FOOD CONTAMINATION: CHARACTERISTICS, TYPES, CONSEQUENCES - NUTRITION - 2025

The food contamination is the presence of any matter that alters food quality and may adversely affect health. The contaminant can be a biological, chemical, or physical agent or condition.

A food can be defined as a substance intended to be ingested for nutritional purposes. Contaminants are materials not voluntarily added or present in an unauthorized concentration.

Protests against transgenic contamination in Spain. Source: Mr. Tickle

The problems of accidental or even voluntary contamination of food have been present throughout the history of mankind. However, at the present time another dimension is incorporated to the problem with industrialization and globalization.

Today, food is processed in many ways, in multiple stages and food chains cross borders. That is why more and more national and international efforts are being made to guarantee food control.

The Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) have joined forces. One of these is the creation of the joint program on Food Standards and the Codex Alimentarius Commission (CAC).

The Codex Alimentarius includes the criteria and standards for the processing and handling of food. In this way, the food web is monitored from primary production, industry, marketing to the final consumer.

The contamination can be of origin, occurring in plants and animals in production or crossed when passing the contaminant from one area to another. Likewise, conscious contamination by adulteration can occur when a component is added or removed to the food, altering its quality.

The source of pollutants can be the environment (air, water, soil) or humans. Therefore, the agencies in charge carry out risk analysis and implement preventive as well as remedial measures when necessary.

Food contamination can be biological when the contaminant is a living organism or its derivatives (bacteria, fungus, toxins, prions). Among the most common bacteria causing food contamination are Escherichia coli, Salmonella and Listeria.

Another form of food contamination is the chemical one that implies the incorporation to the food of foreign chemicals or in dangerous proportion. Contaminants include heavy metals (mercury, lead, arsenic), drugs (antibiotics, hormones), fertilizers, and herbicides.

Likewise, food contamination can be physical when an inert matter foreign to it is incorporated into the food. The contaminating agent can be any body such as pieces of glass, plastic and even radioactive particles.

Any of these types of food contamination has serious consequences for humans. Among these serious public health problems by causing various diseases and even death.

Contaminated food is rendered useless for consumption, increasing hunger and generating economic losses. On the other hand, there are legal implications that carry fines in the smallest of cases and jail in the most serious.

Some examples of food contamination include Creutzfeldt-Jakob disease, a variant that appeared in 1996 in England and other countries. This was due to the consumption of beef contaminated with a prion (misfolded protein) due to poor processing.

In 2008, there were cases of poisoning from infant formula contaminated with melamine (an organic base rich in nitrogen) in China. In this case, the adulteration is suspected to have occurred through intentional manipulation.

In Child Development Centers in Mexico, in 2018 children were poisoned by consuming food contaminated with enteropathogenic Escherichia coli. While in 2019, there were cases of listeriosis (Listeria monocytogenes bacteria) in Spain due to the consumption of contaminated meat.

characteristics

- What is a food?

A food is any material intended to be ingested by humans or other animals for nutritional purposes. Animals are only considered food once they have been slaughtered and plants once harvested.

Medicines, tobacco and derivatives as well as other narcotics are not considered food.

Reasonable probability

According to this principle, any substance that has the probability of being a food will be treated as such until its destination is defined. For example, a vegetable oil can be used for the food chain or other industrial purposes.

As long as its final destination is not specified, it will be treated taking into account the probability of ending up as food.

Food contaminant

It is any substance that has not been voluntarily added to food or was added in a higher concentration than allowed.

- Codex Alimentarius International

The Food Code is the legal instrument that regulates food processing and handling practices. This code was approved by the Codex Alimentarius Commission (CAC), which is the coordinating body of the joint FAO-WHO Food Standards program.

The code is the product of the consensus of 188 countries regarding standards and procedures to guarantee safe and quality food.

- The food industry

In the past, people produced the foods they consumed or were obtained in nearby areas and these were little processed. Today, there are a large number of foods that undergo major industrial transformations and various additives are added to them.

Likewise, food goes through long marketing and transport chains, even transnational ones. All this makes the risks of food contamination and its mechanisms more complex.

