After the application of pesticides, residues of the pesticide active ingredient (or degradation products of the active ingredient) in the treated crops are often unavoidable. Residues from direct treatment or indirectly (post-planting crops, food of animal origin from feeding treated feed) are possible.
Whether residues are found on the crop, and in what quantity, depends on the following factors:
- Type of application: Treatments applied directly to the crop normally result in higher residue levels than, for example, seed treatments applied prior to sowing.
- Application rate: the higher the amount of active ingredient applied to the area, the higher the amount of residue on the crop tends to be.
- Number of applications and the interval between applications.
- Timing of application: the earlier in the crop's growing season a treatment falls, the lower the amount of residue usually is.
- Application in the greenhouse or in the field: due to the largely absent influence of weather (e.g. rain), applications in the greenhouse are more critical than those in the field.
- Time period between application of the plant protection product and harvest (waiting period)
- Degradation behavior of the active ingredient, i.e. how quickly an active ingredient is degraded and to which degradation products it decomposes.
- Physical-chemical properties of the active ingredient: In this context, it is important whether a substance is transported into edible portions via the plant's conduction system (systemic properties of an active substance).
Maximum residue levels (MRL)
Maximum Residue Levels (MRLs) are set at levels that are acceptable based on risk assessment (toxicology, residue behavior). The ALARA principle (as low as reasonably achievable) is applied, i.e. the maximum residue level may only be as high as is really necessary. It is the aim of the assessment in the context of the maximum residue levels derivation to ensure a sufficient safety margin between the maximum permitted amount and the concentration at which a health hazard is possible. Therefore, as a rule, exceeding a maximum level does not automatically lead to a risk for consumers.
The calculated maximum level is only included in Regulation 396/2005 if a health risk for the consumer can be excluded. Until 1.9.2008, different maximum residue levels are applied in different MS oft he European Union. The harmonization process for maximum residue levels valid throughout Europe became directly effective throughout the EU and thus also in Austria on September 1, 2008, when Annexes II, III and IV of Regulation 396/2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin entered into force. As a consequence, the same maximum levels apply throughout the European Economic Area. This eliminates potential trade barriers for agricultural products and ensures a uniform (high) level of consumer protection.
Pesticide Monitoring Reports
Pesticide residues are monitored throughout Europe as part of a control program, which is binding for all member states by regulations of the European Commission. The European Food Safety Authority (EFSA) regularly compiles reports from the data collected in the European states, which on the one hand serve to provide information on the contamination of the foodstuffs available in the EU. On the other hand, the data can be used to assess a possible risk to consumers and to take preventive action, e.g. by changing existing limits.
The control program runs over several years and is coordinated throughout Europe. The European countries also draw up national control programs, which also implement the EU control programs. In Austria, control is implemented in the form of priority actions (SPA). For this purpose, a sampling plan is drawn up annually in cooperation with the Federal Ministry of Social Affairs, Health, Care and Consumer Protection (BMSGPK). This plan specifies in detail which food samples are to be sampled and to what extent, so that the actual situation can be realistically represented by investigations. For this purpose, statistically collected consumption data, the availability of foodstuffs due to production and import and experiences of previous monitoring or control programs are taken into account.
Sampling is carried out throughout Austria by food inspection bodies of the regional official food inspectorates (provincial authorities). In addition to food from conventional production, food from organic production is also monitored. Since the use of synthetic pesticide active substances in organic farming is restricted to certain active substances, food from organic farming may not contain any other pesticide residues.
Situation in Austria - National pesticide residue control programs
According to Regulation (EC) No 396/2005 of the European Parliament and of the Council of 23 February 2005 on maximum residue levels of pesticides in/or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC, Austria establishes annually a national program for the control of pesticide residues.
The program is risk-based and aims in particular at assessing consumer exposure and compliance with applicable legislation. In order to be able to make statements about the exposure of the population to pesticides, sampling for this control program is carried out according to statistical aspects.
Therefore, we establish an appropriate sampling plan. The sampling plan, together with the consumption surveys by the Institute of Nutritional Sciences of the University of Vienna, forms the basis of the national monitoring program. The results of the program are submitted to the European Commission as well as to the European Food Safety Authority (EFSA).
The results are published in the form of the SPA final reports. These can be found here. The results of the national control program are additionally evaluated in more detailed form and published in a comprehensive report:
- National Pesticide Residue Control Program Report (2020).
- Reports national pesticide monitoring since 2003
Member States of the European Union are required to carry out monitoring to ensure that food placed on the market does not contain residues above legal limits. The European monitoring programs together represent one of the most comprehensive food data collection programs in the world, with more than 90,000 food samples analyzed for over 800 different pesticides.
The Pesticides Unit of the European Food Safety Authority (EFSA) is responsible for producing annual reports on the monitoring activities of the EU Member States and the two EEA countries, Norway and Iceland. These reports summarize the results of pesticide analyses of food products, indicate problem areas in terms of compliance with legal limits, and contain estimates of consumer exposure to pesticide residues from food products on the market. In addition, EFSA makes suggestions with regard to how future control programs could be made even more efficient.
