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Pesticide residues and MRLs

Why are growers concerned about pesticide residues? 

Growers have become increasingly concerned about pesticide residue restrictions negatively impacting their ability to sell or export their produce. Pesticide residues are the chemical traces of the active ingredient or one of its metabolites, found in or on the crop after it has been treated with a pesticide spray. The pressure on improving crop yields and quality, coupled with the manner in which pesticides are applied to crops which can then then be analysed, has raised the salience of pesticide residues. 

Pesticides can be applied at various stages throughout the entire growing season: on the seed, the soil, the growing crop, and/or during post-harvest storage periods. As a result, residues can be contained throughout the entire piece of produce, rather than just on its surface. One of the important performance characteristics of foliar-applied pesticides in particular is their rainfastness, i.e. they are intended to not wash off easily with water or rain in order to enhance their effectiveness for longer. It follows that peeling and/or washing the produce may not be enough to remove the pesticide residues if they are present. This is why it is important that crops do not have unacceptable levels of residue by the time they reach the consumer and the reason that residue levels are carefully monitored. 

However, pesticides are only authorised for use once independent risk assessment confirms that correct use of the product will not lead to unacceptable levels of residues and subsequent health concerns. 

What is the relationship between pesticide use and a producer’s ability to export? 

With the rise of consumer concern about pesticide residues on produce, governments have re-evaluated maximum residue levels (MRLs) for pesticide active ingredients and agencies have expanded their residue testing capabilities. MRLs provide a measurable trading standard that helps ensure food produced using pesticides is suitable for human consumption. If the residue levels on produce exceed MRLs, the produce cannot be exported to or sold within the market in question. 

Robust controls determining whether plant protection products are approved and authorised are based on an assessment of potential risks to consumers and the environment. Specifically, MRLs are established by analysing a dossier on the toxicological data and metabolisation of the formulation. The chemical composition of the formulation is studied to ensure that it does not pose a risk to human health, with particular focus placed on whether it is carcinogenic, mutagenic, or an endocrine disruptor. This assessment considers both the acute and chronic risks, studying the effects of exposure to the active ingredients and the pesticide formulation in both the short and long term. This evaluation contains highly conservative assumptions, which provide several layers of security in terms of ensuring human health. Additionally, the risk assessment is carried out under the assumption that all the crops eaten throughout one’s life have this high level, which in reality seldom happens. 

Currently, statutory MRLs are set on an EU-wide basis. They apply to all foods that are placed on the EU market, irrespective of where in the world they have been produced. The UK is expected to respect EU MRL regulations going forward. Within the UK, residue level tests are carried out by a number of external bodies, including the Health and Safety Executive (HSE); the Food Safety Agency (FSA); and the Expert Committee on Pesticide Residues in Food. 

Supermarket Monitoring

Many UK supermarket chains monitor pesticide residues internally, encourage the use of biopesticides and restrict the use of certain pesticides seen to be most hazardous. For example, Marks and Spencer (M&S) actively measures for residues and if any sample is found to have even half the MRL of the pesticide in question, they trigger an internal investigation and challenge their supplier. The company encourages their growers to incorporate biopesticides into their crop protection programmes and funds academic research into alternatives to conventional chemistry. Additionally, M&S are working towards “residue free” produce by actively engaging with their supply chain and already restricts or entirely phases our certain chemistry.

As a result of the increased transparency over farming practices and enforcement of MRLs in recent years, consumers have become more aware of the use of crop production products and have continued to demand produce that is free from pesticide residues. Consequently, under the new “Farm to Fork Strategy” the EU has pledged to reduce the use of synthetic pesticides by 50% by 2030.Such EU regulations are likely to remain in place and become law in the UK following the departure from the EU.

Farmers are sometimes faced with drastic changes in pesticide regulation that impact their market opportunities. For example, in 2019 the EU MRL for iprodione - a conventional synthetic chemical treatment for botrytis - was reduced. This particularly impacted wine grape growers in Australia, who export wine to the EU. Iprodione has been used as part of many vineyard crop protection protocols in Australia but is no longer viable after the changes in MRLs were implemented. Whilst such measures are put in place for consumer safety, growers have found themselves challenged by how to adjust to regulatory changes when there may be very limited options for alternative crop protection products available on the market. 

The solution and role of biopesticides

Fortunately, biopesticides provide a solution that benefits the grower, the consumer, and regulators. Crucially, MRLs do not apply to some plant protection products, which are listed in Annex IV of Regulation 396/2005. It follows that many biopesticides, including those produced by Eden, are MRL exempt, as the chemistry often present in biopesticides is derived from nature and often indistinguishable from natural background levels. Farmers are thus able to meet consumer demand and supply produce that is free from conventional pesticide residues. Subsequently, biopesticides can provide a way for farmers to protect crop yield and quality, mitigate the risk of exceeding MRLs for their key markets, and abate consumer concerns over food safety. 

The active ingredients used in Eden’s biopesticides are known as 'terpenes’. These compounds play a vital role in plants that produce them as a part of their defence systems. Terpenes are found in essential oils and herbs such as thyme, clove cinnamon and many others. These same essential oils have been consumed directly for centuries and are still used in abundance today in food and consumer goods. Terpenes have diverse functions and multiple modes of action and as such have no known risk of promoting the development of resistance in target pests. The emergence of resistance in target organisms is another key challenge for conventional chemical pesticides. 

The use of terpene active ingredients in products such as Mevalone® and Cedroz™ has a proven value for growers when faced with changes in pesticide regulation. For example, following the 2019 alterations to iprodione MRLs in the EU, Australian exporters had to find a viable alternative to protect vines against botrytis. Mevalone has recently been approved in Australia under the brand name Novellus™ as a biofungicide which tackles botrytis in grapes. It provides Australian wine producers with a sustainable alternative to iprodione, which is free from issues associated with MRLs as Mevalone is MRL exempt.

Implementing biopesticides into standard crop protection protocols helps growers to future proof their operations and meet constantly shifting consumer and regulatory demands whilst protecting crop yields and quality. 


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