Food chain

The production of a food involves a series of steps that go from the production of the raw material to consumption. This can consist of a very simple chain, as is the case with the production of fresh food for self-consumption.

In industrialized societies, chains and even food webs are formed. Therefore, the complexity of the steps a food goes through before consumption increases.

For example, producing a canned meat spread involves several interacting production lines. This ranges from raising cattle or pigs, through transportation, slaughter, processing, and canning.

In addition, this chain intersects with the production chains of the other ingredients, additives and preservatives that it includes. In this network, the can production chain is included where the food will be packaged to finally take it to the consumer market.

- Causes and mechanisms of contamination

The longer and more diverse the food chain, the greater the risk of contamination and involves more complex control. In this context, the possible causes of food contamination are variable and contaminants may come from the environment or from human handling.

There are three basic mechanisms for food contamination which are the following:

Source contamination

Source contamination refers to the fact that the food is already contaminated from the primary production area. One of the causes can be a contaminated environment such as vegetables infected with fecal coliforms.

Chain of food contamination by feces. Source: UNICEF Philippines and Luis Gatmaitan / 2014 / Gilbert F. Lavides

Another case may be grass-fed cattle that have absorbed heavy metals like cadmium.

Cross contamination

This type of contamination refers to the transfer of a contaminant from one area to another in food processing. Generally it is a question of a bad handling or failures in the food processing.

For example, when the necessary hygiene of the areas and implements used to process food is not maintained.

Contamination can be the result of adulteration that consists of intentionally removing or adding a component to food.

A variant linked to adulteration is to add a permitted substance to a food (eg, preservative) in a higher concentration than that authorized. In this case, the food is also considered to have been contaminated.

For this, the Food Code establishes the maximum allowed concentration of each substance.

- Food safety and control

Food security is defined as the guarantee of access to food in quantity and quality appropriate to nutritional needs. In this sense, food contamination affects this safety because it deteriorates the quality of the food.

That is why more and more efforts have been devoted to food control in order to protect its quality. In this sense, between 1907 and 1980 there were great improvements in food security mainly in industrialized countries.

An important step was the pasteurization of milk in 1907 and the introduction of strict hygiene protocols in food production chains.

However, the problems of food contamination do not stop appearing and are even increasing. That is why food contamination risk analyzes must be generalized and even acquire international dimensions.

epidemiology

Based on the above, it is essential to start with epidemiology, that is, to define the frequency of the condition, places of occurrence and affected population. In this way, foodborne illness can be traced through the food chain to its source.

- Risk analysis

In order to prevent food contamination or reduce its impact, it is necessary to apply the risk analysis that involves three fundamental stages:

Determination or assessment of risk

In this phase, the risk of contamination is identified and characterized and the risk of exposure is evaluated. Then, the probability of occurrence of an adverse effect for a given population is estimated.

Risk management

Once the potential risk of food contamination has been estimated, the alternatives are evaluated with all interested parties. From here, the appropriate practices for the protection of the health of consumers are established.

Risk communication

It implies the interaction between all the actors involved (risk analysts, public entities, consumers, industry, academics), for decision-making and implementation.

Types of food contamination

- Biological contamination

In biological food contamination, the contaminating matter is a living organism or a derivative of it (toxin or another). There is a great diversity of bacteria, fungi, protozoa and other organisms capable of contaminating food and which can cause serious, even fatal diseases.

Bacteria

Among the bacteria that most commonly cause food poisoning are Escherichia coli, Salmonella and Listeria. The first two mainly in eggs, chickens and pigs, while the listeria mainly in fresh cheese.

Biological contamination by Salmonella. Source:

In addition, problems are added due to the emergence of antibiotic resistance and the development of new strains.

Mushrooms

Many fungi that contaminate food produce toxins (mycotoxins) that are very dangerous to both human and animal health. Mycotoxins are natural secondary metabolites that fungi produce.

These mycotoxins include aflatoxins, ochratoxin A, sterigmatocystin, and several others that can be carcinogenic and mutagenic.

