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Frequently Asked Questions about pesticide residues in food
Updated BfR FAQ, 29 November 2010
Pesticides or plant protection products are used to effectively protect crops against harmful organisms. Around 640 plant protection products are currently authorised in Germany. Even when these pesticides are used properly and according to their intended uses, residues may remain on the harvested crops. These residues should be kept to a minimum so that they will not harm the health of consumers either through long-term daily food intake or short-term consumption of large portions of foods. In order to ensure this, BfR undertakes a comprehensive risk assessment for consumers within pesticide authorisation procedures. This risk assessment then serves as basis for proposed maximum residue levels (MRLs, also known as maximum residue limits).
A maximum residue level is the maximum concentration of a pesticide residue that is legally permitted in or on foodstuffs. The general population is largely unaware of this legislative restriction. Many consumers assume that absolutely no residues of pesticides are permitted in or on foodstuffs. This came to light as a result of the representative survey of the German population on the subject of pesticide residues in foods which was commissioned by BfR.
In response to this, BfR has compiled frequently asked questions regarding the authorisation of pesticides, the setting of maximum residue levels and consequences if these levels are exceeded.
- Why are plant protection products used?
- What is the difference between plant protection products and active substances?
- How many active substances does a plant protection product contain?
- How many plant protection products are authorised in Germany?
- Through what process does a plant protection product become available on the German market?
- Are active substances also authorised?
- What is meant by pesticide residues?
- How is it possible that the use of plant protection products can leave residues on the harvested crops?
- Are pesticide residues allowed in foods?
- Which foods may have pesticide residues?
- What is meant by "good agricultural practice"?
- What influence does BfR have on authorisation of plant protection products?
- How does BfR determine a possible risk to consumers during the authorisation procedure?
- How does BfR determine the toxic effect of an active substance?
- What is an ADI?
- What is meant by the acute reference dose?
- How does BfR establish the ARfD and the ADI?
- How does BfR determine consumer exposure to pesticide residues within the authorisation procedure?
- Which food consumption data does BfR take into account in pesticide risk assessment?
- When does BfR agree to authorisation in regard to consumer health protection?
- Are plant protection products with carcinogenic active ingredients authorised?
- Are the authorisation criteria that are currently in force enough to eliminate consumer risks with enough certainty?
- What happens when a residue exceeds the ADI or ARfD?
- What are maximum residue levels?
- How are maximum residue levels set?
- Which requirements must be met by maximum residue levels?
- How does BfR draw up its proposals for maximum residue levels?
- What are import tolerances?
- Why are maximum residue levels changed?
- What happens when a residue exceeds the maximum residue level?
- Does the health risk increase if a food contains residues of several plant protection products (multiple residues)?
- With what result has BfR assessed monitoring samples with multiple residues thus far?
- Why do multiple residues occur and could they be avoided?
- Who monitors compliance with the maximum residue levels?
- How do consumers estimate the risks they face through residues of pesticides in foods?
- How does BfR judge initiatives by food retailers to reduce pesticide residues on foods?
Plant protection products are designed to offer plants effective protection against harmful organisms such as fungi, weeds or harmful insects and secure the harvest. Furthermore, they are used to protect the harvested crops during storage and transport and to guarantee that food is of a good quality. While far fewer pesticides are used in organic faming than in conventional farming, even organic farmers cannot manage completely without the aid of chemical pesticides.
Active substances are chemical elements and compounds or micro-organisms with general or targeted action against harmful organisms on plants, parts of plants or plant products. Plant protection products are commercially available preparations which contain one or more active substances.
Of those plant protection products authorised in Germany, 71 percent contain just one active substance, 25 percent contain two active substances and four percent contain three or four active substances (status October 2010).
As of October 2010, 641 different plant protection products with 1192 commercial names have been authorised in Germany. These products contain a total of 249 different active substances.
Plant protection products must be authorised before they can become available on the market or used in agriculture. Authorisation is granted for a certain purpose (indication) which is why this is referred to as an authorisation “for indicated uses only”. Plant protection products are authorised on the national level. In Germany authorisation is granted by the Federal Office of Consumer Protection and Food Safety (BVL). The Julius Kühn Institute - the Federal Research Centre for Cultivated Plants (JKI), the Federal Environmental Agency (UBA) and the Federal Institute for Risk Assessment (BfR) are involved in the authorisation procedure. These carry out partial evaluations within the scope of their jurisdiction. BfR assesses the health risks for consumers, workers, residents and bystanders. In future, EU Member States will cooperate closely in authorisation procedures.
