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Contamination is a Growing Food Safety Concern

    Chemical Contaminants in Food

Chemical Contaminants in Food

The WHO has stated that there is a need for more vigilance in food and water safety as contamination of these causes millions of deaths, including that of children. The use of pesticides and fertilisers has grown more than 150 per cent in the past 50 years and therefore these have become major contaminants of food. High use of artificial fertilizers and pesticides during the agricultural process can lead to a number of food-borne diseases. Also there are many chemical contaminants and heavy metals that disperse in the environment from where they can enter the food chain from anywhere. Chemical toxins can also have short term and long term effect particularly on health of children. Mycotoxins in food grains and process contaminants are often overlooked whereas they too can have harmful effects on health.

Contamination of foods a worldwide concern

The UN agencies like WHO and FAO have established an International Food Safety Authorities Network (INFOSAN). Through this body it is possible to quickly share information on any food safety emergencies globally. With the foods being exported from one country to another it is very important to share information. Food that is produced in one country, if contaminated at the source, can affect the health of the consumer in any part of the globe. Contaminants in food not only pose a worldwide health concern but are one of the major reasons that cause barriers in international trade.

Exposure to Heavy Metals

Heavy metals have been used by humans for thousands of years but their ill effects on health have only been corroborated by studies in the more recent times.    Exposure to heavy metals from food has been increasing and the WHO has been regularly reviewing their effect on human health worldwide. Arsenic, cadmium, mercury, lead and inorganic tin are known to cause the most heavy metal poisoning in foods products. Exposure to these heavy metals has been studied and the risk of exposure on human health has been established.

  • Fumes that contain heavy metals when released into the atmosphere can return with rain and contaminate the soil and surface water. These heavy metal residues can easily find their way into agricultural produce from the soil or water bodies.
  • Cadmium products, like batteries, are not recycled and they are dumped together with other waste and from here they leach into soil and water bodies and contaminate agricultural food products.
  • Fish are carriers of toxins and unconsciously can cause serious health issues. People get exposed to mercury through fish which is a major source of methyl mercury exposure and is associated with neurological damage and risk to the foetus in pregnant women. Fish from polluted rivers must be avoided.
  • Glazed food containers and the environment can cause lead exposure.
  • Arsenic enters the food chain mainly through water and it can cause cancer. The presence of arsenic in apple juice has caused worldwide concern and there is a growing concern about the seriousness of heavy metal contamination throughout the food chain.
  • Arsenic and cadmium in pesticides, insecticides, fungicides and commercial fertilizers can be toxic and pose health risks if consumed at high levels over long periods.

A number of other products like protein shakes, baby formula, food grains and fresh foods have been linked to heavy metal contamination.  Heavy metals are a leading health concern and implementing comprehensive testing of food products is the best way to assure food safety.

Chemical contamination is dangerous

Chemical contamination of foods can be either dangerous or more dangerous as almost all chemicals in food are toxic. Chemical contamination can be intentional when certain food additives are added for technological reasons. Another way chemicals can reach food is through the environment, water and soil. Chemical contamination can occur because of

  • Excessive use of pesticides and insecticides on agricultural produce
  • Due to human error when using cleaning agents like bleach, disinfectants, detergents and sanitizers near food
  • Containers that have been used to stores chemicals are sometimes reused, which contaminates water or food stored in them
  • Chemical contamination can take place if chemicals are not handled correctly and with proper precaution especially in food establishments like restaurants or in food packaging areas.
  • Other more dangerous chemicals can reach food from industrial waste, generation of nuclear power, leaching of toxic elements from containers or from utensils that come in contact with food.
  • Another source of chemical contamination is the manufacture of organic chemicals that produce, gases, sludge and liquid effluents.

These chemical contaminants get released into the atmosphere, soil and on the surface of ground water from where they find their way into foods. Health risks depend on the level of exposure and the toxicity of the substance and the level of concentration in food that is being consumed. Levels of chemical contaminants in foods and the concentration of the amounts at which they are being consumed are important. The only way to determine food is safe is to carry out food sample testing for various chemicals.

Microbial contamination in food from various sources

Foodborne diseases are one of the major causes of illness and death worldwide. Foodborne diseases are caused by microorganisms that can contaminate food and beverages in the home, in eating outlets and even in manufacturing plants.  Microorganisms are harmful living organisms that are responsible for outbreaks of diseases like diphtheria, pneumonia, typhoid, amoebiasis, botulism, cholera, dysentery etc.

Some of these microorganisms become resistant to one or more types of antibiotics and this leads to serious consequences or loss of life. Food spoilage by microorganisms can be visible when there are signs like discolouration or food has off odours and flavours but many times there are no visible signs. Product types, preservatives used or not, the manner of processing, packaging, and storing are some of the factors that enable bacteria to multiply in high levels and cause spoilage.