Prions

In some cases, food contamination may be due to the presence of a non-living organic derivative of a different nature than a toxin such as prions. These are the cause of the so-called "mad cow disease" or bovine spongiform encephalitis, which is a variant of Creutzfeldt-Jakob disease.

Rodents

Mice and rats are agents of food contamination, especially due to their excreta and urine. Cases of contamination of grains by excreta are common.

Diseases such as leptospirosis and toxoplasmosis are transmitted through the urine of rodents and other animals.

Genetic contamination

A modern variant of biological food contamination is that derived from genetic engineering. Today, genetically modified organisms (GMOs) can be produced which are organisms that possess genes from other organisms.

This implies that a certain food derived from a GMO will have traces of proteins from a different species. If a person is allergic to this protein, such contamination can pose a serious risk to their health.

Hence the importance of proper labeling of food products derived from GMOs, so that the consumer is informed.

Serious cases of food poisoning have occurred from ingesting foods with traces of substances to which the consumer was intolerant or allergic. For example, traces of dairy in cases of lactose intolerant people, or cashew in cases of allergic people.

- Chemical contamination

In this case, food contamination occurs because food is exposed to the action of various chemical substances. This can occur at source, for example when vegetables are contaminated externally or internally with herbicides or fertilizers.

Heavy metals

Heavy metals can contaminate food either by environmental depositions on them or at source. In the latter case, plants absorb them from the soil and accumulate them or livestock consume the contaminated plants.

The most common pollutants in this case are arsenic, lead and mercury. In any case, both plant and animal products can be contaminated with heavy metals.

For example, cadmium contamination of chocolate has occurred in Venezuela and Peru by absorption of the cocoa plant growing in contaminated soils. Another case is Minamata disease (Japan), caused by the consumption of fish and shellfish contaminated with mercury.

Dioxins

These chemical compounds are generated in processes that involve combustion with chlorine and are linked to the plastic and paper industry, among others. Dioxins have been reported to be carcinogenic, cause bone degeneration, and other problems.

Other agents

Other possible agents of food contamination are food supplements, additives, preservatives, chemical and pharmaceutical residues. Meat, milk and other animal derivatives can become contaminated by preserving drug residues (antibiotics, hormones, etc.).

- Physical contamination

Physical food contamination refers to the presence in the food of inert matter foreign to it. It can be glass particles, stone, pieces of metal, hair or others.

Irradiation on food is also a type of physical contamination in which radioactive particles are deposited on food.

Radionuclides

Drinking water can become contaminated with radionuclides, which are a type of radioactive atoms. The most common radionuclides in drinking water are radium, radon, and uranium.

The Food Code regulates the concentrations of radionuclides allowed in drinking water.

Consequences

Public health

The main consequence of food contamination is food poisoning, which causes morbidity (sick and disabled people) and mortality in the world.

Loss of food

Contamination of food renders it unusable for consumption, which increases the existing food deficit. In some regions of the world, the loss of a batch of food due to contamination implies hunger for large segments of the population.

Economical

Food contamination causes economic losses, in the first place by which it implies the direct loss of contaminated food. Additionally, it involves other economic losses related to non-compliance with sanitary regulations that lead to lawsuits and related legal processes.

On the other hand, the measures required to solve the causes of pollution also bring economic outlays for the companies involved.

Legal

Food contamination, being a serious public health problem and is strictly regulated in most countries. In this sense, non-compliance with the established regulations leads to legal problems.

In addition, if food contamination affects the consumer, criminal lawsuits are involved.

Case examples

- Listeriosis in Spain

The Spanish Ministry of Health reported 210 cases of listeriosis from consuming contaminated meat in September 2019. Most of the cases occurred in Andalusia, but 64 probable cases and 66 suspected cases were in 10 other regions of Spain.

The illness

Listeriosis is a disease caused by a bacterium (Listeria monocytogenes) that has a mortality rate of up to 30%. It is a food contamination of origin, since it is cattle that acquire the bacteria.

The bacteria then pass to humans by consuming raw or undercooked meat, milk or derivatives.

