Chhath politics, foaming Yamuna, and defoamers : Everything you need to know

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By Milan Sharma: The Yamuna is left on its own all year round, but it is in the run-up to the politically sensitive Chhath Puja when the river's foam becomes an eye soar. Every year, images of frothing Yamuna create a storm between the AAP government in Delhi and the opposition BJP, which is currently in power in Delhi’s municipal corporation.

Right before Chhath Puja, where devotees were seen covered in toxic froth and foam performing Hindu rituals in the unclean Yamuna, this time, it wasn’t the foam that became a controversy. It was the “defoamer”.

The Delhi Jal Board (DJB) has been tasked with cleaning the Yamuna by 2025. However, on October 27, when the foam emerged on the river's surface, politics erupted with BJP leaders flocking to the Chhath ghats at Kalindi Kunj, which were opened after two years of Covid shutdown following the order of Delhi LG, VK Saxena.

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On October 27, the DJB official tasked with cleaning or de-frothing the Yamuna brought in a chemical de-foamer called Silicon Defoamer on the banks of the Yamuna.

Seeing this, BJP MP Manoj Tiwari, who was present at the spot, said, “Does the NGT (National Green Tribunal) permit the use of such chemicals in the Yamuna river?

“To hide one toxic poison, another poison is being added to the water, we will seize all these chemicals and give these to the NGT. The moment we reached there [the ghat], the workers spraying that chemical in the water ran away, leaving the chemical behind,” said the BJP MP.

“We have seized about 50,000 litres of the poisonous chemical, and a complaint has also been lodged with the police,” Tiwari added.

DJB officials and experts who have studied the chemical in the Yamuna said that they started using chemicals to defoam only this year after the meeting held on October 21. The officials claimed they sprayed a chemical approved by the National Mission for Clean Ganga (NMCG).

A defoamer or an anti-foaming agent is a chemical additive that reduces foam formation in industrial process liquids. Commonly used agents are insoluble oils, polydimethylsiloxanes and other silicones, certain alcohols, stearates and glycols.

In industrial processes, foams pose serious problems. They cause defects on the surface coatings and prevent the efficient filling of containers. A variety of chemical formulae are available to prevent the formation of foams.

Silicone-based defoamers are polymers with silicon backbones. These might be delivered as an oil or a water-based emulsion. The silicone compound consists of hydrophobic silica dispersed in silicone oil.

Emulsifiers are added to ensure that the silicone spreads fast and well in the foaming medium. The silicone compound might also contain silicone glycols and other modified silicone fluids.

These are also heavy-duty defoamers and are good at knocking down the surface foam and releasing entrained air.

Polydimethylsiloxane is a widely used antifoaming agent. Silicone-based defoamers are also suitable in non-aqueous foaming systems like crude oil and oil refining. For very demanding applications, fluorosilicones may be suitable.

Some defoamers contain polyethylene glycol and polypropylene glycol copolymers. They are delivered as oils, water solutions, or water-based emulsions.

Dr Kabir Sardana, the director professor of the dermatology department at Ram Manohar Lohia Hospital, spoke to India Today about the harmful effects the chemical could have on humans if one is to take a dip in the chemical-laced water.

“This chemical is not meant to be put in drinking or bathing water. Every chemical is tested. This one doesn’t have any human exposure tests. One also says when you use this chemical, one should wear gloves and cover skin,” he said.

Dr Sardana listed several hazards related to exposure to this chemical on the skin. “Prolonged exposure can lead to eye damage and skin irritation. However duration matters,” he said.

The chemical that DJB official was talking about was called Polyoxypropylene, which is also a defoamer and a derivative with similar properties as the silicone defoamers.

DJB officials said, “the product has been approved by the US FDA as a defoamer”.

“Various types of defoamers are available in the market. This is a polyoxypropylene-based defoamer, and it is not poisonous, it is a good-grade chemical, and every chemical has a safety data sheet,” said the officials.

When asked, the DJB official and Assistant Bacteriologist Lokesh Singh Chandolia, who conducted fish bio-assay studies on the Yamuna, said, “We have done studies on the fish and ecology of fish in the Yamuna”.

“We mixed its water with this chemical which was being diluted in the ratio of 1:100 and kept the water mixed in chemical under observation for one day between 2 to 12 hours and even put the fish in it to study changes in the movement and mortality of fish. We did not find any fatality and mortality in fish”.

When asked about human exposure studies, he said that such a study had not been done yet.

The DJB claims the chemical is US FDA-approved. But is it EPA approved? “There is an agency called the EPA, Environment Protection Agency, a US agency, this chemical is not named by the US body on environment protection. Interestingly, even US-based companies have not been named in this list,” said Dr Sardana.

We could not find the Polyoxypropylene chemical on the safe chemical list for defoamers. While chemicals listed with silicon are tagged as yellow – The website says, “Yellow based on some concern for aquatic toxicity.” The chemical composition could not be found in the surfactants list either.

Environmental experts question the use of defoamers in Yamuna. “In my more than 22 years of work on Yamuna, I had never heard of ‘Silicone Defoamer’ was an ‘approved’ anti-pollutant in any country.

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If it was true, governments around the world and especially the Delhi government, should suspend all work on the Yamuna and just purchase tonnes of this chemical and pour it into the river.

Several environmental experts, scientists, and doctors have already flagged the current use of this chemical in freshwater, as it’s never been tested on a drinking water and also not on human skin. The documents available in the public domain clearly state that this chemical is hazardous when it comes in contact with the human body,” said Vimlendu Jha, an environmental activist.

“At most, this chemical will diffuse the froth floating on the Yamuna and make the froth and foam disappear. Pollution won’t decrease, it will increase rather. Instead, Delhi Govt should focus on fixing its sewage treatment plants and effluent treatment plants. 20 per cent of them are not functioning to their capacity.

Additionally, untreated sewage should be completely stopped from entering Yamuna and needs to be treated before that. And most importantly, adequate flow in the river needs to be assured,” he said.

“Whether it is Polyoxypropelene or Silicon Defoamer, both are defoamers both are not safe for human exposure even if the DJB officials say that they have diluted it down,” he said.

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