Consumption of such chemicals used as food colour, flavour, preservative, fruit ripener and sweetener leads to liver cirrhosis, kidney disease, paralysis, diabetes, anaemia and heart disease, they said, adding that even the approved chemicals, if consumed beyond the permitted level, are also equally harmful.

"If taken regularly, any chemical agent or synthetic substance act as a slow poison, damaging liver, kidney, lung, heart and brain in the long run," said Prof Harun Yusuf of biochemistry and molecular biology department at Dhaka University.

Chemical colours such as Orange-II, Auramine, Rhodomine B, Blue VRS, Malachite green, Sudan-III and Congo red that are used to tinge food items cause liver and kidney disorders, said Prof Shams-Ud-Din, head of food technology and rural industry department at Bangladesh Agriculture University.

Malachite green causes tumour in lungs, breast, uterus, liver and skin disease, he added.

Congo red causes disease in brain, kidney and eyes while Auramine, Rhodomine B and Blue VRS are carcinogenic to humans, he said. Amaranth may also cause malignant tumour. Most of these colours are either textile or leather dyes.

These chemicals are applied to tint sweetmeat, ice-cream, cake, biscuit, candy, soft drinks, juice, rice and some vegetables -- Lalshak, Patal, potato -- to make them attractive, said Prof Shams.

"Constant consumption of these chemical agents over the past two decades have resulted in today's wide prevalence of liver, heart and kidney diseases," said Prof ABM Faroque, chairman of pharmaceutical technology department, Dhaka University.

"Children are the worst sufferers as their immature organs are more vulnerable," he said. "All parents must think twice before offering their children any readymade food, including so-called fast food and Chinese food, confectionery and bakery items and artificial drinks."

Unscrupulous traders have been using chemicals like calcium carbide, ethylene, carbon dioxide, acetylene gas and hormone like ethril to ripen fruits such as mango, banana, apple, papaya, pineapple, watermelon and tomato.

Benzoic acid, sodium benzoate, sulphur dioxide and calcium propionate are being used as preservatives, which increase asthma, allergy and migraine.

"If pregnant women take these chemicals, they will have deadly impact on their babies," said Prof Shams.

Formalin, a chemical used to preserve dead bodies in laboratories and museums, is applied in milk and fish, he said, adding that it is highly dangerous to human health.

"Formalin may paralyse the nerve system of a human body," said Prof Golam Mowlah, director of the Institute of Nutrition and Food Science of Dhaka University.

Butylated hydroxyl toluene, a food preservative, is also responsible for liver and kidney damage. Liver is the foremost victim of the chemical agents in food.

Liver disorder leads to jaundice, hyperacidity and distaste, resulting in liver cirrhosis, said Prof ABM Faroque, adding that liver cirrhosis may lead to cancer.

As the excreta of human body are usually water-soluble, insoluble chemical agents destroy nephrons of the kidney, an essential filter in human body.

Foods must be free of artificial colour, he said, if used at all, it has to be natural.

According to international convention, names of colour, flavour, preservative and sweetener must be mentioned on the label of products, a rule often violated in Bangladesh.

Chemical colours like FDC Red-2 and FDC Yellow-5 have been internationally banned since 1975 as they cause cancer, but their use could not be stopped in foods in Bangladesh.

Sodium cyclamate, popularly known as Ghono Chini, is an artificial sweetener that Bangladesh banned its use in drugs in 1982 and in foods in 2003, but still it is being used in food items.

"The ban must be made effective immediately as it is carcinogenic," said Prof Faroque.

Constant and excessive consumption of tasting salt (mono sodium glutamate), which is widely used in potato chips and Chinese and home-made food items, causes temper irritation among the children and brain disorder, Alzheimer's disease, Parkinson's disease and insomnia among the adults, he said.

There are many government agencies and institutions such as BSTI, Institute of Public Health, Institute of Public Health Nutrition, city corporation and municipality, as well as food and health ministries, which are supposed to monitor the quality and standard of foods, but it appears that nobody is responsible for the job.

"We have proposed setting up a single authority to administer both drugs and foods, in the form of Food and Drug Administration of the United States, with adequate staff to punish the culprits," said Health Secretary AFM Sarwar Kamal.

He also said the existing law, which has already been placed at the cabinet for making it up-to-date, is inadequate to punish the culprits.

"The proposed law will define specific authority for the job and we have recommended rigorous punishment for those who adulterate foods and apply banned chemicals in food," he said.

In the United States it is the federal Food and Drug Administration (FDA) that controls drugs, food and cosmetics.

Though once considered as safe food colours, the FDA has recently banned eight chemicals, including FDC Orange-1, FDC Red -4, FDC Red-32, FDC Yellow-1, 2, 3 and 4 and FDC Violet-1.