Food can become contaminated with Microorganisms

  • When it is not properly handled or stored in the manufacturing plant, during transportation, in the retail outlet, in the food outlet like restaurants, eateries, school canteens and even in the home.
  • During food preparation if it is handled unhygienically or if food handlers do not follow personal hygiene according to food safety regulations.
  • In manufacturing plants microbial contamination tales place when conditions are present like moist surfaces along with nutrients for microbes to survive in. This can happen when the process equipment has not been hygienically integrated or if cleaning and disinfection procedures are not properly carried out so organic soil remains on surfaces. Slicing and cutting equipment, filling and packing machines, conveyors, plate heat exchangers that have piping are difficult to clean and so microorganisms that grow here are contaminate food during processing.

Solving food hygienic problems caused by microorganisms is challenging as all microbes do not cause equal contamination. Therefore microbial food sample testing requires conventional sampling along with culture and molecular typing methods. This is essential if the exact route of the microbial contamination has to be detected in the production chain. 

Mycotoxins are natural contaminants 

Mycotoxins can naturally contaminate agricultural commodities like peanuts, maize, rice, wheat, spices and fruit juices. Mycotoxins are species of fungi that grow on crops in the field before they are harvested, during harvesting, storage and even during food processing, especially when fermentation is used. When ingested, inhaled or absorbed through skin, mycotoxins may reduce appetite and cause health problems like toxic hepatitis, certain cancers, kidney failure and may even cause death. According to a report by the Food and Agriculture Organization (FAO) there are more than 77 countries that have specific regulations for acceptable concentrations of mycotoxins in foods which includes India. According to the WHO out of the 400 known mycotoxins the most risk to human health is caused by aflatoxins, fumonisins, ochratoxins, deoxynivalenol, zearalenone, and patulin. Each of these mycotoxins require optimal weather conditions to grow.

  • Hot and dry conditions favour aflatoxin growth and fumonisin build up in hot and humid conditions.
  • Cold and damp conditions produce deoxynivalenol and other trichothecene
  • Patulin grow in temperate climates and are most commonly found in apples.

Crops in tropical and subtropical areas which have high humidity and temperature are contaminated by some of the most dangerous mycotoxins.

According to FAO almost 25% of food crops in the world are contaminated by mycotoxins. Mycotoxin contaminants grow in humid conditions and so the moisture level needs to be below 85 per cent. Also crops must be harvested in time, as late harvesting prevents thorough drying and so causes mycotoxin contamination. Propane driers used after harvesting can therefore prevent moisture in crops. 

Contaminants can be produced during processing 

Process contaminants are chemical substances that are sometimes naturally produced in food during food manufacturing, cooking, which includes home cooking, packaging and processes like fermentation and acid hydrolysis. These types of contaminants are not present in raw foods or raw materials used in making food but are formed when components within the food or raw materials undergo chemical changes during processing. Examples of process contaminants produced by dry-heat cooking are acrylamide in French fries and PAHs in roasted pork.

  • During processing certain undesirable chemicals can be formed because of the reactions of compounds that are found naturally in foods.
  • Sometimes certain food additives are added to foods which react with a compound already present in the foods.
  • When foods are baked or fried or undergo heat processing certain changes take place in their appearance, texture and flavour but sometimes these produce compounds that might not be safe.
  • Sometimes storage as well as processing conditions cause reactions which in normal circumstances would not happen in these foods when raw.
  • Sometimes metal chips from the processing equipment can contaminate food and are identified using metal detection equipment.

Acrylamide and furan, which increase the risk or cancer, may be formed at high temperatures during cooking in manufacturing plants as well as in home cooking.

Chloropropanols and their fatty acid esters, also known as chloroesters, are contaminants formed in processed foods that have been derived from cereals, coffee, fish, meat, potatoes, nuts and refined oils.

Chloroesters may form when these ingredients are processed by heat which releases the chemical 3-MCPD from these materials either during processing or even storage. Toxicological studies imply that chloropropanols/ chloroesters might be risk to human health. In many cases, there is no way to avoid the processing-induced chemicals in food. What is important is to understand the processes used to make these products so that if required the food preparation methods can be changed to reduce or eliminate these chemicals.

Responsibilities of FBOs 

Most food manufacturers safeguard against the microbiological contamination of food from bacteria, viruses, parasites. Still chemicals, additives and other contaminants can cause more than 200 diseases which could range from mild diarrhoea to serious nerve diseases and cancer. All food manufacturers need to be aware that pesticides, heavy metals and mycotoxins from fungus, microbes and process chemicals can contaminate food any time during manufacture, storage or transportation. It should be the aim of all those in the food business community to be aware of these contaminants and take all necessary precaution to provide or supply safe and wholesome food to consumers.

Since it is not possible to merely ensure food safety with visual examination, especially ppm levels of chemicals or the presence of complicated microbial contaminants,  testing of foods must be taken very seriously by those who are in any kind of food business that provide any kind of cooked, processed or raw foods, like vegetables, fruit and cereals, to consumers. Also FBOs must follow and ensure that their FSMS programme is well designed and is in place.


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