The disease becomes systemic when it passes into the bloodstream and produces high fevers and diarrhea. It affects people with weak immune systems, children, the elderly and pregnant women.

- Escherichia Coli

The Escherichia coli bacterium is part of the digestive tract of humans as well as other animals. However, it also has pathogenic strains that cause diseases in various systems (digestive, circulatory, urinary, nervous).

The enteropathogenic E. coli strain is one of the most common causes of diarrhea, especially in children and the elderly. Normally, these pathogenic strains enter the body through the consumption of contaminated food.

For example, in March 2018 117 children were poisoned in four Child Development Centers in Jalisco, Mexico. The symptoms were diarrhea, abdominal pain and fever that all the children managed to overcome successfully.

The tests were able to determine that the cause was the consumption of food contaminated with enteropathogenic Escherichia coli.

- Contamination of powdered infant formula in China

In 2008, an epidemic of poisoning due to contamination of an infant formula with melamine (2,4,6-triamino-1, 3,5-triazine) occurred in China. More than 294,000 children were reportedly affected by the adulterated formula and more than 50,000 were hospitalized, of whom at least 6 died.

Melamine

Melamine is a nitrogen-rich organic base prepared from urea (carbamide). It is used in the manufacture of plastics, fertilizers, adhesives, furniture, tableware and other implements.

Food contamination by adulteration

Apparently the melamine was added to adulterated milk (diluted with water) to mask the lower proportion of protein per liter. This is because the protein level is estimated by measuring the nitrogen content.

Disease

Melamine in the body forms crystals that cause kidney damage (kidney stones), leading to death in severe cases.

- Mad cows

In 1985 the first case of “Mad cow disease” was detected in the United Kingdom and in 1996 the first cases of the human version occurred. Between 1996 and 2008 there were 163 cases in the UK and 35 in the rest of Europe. Outside this continent, there were 4 cases in the United States, 1 in Canada and 1 in Saudi Arabia.

Bovine spongiform encephalopathy or "Mad cow disease" is a disease that affects the nervous system of cattle. There is also a variant of sheep called scrapie.

Prion in human protein for Creutzfeldt-Jakob disease. Source: Cornu (talk) 19:04, 5 June 2009 (UTC)

The disease is not caused by a pathogen, but by a variant of a protein called a prion. This protein is normally found in the brains of cows, humans, and other animals.

How the prion works

If you consume the brain, marrow, eyes, tonsils, spleen, or intestine of an infected cow, you acquire the prion. This folds in a different way than normal, affecting new proteins and accumulates in the brain where it causes neurological damage.

The disease in humans

In these cases, a variant of Creutzfeldt-Jakob disease occurs, already known in humans and of hereditary origin. This new form is caused by food contamination and is called variant Creutzfeldt-Jakob or new variant (vCJD or vCJD).

Type of food contamination

In this case, it is a food contamination of origin, since the food is contaminated when produced. Once the cow has passed through the slaughterhouse, it is considered food and carries the contaminant (prion).

There are two hypotheses of how the disease originated in cows, the first is that contaminated sheep remains were added to the feed to feed the cows. Another explanation is that a mutation occurred in the gene of the cow that produces the normal protein and generated the pathogenic variant.

References

1. Bernard, A., Hermans, C., Broeckaert, F., De Poorter, G., De Cock, A., & Houins, G. (1999). Food contamination by PCBs and dioxins. Nature.
2. Chu, FS (1991). Mycotoxins: food contamination, mechanism, carcinogenic potential and preventive measures. Mutation Research / Genetic Toxicology.
3. Codex Alimentarius. International food standards. (As seen on September 25, 2019). fao.org
4. Elika. Basque Foundation for Food Safety. Types of food contamination (Seen on September 25, 2019).
5. Ingelfinger, JR (2008). Melamine and the Global Implications of Food Contamination. New England Journal of Medicine.
6. Nasreddine, L. and Parent-Massin, D. (2002). Food contamination by metals and pesticides in the European Union. Should we worry? Toxicology Letters.