Balancing environmental risks and benefits: a basic approach.

Abstract

Risk-cost-benefit assessment of a biological control agent is a complex task, given that it should take into account expected risks, costs and benefits of economic values, human and animal health, and the environment. Environmental impacts can not usually be assessed in monetary terms, so therefore they are analysed in a qualitative manner. The proposed procedure for environmental risk-benefit assessment consists of identifying, analysing and evaluating (weighing up) risks and benefits. During the evaluation phase, risks are balanced against benefits by ranking them separately in decreasing order of significance. The highest ranked adverse effects are then compared to the highest ranked benefits. Even though adverse effects of biological control agents are mostly limited to effects on non-target arthropods, uncertainties of effects and the potential long-term and area-wide impacts greatly complicate risk-benefit assessments. Uncertainties are caused by insufficient data, measurement errors, lack of understanding of ecological systems, environmental stochasticity and implementation errors. An example of an environmental risk-benefit assessment demonstrates that the benefits of replacing the insecticide deltamethrin by releases of the egg parasitoid Trichogramma brassicae outweigh the risks posed by the biological control agent itself.