Chemical Risks 

Chemical Risks

Chemicals are the building blocks for everything in the world. Everything that lives, people, animals, plants are made up chemicals. Therefore, all foods consist in chemicals. It is not possible to talk about life without chemistry.

A very important part of the chemicals to be found in foods are carbohydrates, proteins, fats, vitamins and minerals that our body needs for its life, indispensable for our nutrition and desires. Apart from these nutrients, there are naturally non-nutritious chemicals that have a total count of hundreds of thousands. On the other hand, there are:

Chemicals we add to food for technological reasons and to improve the food during the production of food, and it is acceptable for us,
Chemicals we use during the agricultural production but we do not want them in final product as a residue,
Chemicals we do not want to be present in the food. Which may have adverse health effects, but which, exist naturally in the structure of food or either contaminate from outside or occur in a stage of the production chain.

In other words, some chemicals found in foods are useful for humans, while others can pose health risks to humans.

However, this benefit has a fine line in the relationship of cost: It should be noted that all chemicals taken with food can be harmful if taken over a certain period and dose. Paracelsus, the father of the medical doctor and pharmacologist, has a famous saying: “All things are poison and nothing (is) without poison; only the dose makes that a thing is no poison”. Because of this information toxic substance definition is "substances or agents with the capacity to cause adverse, effects or damage to the biological system when used in inappropriate doses and time". For this reason, what we eat and how much we eat during our whole life are the preconditions for a healthy life.



Since it is impossible to address all the chemical risk which are more than thousand, only some of them will be discussed.

International Institutions for Risk Analysis of Chemicals in Foods

All chemicals related to foods are under constant observation by scientific circles and health and food authorities. International independent scientific committees (such as JECFA, JEMRA, IARC, EFSA) CONNECT TO INTERNATIONAL INSTITUTIONS! They work to establish safe levels for these chemicals to ensure protection against harmful effects. These scientific studies also guide those who can decide in the use of chemicals and legal regulations on their quantities.

For example, JECFA (The Joint FAO/WHO Expert Committee on Food Additives) evaluates the effects of these chemicals on human health in the scope of toxicological investigations in the short and long term. As a result of these studies, "NOAEL" is defined as "no observed adverse effect on human health" and as a safety factor, this amount is divided by 100 to create a daily allowance level for people (Acceptable Daily Intake-ADI for additives, Tolerable Daily Intake-TDI for contaminants). Therefore, considering and obtaining the amount of foodstuffs’ consumption with these values, the maximum limits that the chemical can be found in the foodstuffs are determined.

The International Agency for Research on Cancer (IARC) collects all scientific research data about each chemical suspected of being carcinogenic, provides a thorough examination of the subject by a commission of scientists around the world, and reports the results of all these studies to classify the chemical substance in terms of carcinogenic properties. However, the inclusion of a substance in the classification of carcinogens alone is not enough. JECFA, EFSA (European Food Safety Authority) and other institutions make risk assessments of the substances with the results of these IARC studies and the level of exposure of people to the substance and ADI / TDI levels. As a result of these assessments, they provide the necessary information to the public to take decision on whether the intake of a food with this substance constitutes a cancer risk and / or the acceptable level of risk.

Nowadays, publications are being leading to show that many food items or food components are cancerous and very harmful. The way to prevent the confusion of our heads in this matter is to reach IARC's lists, to look at the investigated substance legal limitations from the above mentioned institutions, which are within the carcinogen classification, to the assessments concerned to the substance and the safe limit which does not adversely affect the health even in case of continuous consumption for a lifetime.

Detailed information on this topic and toxicology for typical samples should be made available on the web site of the Turkish Toxicology Society, one of the most competent institutions of our country.


Mycotoxins are highly toxic chemicals produced on (and in) foods by molds that we often encounter in our daily lives. This information is not very old. It was understood that molds produced toxic substances, with the discovery of aflatoxin in the 1960s. Today it is known that there are around 400 mycotoxins. By acting on different organs, mycotoxins can cause serious diseases in the digestive system, kidneys and nervous system as well as affecting the immune system, hormonal (e.g. estrogenic) and carcinogenic effects.

