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About Authors:
Zubair Khalid Labu1; AK Mohiuddin1; M.A Bake*2
1Department of Pharmacy, World University of Bangladesh (WUB), Dhaka-1215, Bangladesh
*2Product Development officer, Gonoshasthaya Pharmaceuticals Ltd., Mirzanagar, Savar, Dhaka-1344.; *

Food is the major source of energy in humans as well as animals. Foods are materials taken into the body by different route which provide nourishment in the form of energy or in the building of tissues. Food contaminants are substances that make food unfit for human consumption. Examples include bacteria, toxic chemicals, carcinogens, teratogens and radioactive materials. The purpose of these studies is to find out the food contaminants which are used in different purposes available in Bangladesh and contaminants detection method. After survey we found that Dhaka is the main city where food contamination by various contaminants in higher percentage. This contamination done by manmade, industrial discharge, poisonous water etc. Government of Bangladesh taking various necessary steps to stop this contamination.

Reference Id: PHARMATUTOR-ART-1570

Contaminated foods and drinks are common sources of infection. Among the more common infections that one can get from contaminated foods and drinks are typhoid fever, Escherichia coli infections, shigellosis or bacillary dysentery, giardiasis, cryptosporidiosis, other salmonelloses, cholera, rotavirus infections, also a variety of worm infestations are more common. Many of the infectious diseases transmitted in food and water can also be acquired directly through the faecal-oral route. Food contamination with poisonous chemicals has been reached a dangerous proportion, posing serious health hazards in the country. Basic food items in the market like rice, fish, fruits, vegetables, and sweetmeats are adulterated with hazardous chemicals in an indiscriminate manner, though food-grade preservatives and colors can be safety used in permissible quantities.

Present situation in our country
Dhaka city now alone generates 3500-4000 tones of solid wastes per day from industrial discharge, fertilizers, fossil fuels, sewage sludge and municipality wastes and they are the major sources of heavy metals in soils and subsequent uptake by crops, vegetables and other food items causing serious health hazards to human beings. A significant transfer of heavy metals like arsenic, cadmium, chromium, copper, lead, mercury, nickel, zinc, molybdenum and vanadium took place from soils to vegetables (spinach, tomato and cauliflower) grown in industrially polluted soils of Konabari at Gazipur and Keraniganj in Dhaka.

In Bangladesh, industrial wastes and effluents are being discharged randomly on soils, into canals, rivers, along the road sides or in the vicinity of the industrial areas without any treatment where polluted river water is being used for irrigation purpose in paddy and vegetable cultivation causing absorption of heavy metals through the food chain by human beings.

In the backdrop of reports of raid and seizure of fake and adulterated food items pouring in everyday, people wonder whether what they are eating is food or poison. With a totally inefficient monitoring system, just having tough laws is hardly enough to keep unscrupulous traders from tampering with food items.

Encouragingly, BSTI revealed that, in the current year, it had conducted countrywide drives against fake and adulterated food through operation of mobile courts, instituted 1,822 criminal cases, and realized over Tk. 4 crore as fine. But realization of fine has not helped to curb this criminal offence. The government can’t allow a handful of unscrupulous traders to play with the lives of the citizens, especially the children, and get away with impunity.

In Bangladesh, about the proportion of adulterated food items in the market varied between 70 and 90 percent. More than 76 percent food items in the market were found adulterated in a random survey by public health laboratory of Dhaka City Corporation in 2004.

According to the International Centre for Diarrhoeal Disease & Research, Bangladesh (ICDDR, B), there is approximately 150 food items in the country. A study by the Institute of Public Health (IPH) revealed that more than 50% of the food samples they tested were adulterated. Textile dyes, which are highly injurious to health, are being randomly used to color many types of food. Fish is considered to be an essential protein for people of all ages.

