ARSENIC IN GROUNDWATER: SOURCES AND ITS IMPACTS ON THE HUMAN BODY. A REVIEW.
ARSENIC AND ITS GEOCHEMISTRY
Arsenic geochemistry is a result of various biogeochemical factors that in turn depend on the primary source of arsenic, pH and various microbial activities.
ARSENIC IN GROUNDWATER - A MENACE
There are several anthropogenic sources affecting this contamination but they don’t have much acceptance. Geogenic sources are widely accepted because they contribute in much greater extent to this contamination.
ARSENIC IN GROUNDWATER: SOURCES
Most of the arsenic contamination of groundwater in the world is very less in terms of area and concentration. The issue lies in the uneven distribution of the element in the ground waters of the world. Specific regions tend to be associated with very high concentrations of arsenic found in the groundwater whereas others don’t.
We shall now look upon the scenario in some of the arsenic affected countries of the world.
A WIDER FOCUS ON THE BENGAL BASIN: THE PLATE TECTONICS CONNECT
6. The continental shelf in the east is more planar than the west making it possible to hold the sediments in a more stable manner.
The United States are highly contaminated in arsenic in their western provinces with the concentration reaching to 2600 μg L−1. The aquifer can be traced back to the Holocene period with alluvial and aeolian aquifers dominating the region. Atleast 10 samples out of every 100 samples tested by Welch et. al, had arsenic content more than 10 μg L−1. The western part of the United States were found to be more contaminated than the eastern part.
ARSENIC AS A HEALTH HAZARD
HEALTH EFFECTS OF ARSENIC
Here is an elaborated description of the health effects caused by arsenic.
1. Dermatological Effects
If the victims discontinue the consumption of arsenic contaminated water, the spot remain as black and white marks on the skin.
Arsenic has very adverse effects on the cardio-vascular system of the body. Amongst the most fatal are the ischemic heart disease, peripheral arterial disease, also known as the ‘blackfoot disease’ and gangrene. These diseases are subject to prolonged exposure of the human body to arsenic. Hypertension can also be caused by exposure to arsenic.
3. Respiratory Effects
Prolonged exposure to arsenic has caused chronic respiratory problems in people. They suffer from cough, congestion, difficulty in breathing as well as malignant and non-malignant lung diseases. This is a more serious problem since people tend to ignore the symptoms and don’t even realise the danger that the source carries.
4. Gastrointestinal Effects
Though the gastrointenstinal effects are not spread over a large scale, they are severe in several cases. Reports of persistent and severe abdomenal pain have been reported. Chronically exposed individuals were diagnosed with dyspepsia. Symptoms of diarrhea, nausea, anorexia are also widely reported.
5. Hepatological Effects
Cirrhosis, fatty degeneration, abnormal cell growth (neoplasia) are the main hepatological effects caused by direct arsenic exposure. Non-cirrhotic portal fibrosis was the first case detected in India. People suffering from these diseases have been subjected to chronic arsenic exposure through direct consumption.
6. Neurological Effects
Limb pain, hyperpathia or allodynia, distal paresthesia and hypesthesia, calf tenderness, distal limb symptom, and diminished tendon reflexes are the symptoms of peripheral neuropathy that are prevalent in arsenic affected areas.
7. Cancerous Effects
Lack of research facilities had confined cancerous arsenic effects to skin cancer only. By now we know that along with skin cancer arsenic also causes several other cancers such as lung, liver, urinary tract, bladder, kidney, and other types of cancers.
COUNTRY-WISE SCENARIO OF HEALTH DISORDERS
BANGLADESH & INDIA
The Huhhot basin in inner Mongolia has been the worst affected in terms of health problems faced by the population. Ba Meng, Tumet Plain and Bayingao second the list of the worst affected areas. Many people are found to have visible skin lesions as a result of drinking arsenic contaminated groundwater. Lung cancer has been found to be the most common disease among the population. About 200 cases of cancer have been reported.
Extensive research and water analysis reports on the arsenic contamination of groundwater in the USA have suggested that the contamination is not restricted to a few parts only but is widely spread all over the western provinces. Generally, the pathway of arsenic into the human body apart from groundwater is the sea food consumption. The acute arsenic poisoning in this area initiates its symptoms with vomiting, throat and stomach pain, bloody diarrhea and in the later stage may lead to shock, seizure, coma and also death. The US National Research Council has noted that as many as 1 in every 100 additional cancer deaths could be expected from a lifetime exposure to arsenic concentrations of 50 µg/l.. Population exposed to chronic low level arsenic concentrations are susceptible to heightened risk of skin cancer. Most data is concerned on a small geographical region and can’t be generalised for the whole country. The people using well water that exceeds the limits of the government imposed guidelines are under very serious risk.
The health issues related to arsenic are very serious and fatal in many cases. Severe skin lesions, keratosis, melanosis, pharyngitis, several cancers are the results of chronic exposure to arsenic contaminated groundwater consumption. In few cases, patients can get into coma and finally death. Children are born with very weak immune system. Women are most susceptible to arsenic toxicity. Researches have proved that even rice and sea food in arsenic affected areas have high concentrations of arsenic. .
Researches are going on to curb the issue and provide safe drinking water to the population on a large scale. Majority help as of now can be proper awareness amongst the public about this issue.
Secondly, I shall thank Dr. Biswajit Ruj for co-guiding me. It has been an honour to work with him. He has taught me every basic that is needed to work on my topic. I am grateful for his every contribution of time, ideas and inspiration. I also thank him for the excellent example he has provided as a successful scientist and advisor.
I am even thankful to all seniors in the department, especially, Sankha Chakrabortty, Ankita Mukherjee, Papia Sarkar, and Nivedita Priyadarshni for teaching me the essentials of lab works along with immense motivation and guidance.
I also want to thank the Indian Academy of Sciences for giving me this opportunity to work in one of the finest labs of our country. My time at CSIR-CMERI has been a great learning experience and I thank Mr. Soumya Sen Sharma, Dr. Sarita Ghosh, Mr. Manas Banerjee and Mr. Partha Sarathi Banerjee for mentoring us throughout the programme.
Lastly, I thank my family for their moral support without which this project couldn’t have been possible.
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