From the time of the crop, there are critical stages that allow the formation of mycotoxins in the production chain of many foodstuffs. Some mycotoxins are formed by the molds that cause disease in plants, and they are formed by the crops in the field and are consumed by the foods that these products are processed. Many, if not taken care of, are able to reach all the stages of moisture and temperature that are necessary for the development of molds. For example, the drying process in dried products such as hazelnut, peanut, dried fruit, spices is critical with regard to the formation of mycotoxin . The drying must be so quickly that it does not allow the formation of mycotoxins. For example, it takes a long time to reach a sufficient level dryness in red dried pepper in natural conditions, depending on the season conditions, in some cases it takes 10-15 days and a drying time greater than 3 days increases the risk of mycotoxin formation. If products such as these are wetted by natural causes such as rain during drying, they will increase the risk of mycotoxin formation. As you can see, a very common belief is that products that are "natural" processed / dried are not always "the best, healthy and risk free". Stages such as storage of inadequately dried products or unsuitable storage conditions, wetting of the product by force of technology during processing also pose risk for mycotoxin formation. All these risky production conditions apply to products made at home.

It should be taken into account that the risk of mycotoxin is always in the foods where the growth of molds is possible. Mycotoxins are chemical substances produced during the metabolism of molds and can be found everywhere in moldy food. For this reason, it is a big mistake that only the moldy portion of the moldy food is thrown away and the rest is consumed.

Because, the mold-grown food can reach mycotoxins into the food through the invisible hyphae, not just on the part where it is found.


However, it is possible to have mycotoxins in large quantities that are not visible to the eye in foods. As this can possible further analysis, official controls at risky levels show great importance. For this reason, in order to prevent consumption of mycotoxin-containing foods, controlled production, that is to say registered or approved, must be consumed as we always emphasize.


Aflatoxins are the most studied group of mycotoxins and we have the most extensive knowledge on. Consumers are also more familiar to aflatoxins than other mycotoxins because they are often subject to international trade news. The molds that produce this mycotoxin group are mainly A.flavus and A.parasiticus strains associated with the genus Aspergillus. The most common type of this group is aflatoxin B1.

Thousands of studies since the 1960s have provided considerable evidence that aflatoxin B1 is causing liver cancer in humans. Depending on these studies, aflatoxins have been classified by the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) as being "sufficient evidence of carcinogenic in humans".

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Acrylamide is a chemical compound formed during frying, baking, roasting and cooking some starchy foods at high temperature or applying heat over 120 oC with low humidity. It is generated as a result of chemical reaction of amino acids and sugars, which majority of foods naturally have. It was identified for the first time in 2002 when it was present in food, possibly since the beginning of the cooking process, and was identified as a potential hazard in 2005 because it showed carcinogenic and genotoxic effects in experimental animals. In the scans made, acrylamide was found in cereal-based foods such as biscuits, toast, and in grilled, fried or roasted potatoes. Currently in the International Agency for Research on Cancer (IARC) classification, the 2A group is found to be cancerous in animal experiments, but there is insufficient evidence of cancer in humans. Regarding to acrylamide, safe limits have yet to be established for food in our country and at international food safety agencies. Only a recommendation has been published by the EU for indicative values. However, studies continue for this purpose.

Likewise, for industrial products, the technologies to reduce the acrylamide formation are being investigated and applied.

To reduce acrylamide risk, it is recommended that:

Less brown in toasting, baking and frying will reduce the risk. The golden color should mostly be preferred.

      Potatoes should not be kept in the fridge since it can increase the acrylamide formation,

     Potatoes should be put in water for 15-30 minutes before frying or boiled shortly in boiling water.

Metals as Food Contaminants

Most of the metals are essential for human nutrition in different forms, but some or some forms and some high doses pose a risk for human health. Cadmium, lead, tin and mercury are natural chemical compounds. They can be found at various levels in the environment, e.g. soil, water and air. From the farm to the table can be transmitted at any stage of the food chain. For this reason, people can be exposed to these metals through food and water as well as the environment. The accumulation of these metals in the body can lead to significant health problems over time.

