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Exposure estimation for plant protection products

Exposure estimation: consumers

Monitoring authorities, quality control laboratories, advisory services and risk management often find it difficult to assess whether a plant protection product residue in a food sample poses an acute or a chronic risk for the consumer. The main reason for this is that often they  have limited access to the necessary information, as some of it is only available to the authorities involved in the authorisation and assessment of plant protection products.

For this reason, the BfR has prepared various assessment aids to support experts in their evaluation whether the residue of a plant protection product in a food sample poses a risk to consumers or not.

Consumption models

For the risk assessment of residues of plant protection products BfR has developed a model for estimating long and short-term intake of residues. It supplements the "VELS Model", which was published back in 2005 and which is based on representative consumption data of German children aged 2 to under 5 years. In addition, comprehensive representative information on the consumption behaviour of the German population aged 14 to 80 years is available from the National Nutrition Survey II (NVS II), which was conducted in 2006. This consumption data is more up-to-date than the VELS data and also takes into account consumption of foods rarely eaten by children. Using the "NVS II Model", risk assessments can be made for children and adults based on consumption data from Germany. Moreover, EFSA provides the "PRIMO" model (Pesticide Residue Intake Model) for calculation of the acute and chronic risk of plant protection product residues based on European consumption data (see external links).

Information on consumption models and related topics can be found here:

• https://www.bfr.bund.de/cm/343/bfr-berechnungsmodell-zur-aufnahme-von-pflanzenschutzmittel-rueckstaenden-nvs2.zip (654.2 KB)
• https://www.bfr.bund.de/cm/343/neues-bfr-modell-fuer-die-deutsche-bevoelkerung-im-alter-von-14-bis-80-jahren-nvs-2.pdf (37.5 KB)
• https://www.efsa.europa.eu/sites/default/files/assets/calculationacutechronic_2.xls

Variability factors

For residue analysisof a plant protection product active substance in food items, mixed samples from several units are normally examined rather than individual units. This provides an overall more representative view on the residue situation. In case an even, uniform mixture of individual units of a food prior to consumption cannot be assumed (e.g. corn),  the assessment must always take into account that consumers eat one, single, highly contaminated unit of a food.

To ensure that mixed samples do not lead to an underestimation of a possible acute risk, the residue in the mixed sample is multiplied by a variability factor. It is standard here to use variability factors of 5 or 7 (depending on the weight of one unit). These are pre-set in the consumption models. A number of specific variability factors were also derived on the basis of empirical data from residue studies with plant protection products in which individual units were examined instead of mixed samples (“variability studies”). In most cases, the specific factors lie between 2 and 3 and substitute the standard variability factor for each active substance/food combination. The BfR provides information on these specific variability factors.

More information on variability factors (in german):

• https://www.bfr.bund.de/cm/343/variabilitaetsfaktoren_fuer_die_abschaetzung_der_kurzzeitexposition_
  von_verbrauchern_gegenueber_pflanzenschutzmittelrueckstaenden.pdf (131.9 KB)

Processing factors

Agricultural products are often not eaten raw, but are processed prior to consumption. Processing may change the residue level of the active substances of plant protection product contained in the agricultural product. The ratio of the residues in the processed product to the corresponding unprocessed product is called the processing factor. It indicates whether residues are accumulated or reduced during processing. Processing factors are determined in laboratory experiments simulating food processing conditions. Details of such studies, which have to be presented by plant protection product manufacturers in the course of authorisation procedures, are not publicly available.

The BfR has therefore been offering a periodically updated compilation of processing factors since 2007. The EU database on processing factors published by EFSA has also been available since 2018. In September 2022, the BfR data collection was integrated into the EU database on processing factors and is now available. However, the BfR has developed a user interface with which the EU database can be searched in a targeted manner and relevant results are presented in graphic and tabular form and reported in the database.

To the web application:

More information:

• https://www.bfr.bund.de/cm/349/eu-database-on-processing-factors.pdf (272.8 KB)
• EU database and accompanying documents: https://zenodo.org/record/6827098
• Data submission sheet.docx (77.9 KB)

Exposure estimation: Users, workers, local residents and bystanders

The BfR analyses and assesses whether the protection of the health of all persons, pets and livestock that may come into contact with the plant protection product during or after application is guaranteed when the product is used properly and in accordance with its intended use.

For this non-food-related exposure, the BfR carries out estimates of its level using models with initially conservative assumptions. These models are based on measured values for the respective type of application. Furthermore, kinetic considerations (such as the question of how much active substance can be absorbed through the skin), and also possible protective measures with which the exposure can be reduced (e.g. protective gloves) are included in the exposure assessment.

The skin is usually the main route of absorption for non-food exposure. Based on dermal absorption studies carried out with the respective plant protection product, specific dermal absorption values can be derived for the exposure assessment according to the guidance on dermal absorption (EFSA, 2017).

Guidance on calculating exposure for operators, workers, residents and bystanders is harmonised in the EU and published by the European Food Safety Authority (EFSA, 2014/2022).

Calculating exposure for operators, workers, residents and bystanders in the case of non-professional use in home gardens and allotments is carried out according to the EU harmonised guidance “Non-professional use in home gardens – exposure assessment” (izSC, 2022).

• EFSA 2014, Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment for plant protection products, EFSA Journal 2014;12(10):3874

• EFSA 2017, Guidance on dermal absorption. EFSA Journal 2017, 15(6), 4873

• EFSA 2022, Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment for plant protection products. EFSA Journal 2022, 20(1), 7032

• izSC 2022, Non-professional use in home gardens – exposure assessment. Agreement on the consolidated Version 1.3 by the izSC (Interzonal Steering Committee on 2022-03-09).

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