Pesticides - your questions answered

Last updated:
14 May 2012
Frequently asked questions about pesticides and pesticide residues.
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What are pesticides?

Pesticides are chemical or biological substances that are used to kill or control pests that harm our food, health or environment. Pests include rodents, insects, fungi and plants. Only officially approved pesticides may be used. Plant growth regulators, which are used to influence particular growth processes in plants (for example, slowing down the growth of sprouts on potatoes) are also regulated as pesticides.

Why are pesticides used?

Pesticides are mainly used in agriculture to keep crops healthy and prevent them being wasted by disease and infestation. They are particularly used in food production because pests can have devastating effects on the quantity and quality of crops. Pesticides are also used to protect public health by controlling various pests and disease carriers, such as insects, rats and mice.

How can I get information about a specific pesticide?

The Chemicals Regulation Directorate (CRD) has information on specific products and ACP evaluation reports on some active substances. The Joint FAO/WHO Meeting on Pesticides Residues also has toxicological evaluations, and you can also search for information on specific active substances on the European Food Safety Authority website.

Links to these websites can be found on the right hand side of this page.

How are pesticides assessed for health effects?

A package of toxicological studies is carried out on all pesticides before they are approved for use in the European Union. These studies follow internationally agreed guidelines. Based on these studies, levels of exposure to the pesticide that pose no appreciable health risk are determined. Both long term and short term exposures to pesticides are considered during the safety assessment.

For long term dietary exposure to pesticides, the ADI (Acceptable Daily Intake) is used to estimate the amount of a substance that people, including the young, the elderly and pregnant women, can eat daily over their entire lifetimes without having an appreciable risk to their health, based on current scientific knowledge.

For short term exposure the ARfD (Acute Reference Dose) is used. This is the amount of a chemical that can be taken in at one meal or on one day without appreciable health risk to anyone consuming it.

The risks from pesticide residues in food are considered acceptable if short term dietary intakes are expected to be within the ARfD, and daily intakes averaged over the longer term within the ADI, respectively.

What do people mean when they talk about a 'cocktail effect' in relation to pesticides?

Individual foods can contain a mixture of pesticides, and people may eat foods containing different pesticides at the same time. Some people are concerned that being exposed to such a 'cocktail' of pesticides may harm people's health.

The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) published a report in October 2002, which concluded that the risk to people's health from mixtures of residues is likely to be small. It also said that children and pregnant or breastfeeding women are unlikely to be more affected by the 'cocktail effect' than most other people.

However, the report identified areas of work for further investigation and made several recommendations. The Agency set up a research programme to address the recommendations. See Mixtures of Pesticides for more information.

What are pesticide residues?

Pesticide residues are the very small amounts of pesticides that can remain in or on a crop after harvesting or storage and make their way into the food chain. Not all foods contain pesticide residues, and where they do occur they are typically at very low levels. Pesticide residues also include any breakdown products from the pesticide. Pesticide residues can remain even when pesticides are applied in the right amount and at the right time. Sometimes they need to stay on the crop to do their job. For example, they may need to be on the surface of a fruit or vegetable to protect it from pests during storage. Some pesticides are applied after harvest for this purpose.

How much pesticide residue is allowed in food?

When a pesticide is approved for use on crops in the European Union, limits are set on how much residue can legally remain in food. These limits are called Maximum Residue Levels (MRLs). Pesticide MRLs are required to be set at safe levels but they are not safety limits. They are based on the highest residue levels that are expected to occur when pesticides are used in accordance with good agricultural practice. Imported food must meet the same limits. You can find out more about MRLs on the Chemicals Regulation Directorate (CRD) website. The MRLs applicable in the UK for particular pesticides in particular foods can also be found on the CRD website.

What is the process for setting pesticide MRLs in the EU?

From 1 September 2008, a European Regulation (EC) No 396/2005 came into force to harmonise all pesticide MRLs for the EU. For more information on this see 'How Regulation 396/2005 affects pesticide regulation in the UK?' on the Chemical Regulation Directorate (CRD) website. Under this legislation, the European Food Safety Authority (EFSA) assesses MRL applications for new pesticides. The regulation also provides for the setting of a default limit of 0.01 mg/kg for all pesticide/commodity combinations for which no MRLs have been set (unless MRLs are not required or different defaults have been fixed).

Why is food checked for pesticide residues?

An official pesticide monitoring programme checks pesticide residues in the UK food and drink supply, to ensure that there aren't any unexpected residues, to check that residues are not more than the maximum residue levels (MRLs), and to ensure that pesticide residues are not posing a risk to people's health.