Many fish sellers spray fish with formalin in an indiscriminate manner, It makes the fish or fruits stiff and keeps them looking fresh for longer.Undoubtadey human heath is now under the possession of formalin, in our country about 400 tons formalin is being imported which are goes to human stomach, even though for laboratory or research purposes 100 tons of Formalin is quite enough, 80% of the imported formalin being added to food only for business purposes. Milk in rural areas is usually adulterated with dirty water, which can cause hepatitis. People have now come to know about a new milk adulteration technique that uses a thickening agent, sorbitol, and detergent.

Vegetable and fruit samples collected from around Savar, Dhamrai and Tongi show the presence of textile dyes, which, in the short-term, will cause diarrhea, food poisoning and gastrointestinal problems, but in the long-term toxic materials will accumulate in the body with serious health implications. In the absence of effluent treatment plants (ETP), the factory wastes are drained out at will into the farmlands, and ultimately contaminate the farm produce.

In our country we have allowed things like pollution and food contamination to run riot. Till now, no agency, either under the health ministry or the ministry of science and technology or the ministry of industries, has conducted any examination of the pesticide- residue levels or toxic chemicals in the foodstuff being marketed.

Table 1. Name of toxic food contaminants and purpose of application




Preservation of fish, Meat, Milk

Calcium carbide(CaC2)

Fruit to ripen

Brick dust

Chili powder


For whiten rice and puffed rice

Saw dust

Loose tea


Milk products



Artificial sweetener, coal tar & textile dyes


Sulfuric acid

Milk condensation


As insecticide during drying fish

Ethylene oxide

To ripe of Papaya and bananas

Impact of food contaminants on public heath
The safety certi?cation is achieved assessing the potentially health adverse effects of food contamination. Three main food contamination groups can be identi?ed: i. physical; ii. Microbiological; iii. Chemical. Physical contaminations are due to the presence of extraneous bodies in food (plastic, woods, glass and others) as the results, for example, of food packaging and/or transformation and/or storage. The substances present in those materials are not for human consumption, but when  in  contact  with  food  they  migrate into it and risk of being ingested (for example, the per?uorinated chemicals used in greaseproof packaging for fast foods). Microbiological contamination refers to the presence of one or more natural biological agents, such as various bacteria, yeasts, mould, fungi, protozoa or their toxins and by-products, which can adulterate food properties and safety. Microbiological agents are responsible for “food diseases” such as food borne infections and intoxications (Botulinum, Listeria, and Hepatitis A) and epidemic episodes (e.g., Salmonella enteritidis). Chemical contaminants or xenobiotics can originate from many different sources and include heavy metals, pesticides, phytopharmaceuticals, antibiotics, additives, dioxins and PCBs. Nowadays; chemical contaminants are a major concern for food safety because of the increased role of man-made chemicals due to our modern lifestyles.



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Table 2. Common Food Contaminants and Related Health Hazards


Health hazard

Formalin:Formalin is a 37% formaldehyde aqueous solution.

WHO average         daily exposure

Food                           9.4 mg/d

Inhalation                   1.0 mg/d

Water                         0.15 mg/d

Total:                        10.55 mg/d

Naturally Occurring Formaldehyde in Food

Food type        Formaldehyde level (ppm)

Cow’s milk                <3.3

Shrimp                     1-2.4

Beef                         4.6

Poultry                     2.5-4.2

Potato                     10.0-13.5

Cucumber                 2.3-3.0

Cabbage                   3.5-5.2

Exposure to formaldehyde is possible in two ways. One is through breathing air with formaldehyde and other is the absorption of formaldehyde through the skin. The harmful effects of such exposure can range from mild to life-threatening ones.

If the level of formaldehyde is between 0.1 to 5 ppm, irritation of the eyes, tears, skin and respiratory tract irritation can be caused. If the formaldehyde level is between 5 to 20 ppm, it may cause breathing trouble, cough and burning of the eyes and skin. In case of high formaldehyde levels, i.e. 20 to 100 ppm, severe symptoms like irregular heartbeat, chest pain, lung irritation, pulmonary edema and even death may happen.
Formaldehyde exposure can also be classified on the basis of period of exposure. It can be either an exposure for a brief period or a regular one, as in the case of some industrial workers. Regular exposure is said to cause long-term health issues. In case of regular exposure, which is considered as chronic, the person may develop lesions inside the lungs, which may cause lung damage.

