsenic from hand tubewell water?
Ans: If the water contains considerable amount of dissolved iron, that will co precipitate some
amount of arsenic and lessen the concentration. We have found arsenic co precipitate easily and
overall 70-80% of arsenic from water is removed.
18. Does boiling remove arsenic from water?
Ans: No, arsenic can not be removed by boiling as it is not a volatile substance rather its
concentration gets increased as water gets evaporated during boiling.
19. How we will recognize arsenic patient?
Ans: Arsenic patient can be identified if a person by showing a variety of skin manifestations of
arsenic toxicity (i.e., diffuse and spotted melanosis, leucomelanosis, keratosis, hyperkeratosis,
dorsal, Bowen’s disease). Presence of both melanosis and keratosis confirms the effect due to
arsenic toxicity. In early stages disease melanosis occurs followed by spotted melanosis.
Keratosis usually is late manifestation.
20. Is arsenical toxicity contagious?
Ans: No it is not contagious.
21. How do we treat arsenic patient?
Ans: There is no appropriate medicine for persons suffering from chronic arsenic toxicity; safe
water and nutritious food are the only options for treatment.
22. How do we know someone is drinking arsenic from water?
Ans: Elevated arsenic in urine is an indication.
23. How can one know his tubewell is arsenic contaminated?
Ans: Arsenic has no distinctive taste, color and odor. After proper collection and preservation,
the water sample has to be analyzed for arsenic from an authorized analytical laboratory.
Certified field kit can also serve the purpose, but it is qualitative.
24. What are the simple methods to test arsenic in water?
Ans: Depending on the range of concentrations arsenic can tested by various analytical
instruments like ICP-MS, FI-HG-AAS, ICP –AES, UV-Visible Spectrometer etc. from the
authorized laboratories. Colorimetric method using AsH3 generation followed by absorption in
Ag-DTDC is the most simple method. Field kit can also determine arsenic in water but it is
qualitative.
25. Is there any taste in arsenic contaminated water?
Ans: No there have no difference in taste between Arsenic free and arsenic contaminated water.
26. What are acute / chronic toxicity effects of arsenic?
Ans: The health effects of arsenic depend on the dose and duration of exposure. When high
concentration of arsenic is ingested, a person may suffer from acute arsenic toxicity. The
symptoms are non specific effects like gastrointestinal effects, such as diarrhea, vomiting,
hallucination, cramping and may even led to death if taken in lethal amount.
Chronic exposure to inorganic arsenic may give rise to several health effects including effects on
the respiratory tract, gastrointestinal tract, skin, liver, cardiovascular system, hematopoietic
system, nervous system etc.
27. How long and how much arsenic can make one arsenic patient?
Ans: A few important interrelated factors need to be considered: (i) duration of exposure, (ii)
dosage, (iii) concentration of arsenic in drinking water, (iv) nutritional status, (v) inter individual variability, and (vi) confounding factors like recreational habits (smoking, drinking,
etc).
28. How arsenic can come in food crop?
Ans: When agricultural fields are irrigated with arsenic contaminated groundwater inorganic
forms of arsenic absorbed by plant through root.
29. What are the crops observed to be accumulating arsenic, and in what level?
Ans: Generally crops grown under the soil contain elevated levels of arsenic but the level of
arsenic depends on various factors such as arsenic concentration of soil, irrigation water, plant
variety etc. It has been found that the concentration of arsenic is higher in roots then in stem and
minimum in leafs or fruits.
30. Is arsenic always harmful in food?
Ans: If arsenic is present in inorganic form and available to body, they could be toxic like arsenic
to arsenate. But organic forms of arsenic like arsenobetaine, arsenocholine, arsenosugar, are nontoxic (these forms are mainly present in sea foods).
31. Do cooking method influence arsenic in cooked food item?
Ans: Yes, arsenic content in cooked food may differ from that of raw food depending on the
process of cooking, and ingredient added during cooking.
32. What is the guideline value of arsenic in drinking water?
Ans: The guideline value of drinking water is 10μg/L (according to WHO) and followed by most
of the developed countries and 50 μg/L for many developing countries.
33. What are the biomarkers of arsenic?
Ans: Hair, Nail, Urine and skin scales of the person consuming arsenic contaminated water.
34. When and where first groundwater arsenic contamination in India was known?
Ans: In 1976 arsenic contamination was reported in Punjab, Haryana, Himachal Pradesh and
Uttar Pradesh, Northern India.
