Throughout human history, increasing population growth and changing dietary patterns have resulted in more and more land moving from forest or grasslands into agricultural production. Over the past few decades, the greatly increased use of chemical fertilizers and pesticides, plus changes in irrigation practices and improved seed stock, have enabled land already under cultivation to be farmed much more intensively. Given current population trends United Nations’ projections anticipate as much as a doubling of world population by 2050 (32) substantial intensification of agriculture on hectares now in cropland is certain, and conversion of more land to agricultural use is likely, especially in developing countries. Both actions will have far-reaching implications for environmental quality and human health.
Over the long term, increased food production is a prerequisite for a healthy world population. More people will be seeking better diets; and as incomes rise, dietary patterns shift to include more animal protein. The methods used to grow this additional food, as well as the nature and extent of land conversion, will determine whether significant negative health impacts will arise.
Health concerns related to agricultural intensification stem from increased exposure to toxic substances such as pesticides, a higher incidence of infectious diseases associated with expansion of irrigation systems and the use of wastewater for irrigation, and increased human exposure to infectious agents as tropical forests and other ecosystems are converted to agricultural land. Agricultural intensification could undermine health in less direct ways as well. If practices now common in some parts of the world persist or spread, basic agricultural resources could be degraded through soil erosion, loss of soil fertility, loss of genetic variability in crops, and depletion of water resources. This would eventually deplete agriculture’s global productive capacity.