Poisonous coloring agentslike, Aurmine, Rhodomine b, Malachite green, yellow g, Allura red

-Damage liver & kidney

-Stomach cancer

-Asthma and

-Bladder cancer

Calcium carbide

Cancer in kidney, liver, skin prostate and lung





Infertility of women


-Damage of kidney & nervous system

-Respiratory problem

Sulfuric acid

-Damage cardiac system

DDT(It is a widely used insecticide, It can enter into the body as food adulterants)

-DDT at concentration of 236 mg per kg of body weight is lethal to the body while at concentration of 6-10 mg/kg leads to such symptoms as headache, nausea, vomiting, confusion, and tremors.

-Long term exposure to DDT may affect the liver.

-Short term exposure to DDT in food may have a harmful on effect on reproduction.

-Oral exposure to DDT can cause liver cancer.

Melamine(an organic base and a trimer of cyanamide. Melamine is sometimes illegally added to baby food products in order to increase the apparent protein content. Standard tests, such as the Kjeldahl and Dumas tests, estimate protein levels by measuring the nitrogen content, so they can be misled by adding nitrogen-rich compounds such as melamine)

Permitted Amount of Daily Intake of Melamine

  • European Union : 0.2 mg/kg body mass
  • Canada: 0.35 mg/kg body mass
  • USFDA:  0.063 mg/kg body mass
  • WHO: 0.2 mg/kg body mass

Toxicity of Melamine:Chronic exposure may cause cancer or reproductive damage. Eye, skin and respiratory irritant.” U.S. Food and Drug Administration (FDA) scientists explained that when melamine and cyanuric acid are absorbed into the bloodstream, they concentrate and interact in the urine-filled renal microtubules, then crystallize and form large numbers of round, yellow crystals, which in turn block and damage the renal cells that line the tubes, causing the kidneys to malfunction.

Brick dust

Respiratory problem

Ethylene oxide


Quick Tests for some adulterants in the food
An integrated approach to face this problem requires a strong cooperation by the food industry, food distributors, the scienti?c community, governments, managers and local administrators in order to build consumers’ trust and con?dence.

Table 3. Methods Used to detect Common Food Adulterants

Name of Food Article


Simple Method for detection of Common Adulterants




The presence of water can be by putting a drop of milk on a polished slanting surface. The drop of pure milk either or flows lowly leaving a white trail behind it, whereas milk adulterated water will flow immediately without leaving a mark.



Add a few drops of tincture of Iodine or Iodine solution. Formation of blue color indicates the presence of starch.

Iodine solution is easily available in the medical stores.



Take a teaspoon of milk in a test tube. Add ½ teaspoon of soybean or arhar powder. Mix up the contents thoroughly by shaking the test tube. After 5 minutes, dip a red litmus paper in it. Remove the paper after ½ a minute. A change in color from red to blue indicates the presence of urea in the milk.



Take 10 ml of milk in a tests tube and add 5 ml of con sulfuric acid from the sides of the wall without shaking. If a violet or blue ring appears at the intersection of two layers then it shows presence of formalin.

Formalin enhances the life of milk and thus is added for preservation purpose.


Synthetic milk

Synthetic milk has a bitter after taste, gives a soapy feeling on rubbing between the fingers and turns yellowish on heating



Take 10 ml milk in a test tube and add 5 ml HCl then add 1 gm resorphenol. Then keep it in hot water for few minutes, if red color is appearing then sugar is presence.



Diabetes examination strip immersed in milk, if glucose present then strips color changed.


Hydrogen peroxide

Take 5 ml milk in a test tube add 5 ml alcohol then add 5 drops of rezolic acid. Presence of hydrogen peroxide solution color will be red in color.

Ghee, cottage cheese, condensed milk, khoa, milk powder etc,

Coal Tar Dyes

Add 5 ml of dil. H2SO4 or conc. HCl to one teaspoon full of melted sample in a test tube. Shake well. Pink color (in case of H2SO4) or crimson color (in case of HCl) indicates coal tar dyes. If HCl does not give color dilute it with water to get the color.