In this web page, you can find summary information on the heavy metals, which are determined by the regulation in our country, about the highest quantities allowed to be present in foodstuff.


Cadmium is a heavy metal rarely found in nature and mostly not in pure form, but in compounds such as cadmium oxide, cadmium chloride and cadmium sulphide. Foods are the main source of cadmium for humans after smoking. As cadmium is used in many jobs in the industry, it contaminates wastes, sewages and soils, and can also be transmitted to food through them. It is most commonly found in grains, cereals and products, vegetables, starchy roots and potatoes, meat and meat products, fish, crustaceans. Bivalve mollusks and those who consume wild mushrooms are also at risk.

Cadmium and its compounds primary affect the kidneys and may cause renal failure. It is classified by the IARC in the human carcinogen group and recent studies highlight the risk of cadmium for lung, endometrium, bladder and breast cancer.


Lead can be in organic and inorganic forms, naturally occurring, but at a larger size, resulting in human activities such as mining, and inorganic form is very common in the environment.

Lead mainly affects the central nervous system and this neurotoxic effect of lead is more sensitive to the fetus, infants and children in the mother's womb. Besides from neurotoxic effects in children, adults also have cardiovascular and nephrotoxic effects.

In terms of exposure to lead: all type of meats (red, winged, and fisheries), cereals and cereal products, legumes, fruits and particularly berry fruits such as grape, raspberry, blackberry, fibrous vegetables, margarines and oils, milk and milk products are the main risky foods.


Mercury is found naturally in the environment and also as a result of human activities. There are a number of complex transformations and cycles in the atmosphere, sea and land. The most common form in the food chain is methylcysteine.

The primary targeted organ for toxicity is the kidney, but it also affects the liver, nervous system, immune system, reproduction and development systems.

Other seafood, especially fish, are risky foods due to inorganic mercury. Among the fish, it is seen that the highest risk is found in dogfish, tuna fish, salmon and swordfish.


The natural concentration of tin in plant and animal tissues is low. The main source of tinned food is canned tinned beans and although there are other sources, the tin transition rate to food is very low. Coating tin in tin cans is a method that has been in used since 1800's. Tinned cans are usually coated with a lacquer to cut the tin migration to food. However, in poorly or uncoated tin cans, high-purity tin may pass through the food, due to corrosion occurring after the reaction between the food and the tin. More advanced coating techniques have reduced the amount of tin to food, but metal canisters are still the main source of tin in the kitchen. The level of tin in canned foods depends on factors such as quality of the coating, keeping the food inside the can after it is opened, storage conditions, acidity of the preserved food, presence of oxygen, food characteristics.

After opening these types of canneries, food should not be kept inside and stored in the cold to prevent the passage of tin.

The regulations on contaminants have limit values for inorganic tin originated from tin cans.

Dioxin and Dioxin-Like Polychlorinated Biphenyls (PCBs)

Dioxins and polychlorinated biphenyls are polychlorinated aromatic compounds with similar structure and chemical, physical properties.

• Dioxins rare colorless, odorless and organic compounds containing carbon, hydrogen, oxygen and chlorine, and dioxin is a broad chemical group containing 210 different compounds. Seventeen of these are toxicologically hazardous compounds. Dioxins do not have a technological or other use in their own right, but thermal and industrial processes are the resultant products. Volcanic eruptions can occur during natural events such as forest fires and as a result of activities such as agriculture, paint, steel production, exhaust emission, and burning. For example, when chlorinated wastes are burned uncontrolled in a garbage oven, dioxin can be released into the air.

• Polychlorinated Biphenyls (PCBs) are prohibited and restricted in the Stockholm Convention due to their negative effects on the environment and human health. But are persistent organic pollutants (POPs) that remain a threat to human health and to the environment, because they remain for long periods when they enter to the environment, due to their high resistance. Before PCBs were banned, they could be found at levels that will be dangerous to the environment because they were widely used in transformers, building materials, coating materials, plasticizers and inks. Because of the POPs, PCBs can also spread along long distances around the world with air currents, and they can enter in the food chain and accumulate in animal and human tissues.

