Almost 6,000 kgs of prawns preserved in formaldehyde were seized at the border check post of Walayar, in Northern Palakkad district of Kerala\u00a0on Sunday. This came a week after Food Safety department officials seized 14,000 kgs of fish laced in the chemical, and sent them back ordering to destroy those immediately. Formalin or formaldehyde is a carcinogenic chemical that is usually used to preserve dead bodies, and its effect does not go away even after the fish is cooked. When ingested, it ends up releasing toxins in the body which causes cancer. Hindustan Times reported that tests conducted in the Central Institute of Fisheries Technology in Kochi found that a kilogram of fish contained 63.9 mg of formalin. A health expert Dr Mathew Thomas said, \u201cFormalin poses serious health hazards. It triggers a metabolic process and produces toxins, once inside the body. While cooking, its toxicity never gets spoiled.\u201d This raid was carried under 'Operation Sagar Rani', an initiative launched by the government of Andhra Pradesh to look after the hygiene and safety of fish imports and distribution centres. Assistant food safety commissioner A K Mini told HT, "The department has decided to step up the vigil and conduct random tests at fish markets to look out for chemical mixed fish." She further added that the department has appealed to the state government to allow refrigerated fish trucks only.