1 ES/RP 532 Applied Environmental Toxicology Lecture 9 Pesticides: Regulations, Chemistry, & Toxicology Regulatory Definition of Pesticide • FIFRA (1947) • Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest • Pest: insect, rodent, plant, or animal life or viruses, bacteria, or other microorganisms, except viruses, bacteria, or other microorganisms on or in living man or other animals • Pesticide includes plant regulators, defoliants, or desiccants • Pesticide includes disinfectants Natural Ecosystems Self-sustaining as a result of biological (genetic) diversity – Diverse in species and function Responsive to system perturbations – System can quickly recover after disruptions Energy flow balanced –Nutrients recycled –Soil stores plant nutrients Why Use Pesticides Natural vs. Agricultural Ecosystem Characteristics Agroecosystems Limited biological diversity by design – monocultures & bicultures System cannot adapt – One organism can become dominant to detriment of others Energy flow unbalanced – nutrients constantly removed with crop harvesting Yield (bushels/acre) Year Acres Harvested 0 20000 40000 60000 80000 100000 120000 0 20 40 60 80 100 120 140 1890 1910 1930 1950 1970 1990 2010 Corn Production--USA A A. Hybrids B B. Mineralized Fertilizers C C. Soil Insecticides D D. Transgenic Crops Impact of Technology Advantages of Pesticides Many times they are the only practical or available technology Rapid action – can be used in an emergency – biodegradable (modern pesticides) Wide range of properties, uses, and methods of application – broad spectrum to selective
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ES/RP 532Applied Environmental Toxicology
Lecture 9Pesticides:
Regulations, Chemistry, & Toxicology
Regulatory Definition ofPesticide
• FIFRA (1947)• Any substance or mixture of substances
intended for preventing, destroying, repelling,or mitigating any pest
• Pest: insect, rodent, plant, or animal life orviruses, bacteria, or other microorganisms,except viruses, bacteria, or othermicroorganisms on or in living man or otheranimals
• Pesticide includes plant regulators, defoliants,or desiccants
• Pesticide includes disinfectants
Natural EcosystemsSelf-sustaining as aresult of biological(genetic) diversity– Diverse in
species andfunction
Responsive to systemperturbations– System can quickly
recover afterdisruptions
Energy flow balanced–Nutrients recycled–Soil stores plant
nutrients
Why Use PesticidesNatural vs. Agricultural Ecosystem Characteristics
System cannot adapt– One organism can become dominant
to detriment of othersEnergy flow unbalanced– nutrients constantly removed with
crop harvesting
Yield(bushels/acre)
Year
Acres
Harvested
0
20000
40000
60000
80000
100000
120000
0
20
40
60
80
100
120
140
1890 1910 1930 1950 1970 1990 2010
Corn Production--USA
A
A. Hybrids
B
B. Mineralized Fertilizers
C
C. Soil Insecticides
D
D. Transgenic Crops
Impact of Technology Advantages of Pesticides
Many times they are the only practicalor available technologyRapid action– can be used in an emergency– biodegradable (modern pesticides)
Wide range of properties, uses, andmethods of application– broad spectrum to selective
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Economic return-cost ratio favorable– $4 - $29 returned per $1 spent– However,
• Ratio goes down when– price of crop decreases but pesticide cost is
fixed;– a product is used and pest populations are not
at a level that will cause economic damage– development costs for a new product are high
Advantages of Pesticides
1989 2000
Insecticide Use in WA StateApple Orchards Has Decreased
PoundsUsed
Per Year
The Down Side ofPesticides
