Study flags chemical contamination risk to endangered Gangetic dolphins

A scientific study has revealed alarming levels of toxic chemicals in the Ganga river, threatening the health and survival of the endangered Gangetic dolphins.

Published in the journal 'Heliyon', the study by the Wildlife Institute of India found that these freshwater mammals are being exposed to a hazardous cocktail of endocrine-disrupting chemicals (EDCs) through their diet.

The researchers analysed the dietary exposure risks of 39 EDCs in fish species consumed by Gangetic dolphins.

The findings indicate significant bioaccumulation of industrial pollutants such as di(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) in the prey base of the dolphins.

Residues of banned pesticides like DDT and Lindane (γ-HCH) were also detected, pointing to poor enforcement of environmental regulations in the Ganga basin.

The Gangetic dolphin population has declined by over 50 per cent since 1957, and their range has shrunk by nearly a quarter, despite being designated as India's national aquatic animal.

With only five species of river dolphins left globally, all of them threatened, the study warned that India could risk a repeat of the Yangtze River tragedy, where a similar species went extinct due to unchecked human activities.

The study attributes the contamination to several sources: runoff from agriculture, untreated industrial effluents from the textile sector, vehicular emissions, poor solid waste management, and rising tourism in ecologically sensitive areas.

The effects of EDCs are particularly worrisome as they can disrupt hormonal systems and reproductive functions in mammals, and persist in the ecosystem for long periods.

Although toxicity risk quotients based on standard values were found to be low, when analysed against the reference dose --” a more realistic measure of exposure risk --” the dolphins were at a high risk from seven key pollutants -- DEHP, DnBP, DDT, arsenic, mercury, cadmium, and polychlorinated biphenyls (PCBs).

The study recommended the urgent inclusion of these chemicals in dolphin conservation-monitoring programmes and calls for a scientifically informed national framework to assess and regulate chemical contamination in river ecosystems.

The Gangetic dolphin is protected under Schedule I of the Wildlife Protection Act, 1972, but the study stresses that protection on paper must translate into actionable policy and pollution control if the species is to survive.

The research from last year was among several key documents unveiled on a new portal launched by the Ministry of Jal Shakti to promote access to ecological data and conservation insights.