35. When groundwater arsenic contamination of West Bengal was known?
Ans: In 1984 groundwater arsenic contamination was first reported (R. Garai, A. K. Chakraborti,
S. B. Dey, K.C. Saha, Indian Med. Assoc. 82(1) (1984) 34-35.) in lower Ganga Plain of West
Bengal.
36. Should we accept field kit analysis results of arsenic in water?
Ans: The field kit analysis results may be accepted after verification with authorized analytical
laboratory. From our filed experience we have observed that often the field kit analysis results
may turn out to be erroneous. There are various factors for success of field kit. Digital small
instruments will be more reliable than color metering.
37. How arsenic is eliminated from body?
Ans: When ingested in dissolved form, inorganic arsenic is readily absorbed. About 80-90% of a
single dose of arsenite As(III) or arsenate As(V) was absorbed from the gastrointestinal tract of
experimental animals. In most of experimental animals, inorganic arsenic is methylated to
monomethyl arsonic acid (MMAA) and dimethyl arsinic acid (DMAA) through liver and kidney.
The methylated forms of arsenic are excreted though urine.
38. Are animals also similarly affected by arsenic?
Ans: If animals drink arsenic contaminated water and take arsenic contaminated fodder they may
also be affected. The specific effects of arsenic on animals are still under investigation.
39. What are the simple ways to eliminate arsenic from contaminated water?
Ans: Domestic arsenic filters, community filters (Arsenic Removal Plants) can be used but their
success depends on the maintenance of the unit, backwashing of the unit. We have observed if the
hand tubewell contains high iron (>5000 μg/l) then on keeping overnight iron is precipitated as
iron oxy-hydroxide and co-precipitate arsenic. Upto 70% of the arsenic can be removed in this
way.
40. Do you recommend Arsenic Removal Plants (ARP) in village level?
Ans: To run successfully ARP need regular maintenance if the users can take this responsibility
ARP may be successful.
41. How do you test for current arsenic exposure?
Ans: Testing urine samples of the affected persons for arsenic concentrations can be one of the
confirmatory tests. If the urine samples show elevated arsenic content we can be sure of current
arsenic exposure.
42. Do you consider 50 μg/L standard for arsenic in drinking water in the developing countries
like India and Bangladesh is correct?
Ans: Of course not! Owing to higher water intake, poor nutritional status, added arsenic
consumption through food, and other factors the population living in the arsenic affected areas in
the developing countries like India, and Bangladesh are more susceptible to arsenical toxicity and
related health effects. Secondly its is quite proven that consuming arsenic contaminated water at
50 μg/L, may have elevated cancer risks in comparison to corresponding at 10 μg/L.
Considering all these facts it is scientifically incorrect to put the standards at 50 μg/L.
43. Are children similarly arsenic affected as adults?
Ans: Research shows the children are more susceptible to arsenic toxicity than adults.
44. Are adult males and females are similarly affected by arsenic?
Ans: There is no substantial evidence yet to infer arsenical effects has gender specificity,
but sporadic research efforts have mentioned differences (male more affected than female).
45. Is arsenic skin lesions is simple skin lesions or serious indications of arsenic toxicity?
Ans: Arsenic skin lesions need to be differentiated from simple lesions by proper dermatological
examination. If confirmed they are serious indications of internal damage.
46. If a person is affected with arsenical skin lesions what are chances for his recovery?
Ans: With our long field experience we have observed that if the patient with mild skin lessions
take safe water and nutritious food, recovery is possible. For moderately affected people, the
chance is 50-50. But for severely affected people, the chance is less.
47. Which form of arsenic is present in tubewell water?
Ans: Mainly inorganic soluble forms of arsenic, arsenite [As (III)] and arsenate [As (V)], are
present in tubewell water.
48. Why there is no arsenic contamination in surface water?
Ans: Normally surface water is not arsenic contaminated and the reason is due to presence of
oxygen in ambient air and dissolved or suspended solid (like iron oxy-hydroxide), arsenic is
precipitated and goes to sediment. But if removal of arsenic by natural process is not complete
arsenic may be present in surface water.
49. Are deep tubewells free from arsenic?
Ans: We have already known that with depth of tubewell arsenic concentration decreses. Deep
tubewells may be arsenic free if there is thick clay barrier below the contaminated aquifer.
However if the sub-surface geology of the affected area is unconfined then deep tubewell may not
be arsenic free. Deep tubewell construction also play important role whether it will be arsenic
contamination free or not.
50. Are there any other skin lessions similar to arsenical skin lessions?
Ans: Yes, There are many skin lessions similar to arsenical skin lessions. But when melanosis
and keratosis occurs together, it is sure test for arsenic toxicity. Even then arsenic in biological
samples are analysed to verify it.