The Indian Institute of Technology-Kharagpur has developed an ultra-low cost eco-friendly laterite based arsenic filter for providing safe drinking water. It is made from naturally occurring red laterite soil. This material has undergone chemical treatment to enhance its capabilities to adsorb arsenic. The innovation has won Sirshendu De, the head of chemical engineering department, the Innovation Award 2016 from the Indian Desalination Association (South Zone).

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           Arsenic,a natural element which behaves like a metal, is a poisonous substance, which is released both from certain human activities and naturally from the Earth’s crust. The Earth’s crust is an abundant natural source of arsenic. It is present in more than 200 different minerals, the most common of which is called arsenopyrite. About one-third of the arsenic in the Earth’s atmosphere is of natural origin. Volcanic action is the most important natural source. The next most important source is arsenic-containing vapor that is generated from solid or liquid forms of arsenic salts at low temperatures. Arsenic contamination of groundwater is widespread and there are a number of regions where arsenic contamination of drinking-water is significant.

Inorganic arsenic of geological origin is found in groundwater used as drinking water in several parts of the world, for example Bangladesh, India and Taiwan.  Humans may be exposed to arsenic mainly through food and water, particularly in certain areas where the groundwater is in contact with arsenic-containing minerals.More than 200 million people are affected worldwide by arsenic menace and over 100 million people in India and Bangladesh are exposed to arsenic contamination risk.

Long-term exposure to inorganic arsenic, mainly through drinking of contaminated water, eating of food prepared with this water and eating food irrigated with arsenic-rich water, can lead to chronic arsenic poisoning. Skin lesions and skin cancer are the most characteristic effects; usually observed in the skin, and include pigmentation changes, skin lesions and hard patches on the palms and soles of the feet (hyperkeratosis). These occur after a minimum exposure of approximately five years and may be a precursor to skin cancer.

 Laterite soil is rich in aluminium and iron, formed in wet and hot tropical areas, but are deficient in potash, phosphoric acid, lime and nitrogen. Due to the presence of iron oxides the colour of laterite soil is basically red. This soil is poor in lime content and hence it is acidic. Laterite soils in India are found in the Eastern Ghat of Orissa, the Southern parts of Western Ghat, Malabar Coastal plains and Ratnagiri of Maharashtra and some part of Andhra Pradesh, Tamil Nadu, Karnataka, Meghalaya, western part of West Bengal. The Laterite soils in India are not fertile at all and are not suitable to agriculture. They are coarse in texture and poor in nitrogen, phosphoric acid, potash and urea. Plants like cashew grow well along with Tapioca. These soils are also used as building materials in India. But agriculture can be practiced with the help of fertilizer.