Prelims cum Mains Science & Tech

Fish samples in Chennai test positive for formalin

The News

  • 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.
  • This is the first time samples of fish in Tamil Nadu have tested positive for formalin.




  • In recent times complaints over the sale of formalin-laced fish have mounted across the country in general and in coastal states like Kerala, Andhra Pradesh, Tamil Nadu and coastal Karnataka in particular.
  • Food Safety Departments of different states have launched campaign drives against the sale of adulterated fish in markets.
  • Operation Sagar Rani is an example of the drive launched by Kerala government to ensure safety and hygiene at fish handling and distribution centres.
  • Further a formalin testing kit –supplied by Central Institute of  Fisheries Technology (CIFT) has been deployed across states to test the fish samples for ascertaining if they contained the carcinogen that is used widely as a preservative and disinfectant.
  • Besides, states like Punjab, Delhi, Mizoram and Nagaland have also put a ban on sale of fishes tested positive for formalin and other contaminants.
  • Despite all these efforts samples of fish species have continued to test positive for formalin.


Why Formalin is used?

  • Fish is a high-value crop with increasing consumer demand.
  • Fish are prone to rapid post-harvest spoilage because of their composition.
  • Inadequate preservation facilities and lengthy transport from distant places lead to considerable decreases in fish quality by the time the products reaches consumers.
  • Therefore formalin or formaldehyde is sprayed on the fish or injected into the fish or the fish is dipped into the solution.
  • Besides formalin is also found in ice that is manufactured for preserving fish.
  • This helps keep the fish fresh for a longer time preventing spoilage and increasing shelf life.
  • When formalin is used the gills remain red for longer periods which indicates the fish is fresh.


What is Formalin?

  • Formalin is a poisonous and anti-decomposition chemical agent.
  • It is commonly used as an antiseptic, disinfectant and preservative in various items especially to preserve dead bodies.
  • It is derived from formaldehyde, which is a substance that is carcinogenic to humans.
  • Formalin is listed as a group 1 carcinogen by the International Agency for Research on Cancer.


Harmful effects of Formalin

  • Formalin causes irritation in the eyes, throat, skin and stomach causing abdominal pain, vomiting, unconsciousness, and sometimes even cause death.
  • In the long run continued exposure causes harm to the kidneys, liver and can even cause cancers.
  • The widespread use of the deadly chemical now-a-days in preservation of fish, fruit and other food items is posing a great threat to public health.


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