Agriculture and Environment: Rice

Environmental Impacts of Production: Pollution from Pesticide Use

Pesticides are perhaps one of the most important environmental problems posed by rice cultivation as a result of both their overuse and misuse (Witte et al. 1993).

Pesticides disrupt healthy ecological processes, as noted above. Equally important, pesticide poisoning is a health issue for both farmers and workers.

Modern rice production uses insecticides, herbicides, molluscicides, and to a small extent fungicides. In the major rice-producing countries of Asia, more agrochemicals are used o rice than on all other crops combined. In the Philippines, for example, 47% of all insecticides and 82% of all herbicides were used on rice (Witte et al. 1993).

In the late 1980s and early 1990s pesticides that had been banned in other countries were still being used in Thailand and the Philippines. These pesticides include chlordane, DBCP, DDT, dinoseb, HCH (hexachlorohexane, better known as lindane), hexachlorobenzene, methyl parathion, mercury compounds, and PCP (pentachlorophenol). In the Philippines 4 pesticides (monocrotophos, methyl parathion, azinphos-methyl, and endosulfan) constituted 70% of the pesticides used in rice cultivation in the early 1990s (Witte et al. 1993).

Another impact of the increased use of agrochemical inputs is that many bioaccumulate. This means that people absorb chemicals not only from the rice, but also from other plants, and in concentrated doses from any animals that accumulate the chemicals from what they eat. One survey found tat organochlorine insecticides were present in low levels in half of the blood samples taken from Filipino farmers.

A report prepared for the Institute of Agricultural Economics in Hanover, Germany, estimates that nearly 40.000 farmers in Thailand suffer from various degrees of pesticide poisoning every year, and that the associated health costs amount to more than U.S. $300,000 per year. The external costs of health care, monitoring, research, regulation, and extension amount to as much as U.S. $127.7 million per year in Thailand alone (Rice Today 2002). Studies in Thailand have shown that pesticide residues exist in more than 90% samples of soil, river sediment, fish, and shellfish (Rice Today 2002).

One of the problems of restricting or prohibiting the use of pesticides within a country, much less between countries when the products are traded, is to sort out the exact names of the pesticides that are used. Pesticides are often sold under brand names without reference to the chemical compounds included in them.

One chemical, for example, is marketed under 296 trade names, another under 274 (Rice Today 2002). This makes transparency for users as well as monitoring by governments very difficult.