Whether the intermediaries who use formalin, a cancer-inducing chemical, to prolong the shelf-life of fish know about its harmful effects or not is debatable. But the scare the practice has triggered is real and certain.

Formalin is being used by unscrupulous agents in the fishing industry to increase the shelf-life of fish, especially in consignments meant for other States, according to stakeholders. However, some of these carcinogenic fish land at the dining table of homes in Tamil Nadu including Chennai, as The Hindu found in an exclusive laboratory test conducted by the scientists of the Tamil Nadu Dr. J. Jayalalithaa Fisheries University.

"In most cases, fish stored and meant for other States are found to have formalin," said R. Jeyashakila, head of the Referral Lab for fish quality at the university.

Ms. Jeyashakila is a member of the team led by G. Jayasekaran, Director of Research at the university, and R. Shalini, an assistant professor, which started work on developing a formalin test kit a few years ago when there was a scare in Punjab where fish sourced from Andhra Pradesh was found to have formalin.

"Only recently the kit was developed," said Ms. Jeyashakila. The lab kit was used to detect the presence of formalin in 11 samples of fish purchased from Chennai’s busiest fish markets in Chinthadripet (eight samples) and Kasimedu (three samples).

The fish samples were transported in iceboxes to the testing facility in Madhavaram where they were labelled and tested.

M.D. Dayalan, the president of Indian Fishermen Association, alleged that a section of intermediaries was responsible for the formalin content in some fish. "The vendor does not know about its presence since it is colourless and odourless and it requires a proper test for detection. None of the fish purchased and sold fresh from Kasimedu contain formalin since fishing boats have very good fish storages," he claimed.

Other chemicals too are used to extend the "freshness" of the fish. Sodium benzoate was a preservative that was mixed when the ice was formed, industry insider and university officials said. Though the chemical was used in permissible amounts in dry fish, it was not permitted in fresh fish, officials said. Ammonia is also added to the ice, but it is done to prevent the ice from melting.

Fishermen worried

Nanjil Ravi of the Akil Indhiya Meenavar Sangam said that with the fish ban in Tamil Nadu lifted just last month, fishermen were expecting good rates this season from sales in Kerala. "Instead, they are losing money since traders are only paying half the usual rates. In some places in Kerala, there is a ban on fish from our State and fish is being sent back on fears that it contains formalin," he said.