Pesticides in tropical marine environments: Assessing their fate

by P.P. Carvalho and R.J. Hance hile forecasts of economic and population trends are notoriously contentious, it seems to be fairly widely accepted that there will be approximately 11 000 million people to feed in the year 2050, which is about twice as many as there were in 1990. Simultaneously the stock of agricultural land will diminish as a consequence of urbanization, erosion, and desertification. It has been predicted that the arable area per person, which was 0.3 hectares in 1981 will decline to 0.22 hectares in 2000 and 0.13 hectares in 2050. There seems little doubt that pesticides will remain an essential component of many agricultural systems. Although it is estimated that insect pests alone still destroy about one-third of the world's crops, yields would probably decline by a further 30% to 75% without crop protection chemicals. It is hardly surprising therefore that worldwide pesticide usage is on the order of 5 million tons per year with a value of US $26 billion. Undoubtedly agrochemicals will be used in more refined ways as increasing use is made of the various biological and cultural strategies but it is difficult to envisage their disappearance. Whether the current range of materials and uses will continue is less certain as far as developed countries are concerned. (See graphs, page 17.) Those used in developing countries seem unlikely to change rapidly simply on grounds of cost.