New strategies for pest management options

Pesticide registration systems throughout the world largely rely on methods of analysing the risk of each pesticide independently of other options. Users have no means of knowing which chemical or product carries the least risk to health or the environment. A progressive new approach offers a different basis for regulating pesticides. Christopher Stopes and David Buffin report.

If we are to achieve the safest and most sustainable approaches to pest management, we must find a way that encourages the widespread adoption of non-chemical approaches. At present pesticide approval is based on a consideration of the hazard of the active substance and an assessment of the risk of harm of the product in use, both to human health (users, bystanders, or consumers of the food containing residues) and the environment. In the UK, this process proceeds product-by-product with no consideration given to the relative merits of other products or active substances that may be used to control the same pest, disease or weed. The scope for non-chemical approaches is not considered. 
    By failing to promote the least hazardous or risky approach to pest management current regulation does not take proper account of the precautionary principle. It increases the risk of long-term harm to human health and the environment. The most effective implementation of the precautionary principle is to remove from use substances where there is uncertainty over adverse effects. 
    Comparative risk assessment (CRA) encourages precautionary approaches when regulating pest management in food production. CRA involves the simultaneous consideration of the risk of harm to human health and/or the environment of active substances with the same or similar fields of use. It can be applied to active substances or products. 
    CRA enables the approval of the least risky substance or product, and consequently its substitution for those that are more risky. CRA can be a mandatory requirement in the approvals process, or it can underpin detailed information for users to enable them to select from alternative products. 
    With pesticides, the scope for CRA depends on there being an overlap between similar uses of different products or active substances. This is not necessarily always the case. The situation can be made more complex where resistance management is necessary or where products have specific fields of use (for example during stages of crop growth, or where crops are grown on different soil types). Choosing the safest approach is complicated by differential risks. A product or substance may pose a lower risk to human health, but a higher risk to the environment. 

Including non-chemical control 
Where pest, disease or weed control can be achieved by non-chemical methods, for example by crop husbandry, rotation or variety choice, this non-chemical method could be included in the CRA. The approach could prioritise methods that are significantly less risky and equally cost effective. Only non-chemical methods have the scope to remove the risk of the use of hazardous substances from the food chain and the environment. On what basis could the substitution of chemical by non-chemical methods be considered?

CRA and regulation of pesticides
The European Union has included the principle of CRA in the form of chemical substitution in the Non-agricultural Biocides Directive (98/8), but there is no reference to it in the Agricultural Pesticides Directive (91/414). In reviewing the operation of this Directive, the Council has called on the Commission to examine the scope for substitution and comparative assessment. It is open to debate whether this would be at the level of active substance, product, target and use, or method of application. The European Commission will hold a workshop in 2003 to discuss the concept and possible applications. 
    In the Biocides Directive, comparative assessment will be applied to active substances, with the proviso that substitution can only occur within the same product type. If the same approach were to be applied to the CRA of pesticides, it would ignore product formulation, rate of application, crop and site of use. The comparison would be based on intrinsic hazard rather than risk. Some believe that CRA and substitution could only operate at the level of products, targets and uses.
    To date, Sweden is the only country in the EU to implement CRA. The Swedish chemicals agency (KEMI) estimates that about 15% of withdrawals under its review programme were the result of substitution following comparative risk assessment. The Swedish system compares products, not active substances. 
    In June 2001, the Advisory Committee on Pesticides (ACP) considered the scope for the introduction of CRA into the regulation of pesticides in the UK. The Committee has provided an evaluation of alternative approaches to implementation, and Ministers will consider this advice during the ongoing re-negotiation of the directive (91/414).
    The ACP’s evaluation showed a clear split between industry and public interest groups. The agrochemical industry consistently argued against the regulatory deployment of CRA whilst the other interest groups almost universally supported CRA. 
    At a recent EC stakeholder workshop held in Greece in July 2002 participants included representatives of the agrochemical industry, the European Commission, EU member states and environmental public interest groups. Most, though not all, stakeholders considered that CRA should be applied at the product level within each member state. 

CRA – voluntary or mandatory?
CRA can be implemented in two ways – whether the risk assessment and substitution is implemented on active substances or products. Under a mandatory regulatory procedure, an active substance or product would be either approved or substituted by a lower risk product or substance. Producers would not have access to a substance or product that had a safer alternative. 
    Secondly, CRA could be a ‘semi-regulatory’ tool, where the substance or product is assigned to a CRA band (low, medium or high). This banding would require or enable users to select a product of lower risk. 
    The greatest benefit would arise from the mandatory application of CRA and substitution, which would help to establish a level playing field across Europe. A semi-regulatory approach may not be evenly applied throughout Europe – some member states may apply it vigorously, others hardly at all. More importantly, it would be difficult to enforce. 

The benefits of CRA
CRA may be complex to implement, but it is crucial for developing safer methods of pest management. CRA will facilitate the application of the precautionary principle in the pesticide approvals process. It could be seen as a central component of precaution in practice. 
    Although there may be conflicting priorities in balancing the concerns of substances’ impact on human health or the environment, CRA will force regulators to make a qualified and transparent judgements which will help provide a practical approach to risk management with widespread public support. 
    The use of CRA as a mandatory part of the pesticide approvals process could make an important contribution to safer pest management in food production and more widely. It has the support of a diverse range of stakeholders, and although it may place a greater burden on regulators and on the agrochemical industry, it will stimulate the search and commercial development of least risky solutions to pest management problems.

Christopher Stopes is a member of the UK Advisory Committee on Pesticides.

PAN UK is organising a conference on Comparative Risk Assessment (see page 2).

[This article first appeared in Pesticides News No. 57, September 2002, page 11]