Active substances are not approved separately but always as part of a plant protection product. On the European Community level a positive list is currently being drawn up in which active substances are included after they have been examined in the European Union according to uniform principles. Only listed substances may be used in plant protection products.
Pesticide residues is the term used for any remains of active substances and their degradation products in or on food and feed. Degradation products may be formed during plant metabolism (“metabolites”) or, for example, under the influence of sunlight.
How is it possible that the use of plant protection products can leave residues on the harvested crops?
Residues on harvested crops cannot be completely avoided even in the case of good agricultural practice and the proper use of pesticides. Plant protection products are used at different times during the growth season. The degradation rates of their active substances vary. Residues must be expected at the time of harvesting, particularly when plant protection products are applied shortly before harvesting or when their active substances are persistent. However, the levels must be low enough that they do not pose a human health risk.
Residues of plant protection products are allowed up to each maximum residue level. There are no adverse effects on human health up to these concentrations.
Pesticide residues may be found on foods of plant origin. However, foods of animal origin may also have residues when the animals have eaten feed of plant origin that contained residues.
The principles of "good agricultural practice" also called "good plant protection practice" are instructions and apply to everyone who carries out plant protection measures. They stipulate that pesticides must be used in a manner that is adequate to suit the location, crop and situation, and that their use must be kept to the necessary minimum. Plant protection products should only be used when there is a case of infestation that "requires control". The necessary plant protection measures must be carried out appropriately and documented.
BfR is involved in the authorisation procedure as a consenting agency. It only agrees to the authorisation of a plant protection product when the residues which may remain on foods after correct use do not pose a health risk. The BfR opinion is taken into account when a decision on authorisation is made.
BfR carries out a risk assessment to ascertain a possible consumer risk from pesticide residues. Two factors are taken into account: the harmful (toxic) effect of a dose of a pesticide and the amount of this pesticide which is ingested by a consumer from contaminated products. This intake is described as "exposure".
The toxic effect is determined on the basis of study results. These are mostly animal studies which provide information on the acute, subchronic and chronic toxicity of an active pesticide substance. Furthermore, these provide information on possible DNA-damaging (genotoxic) and cancer-causing (carcinogenic) properties of the substance as well as whether it is toxic for reproduction. BfR derives two important toxicological threshold values from these studies: the acute reference dose (ARfD) and the acceptable daily intake (ADI). The ARfD refers to the acute and the ADI to the chronic effect of a substance.
ADI stands for "Acceptable Daily Intake" and indicates the amount of a substance which can be ingested daily over a lifetime by consumers without any appreciable health risk. The ADI is used to assess the chronic risk.
The “Acute Reference Dose” (ARfD) is the amount of a substance which a consumer may ingest during one day (spread over one or more meals) without any appreciable health risk. The ARfD is used to assess the acute risk.
In suitable animal experiments the “No Observed Adverse Effect Level” (NOAEL) is established for the most sensitive species and the most sensitive gender. Short-term studies are normally used to establish the ARfD. The ADI is determined from toxicity studies in which chronic endpoints were examined. These are often carcinogenicity, reproduction or multigeneration studies. The no observed adverse effect level established from the relevant studies is then divided by a so-called (un)certainty factor which should take into account both inter-species differences (i.e. between animals and humans) as well as intra-species differences (i.e. between individuals). The factor 100 is normally used for this.
Consumer exposure to food (dietary intake) is determined from the level of residue in the food and the amount of food consumed. The concentration of the residue in the food is determined in studies in which the pesticide was used under real conditions (so-called supervised residue trials). The relevant portions of foods consumed are taken from so-called food consumption surveys.
The portions of food which are currently relevant for consumers in Germany were collected in a food survey published in 2005 on German children aged two to under five years. This subgroup is considered being particularly vulnerable because of its comparably high dietary intake in conjunction with low body weight. This group is used as a surrogate for the whole population in risk assessment. In early 2011 additional consumption data will be available for pesticide risk assessment. These were collected for German consumers aged 14 to 80 years during the National nutrition survey II (NVS II).
In addition to German consumption data, BfR also takes consumption data from other European Member States into account.
The risk for the consumer is only unlikely enough to justify the authorisation of a pesticide from the perspective of consumer health protection if the assessment concludes that neither ADI nor ARfD are exceeded as a result of residues from the use of the pesticide.