Exceedance of the maximum level
Exceeding a maximum level does not necessarily imply a health risk for consumers. In the event of a statutory maximum level being exceeded, an additional check is carried out (including exposure) to determine whether toxicological reference values such as ARfD (Acute Reference Dose) or ADI (Tolerable Daily Intake) are exceeded. Only when these toxicological reference values are exceeded can a health risk for consumers no longer be completely ruled out and only then is the food to be assessed as "not safe - unsuitable for human consumption" or as "not safe - harmful to health".In these cases, a report is made to the food supervisory authority, the Federal Ministry of Social Affairs, Health, Care and Consumer Protection (BMSGPK) and to the European Rapid Alert System for Food and Feed (RASFF), which enables further measures to be taken for consumer protection.
In the actual risk assessment, the health-related limit values (ADI, ARfD) are compared with the possible exposure (residues in food of animal and plant origin). For consumers, the exposure corresponds to the intake of the substance to be assessed via food.
For the risk assessment of pesticide residues on foodstuffs, the amount of intake of the residue via food is to be expected in the worst case must be smaller than the toxicological reference values (ADI or ARfD). Both a single intake (usually via a meal) and a lifetime intake of pesticide residues are taken into account.
If the estimation of intake levels leads to an exceedance of the amount of active ingredient that is considered critical for consumers (i.e. toxicological reference value), the risk can be reduced by appropriate risk management measures. Optional measures are an extension of the waiting period, a reduction in the application rate or even the refusal of approval or the abandonment of an application.
The combination effect of pesticide residues ("cumulative risk assessment") is being discussed internationally. A corresponding model for risk assessment for consumers is not (yet) used for setting maximum residue limits. In the concentration range in which pesticide residues are expected, a combinatorial effect cannot be assumed; it is only conceivable that an additive effect could be observed. Accordingly, groups of active substances have been and will be identified which exhibit comparable effects on organs/organ systems with regard to their toxicological properties ("cumulative assessment groups"). The aim will be to combine the results of monitoring reports and the results of residue trials in order to be able to make a statement regarding a possible risk.
Possible health-damaging properties of plant protection products and their active substances as well as metabolites are identified with toxicological studies. In the toxicological evaluation two basic possibilities of exposure to plant protection products are considered, for which different health-related reference values are determined: On the one hand, humans may be exposed to plant protection products and their active substances via inhalation and/or skin contact during the application of the plant protection product and subsequently during re-entry for work in the treated field. On the other hand, consumers can ingest residues of plant protection products through their food. For the risk assessment of consumers, the following two toxicological reference values are derived on the basis of the relevant toxicological studies:
ADI value (Acceptable Daily Intake).
The so-called ADI value is used as a limit value for the health assessment of the long-term intake of a pesticide active substance with food. The ADI value defines the amount of substance that consumers can take in daily and for a lifetime without any recognizable risk to their health, taking into account all available knowledge.
Acute Reference Dose (ARfD)
In addition to the ADI value, the acute reference dose (ARfD) was introduced for active substances of plant protection products that have a high acute toxicity and show adverse health effects in animal experiments even after a single or short-term treatment. The acute reference dose defines the amount of substance that can be ingested via food within one day or with one meal without resulting in a recognizable health risk for consumers.
Residue definition (type of residue)
The degradation behavior of pesticide active ingredients is investigated by metabolism studies in plants and animals, whereby metabolites (degradation products of the active ingredient) are also identified. The result of these studies feed back into the residue definition.
The residue definition is the basis for the setting of maximum residue limits, the development of suitable analytical methods for the control of harvested products, and risk assessment.
Determination of the amount of residues in trials
The level of residues to be expected on the crop after a pesticide application is determined by means of field studies on crops and feeding trials with farm animals. In these studies, crops for which registration of the crop protection product has been applied for are treated with the crop protection product or animals are fed with feed containing the expected level of residues
Based on the results of the residue tests, a maximum residue level (MRL) is determined for the plant protection product active substance concerned and/or its metabolites by means of statistical calculation methods.
Furthermore, the influence of processing on the type and amount of residues is investigated. On the one hand, it is determined whether additional metabolites can be formed during processing oft he product. Furthermore, on the basis of processing studies (e.g. grain to bread, grapes to wine, hops to beer), the so-called processing factors are derived, which provide information on the extent to which a reduction of residues (dilution) or a concentration of residues (e.g. by drying) takes place. These processes are also included in the risk assessment.
The residue situation in possible crops to be cultivated subsequently (crop rotation) is also assessed as part of the approval process; it may well be that maximum residue levels (MRLs) have to be derived for crops that are not treated directly with the plant protection product (uptake of residues from the soil).
Last updated: 29.11.2022