Worker exposure & poisoningPest resistanceReduction of natural enemiesPotential for adverse environmentalhealth effectsPotential for human health effects
Historically Parallel Regulations
Pure Food & Drug Act(1906)
Insecticide Act(1910)
Pure Food & Drug Insecticide Act
Health Protection
Prohibit Misbranding and Adulteration
Ensure Efficacious Product
Adulteration Standard Placed the Laws in Conflict
Historically Parallel Regulations
Pure Food & Drug Act(1906)
Insecticide Act(1910)
Federal Food, Drug &Cosmetic Act (FFDCA,1938) Federal Insecticide,
Fungicide & RodenticideAct (FIFRA,1947)
registrationlabeling
residue tolerances
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Historically Parallel Regulations
Pure Food & Drug Act(1906)
Insecticide Act(1910)
Federal Food, Drug &Cosmetic Act (FFDCA,1938)
Federal Insecticide,Fungicide & RodenticideAct (FIFRA,1947)
Miller Amendment(1954)
Food Additives Amendment(Delaney Clause) 1958
FFDCA Amended(Food & Drug Admin.-FDA)
FIFRA(USDA)
EPA(1970)
Federal Environmental Pesticide Control Act (FEPCA, 1972)
FDA (food residues)
Shared Responsibilities
U.S. Pesticide Law 101
FIFRA(1947)
FFDCA(1938)
Tolerance (“MRL”)
FEPCA(1972)
Labelling Registration
Risk Assessment
FQPA(1996)
Miller (1954)Delaney (1958)
Mandate of the FQPA
• Tolerances will be “safe,” i.e., “areasonable certainty that no harm willresult from aggregate exposure”
• The assessment of risk to consumers isnow guided by the mandates of theFQPA– No benefits consideration (with one
exception)• The assessment of risk to workers and
the environment is pretty much thesame as before the FQPA– But, benefits of pesticide use can be
considered
Consent Decrees Drive RA• In late 1999, the NRDC (Natural Resources
Defense Council) and several otherenvironmental advocacy groups sued EPAclaiming failure to properly implement theFQPA– The main issue was failure to consider cumulative
exposure• Consent Decree signed Spring, 2001
– Provisions to ensure cumulative exposureassessment and publication of determinations
– Provisions to include worker exposureand ecological effects
• Inhibition of mitosis (dinitroanilines-e.g.,trifluralin)
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Physicochemical Properties• General Rule of Thumb
– DDT and chlorinated cyclodienes tend to be ofvery low water solubility
– OPs tend to be lower than carbamates– Herbicides tend to have much higher solubilities
than insecticides, but watch out for exceptions• For example, trifluralin <3 ppm• Paraquat is cationic so it strongly sorbs,
especially to clays
Long Term DDT Experiment(Spencer et al. 1996, JEQ)
• Treat plots in 1971• Measure air and soil residues after
application and in 1994
(based on Spencer et al. 1996) (based on Spencer et al. 1996)
N
ClClHO
ClC2H5O
C2H5O
S
P- OH
N
ClCl
ClC2H5O
C2H5OP-O
S
+
N
ClCl
ClC2H5O
C2H5OP-OO
+C2H5O
C2H5O
O
P- OHN
ClClHO
Cl
Diethoxyphosphorothioate
trichloropyridinol
Diethoxyphosphoroate
NN
N
Cl
NH 2NCH 2CH 3
NN
N
Cl
NH 2H 2N
CH 3
NN
N
Cl
NH
H2N CHCH 3
NN
N
Cl
NH
NCH 2CH 3 CH
H
CH 3
CH 3
atrazine
hydroxy atrazine
CH 3
CH 3
NN
N
OH
NH
NCH 2CH 3 CH
H
de-isopropyl atrazine de-ethyl atrazine
diamino atrazine
Soil transformations of atrazine
Metabolitesfrequentlyfound in water
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Pesticides:A Technology in Transition
Per acre application rate has decreased by10 to 100 foldAcute toxicity has dramatically decreased by100-fold or moreNot stored in bodyPotential for carcinogenic, reproductive,endocrine effects are nil
Although we will focus on historical and recurrentissues or problems with pesticides, the technologyhas changed greatly since DDT and is in a transitionto greatly reduced risk products