Mashed Potatoes, Sweet Potatoes and other starches.

The presence of mashed potatoes and sweet potatoes in a sample of ghee can easily be detected by adding a few drops of Iodine, which is brownish in color turns to blue if mashed potatoes/sweet potatoes/other starches are present.


Vanaspati or Margarine

Take about one teaspoon full of melted sample of butter with equal quantity of concentrated Hydrochloric acid in a stoppard test tube and add to it a pinch of sugar. Shake for one minute and let it for five minutes. Appearance of crimson color in lower (acid) of Vanaspati or Margarine.

The test is specific for sesame oil which is compulsorily added to Vanaspati and Margarine. Some coal tar colors also give a positive test. If the test is positive i.e. red color develops only by adding strong Hydrochloric acid (without adding crystals of sugar) then the sample is adulterated with coal tar dye. If the crimson or red color develops after adding and shaking with sugar, then alone Vanaspati or Margarine is present

Black pepper

Light black pepper

Float the sample of black pepper in alcohol (rectified spirit). The black pepper berries sink while the papaya seeds and light black pepper float.

Black pepper

Coated with mineral oil

Black pepper coated with mineral oil gives Kerosene like smell.

Mustard seed

Argemone seed

Mustard seeds have a smooth surface The argemone seed have grainy and rough surface and are black and hence can be separated out by close examination. When Mustard seed is pressed inside it is yellow while for Argemone seed it is white

Use magnifying glass for identification

Chilies powder

Brick powder, salt powder or talc, powder

Take a tea spoon full of chilies powder in a glass of water. Colored water extract will show the presence of artificial color. Any grittiness that may be felt on rubbing the sediment at the bottom of glass confirms the presence of brick powder/sand, soapy and smooth touch of the white residue at the bottom indicates the presence of soap stone. To a little powder of chili add small amount of conc. HCl and mix to the consistency of paste, dip the rear end of the match stick into the paste and hold over the flame, brick red flame color due to the presence of calcium slats in brick powder.

This test is only for earthy material

Chilies powder

Artificial colors

Sprinkle the chili powder on a glass of water. Artificial colorants descend as colored streaks.

Chilies powder

Water soluble coal tar color

Water soluble artificial color can be detected by sprinkling a small quantity of chilies or turmeric powder on the surface of water contained in a glass tumbler. The water soluble color will immediately start descending in color streaks

Green chili and green vegetables.

Malachite green

Take a cotton piece soaked in liquid paraffin and rub the outer green surface of a small part of green vegetable. If the cotton turns, green, we can say the vegetable is adulterated with malachite green.



-Firstly, the fish will be washed with small volume of clean water.05 ml of washed water (fish) taken into a clean and dry test through a dropper. Add solution No. 1, 15 drops into the fish washed water into the test tube and shake vigorously and wait for 30 seconds. Again add solution No. 2, 15 drops and shake vigorously and wait 30 seconds. Lastly, add solution No. 3, 15 drops into the test tube :(i)   if the color of the solution changes from colorless to PINK OR RED (ii)  if there is no change of color of the solution.

(i)  Formalin is present.

(ii)  Formalin is absent.

Kitchen tricks to expose food adulteration
In a country where official systems set for food safety and prevention are constantly outdone by a booming adulteration business, the onus of safeguarding one's family against contaminated food, unfortunately falls on citizens themselves. From loose packed ground spices, to wet produce such as milk, khoya, paneer, to dry spices and grains, almost everything you can buy has a potential of being adulterated, if purchased from an unauthorized vendor in a box unmarked and tested. While some of these could be less harmful, such as water or bran, chemicals and coloring agents such as Metanil Yellow, Lead Chromate, Sudan Red III, are known to be carcinogenic. Following test asks for the presence of an acid, you could use common toilet-cleaning acid, or easily found citric acid or even lemon juice.



