The lowering of the water table in Kerala is likely to trigger arsenic contamination at deeper levels, posing a serious health hazard, a study by the Kerala State Council for Science, Technology and Environment (KSCSTE) has warned.

The study, conducted in association with the Department of Geology, University of Kerala, the Integrated Rural Technology Centre, Palakkad, and the Agriculture and Ecosystem Management Group (AGES), Thiruvananthapuram, has warned that the particular geological set-up in Kerala can trigger the release of arsenic from rocks if the groundwater level declined uncontrollably. This, it says, could have far-reaching consequences on water quality.

Presenting the findings of the study at a two-day regional seminar on Water Quality Assessment and Management, which concluded here on Wednesday, Kamalakshan Kokkal, Joint Director, KSCSTE, stressed the need for regular monitoring of groundwater for arsenic contamination. He said it was essential to discourage the dependence on borewells for drinking water and promote the use of dug wells instead.

Exposure to arsenic results in skin lesions, respiratory and gastrointestinal complaints, gangrene and cancer. In India, arsenic contamination of groundwater has been reported from Bihar, Uttar Pradesh, Jharkhand, Chhattisgarh, West Bengal, Assam and Manipur.

Highlighting the adverse impact of the decline in groundwater resources, Dr. Kokkal said many areas in Kerala had reported a permanent lowering of the water table. The studies indicated that the lowering of the water table results in salinity intrusion, high fluoride content and possible arsenic contamination.

Fluoride problems

“Fluoride problems were reported in Palakkad and Alappuzha districts. Chittur block, Kozhinjampara and Kanjikode were the worst affected in Palakkad district. As much as 42 per cent of dug wells and 70 per cent of borewells in the district had reported abnormally high levels of fluoride. The weathering of mineral-rich gneiss and hornblende biotite schist rocks appears to be the chief source of fluoride,” he said.

Dr. Kokkal said the local people were using the contaminated water for drinking without de-flouridation. “A school-level survey showed that 10 per cent of the students had dental fluorosis. In Alappuzha, fluorides were reported from tube wells that penetrate deeper aquifers,” he said. “Exposure to high fluoride over a prolonged period of time results in acute chronic skeletal flourosis, affecting the neck, spine, knee, pelvic and shoulder joints.”

Dr. Kokkal observed that the groundwater situation in Kerala had undergone a drastic change since 1992 when all developmental blocks were in the safe (white) category. In 1999, 15 blocks moved out of the safe category, with three blocks categorised as overexploited, five critical and six semi-critical. In 2004, the number of unsafe blocks went up to 50 with five overexploited, 15 critical and 30 semi-critical. In 2012, Chittur block in Palakkad had been categorised as overexploited, three blocks classified as critical and 22 blocks semi-critical.”

The KSCSTE carried out a water-quality monitoring programme in 22 river basins as part of the study.

Exposure to arsenic results in skin lesions, respiratory and gastrointestinal complaints, and cancer.