Long-term exposure to dioxins and dioxin-like PCBs whose presence has been caused, in Europe during the 1970s, reproductive functions, skin diseases, nervous system, endocrine system and immune system diseases. Dioxin-like PCBs are among the human carcinogens in the International Agency for Research on Cancer (IARC) classification. That is why today is one of the important public health concerns.

Since some of toxicological properties are similar to dioxin, some of PCBs have been defined as "dioxin-like PCBs". However, even though these effects are not similar, non-dioxin-like PCBs also have significant negative health effects.

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Pesticide Residues

Pesticides are chemical substances that prevent, destroy or control a harmful organism or disease and are used to protect plants and plant products during agricultural production, storage and transport. Insecticides against insects, fungicides against fungi and herbicides against weeds are the most common and widely used pesticides.

Pesticides are mainly used in agricultural production, as well as in forestry, horticulture, landscaping and home gardens. The chemicals used against mosquitoes and black flies in our living spaces are also pesticides.

The substance which is mainly effective against the pests in the pesticides is defined as "active substance" and the substances subject to the residue are these.

The disease, which is an important problem in agricultural production, in order to be economically protected from the harmful effects of weeds, pesticide use cannot be abandoned today in all over the world. However, the use of excess amount and unconscious pesticides creates negative effects on human and environmental health by leaving residues in our foods. For this reason, studies are being carried out to ensure that pesticide applications are suitable for the purpose and minimize risks. Now, in developed countries, pesticide utilization is controlled and conscious. The use of risky pesticides is severely restricted, and appropriate alternatives for human and environmental health are encouraged.

It would be good to explain with an example what conscious use is. Just as with medicines, the use of each pesticide is very important. It must be used absolutely according to the description on the label and / or the opinion of an expert. For example, from the application time of the pesticide till the harvest time is very critical in terms of the level of the residue, since the pesticides has a degradation time. As would be expected, if this timing is not followed, the pesticide residue will be high in the urine. Likewise, examples of unconscious use such as "the more will be more effective", with the wrong perceptions, the dose being higher than the order and the application being made more frequently.

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Bisphenol A (BPA)

BPA is a chemical used mainly in the production of plastics and resins. For example, BFA in polycarbonate is used for the production of a transparent and rigid plastic. Polycarbonates are also used in many food contact materials such as plates, glasses, recycled beverage bottles. In addition, BPA-containing epoxy resins are used in the inner lining of canned food and beverage containers and coating of containers used in food processing (lacquer). BPA can pass to food and drinks in small quantities from these food contact materials. People can also be exposed to BPA from some sources other than food (dentistry, some kind of paper, some toys).

Independent scientific studies have shown that even if BPA is taken at high levels, the toxin property is detoxified (detoxified) and discarded after the body is rapidly absorbed. The World Health Organization with European Food Safety Authority (EFSA) has identified how much newborn babies and children and adults may be exposed to BPA in these days and concluded BPA would not create a health problem with these levels of exposure. The reassessment of EFSA in early 2015 confirmed this view; which means that exposure will not cause any adverse effects in the event of a lifetime of daily intake (TDI) and therefore does not pose a health risk to any age group, including infants and children. Legislative regulations that set limits on BPA have been made on the direction of these evaluations.

Our country also has legislation in line with the EU regarding BPA. Accordingly, BPA is allowed to be used in plastic materials with food and / or contact materials in accordance with the rules and limit values. A ban was imposed on the use of bottles with the amendment made in 2011 with the aim of being more cautious about infant feeding, as it is in the legislation on almost every risky substance.


Melamine is a subsidiary product of the coal industry and contains a high amount of nitrogen. There are many industrial uses such as the production of plastics, culinary materials, commercial filters, adhesives, coatings.

