Environmental Aspects of Development Paul Streeten Both Teddy Prager and Philipp Rieger have shown concern for the physical and social environment in which we live. Some thoughts on this subject might therefore be an appropriate contribution to a volume honouring them. Since my main recent work has been concerned with the developing countries, I shall link this environmental concern with development, although I believe that much of what I shall say also applies to the industrialized countries of the North. As in other fields, the initially separate study of the problems of the developing countries has yielded a bonus for the understanding of our industrialized counĀ¬ tries. Threats to the environment of developing countries The principal threats to the environment of developing countries can be grouped under the following headings. 1. Continuing rapid rates of population growth 2. Accelerating rates of urbanization 3. Atomic energy 4. Damage done by persistent pesticides 5. Damage done by industrial trace materials 6. Destruction of forests and soils It will be seen that this list overlaps, but is not identical, with a similar list that could be drawn up for developed countries. The rapid rates of population growth are the result of the introduction of modern death rates, resulting from modern death control, into societies with traditional birth rates, with little birth control. The transition from an equilibrium in which both death rates and birth rates 415