Similarly, in cases where biodiversity benefits are exceptionally high, when the adverse environmental impacts (i.e. social costs) are high (e.g. the pesticide DDT*) and/or when benefits are poorly understood (due to lack of scientific understanding and thus uncertainty) which may call for a precautionary approach, then prohibitions or restrictions on access, such as via the creation of natural parks, may be the best form of government intervention. These instruments will also have distributional implications which need to be considered and addressed as appropriate. Their purpose is to provide “correct” price signals to producers and consumers (to alter their production and consumption patterns) so as to close the gap between the marginal private costs and benefits and marginal social costs and benefits of biodiversity conservation and sustainable use.