A threat to consumer health is not expected if the following conditions are met:
- The estimated maximum dietary intake of a pesticide residue is below the ARfD. The maximum dietary intake is calculated for each food individually from the highest amount of residue that occurred in the supervised residue trials in conjunction with the “large portion” from food consumption surveys.
- The estimated average intake of pesticide residues remains below the ADI. The average intake is calculated from the median of the results of the supervised residue trials and the average portion from food consumption surveys and is added up for all foods consumed.
Cancer-causing substances must be separated into those that are both carcinogenic and genotoxic and those that can cause cancer without damaging genetic material. A threshold cannot be determined for substances that are carcinogenic and genotoxic at the same time because any amount can be damaging to human health. Plant protection products that contain such substances are categorically never authorised in Germany.
According to the current state of scientific knowledge, substances that are carcinogenic without damaging genetic material do have a threshold. Below this amount, a carcinogenic effect is not expected. These substances do not cause adverse health effects as long as consumer exposure does not exceed the threshold value for chronic exposure (ADI).
Are the authorisation criteria that are currently in force enough to eliminate consumer risks with enough certainty?
From the risk assessment perspective, current authorisation criteria eliminate consumer risks with enough certainty and comply with the precautionary principle that exists in the European Union. This principle comes into effect anytime there is reasonable cause for concern and the scientific evidence does not provide enough information to dispel concern. Through its uniform principles for evaluation and authorisation, the European Commission has provided a high level of protection in regard to pesticides: Pesticides may only be authorised if their use according to good agricultural practice does not have any adverse effects on human health. In order to fulfil the conditions of authorisation, comprehensive studies regarding toxicity, residue behaviour, methods of residue analysis, the fate and behaviour in the environment as well as effects on flora and fauna must be provided. Active ingredients in pesticides are thus among the most well analysed and characterised chemical substances concerning possible health risks and hazards.
Based on the adverse effect and the dose-response relationship that have been determined through toxicological testing it is generally possible to characterise and quantify the occurrence of adverse effects as a result of a defined exposure. It is similarly possible to estimate the dose ranges in which adverse health effects can be practically excluded. The likelihood of a possible health risk for consumers can be determined with sufficient certainty.
A one-off exceedance of the ADI is not relevant and even the short-term exceedance of the ADI does not lead to a risk for consumers because this value is established on the basis of daily lifelong exposure.
In contrast, possible adverse health effects cannot be automatically ruled out when there is a one-off or short-term exceedance of the ARfD. Whether adverse health effects could actually occur must be determined on a case-by-case basis.
A maximum residue level indicates the maximum admissible concentration of an active pesticide substance in or on a food. Maximum residue levels serve as binding trade standards to guarantee the free movement of goods. Foods are only marketable when they comply with maximum residue levels.
The procedure for setting maximum residue levels is formally independent from the authorisation procedure for pesticides. Maximum levels are derived in a Community procedure by experts from the Member States and the European Food Safety Authority (EFSA) and tested for their safety. They are then approved and published in legally binding form by the European Commission. Since these are EU Regulations, the same maximum levels automatically apply in all Member States.
Before a maximum residue level can be laid down, it must be possible to monitor the residue. A suitable analytical method is needed, preferably through a fast and easy routine analytical procedure. Furthermore, maximum residue levels may constitute neither an acute nor a chronic risk for consumers. In order to be able to assess this, a toxicological assessment of the active substance and its residue behaviour must be carried out.
Maximum residue levels are never set higher than is necessary on the grounds of good agricultural practice. This complies with the minimisation principle for the use of pesticides.
The basis for setting maximum residue levels are supervised residue field trials conducted in line with the applied use of a pesticide for controlling a harmful organism. The trials are designed in such a way that, under controlled conditions, the most critical approvable application is tested: the highest admissible application rate, the highest admissible number of applications, the latest admissible time of application and the shortest interval between the last application and harvesting (PHI, pre-harvest interval). Test results serve as basis in order to establish which (unavoidable) pesticide residue remains on the harvested crops following correct use. A corresponding proposal for a maximum level is derived from the residue data. If applicable, further factors like residue behaviour after processing are also taken into account. Finally, the derived maximum residue level is tested for its acceptability in regard to human health, i.e. whether or not residues of this amount constitute an acute or chronic risk to consumers. BfR proposes any maximum residue levels only if there are no indications that suggest a consumer risk.
