Residues - from production to the plate

In agricultural production, various aids are used for quality assurance and yield increase. These include fertilizers, pesticides and veterinary drugs. Incorrect use may result in food residues.

Residues are residues of substances that are used during the original production of plant or animal foods in order to achieve certain effects. They are used, among other things, to protect crops from spoilage, to ensure or improve crop yields, and to deliver hygienic products. Legal provisions state that their use is kept to a minimum. If these substances are not completely degraded during the lifetime of the plants or animals or until the food is consumed, they remain as residues in the food. Legislation sets maximum levels for these residues for the protection of the consumer. Compliance with these limits is regularly monitored by the authorities.

Plant protection products in sweet peppers

Such terms as herbicides, fungicides and insecticides include agents for protecting crops from weeds, fungal diseases and insects. Depending on their function, they are toxic to the target organisms and protect the plant, for example, from infestation with unwanted plant diseases. At the same time, however, they can bring about unpleasant side effects for humans and the environment. The use of these crop protection products is subject to strict legal regulations, which has led to a steady decrease in the burden of plant-based products over the last few decades. Nevertheless, residues of these substances in food can not always be ruled out, especially if used improperly. According to the 2004 report on food monitoring, exceedances of maximum levels have been identified, in particular in sweet peppers, lettuce, rocket, apples and shrubby fruit. Furthermore, it was found that imported goods are often much more heavily loaded than domestic products. For example, in sweet peppers - especially samples from Spain and Turkey - were conspicuous. In addition, studies show that the residue content of pesticides is higher outside the natural growth periods of the plants.

Nitrate in lettuce and rocket

Nitrate is a naturally occurring substance that is essential for the growth of plants. For optimum plant growth, fertilization measures in the agricultural production are constantly providing for nitrate replenishment in the soil. Intensive agricultural fertilization can lead to higher nitrate levels in groundwater and soil. From there, nitrate also reaches the food plants via the roots. The nitrate content is not only dependent on fertilization. There are vegetables that store nitrate to a high degree, while other varieties have little tendency for enrichment. Above all leafy and root vegetables, such as lettuce, lamb's lettuce, Swiss chard, spinach, radish, radish and beetroot sometimes have very high nitrate concentrations. In the framework of the 2004 Food Monitoring, particularly high levels of nitrates were found in lettuce and rocket.

From nitrate to nitrite to nitrosamines

Nitrate itself does not exert an immediate health risk on humans. Only after conversion to nitrite can it endanger human health. The conversion into nitrite can be done by bacteria, eg. B. at long storage of food at room temperature, but also by bacteria in the mouth and stomach.

  • Nitrite may inhibit the transport of oxygen in the blood of infants and cause "methaemoglobinaemia" with cyanosis.
  • Nitrite, in combination with secondary amines - which are nitrogen-containing chemical compounds found in many foods and also produced during digestion - can form so-called nitrosamines. Animal experiments have shown that certain nitrosamines have a strong carcinogenic effect.

In the production of animal foods, medicines are used not only for the treatment of diseases but also as master remedy. Antibiotics such as chloramphenicol and beta-agonists such as Clenbuterol are said to improve the overall result. Wait times are set for each medicine and must be adhered to. (The waiting period is the time that must elapse before the animal can be slaughtered.) Increasingly, the problem of developing resistance to antibiotics, which may be promoted by the widespread use of antibiotics in animal production, is being discussed. Also unclear is a possible contribution of veterinary medicines to the development of allergies. Also, little is known about possible long-term effects of these substances on the human body. For this reason, the use of antibiotics as growth promoters in animal feed has been banned throughout the EU since the beginning of this year. Overall, however, the residue problem in animal foods appears to be of minor importance. The results of the National Residue Control Plan show that only 0.19 percent of the samples of animal origin examined in 2004 exceeded the statutory limits. As part of the National Residue Control Plan, the federal states carried out more than 350, 000 studies on over 46, 000 animals and animal products such as meat, milk, eggs or honey.

Food without residues

The current results on the safety of our food show that our daily diet is only marginally contaminated. At least only a small percentage of the maximum values ​​are exceeded. However, our food is not completely free from residues. It is also unclear what effect multiple residues, ie the combination of different agents, on our body is exercised. When buying and processing food, some things should be kept in mind to minimize the intake of residues.

  • Always wash fruits and vegetables thoroughly before eating. Residues of pesticides can thereby be reduced.
  • Do you need strawberries in the winter? Eat on a seasonal basis. Outside of seasonal growth, higher doses of pesticides, etc. are often needed.
  • Do not eat nitrate-rich vegetables too often.
  • Do not keep nitrate-rich vegetables warm for long. Bacteria can multiply optimally at these temperatures and convert nitrate to nitrite. It is best to store leftovers in the refrigerator and reheat them if necessary.
  • Pay attention to a good quality of animal foods. Numerous producers undertake to offer high-quality and safe food within the framework of quality seals and quality labels.
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