Food components: from nutrients to contaminants
All substances entering the body with food can be divided into natural and foreign.
Natural substances include nutritional nutrients (proteins, fats, carbohydrates, vitamins, minerals) and flavoring compounds (organic acids, esters, tannins). Natural products also contain anti-nutritional substances (antienzymes, antivitamins). They are not toxic, but they can block or inhibit the absorption of beneficial components.
In contrast, xenobiotics represent a serious environmental problem. These are extraneous contaminants that enter food due to external factors. The main reasons for their appearance in food:
- Violations of agricultural practices and the use of unapproved food additives (preservatives, antioxidants).
- Use of toxic containers and packaging materials.
- Introduction of genetic engineering, new technologies of microbiological synthesis, and livestock breeding.
- Incorrect culinary processing (e.g., frying and smoking).
- Global environmental pollution (air, water, and especially soil).
Migration pathways and accumulation in food chains
Foreign substances are distributed by intake routes as follows: humans receive 20% of toxins from the air, 10% from water, and 70% from food. Toxicants migrate through complex ecological chains. Most often, they follow the route: air/water → soil → plants → animals → humans.
An extremely dangerous property of certain preparations is cumulation—the ability to accumulate in living organisms, increasing in concentration multiple times at each subsequent stage (trophic level). A classic example of biological amplification is demonstrated by the insecticide DDT (dichlorodiphenyltrichloroethane). Historically, it helped defeat the vectors of epidemic typhus and malaria (for which its creator received the Nobel Prize), but later its colossal persistence was revealed.
DDT accumulation scheme:
- Silt at the bottom of the reservoir — conditional concentration of $1 \times 10$.
- Algae — $10 \times 10$.
- Small crustaceans — $100 \times 10$.
- Small fish — $1000 \times 10$.
- Predatory fish — $10\ 000$.
As a result, humans or animals eating predatory fish receive massive, toxic doses of the insecticide.
Main types of food xenobiotics
In addition to pesticides (such as DDT), food safety is threatened by many other contaminants:
- Mercury. Often enters the environment from fungicides used to treat seed grain against pathogenic fungi. Eating such grain by birds leads to the death of both grain-eaters and predators, and the toxin accumulates massively in chicken eggs. When mercury washes into water bodies, seals feeding on contaminated fish die from it.
- Heavy metals. Include lead and cadmium, which easily penetrate crops from contaminated soil.
- Hazardous chemical compounds. Polycyclic aromatic hydrocarbons (PAHs), dioxins, nitrosamines.
- Veterinary and agricultural preparations. Hormones (estrogens) are often used to stimulate growth in slaughter livestock, beta-blockers to relieve stress before slaughter, and antibiotics to prevent infections. Predictably, residues of these substances end up on the consumer's table.
Hygienic standardization of toxicants
Due to the enormous variety of products, it is impossible to establish a single standard for the content of FCS in all foods. Therefore, hygienists use the concept of MPC (maximum permissible concentration).
It is calculated based on two main values: ADI (acceptable daily intake) or PTDI (provisional tolerable daily intake). These values are derived from threshold doses of the toxicant, which are additionally reduced by a strict safety factor.
When approving hygienic standards, four main indicators are taken into account:
- Organoleptic (preservation of taste, color, and odor).
- General hygienic (prevention of a decrease in biological value).
- Technological (compliance with production regulations).
- Toxicological (guarantee of health safety).
Ideally, food should meet the status of an ecologically clean product—be wholesome, biologically complete, and completely free of xenobiotics or contain them in safe, pre-threshold concentrations.
Briefly: answers to topical questions
Which heavy metals are subject to mandatory hygienic standardization in food products?
Sources indicate the following controlled toxic elements for food products:
- lead;
- arsenic;
- cadmium;
- mercury.
In guidelines, these substances are listed as toxic elements; arsenic is not classified specifically as a heavy metal in the cited sources.
What toxic effects and diseases are caused by chronic cadmium intake with food?
Chronic cadmium intake with food causes a number of severe diseases and pathological conditions. The main toxic effects include:
- Itai-itai disease—accompanied by severe impairment of the musculoskeletal system (occurs when consuming contaminated rice).
- Anemia—develops in children and pregnant women.
- Congenital malformations—occur when the toxicant affects the body of expectant mothers.
- Neoplasms—cadmium has a pronounced carcinogenic effect.
What specific disease is caused by chronic alimentary poisoning with mercury compounds?
The specific name of the disease is not specified in the sources. Poisoning with mercury compounds occurs when consuming organisms living in contaminated water bodies. In water bodies, mercury accumulates in aquatic plants and fish.
Which classes of hazardous chemical compounds are classified as food contaminants?
Food contaminants (foreign chemical substances) include the following classes of hazardous compounds:
- Pesticides—residual amounts of insecticides (e.g., DDT).
- Heavy metals—salts of lead, cadmium, and mercury.
- Chemical compounds—polycyclic aromatic hydrocarbons (PAHs), dioxins, and nitrosamines.
- Agricultural and veterinary substances — hormones (estrogens), beta-blockers, and antibiotics.
- Radionuclides — radioactive isotopes.
- Biological toxins — mycotoxins and alkaloids.
- Food additives — when used in excessive doses or without official approval.
To remember the main food chains of toxin migration, keep this rule in mind: "As the soil, so are the foods." All pollutants from the air and water settle in the soil, from where they pass into flora, then fauna, and ultimately reach humans.
Class and exam questions
What is the difference between antinutrients and xenobiotics?
Antinutrients are natural components of a food product and are not toxic; they only temporarily inhibit the absorption of nutrients. Xenobiotics are foreign chemical pollutants that cause direct toxic harm to the body.
Why is the alimentary route of toxin intake considered dominant?
Up to 70% of foreign substances enter through food because agricultural lands (soil) serve as a massive natural reservoir for toxic waste from the atmosphere and groundwater.
What is the calculation of MPC for food products based on?
The MPC (maximum permissible concentration) is calculated based on the acceptable daily intake (ADI) of the substance and the amount of a specific contaminated product in a person's daily diet.
What else to study on this topic
- The global socio-economic problem of food security and world hunger statistics.
- Demographic forecasts and the depletion of agricultural land.
- Mechanisms by which various culinary processing methods influence the formation of toxicants in food.
- Specific effects of mycotoxins and alkaloids as specific contaminants.
- Classification of antinutrients: antienzymes, antivitamins, and demineralizing compounds.
Master the entire topic in the "Hygiene" course
This is a summary. The course covers everything tested in classes and exams.
- The complete study guide on "Food Contamination by Xenobiotics" and 530+ more pages on the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 95 video lessons for the subject
Other topics in "Chapter 5. Ecological and hygienic problems of population nutrition"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.