Pesticides - a changing landscape that demands close monitoring

Discussion around the use of pesticides, or 'plant protection products', can often be emotive, and occasionally the lines between scientific and political argument can become somewhat blurred. There is little doubt, however, that they are an important part of modern agricultural practice. Without them it has been estimated that we would see a 40% increase in UK food prices, and they are considered an essential tool in providing food security to a growing population. Figures from the Food and Agriculture Organisation of the United Nations suggest that global agricultural productivity will need to increase by 70% to feed a predicted population of 9.5 billion by 2050. The challenge is to achieve that through improved efficiency rather than the cultivation of more land.

Why all the regulations?

Pesticides by their very nature tend to be toxic. Insecticides control pests by poisoning them using a number of different modes of action. In some cases that toxicity is extended to non-target organisms, including humans, due to shared biology, e.g. organophosphates inhibit acetylcholinesterase, an enzyme required for the metabolism of the neurotransmitter acetylcholine, found in most animals. Therefore it is essential that there are a set of rules in place regarding what active substance (a.s.) can be used as well as the manner of that use. Not only do the Regulations protect the consumer, they also protect the workers within the agricultural industries and the wider environment.

Why are we seeing so many plant protection products being withdrawn?

A number of different factors account for the significant levels of product withdrawal seen. Firstly, European Commission Regulation (EC) No. 1107/2009 as amended is the current legislation regulating the use of all plant protection products in the EU. One of the key departures from the rules laid out in the previous legislation, 91/414/EEC, was that a hazard-based approach should be used to assess products submitted for approval in favour of the older risk-based system. Essentially this means plant protection products are assessed for toxicity without consideration of how they will be used. Products that were considered safe to use under risk management conditions, such as low rate use and reduced operator exposure (PPE), are now being rejected at application; in some cases, existing products are being reassessed and approval revoked.

Secondly, Regulation (EC) No. 396/2005 as amended, which specifies the system for setting Maximum Residue Limits (MRLs) for pesticides applied to foods, is subject to continuous updating through further regulations amending the relevant Annexes. Typically a.s. with higher toxicity levels, Category 1-3 under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), will have lower permitted MRLs and in some cases this has affected the product’s efficacy. If a manufacturer is unable to provide supporting evidence that satisfactory control of the pest or disease can be achieved at the specified rates then it is likely to be withdrawn. Crop science companies are very aware of these issues and may choose to cease support of a product as part of their own commercial strategy. In 2015 further legislation was introduced which created the “candidates for substitution list”. This is a list of currently approved a.s. that have “one or more characteristics which are less favourable than most active substances”. Any a.s. included on this list is subject to a process known as comparative assessment at such time as it requires renewal or any amendment to an authorisation. The comparative assessment process compares the safety and efficacy of the a.s. in relation to that of products containing alternative a.s. The intention is that only the best, safest a.s. will be authorised for a particular use. The full effect of the candidates for substitution list has yet to be seen, as many a.s. are due for renewal in the next 3-5 years, but it is likely to further reduce the choice available to growers.

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