Chuleemas Boonthai Iwai

Using Zooplankton, Moina Micrura Kurz to Evaluate the Ecotoxicology of Pesticides Used in Paddy Fields of Thailand

Thailand is an agricultural country where agriculture is a very important part of the economy. Thailand expanded exports of agricultural products and also imports fertilizers and pesticides intensively. Pesticides are used widely in agriculture and trade of agricultural products to increase agricultural yield and to protect plant from diseases, weeds and insect damage (Department of Agricultural, 2010). Since pesticides were first imported into Thailand under the “Green Revolution Policy” as part of the 1st National Economic and Social Development Plan in 1966, the total amount of imported pesticides has dramatically increased year by year. Most pesticides used in the country are imported (Department of Pollution Control, 2005), and the quantities of imported agricultural pesticides have increased 3 times from 1994 to 2005, reaching more than 80 thousand tonnes in 2004. Pesticides are applied in the highest quantity in vegetable and fruit farming, where market pressure for appearance is higher. In 2000, organophosphates contributed the majority of imported pesticides followed by carbonates and organochlorines; most were herbicides, followed by insecticides, disease control agents and plant growth regulators (Department of Pollution Control, 2002). The result from increasing pesticides uses has resulted in significant increased crop contamination and human health hazard (Office of Epidemiological, 2009). The risk of pesticide contamination in fruits and vegetables in Thai market often occurs. Rice is the major crop and food source for most Asian countries including Thailand. Rice production from paddy fields faces variety of pests that require a range of pesticides and herbicides to manage the presence of insects and weeds, as well as fungal and bacterial pathogens. Indeed, losses of the total world rice crop due to insects have been estimated to occur at a rate of 28% per annum, which is four times greater than the average for other world cereal crops. More than 90% of the global end-user market in pesticides for rice production is applied in Asia (Abdullah, 1995). In Thailand, pesticides play an important part and widely use on rice production because its benefits in pest control and increased rice production. Therefore, pesticide contamination in draining water from paddy field has been one of non-point source pollution in aquatic ecosystem (Sanchez et al., 2006).

Ecotoxicological assessment of diffuse pollution using biomonitoring tool for sustainable land use in Thailand.

As a developing country, Thailand has a significant issue with diffuse pollution of the soil ecosystem due to an indiscriminate use of agrichemicals and poorly regulated disposal of a wide variety of hazardous wastes. Practical risk assessment tools based on locally-occurring species are needed to assess the effects of diffuse pollutants on the soil ecosystem in Thailand because reliance on soil criteria developed for overseas conditions may provide inadequate protection. Native soil organisms in Thailand may be more or less sensitive to contaminants compared to overseas test species. This article described a biological indicator approach for ecological risk assessment of diffuse pollution in the soil ecosystem of Thailand from pesticide application with the aim of developing standardized protocols using native species and locally generated data to better evaluate the ecological risks of non-point source soil pollution. It was found that ecotoxicological assessment provided a better understanding of the ecological impacts that diffuse pollution induced on Thai environmental conditions. Thai soil biota species were more sensitive to soil contaminants than similar species overseas. Soil series also had an influence on the ecotoxicology of contaminants to soil biota. Collembolan, Cyphoderus sp., was demonstrated as a useful alternative test species to Folsomia candida (international test species) for terrestrial ecotoxicological testing of Thai soils. In addition, the soil biota activities such as soil respiration and earthworm avoidance including soil biodiversity and the litter bag decomposition technique are also good tools to assess the effects of diffuse pollution by pesticides on the soil ecosystem of Thailand.