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Table 4. Kitchen tricks to expose potentially harmful Food Adulterants

Name of Food Article


Detection Method

Potential Harm

Turmeric, dals and pulses such as moong or channa

Metanil Yellow and Kesari Dal (enhance food yellow color)

Dissolve half a spoon full of besan or turmeric powder in 20 ml of lukewarm water. Add a few drops of hydrochloric acid or any commonly available acid at home. If the water turns pink, violet or purple, it shows the presence of Metanil yellow.

It's highly carcinogenic and if consumed over a continuous period of time it can also cause stomach disorders.

Green chilies, green peas and other vegetables

Malachite Green (To accentuate vegetable green color)

Take a small portion of the sample and place it over a moistened white blotting paper. Colored impressions on the blotting paper indicate the presence of Malachite green.

It's a colored dye that has proven to be carcinogenic for humans if consumed over a long period of time.

Mustard seeds and mustard oil

Argemone seeds (used to add bulk and weight)

When pressed or crushed, argemone seeds are white inside and have a rough outer surface whereas mustard seeds are smooth on the outside and are yellow on the inside.

The consumption of these could cause epidemic dropsy and severe glaucoma. Young children and senior citizens with poor immunity are more susceptible this.

Paneer, khoya, condensed milk and milk

Starch (used to give it a thick, rich texture)

Take a small sample of the product in a test tube, add 20 ml of water and bring to a boil. Cool to room temperature and add a drop or two of iodine solution. If the solution turns blue, it marks the presence of starch.

Unhygienic, unprocessed water and starch can cause stomach disorders. Starch greatly reduces the nutritional value of the ingredient.

Ice cream

Washing powder (to add a sheen and lightness of flavor)

Squeeze a few drops of lemon juice on the ice cream. If it starts to froth and bubble, it marks the presence of washing powder.

It can cause severe stomach and liver disorders

Black pepper

Papaya seeds (used to add bulk)

Float the sample in alcohol. Mature black pepper corns will sink where as papaya seeds will float to the surface.

Papaya seeds can cause serious liver problems and stomach disorders.

Coffee powder

Tamarind seeds, chicory powder

Gently sprinkle coffee powder on the surface of water in a glass. The coffee will float whereas chicory will start to sink within a few seconds. Also, the falling chicory powder will leave a trail of color behind due to the large amounts of caramel it contains.

These can cause diarrhea, stomach disorders, giddiness and severe joint pains.

Suggested Precautions

  • To avoid illness, one is advised to select foods with care.
  • All raw foods must be checked for contamination particularly in areas where hygiene and sanitation are inadequate.
  • To avoid salads, uncooked vegetables, and unpasteurized milk and milk products such as cheese and to eat only food that has been cooked and is still hot. Undercooked and raw meat, fish, and shellfish can carry various intestinal pathogens.
  • Cooked food that has been allowed to stand for several hours at ambient temperature can provide a fertile medium for bacterial growth and should be thoroughly reheated before serving.
  • Consumption of food and beverages obtained from street food vendors has been associated with an increased risk of illness. So avoid taking street food.
  • In areas where chlorinated tap water is not available or where hygiene and sanitation are poor, one is advised that only the following might be safe to drink.
  • Beverages, such as tea and coffee, made with boiled water.
  • To avoid out of season fruits because chemicals are used to preserve them during the off-season.

Implementation of Rules and Regulations
There are several laws in Bangladesh for maintaining health and safety standards.
(a) The Bangladesh Pure Food Ordinance, 1959: This is an ordinance to provide better control of the manufacture and sale of food for human consumption. Now, this Ordinance is under revision as 'The Bangladesh Pure Food (Amendment) Act'. Under this Act, it has been proposed to constitute a National Food Safety Council, headed by the Ministry of Health and Family Welfare as well as to establish Food Courts.

(b) The Bangladesh Pure Food Rules, 1967: In this Rule, there are generic standards for 107 food products. Now, this 'Rules' is under revision.

(c) The Food Grain Supply (Prevention of Prejudicial activity) Ordinance, 1956 (Ord. xxvi of 1979): This ordinance provides special measures for prevention of prejudicial activity relating to the storage, movement, transshipment, supply and distribution of food grains. It provides basis for the protection of false statement or information.

