In agricultural production, various inputs are used to ensure quality and increase yields. These include fertilizers, crop protection products and veterinary medicines. If used improperly, residues in food can result. Residues are residues of substances that are used during the primary production of plant or animal foods in order to achieve certain effects. Among other things, they are used to protect crops from spoilage, to ensure or improve yields, and to provide hygienically safe products. Legal regulations stipulate that their use must be kept to a minimum. If these substances are not completely degraded during the lifetime of the plants or animals or by the time the food is consumed, they remain in the food as residues. For these residues, maximum levels are set by the legislator to protect the consumer. Compliance with these maximum levels is regularly monitored by the authorities.
Plant protection products in sweet peppers
Behind such terms as herbicides, fungicides and insecticides are agents used to protect crops from weeds, fungal diseases and insects. According to their function, they are toxic to the target organisms and thus protect the plant from infestation with undesirable plant diseases, for example. At the same time, however, they can have unpleasant side effects for humans and the environment. The use of these pesticides is subject to strict legal regulations, which has led to a steady reduction in the contamination of plant products over the past decades. Nevertheless, residues of these substances in food cannot always be ruled out, especially if they are used improperly. According to the 2004 food monitoring report, exceedances of the maximum levels were found in particular in sweet peppers, lettuce, arugula, apples and bush fruit. Furthermore, it was found that imported goods are often significantly more contaminated than domestic products. For example, in the case of sweet peppers – samples from Spain and Turkey in particular – were conspicuous. In addition, studies show that pesticide residue levels are higher outside the plants’ natural growing seasons.
Nitrates in lettuce and arugula
Nitrate is a naturally occurring substance that is essential for plant growth. For optimal plant growth, fertilization measures in agricultural production continuously provide for nitrate replenishment in the soil. Intensive agricultural fertilization can lead to higher nitrate levels in groundwater and soil. From there, additional nitrate reaches the food plants via the roots. However, the nitrate content is not solely dependent on fertilization. There are vegetable varieties that store nitrate to a high degree, while other varieties have little tendency to accumulate it. Leaf and root vegetables in particular, such as lettuce, lamb’s lettuce, chard, spinach, radish, radish and beet, sometimes have very high nitrate concentrations. In the 2004 food monitoring, high nitrate levels in lettuce and arugula stood out in a particularly negative way.
From nitrate to nitrite to nitrosamines.
Nitrate itself does not pose an immediate health hazard to humans. Only after conversion to nitrite can it pose a threat to human health. Conversion to nitrite can occur by bacteria, such as when food is stored at room temperature for a long time, but also by bacteria in the mouth and stomach.
- Nitrite can hinder oxygen transport in the blood of infants, causing “methemoglobinemia” with cyanosis.
- Nitrite can form so-called nitrosamines in conjunction with secondary amines, which are nitrogen-containing chemical compounds found in many foods and also formed during digestion. Animal studies have shown that certain nitrosamines have a strong carcinogenic effect.
In the production of animal food, drugs are used not only to treat diseases but also as fattening aids. Antibiotics such as chloramphenicol and beta-agonists such as clenbuterol are intended to improve the master result. Waiting periods are specified for each drug and must be observed. (Waiting time is the time that must have passed before the animal may be slaughtered).Increasingly, the problem of the development of resistance to antibiotics is being discussed, which may be promoted by the widespread use of antibiotics in animal production. Also unclear is a possible contribution of veterinary drugs to the development of allergies. Little is also 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 legally specified maximum levels. Under the National Residue Control Plan, the states conducted more than 350,000 tests on more than 46,000 animals and animal products such as meat, milk, eggs and honey.
Eating without residues
The current results on the safety of our food show that our daily diet is only slightly contaminated with residues. At least, only a small percentage exceeds the maximum levels. However, our food is not completely free of residues. It is also unclear what effect multiple residues, i.e. the combination of different active ingredients, have on our bodies. When purchasing and processing food, some things should be considered to keep the intake of residues as low as possible.
- Always wash fruits and vegetables thoroughly before eating. Residues of pesticides can be reduced by doing so.
- Do strawberries have to be on the menu in winter? Feed yourself seasonally. Out of seasonal growth often requires higher doses of pesticides, etc..
- Do not consume nitrate-rich vegetables too often.
- Do not keep nitrate-rich vegetables warm for a long time. Bacteria can multiply optimally at these temperatures and convert nitrate to nitrite. Keep leftovers best in the refrigerator and reheat as needed.
- Make sure that animal foods are of good quality. Many producers undertake to offer high quality and safe food within the framework of quality seals and quality labels.