The reason that melamine is one of the safe food topics is the fact that melamine is involved in food and feed for cheating as it allows the protein content to look fake high in food and feed. One of the standard and widely used methods of measuring the protein content of foods is to measure the nitrogen level and the amount of protein to be calculated according to the nitrogen. Due to the high nitrogen of melamine, such a test leads to a high-protein content error. For example, when it is added to the milk diluted with water, this adulteration will not be understood because of high protein content.

The first use of melamine for this purpose was revealed in 2008 when melamine was found to be high in children's milk and other dairy products in China. This adulteration caused very serious health problems in infants and children in China. At least 4 children who died of kidney failure because melamine was added to the milk powder and more than 50,000 babies and children had kidney problems.

Therefore, methods have been developed that can detect the presence of melamine and do not measure protein levels through nitrogen.

Although many countries banned the importation of dairy products from China on this occasion, there was also concern about foods such as biscuits and chocolates, in which milk powder could have been used. However, EFSA has commented that it would not create a significant health problem due to the rate of use in these products is assessed according to the highest level of melamine, and limits were set within this view. Turkey has made melamine regulation in accordance with these limits.

Veterinary Drug Residues

Veterinary medicines are used to heal or to treat diseases of animals raised for food. If these medicines are used improperly or if the animal is cut and the products such as milk or eggs are served for consumption without consideration of the time of elimination of the medicinal product (withdrawal time ) from the body, the residues in these products may lead to health problems in humans. The contaminants may be in the form of metabolites, which can be harmful to humans by altering the drug's own active metabolite or the metabolism.

Withdrawal time can vary according to the duration of breakthrough in eatable tissues as well as the amount and type of drug used. Veterinary medicines must be licensed and used in accordance with their instructions for all animals raised for food, such as cattle, sheep, goats, winged. Their licenses are also granted by the Ministry of Food, Agriculture and Livestock.

Veterinary drugs residues are also controlled and supervised by the same Ministry. The level of residues in the environment of a food or treated animal should not exceed the maximum limits (MRL) determined by statutory regulations. These limits are also determined by considering the amounts that will not cause health problems (ADI value) even when they are consumed on a daily basis over a lifetime

The most controversial antibiotics in the public are prohibited as growth-promoting factors, but they are permitted for therapeutic use. Important for therapeutic uses are the use of international maximum residue limits and the time of their removal.

The way to avoid the health problems that veterinary drug residues can cause is to consume the products of registered / approved enterprises, which are of course authentic, and to stay away from unregistered products.

Hormone Use in Meat Animals

The use of accelerated substances such as estradiol, testosterone, progesterone, zeranol has been proved to be a health problem in humans. Since the 1980s its use has been forbidden in all food-derived animals, including chickens.

The use of antibiotics, which are effective for growth and development as well as treatment, is forbidden as a growth and development factor of poultries in European Union (EU). Since this date, antibiotics have been used only for treatment-purposes.

Differences in the time to reach certain weights of the poultries depend genetic differences, breeding methods and feed contents, not hormone use.

This information also shows that we should choose approved products to protect ourselves from illegal practices.

Polycyclic Aromatic Hydrocarbons (PAHs)

PAHs are the contaminating group that can occur as a result of incomplete combustion of organic substances in the environment. It occurs naturally, with forest fires or volcanic explosions. Human-induced formations are through industrial sources, motor vehicles and cigarettes. Industrial sources include waste incineration, cement factories, oil refineries, cocci and asphalt production, aluminum, iron and steel production. Solid fuels such as coal, wood, and fossil fuels used for heating and energy also cause PAH formation.

Although there are more than 100 PAHs, some of them have toxic effects. One of the common examples is the benzo(a)pyrene, some of which are carcinogenic. Humans are also exposed to environmental or industrial contamination of these materials or to foods contaminated with these substances. PAH can be found in contaminated soil, air and water-bearing crops.

During the vegetable oil production, because of the heat treatments applied to remove water from the high moisture pomace, PAHs can form, and such oils are among the risky foods. Studies have shown that PAHs are formed during smoked foods and cooking in barbecue.

In recent years, many countries and our country have made legal arrangements regarding the highest levels of PAHs that can be found in risky meals.