Import tolerances correspond to the maximum residue levels but refer to foods which are imported into the European Union (e.g. rice, tropical fruit). Import tolerances are only granted for active substance-food combinations for which applications have been submitted when BfR comes to the conclusion that residues of the applied-for amounts do not constitute a health risk for consumers.
The setting of maximum residue levels is an ongoing process. As soon as applications for new uses and/or new pesticides are received and corresponding residue studies are submitted, the existing maximum level must be re-evaluated and, if necessary, amended.
Furthermore, maximum residue levels are adapted in line with improvement of scientific knowledge. New toxicity studies or new consumption data, for instance, may lead to a change in existing maximum residue levels because risk assessment has been updated and the safety of maximum residue levels has been reviewed.
The exceedance of a maximum residue level constitutes a violation of applicable law. The product in question is not marketable. This does not necessarily mean that the identified residue constitutes a risk for consumers as maximum residue levels are not toxicological threshold values. Normally far higher residue concentrations would be needed to reach toxicological threshold values (ADI or ARfD). When the level is exceeded, a risk assessment is undertaken. In most cases in the past the residue identified was not harmful for consumers.
Does the health risk increase if a food contains residues of several plant protection products (multiple residues)?
According to the most current state of knowledge, a health risk does not increase through residues of several active pesticide substances in one food.
Within the authorisation procedure of plant protection products and the regulation of maximum residue levels, one dose is determined experimentally for all active pesticide substances below which no toxic effect is detectable. Therefore, the dose range within which these substances are without adverse health effect can be assessed even when several substances are in a food at the same time. Maximum residue levels usually correspond to concentrations that are below the NOAEL (no observed adverse effect level) by more than one safety factor of 100. Thus, as long as the permissible maximum residue levels of individual active substances are not exceeded, additive or synergistic effects of pesticide residues in foods that could lead to adverse human health effects for the consumer are virtually eliminated.
BfR experience with assessments of food samples that contained multiple residues shows that most substances were present only at very low concentrations. In most cases, the total residue amount was dominated by one active substance. It was also clear that active substances that were present at the same time were often members of different classes of pesticides with vastly different toxicological modes of action. Additive or synergistic effects, as they are primarily expected from substances that have similar effects on the organism, were virtually non-existent in these cases. Even if samples contained several active substances of the same class of pesticides, the cumulative assessment of these substances did not lead to a fundamentally different result than assessments of single substances.
The most recent active pesticide substances distinguish themselves through their targeted effects on certain harmful organisms, while substances of earlier generations have more broad effects and thus also more side effects. The targeted effect is better for humans and the environment. However, as a result many different pesticides are used depending on the type of infestation. All of these can leave residues on the harvested product.
The active substance used may also be changed in order to prevent the development of resistance. Resistances must be prevented because they would mean that in the long run, certain harmful organisms could no longer be controlled.
Multiple residues are thus the result of appropriate and targeted application of plant protection products and not always avoidable.
Every party involved in food marketing and distribution is obliged to guarantee compliance with maximum residue levels. Food retailers normally conduct internal quality controls. The official control authorities of the federal states draw up monitoring and surveillance programmes to make sure that companies perform their duty of care and consumers are sufficiently protected.
Consumers themselves estimate that residues of pesticides in food constitute a relatively high health risk. However, thus far pesticide residues in food have never known to have had any adverse health effects for consumers in Germany. As a result, BfR continually aims to inform consumers in order to provide them the basis for a realistic assessment of the risk. In order to do so, BfR cooperates with a number of stakeholders and multipliers.
If the statutory maximum residue levels are adhered to, foods are safe. However, some retail chains issue additional requirements regarding maximum levels for pesticide residues in foods for their suppliers. These are much stricter than legal requirements (so-called secondary standards).
In general BfR values all endeavours that aim to minimise the application of plant protection products in agricultural practice and those that minimise residues on foods. However, BfR is also aware of the hazards associated with undesirable effects that secondary standards can have on the use of pesticides. The conscious evasion of a change of active substance (with the aim to minimise the total number of detectable active substances in foods) can lead to increasing resistance of harmful organisms. As a result, these can no longer be controlled or only with great difficulty. In order to minimise residues in harvested products, producers increasing feel compelled to apply pesticides preventively and early on in the growing season instead of according to need and situation as it would correspond with "good agricultural practice".
Furthermore, the establishment of secondary standards could also worry consumers which may wrongly lead them to loose confidence in legal regulations and official risk assessments.