ปัญหา สาเหตุ และ ผลกระทบจากการใช้ สารเคมีกำจัดศัตรูพืชต่อ สิ่งแวดล้อม โดย ผศ. ดร. อรัญ งามผ่องใส ภาควิชาการจัดการศัตรูพืช คณะทรัพยากรธรรมชาติ มหาวิทยาลัยสงขลานครินทร์

Problems and Background World’s population increase 1997  5.8 Billion 2030~ 8.4 Billion Lack of foods

Green Revolution “The Green Revolution is a process of technological development of a techniques that began in Mexico in 1944 and has since spread throughout the world”

Technology Hybrid strains Agricultural techniques Chemical fertilizers Irrigation Heavy machinery Pesticides

What is pesticides? “A substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Also, any substance or mixture of substances intended to regulate plant or leaf growth”

Use situation of pesticides North America29.4 % 30.6 % Western Europe26.2 % 26.0 % Asia24.5 % 22.5 % Latin America10.4 % 11.9 % Rest of the world9.5 % 9.0 % Global pesticide market > US$ 30,000 million (1996) > US$ 31,250 million (1997) Source: Agrow: World Crop Protection News (1997)

World market of pesticides

World market of pesticides (2001 estimates)

Use situation of pesticides Herbicide48 % Insecticide28 % Fungicide19 % Others5 % Global pesticide market share (1997) Source: Agrow: World Crop Protection News (1997)

Use situation of pesticides in Thailand Herbicide49.5 %43.5 % 29.5 % Insecticide33.0 %40.1 % 59.7 % Fungicide12.6 %11.4 % 8.3 % Others4.9 %5.0 %2.5 % Value (mil. B)

Where are pesticides used? Agricultural areas Non-agricultural areas – household pest control –vector control –golf course

Problems of pesticide use in Thailand 1. Most pesticides are imported increasingly every years

Problems of pesticide use in Thailand 2. Rapid increase of pesticide use –Fruit and vegetable crops have been extensively produced. – The government’s reduction of the import duty of pesticides from 5% to 0% in 1992 – DOAE provided farmers with free pesticides in case of outbreak.

Problems of pesticide use in Thailand 3. Inefficient use –Lack of knowledge –Misuse of application Over recommended dose spray “Cocktail” spray

Effects of pesticide use on environment What is the environment? Sources of pesticide contamination Sensitive areas Pesticide movement in the environment Harmful effects on non-target plants and animals Effects on aquatic ecosystems Effects on soil ecosystems

What is the environment? “The environment is everything around us. It includes not only the natural elements that the word "environment" most often brings to mind, but also people and the manmade components of our world. The environment is not limited to the outdoors -- it also includes the indoor areas where we live and work”

Sources of pesticide contamination Point source contamination Non-point source contamination

Sensitive areas Sensitive areas are sites or living things that are easily injured by a pesticide Sensitive areas outdoors include: areas where ground water is near the surface or easily accessed (wells, sinkholes, porous soil, etc.); areas in or near surface water; areas near schools, playgrounds, hospitals, and other institutions; areas near the habitats of endangered species; areas near apiaries (honeybee sites), wildlife refuges, or parks; and areas near ornamental gardens, food or feed crops, or other sensitive plantings

Sensitive areas Sensitive areas indoors include: –areas where people -- especially children, pregnant women, the elderly, or the sick -- live, work, or are cared for; –areas where food or feed is processed, prepared, stored, or served; –areas where domestic or confined animals live, eat, or are otherwise cared for; and –areas where ornamental or other sensitive plantings are grown or maintained.

Pesticide movement in the environment

In air, through wind or through air currents generated by ventilation systems, In water, through runoff or leaching, On or in objects, plants, or animals (including humans) that move or are moved offsite.

Harmful effects on non- target organisms Non-target organism: Any plant or animal other than the pest that is being controlled Two ways of harmful effects –the pesticide may cause injury by contacting the nontarget organism directly, or –the pesticide may leave a residue that causes later injuries

Effects of pesticide on aquatic ecosystems Sources and roles of water How pesticides enter surface and ground water? How pesticides influence aquatic animals? Factors affecting pesticide toxicity to aquatic animals How to reduce pesticide risks in aquatic systems?

Sources of water in the world ~ 1.7 % of all of Earth's water is ground water about 30.1 % of freshwater on Earth occurs as ground water about 5,614,000 cubic miles (mi 3 ), or 23,400,000 cubic kilometers (km 3 ), of ground water exist on Earth About 54 percent is saline, about 46 percent, being freshwater.

Roles of water –Industrial utilization –Household utilization –Drinking water

How pesticides enter water? Surface runoff Leaching Erosion

Pesticide properties influencing water pollution Formulation Toxicity Persistence Volatility Water solubility Soil adsorption

How pesticides influence aquatic animals? Lethal effects Sublethal effects Habitat alteration -Fish behaviour -Weight loss -Impaired reproduction -Inability to avoid predator -lowered tolerance to extreme temperatures -reduce the availability of plants and insects that serve as habitat and food for fish and other aquatic animals

Factors affecting pesticide toxicity to aquatic animals Toxicity values Exposure time Dose rate Persistence LD 50 or LC 50 The length of time the animal is in contact with the pesticide Time pesticides exist in the environment

How to reduce pesticide risks in aquatic systems Guidelines to help safeguard water sources –The site –Planning –Mixing and loading –Application –Storage –Disposal

Maximum Contaminant Level (MCL) M CL is the standard for drinking water set by EPA Contaminants 2,4-D Alachlor Atrazine Ethylene dibromide Glyphosate M CL (ppm)

Effects of pesticide on soils Role of organisms in soils Effect of pesticides on soil microbial population Effect of pesticides on nitrification

Role of organisms in soil Many organisms living in soils –bacteria –fungi –nematodes –arthropods –crustaceans –earthworms Degradation of plant and animal residues other organic matter nitrogen fixation nitrification release of nutrients from soil mineral

Effect on soil microbial populations Microbial population Environmental change Pollution with xenobiotic chemicals

How pesticides affect microbial population? Reduction in population (long term effect) –atrazine bacteria and fungi reduction (Canada) –methamidophos bacteria (China) –monocrotophos, carbaryl and methomyl bacteria & fungi (Egypt)

Effect of pesticides on nitrification What is nitrification? Nitrification or 'ammonium oxidation' is a two-step respiratory process occurring in sediment (benthic nitrification) or the water column (pelagic nitrification) in which bacteria oxidise ammonium (NH 4 ) to nitrite (NO 2 ) and nitrate (NO 3 ) Nitosomonous spp. and Nitrobacter spp. are the main organisms responsible for nitrification process

Effect of pesticides on nitrification Reduction in nitrification process (long term effect) –atrazine nitrification reduction (Canada) –methamidophos and dimethoate Nitrification reduction (China)

Factors affecting pesticide behavior in soils Adsorption Absorption Volatilization Runoff Leaching Degradation

Environmental risk of pesticides Environmental Risk = Persistence x Mobility x Nontarget toxicity x Volume of use