Number One Toxic Environmental Contaminant Element

摘要

Arsenic is a ubiquitous metalloid element ranks as the number one toxic environmental contaminant. Inorganic Arseic is considered the most potential human carcinogen in ground water . It is generally present as dissolved Arsenite As3+ or Arsenate5+ besides the organic form. Arsenites are much more soluble, mobile and toxic than Arsenates in aquatic and soil environments. Pronlonged drinking of arsenites rich water leads to arsenicosis and result in various pathophysiological condition like alteration of skin colour ,hard patches on palms and soles of feet , cancer of the skin bladder, kidney ,lung & vascular disesses in humans. WHO has recommended provisional guideline value of total arsenic concentration in drinking water is 0.01mg/L. Since 1993 however the national standard for maximum acceptable concentration in drinking water is 0.05mg/L. The occurence of As in ground water was first reported in 1980 in West Bengal in India and the first case of Arsenic poisoning in Human was diagnosed at the school of Tropical Medicine Calcutta in 1983. Although human exposure to arsenic is caused mainly through arsenic contaminated underground drinking water. Recent studies have shown that Besides drinking water food chain is a major contributor to arsenicosis. Thus contaminated water for irrigation result in possibility of arsenic uptake into crop plant. Arsenic content in straw grain and husk of rice is especially important since paddy fields are extensively irrigated with underground water having high level of arsenic concentration. Straw, husk are widely used as animal feed. So arsenic gets deposited into the animal body through feed ,rice , straw & husk as well as from drinking water which inturn finds a route into the human body through food chain that is through the consumption of animal products like beef ,mutton, pork ,chicken, egg ,milk & fish. As rice and fish are the staple food in Bengal hence the Deltaic region is worst affected by arsenicosis. It is important to know the Accumulation of arsenic in fish and its contribution for human exposure through food chain and the consequent effect of arsenic load on fish health as it could have significant implications on aquaculture. Accumulation of arsenic in different tissue and organs of fishes in contaminated water has been reported. Recent studies have shown that arsenic is carcinogenic to other animal also.