At a Girgaum factory, artist Pradeep Maduskar has been making clay Ganpati idols for the last 35 years. "Clay idols are not harmful to the environment or marine life. Plaster of paris, fibre or paper pulp idols are," said Maduskar.
"The clay idol has always been a part of the Hindu tradition."
Swagata Yadavar from greenbappa.com, a website giving tips for making the festival eco-friendly, said: "Traditionally, people made idols from riverbed clay and returned the idols to the river, based on the notion, 'from form to formlessness'. Now, people use paints and decorations making Ganeshotsav an excuse to pollute the environment."
Unlike plaster of paris (PoP) idols that are harmful, Yadavar and Maduskar insist one can easily make clay idols. PoP idols contain chemicals like gypsum, sulphur, phosphorus and magnesium, that take months to dissolve making water bodies toxic.
Chemical paints used for idols contain mercury, lead, cadmium and carbon, increasing the acidity and heavy-metal content in the water. Other 'pollutants' such as plastic flowers, cloth, incense and camphor, when immersed with the idols, also pollute the water bodies.
Experts say the very act of immersing the idols is not 'eco-friendly'. In a report titled 'Preventive Environmental Management Plan for eco-friendly Ganpati Festival', professor Shyam Asolekar, head of the Centre for Environmental Science and Engineering, IIT-Bombay, says: "There is no eco-friendly way when it comes to immersing idols in water bodies. Ideally, people should immerse idols in a tank at home, and remove them immediately."
Deepak Apte, marine biologist, Bombay Natural History Society, said: "Clay and sand form a substrate that can disturb the food chain. Also, clay has to be mined which in itself isn't environment-friendly."