Ecotoxicology.

1. Ecotoxicology is concerned ultimately with the effects of pollutants on populations not individuals. Sub-lethal effects, and changes to the environment, can have a greater impact on population size than does acute toxicity. 2. Effective concern about effects of pollutants on wildlife developed after the Second World War with the advent of synthetic pesticides, and the difficulties encountered then in the evaluation of the effects of insecticides are still with us. 3. Effects on wildlife are probably often unnoticed and to demonstrate causes of observed effects is usually difficult. 4. Two underlying problems are that ecology is still a relatively young science and that we lack a consensus on the value of wildlife. 5. We need to improve our predictive abilities for effects of pollutants and we also need long-term monitoring schemes that have clear objectives.