Status of Arsenic Toxicity in Ground Water in West Bengal, India: A Review

Abstract

Submit Manuscript | http://medcraveonline.com purposes [1]. A large area of the world experiences a huge contamination in groundwater due to mixing of different toxic and minerals and heavy metals either naturally or unorganized development of human civilization [2,3]. The Arsenic is one of the most important and fatal among these minerals. The high concentrations of arsenic (As) in drinking water in inorganic form causing skin, liver, lungs and other organs damages in several parts of the world [4]. There are more than 25% of domestic wells presented in alluvial aquifers of this state carry arsenic in drinking water beyond the permissible limit of WHO, 1993, 2017 (0.01 mg/L) [5,6]. West Bengal lies within the Ganga–Brahmaputra delta basin has high contamination of arsenic (<0.05mg/ml) mainly in groundwater [7]. West Bengal can be divided into three arsenic prone zones [8] i.e. highly affected areas cover eastern side of Bhagirathi River; mildly affected areas include northern part of the Bhagirathi river and the unaffected region carries western part of the state. This study reveals the condition of arsenic toxicity and stratigraphic and litho logical condition in West Bengal, a state of India and the fatal effect on human health due to arsenic toxicity. In India Arsenic contamination in ground water was first reported in West Bengal in 1978 [9] and it includes79 blocks in 8 districts among 26 districts where arsenic concentration in ground water exceeded 50µg/L. According to Das, 2015, this problem is expanding rapidly and in 2006 almost 3235 villages were affected including North 24 Parganas, South 24 Parganas, Nadia, Murshidabad and Burdwan, Howrah, Hooghly and Maldah districts (Table 1). The severely affected districts are Murshidabad, Maldah, Nadia, North and South 24 Parganas, Burdwan, Howrah and Hooghly. The values of arsenic contaminated ground water of the affected districts are discussed below in (Table 2). In course of this study, the numbers of affected blocks under the affected districts were too high. Almost all the district contains over 50% to 100% arsenic contaminated block. The condition of arsenic contamination in block level is discussed herewith in (Table 3) [9]. Stratigraphy and Lithology of Arsenic Contaminated Aquifers The stratigraphic analysis of arsenic prone aquifer zones of the southern part of West Bengal occurred beneath the alluvial plain. Soil thickness of the young delta plain (YDP) is 1-2 m thick with a top of soft Fe-Mn concretions up to 0.2 m, and lower section contains calcretes. In West Bengal, part of the Bengal basin of Bhagirathi, morpho stratigraphic units of the subsurface continuity have been established [10,11], whereas, lower subsurface units from YDP do not out cropped. The recognition of the quaternary section was difficult, but in many boreholes of western gangetic plains the sequence is mostly clay and sand. These have formed in saline water and contain microfossils locally to an Upper Pliocene age [12]. The presence of the Toba-ash bed marker (75,000 years b.p.) has been recorded to present in the basal parts of the quaternary profile of the Brahmani and Barakar River sections, slightly to the west of the Ganga-Brahmaputra basin margin [13]. The arsenic-bearing aquifers are present in the Holocene sediments beneath YDP. Arsenic toxic YDP sediments partly encroached into the Barind area which is presented in north of Ganges channel, e.g. the Malda district of West Bengal [14]. These Holocene valleys are filled with silt and clay which are deposited in deeply eroded Volume 3 Issue 5 -2017 Abstract Arsenic toxicity is a great threat in human civilization specially in West Bengal, India. Almost half of the state is under the toxicity of this heavy metal. Several litho logical and stratigraphic studies revealed the stratigraphic position and the possibility of arsenic contamination in the lower gangetic delta region. A number of physiological anomalies in the human system such as Skin, respiratory, cardiovascular, Hematological disorder have been observed due to the chronic exposure to this. Apart from these disorders diabetes, genotoxic and cancer related complications have benn arised due to the exposure of arsenic. The present study revealed the present status of arsenic toxicity, stratigraphic condition of this state and the physiobiochemical consequence of chronic exposure of arsenic toxicity on human health.