Chemical pesticides industry • Worldwide: $32 billion • U.S.: $11 billion
Benefits of pesticide use • Control of crop pests • Food is cheaper, safer and available year-round • Control of disease-transmitting organisms • Control of pests of veterinary importance • Control of structural and household pests • Less land needs to be used for food production
Risks of pesticide use • Increased incidence of diseases – cancers = Human health risks • Damage to sensitive nontarget species = Environmental risks
Problems with older pesticides
Birds of prey • Eagle population declines • Other hawks and falcons § Peregrine
falcons late 1960s
– Egg shell thinning
Direct effects of modern pesticides • Effects on the organism’s physiology, nervous system, etc. • Can be lethal and/or sublethal
Indirect effects of modern pesticides • Effects on an organism’s food supply and/or habitat
What’s in the water?
Drift
All spray applications produce drift
Volatility - The ease with which a pesticide turns into a gas or vapor Temperature Wind Humidity
= higher volatility
Runoff
Leaching
Movement of pesticides through soil to water table
Pesticides in surface waters
• Pesticide concentrations fluctuate • They pulse through rivers and streams after applications and dilute • Background levels can be present for long times depending on the pesticide
The National Water Quality Assessment Program (NAWQA) • USGS pesticide survey of U.S. surface and groundwater systems (late 1990s – early 2000s) • Found pesticide mixtures everywhere
Certain pesticides were found more commonly in urban and suburban areas than in waters draining agricultural lands
Pacific salmon species • Coho – Silver salmon • Chinook – King salmon • Sockeye – Reds • Pinks – Humpies • Chum – Dog salmon • Steelhead
Wild Pacific salmon populations are in decline • Habitat Loss • Hydropower • Harvest • Hatcheries • Pollution?
Some populations have declined 95% since the 1940s
Studies on the effects of pesticides on aquatic organisms Diazinon disrupts antipredator and homing behaviors in chinook salmon Scholz et al.
Canadian Journal of Fisheries and Aquatic Sciences, 2000; 57(9): 1911-1918
Studies on the effects of pesticides on aquatic organisms The Synergistic Toxicity of Pesticide Mixtures: Implications for Ecological Risk Assessment and the Conservation of Threatened Pacific Salmon Cathy A. Laetz, David H. Baldwin, Tracy K. Collier, Vincent Hebert, John Stark, and Nathaniel L. Scholz
Environmental Health Perspectives, 2009; 117:348-353.
Organophosphates and carbamates are old technologies • New insecticides are used at lower concentrations and claim to affect nontarget organisms much less
Spinosad • A new supposedly safe natural insecticide registered for use in organic farming • Marketed for control of a range of pest species • A natural product derived from fermentation of a soil bacterium • Registered as an organic insecticide
University of Minnesota
Studies on the effects of pesticides on aquatic organisms Acute Toxicity and Hazard Assessment of Spinosad and R-11 to Three Cladoceran Species and Coho Salmon Deardorff and Stark
Imidacloprid • Another fairly new insecticide • One of the most widely used insecticides in the world • Mode of action is based on nicotine
daphnia.food4fish.com
Other insecticides being evaluated • New insecticides for control of codling moth on apples § Rynaxypyr § Pyriproxyfen § Spinetoram
Solutions • Identify the bad players (individual chemicals and mixtures)
• Reduce or eliminate uses of these products • Educate homeowners on proper pesticide application • Use safer products • Incorporate Low Impact Development (LID) and other stormwater controls to reduce inputs