As many as 11 out of 30 samples of fish species purchased from Chinthadripet and Kasimedu, the two major fish markets in Chennai, on two different days, have tested positive for formalin, a cancer-inducing chemical used illegally to preserve fish.
The fish were tested by scientists of the Tamil Nadu Dr. J. Jayalalithaa Fisheries University exclusively for The Hindu .
A low-cost formalin detection kit developed by researchers of the State-run university was used to test the samples purchased by The Hindu for ascertaining if they contained the carcinogen that is used widely as a preservative and disinfectant.
The tests were conducted on July 4 and July 8, the days when the fish were purchased.
Only one of 13 samples of fish purchased last Wednesday from the Chinthadripet, Velachery and Neelankarai markets tested positive at the university’s referral laboratory in Madhavaram.
However on Sunday as many as 10 of the 17 fish samples purchased from Chinthadripet and Kasimedu markets tested positive for the carcinogen, causing alarm.
Formalin causes irritation in the eyes, throat, skin and stomach. In the long run continued exposure causes harm to the kidneys, liver and can even cause cancers.
This is the first time samples of fish in Tamil Nadu have tested positive for formalin.
Food Safety and Standards Authority of India (FSSAI) officials have been undertaking tests at fish markets and harbours across the State to test for formalin following a scare in neighbouring Kerala that fish sourced from here were chemically contaminated.
Fisheries Minister D. Jayakumar said use of formalin as a preservative cannot be allowed at any cost. Tests had been conducted in Thoothukudi and other places based on information received by the department but none of those samples had any formalin.
Will lift samples from markets: Minister
“Since The Hindu has brought the [Chennai] test results to our notice, we will lift samples [from fish markets] and conduct tests. We will not hesitate to take strict action against those indulging in such acts,” Mr Jayakumar said.
Both big and small lizard fish or panna or kezhanga and paarai ( Malabar trevally ) were found to have formalin content of above 20 ppm (parts per million). Other varieties such as sura, octopus, eri vavvaal, ottu kanava, peikanava and kelithi had formalin of around 5 ppm.
For the test, a two gram piece of meat from the fish was taken and put inside four ml of diluent and shaken so that the formalin will get into it. Then this diluent was poured into the bottle containing the reagent that turned yellow revealing that it had tested positive.
“It is a very sensitive reagent and can detect up to 0.5 milligram per kilo. The actual test takes only 10 minutes,” explained Felix, Vice Chancellor of the university.
Fish industry experts said formalin or formaldehyde is sprayed on the fish or injected into the fish or the fish is dipped into the solution. This helps keep the fish fresh for a longer time. Usually people who buy fish check the gills for freshness, if it is red it denotes freshness, when formalin is used the gills remain red for longer periods. In some cases, fishermen also apply kumkum to retain redness.