(d) The Radiation Protection Act, 1987: Under this Act, the Institute of Food and Radiation Biology (IFRB) of Bangladesh Atomic Energy Commission is primarily involved in food irradiation research and development in the country.

(e) The Iodine Deficiency Disorders (IDD) Prevention Act, 1989: The Government has enacted "The Iodine Deficiency Disorders Prevention Act, 1989 for universal salt iodization and banned non-iodized salt from market, aimed at virtual elimination of IDD from the country.

(f) The Essential Commodity Act, 1990: The purpose of administering this act is to stabilize, maintain or increase supply of essential commodities including foodstuffs. The mandate of Essential Commodity Act also includes broad spectrum of activities like storage, transport, distribution, disposal, acquisition, use or consumption of any essential commodity.

(g) Fish and Fish product (Inspection and Quality Control) Rules, 1997: Under this section of the Fish and Fish products (Inspection and Control) Ordinance 1983 (Ord xx of 1983) and in conjunction with fish and fish products Inspection and Quality Rules 1989, and other related provisions made there under, the government has made the Rules: Fish and Fish product (Inspection and Quality Control) Rules, 1997. These Rules are basically meant to develop quality improvement to promote export trade. The quality control of fish and fish products in the country has earned reputation among the importing countries.

(h) Other Laws and Regulations: In addition, a number of other Laws and Regulations exist in the country to ensure the safe and quality food viz. The Animal Slaughter (Restriction) and Meat Control (Amendment) Ordinance, 1983 (it is under revision); The Pesticide Ordinance, 1971 & the Pesticides Rules, 1985; Destructive Insects and Pests Rules (Plant Quarantine), 1966, amended up to 1989; Agricultural Products Market Act, 1950 (revised in 1985); Fish Protection and Conservation Act, 1950 (amended in 1995); Marine Fisheries Ordinance 1983 and Rules, 1983; Procurement Specifications, Ministry of Food, Rice Mill Control Order etc.

(i) The Bangladesh Standards and Testing Institution Ordinance, 1985: This ordinance relates to establishment of an institution for standardization, testing, metrology, quality control, grading and marking of goods. Within the framework of this ordinance, the government has established the Bangladesh Standards and Testing Institution (BSTI). One import task of this organization is to certify the quality of commodities, materials, whether for local consumption or for export and import. The Ordinance has been amended as The Bangladesh Standards and Testing Institution (Amendment) Act, 2003.

1.    Risks from food and drink from dkl, Houston County Health Department
2.    Food adulteration rings alarm bell The Daily Star Editorial Thursday, August 11, 2011
3.    Beware of adulterated food The Daily Star Editorial Saturday, July 14, 2012
4.    Improving Food safety, Quality and Food Control in Bangladesh FAO of the UN June 2010
5. PDF
7.    Quick Tests for some adulterants in the food Instruction Manual Part 1 by Food Safety and Standard Authority of India (FSSAI)
8.    Bitter Truth Rampant adulteration still a havoc by Md. Asadullah Khan The Daily Star Saturday, July 9, 2011
9.    Risks from Food and Water from Travel Tips
10.    Slow poisoning continues unabated by MD. Asadullah Khan The Daily Star Saturday, August 14, 2010
11.    Some Cautions before eating, Article from
12.    Kitchen tricks to expose food adulteration Divashri Sinha, Mumbai Mirror May 30, 2012
13.    Food Safety and Quality Control in Bangladesh by Dr. Md. Hossain The Financial Express Wednesday September 10, 2008
14.    Monitoring Contaminants in Food Chain and Their Impact on Human Health CNR Environment and Health Inter-departmental Project
15.    “Formalin Aggrasion “in editorial page the daily news paper Bangladesh Protidin on 4th November
16.    Food contamination causes serious health hazard to humans: Study conducted by the Bangladesh Agricultural University (BAU)
17.    Wikipedia
18.    Encyclopedia Britannica
19.    Food & Drug Admininistration Uttar Pradesh



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