Cuttack: Devotees on Saturday floated miniature boats in the Mahanadi and Kathajodi rivers here as part of the Boita Bandana celebrations.

However, only a few appeared to know that the thermocol-made miniature boats pollute the rivers.

Jala Surakhya Manch president Akhaya Das said: "People float thermocol boats as there is a lack of awareness among them about the material being an environmental hazard."

Eco-friendly plantain trunks were used to make the boats. Decades ago, these gave way to paper boats of shola pith (a milky white spongy wood). But the use of thermocol, coloured papers and lead-based paints to make the boats has increased in recent years. The shift is attributed to the dwindling supply of shola pith.

"Thermocol is the best option to make the boats as shola pith is not easily available these days," said Radhamohan Sahu, who sells homemade miniature boats near Kanika Road.

According to experts, thermocol contains an important thermoplastic compound, polystyrene, which is obtained by polymerisation of styrene or phenylethene. The chemical properties of phenylethene are identical to polythene.

"It is high time that the authorities thought of banning the use of thermocol to make the miniature boats," lawyer and environmental activist Pravat Ranjan Dash said.

"After the ritual, the civic body ensures that the debris is removed from both the rivers," Cuttack Municipal Corporation's standing committee for health and sanitation chairman Ranjan Kumar Biswal said.

A Odisha State Pollution Control Board official said pollution in rivers because of the boats was negligible. Hence, it has not warranted regulation on the sale of miniature boats.