What does the pesticide residue monitoring programme show?

The results of the official monitoring programme are published quarterly and annually by PRiF. Around 4,000 food and drink samples are tested each year, with more than 250 pesticides tested for. A wide variety of fruit and vegetables, cereals and cereal products, fish and fish products, and products of animal origin, are monitored on a rolling basis every few years. Foods that are monitored regularly include those that are eaten as a major component of the diet, such as potatoes, milk and bread. Among the pesticides that are tested are those that are more likely to be found on particular foods, including non-approved pesticides that might have a specific use on a particular crop.

Annually, over 98% of samples that are tested do not contain residues above legal limits or residues of non-approved pesticides. In all cases where there was a concern about people's potential intakes of pesticide residues, a risk assessment was carried out by both the CRD and the FSA and any necessary follow-up action was taken, such as notifying retailers, suppliers or growers. Some special follow-up surveys and enforcement investigations are also undertaken. In almost all cases the residues do not present an appreciable risk to people’s health. The detailed results of the official monitoring programme can be found on the PRiF website.

Why do some foods contain pesticide residues when others don't?

Pesticide use varies according to the crop, the climate, types of pest present and the numbers of these pests in a given year. The conditions under which particular crops are grown can also affect the need for pesticides. For example, tomatoes grown under cover need no pesticides or fewer pesticides than those grown outside. In addition, some pesticides, such as those used post-harvest, are designed to stay on particular crops to ensure they perform their function properly. In contrast, other pesticides break down so that no residues are left by the time the crop is harvested. In all cases, the use of the pesticide is taken into account when they are authorised and MRLs are set to ensure that residues left on or in the food will not present an unacceptable risk to consumers.

Are there higher levels of pesticides in imported food?

Imported food sold in the UK must comply with all UK/EU MRLs just like food produced domestically. Residues may be found in a slightly higher percentage of imported foods than in UK or EU foods, but the residue levels typically found don't present a health concern. Where residues exceed MRLs with consequent health concerns, the UK can take this up with the country concerned and also highlight the issue within the EU. Foods are removed from the market if they represent a significant food safety concern.

Recent surveillance results have shown that there is likelihood for the presence of residues of some pesticides, unauthorised in the EU, in feed and foods imported from non-EU countries. Further safeguard controls on certain 'high-risk' feed and food of non-animal origin have been introduced by the EU under a new Regulation (EC) No. 669/2009, as amended. Further details of this can be found at the link below.

Are there pesticide residues in manufactured baby food?

Manufacturers take stringent precautions to make sure that pesticide residues in baby foods comply with MRL legislation. Infant formula and manufactured baby food are monitored as part of the official pesticides monitoring programme overseen by the Defra Expert Committee on Pesticide Residues in Food (PRiF).

Do I need to wash and peel fruit and vegetables to remove pesticide residues?

You don't need to wash or peel fruit and vegetables that would not ordinarily be peeled before consumption (for example apples) because of pesticide residues, as no assumption is made that such foods are peeled when deciding whether a pesticide can be approved for use or setting a legal limit (maximum residue level, MRL).

Is there anything I can do to remove pesticide residues?

Washing, peeling fruit and removing the outer leaves of vegetables may reduce residues of certain pesticides. But some pesticides are systemic, which means they are found within the fruit or vegetable. For some fruits, such as oranges, peeling will usually remove most of the residues that might be present, but small amounts of some residues may still remain in the fruit.

Does cooking reduce pesticide residues?

Processing, including cooking, may reduce the level of some pesticides in food. This is because processing may break down the pesticide, or remove the part of the plant that carries the residue.

Are pesticides used on organic food?

In most cases, organic food is produced without using pesticides. However, EU organic food regulations do allow a very limited range of pesticides in organic food production to be used but only on some types of crops.

Some organic foods are sampled as part of the official residue monitoring programme overseen by the Defra Expert Committee on Pesticide Residues in Food (PRiF). In addition, some pesticides approved for use in organic production have recently been included in the range of pesticides that are looked for in the official monitoring programme.

Can pesticide residue cause food allergy

The safety of pesticides is carefully evaluated before approval. This safety evaluation considers possible adverse effects on the immune system. Additional, more specialised, tests may be performed on substances with suspected immunotoxic properties. People who are already sensitised to a chemical from other sources may react to residues of that chemical in food. There is no published scientific evidence to suggest that exposure to low level residues of pesticides in food increases the prevalence of food allergy or food intolerance.