Special Topic: Pesticide Residues in Food

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Develop an introductory understanding of pesticide use and monitoring in the human food chain. • Know the major classes of pesticides. • Understand the legal basis for monitoring. • Comprehend the risk vs. benefits analysis basis of – FIFRA, FQPA Special Topic: Pesticide Residues in Food Principles of Environmental Toxicology Instructor: Gregory Möller, Ph.D. University of Idaho

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Principles of Environmental Toxicology Learning Objectives • Develop an introductory understanding of pesticide use and monitoring in the human food chain. Special Topic: • Know the major classes of pesticides. Pesticide Residues in Food • Understand the legal basis for monitoring. • Comprehend the risk vs. benefits Principles of Environmental Toxicology analysis basis of – FIFRA, FQPA Instructor: Gregory Möller, Ph.D. University of Idaho 2 Principles of Environmental Toxicology Principles of Environmental Toxicology Pesticides Pesticide Data Program • USDA: Annual survey of target • Economic and public health commodities for target chemicals poisons. and multi-residue screening – Control of insects, weeds, rodents (12,446 samples). and other pest animals. • Year 2004 overall results. – Bacterial, fungal and viral infection – Detectable residue. in agriculture, homes and public • 70% of fruit & veg samples. health applications. • >50% of drinking water samples. • Natural chemicals, synthetic – Residue exceeding tolerance. chemicals, biological agents. • 0.2% of samples. • Residue ≠ or = Risk – Residue without tolerance. • 5.2% of samples. – http://www.ams.usda.gov/science/ pdp/Summary2003.pdf 3 4 Principles of Environmental Toxicology Principles of Environmental Toxicology Scope of US Commercial Activity Trends in Regulation and Use • Lower use rate. • About 865 Active Ingredients (1996). • Low-volume application. – 350 in food chain. – ~20,000 products, 9000 tolerances. • Risk mitigation requirements. – 1.25 billion pounds (AI) pesticides. • Integrated Pest Management – Herbicides are >50% of volume, >50% (IPM). sales; most top 10 use. • Conditional registration • Retail sales. (monitoring). – >$10 B (Ag, Non-Ag). • Safer chemicals. – >$8 B (Agricultural). • Biopesticide use. • Increased exposure concerns. – Patterns, routes and levels. 5 6 – Applicator training. •1
Principles of Environmental Toxicology Principles of Environmental Toxicology Major Classes of Pesticides Special Application Chemicals • Insecticides. • Acaracides, Algicides, Avicides, Bactericides, Piscicides, Virucides, • Herbicides. Molluscicides. • Fungicides. • Insect attractants, Insect repellants, Bird • Rodenticides. repellents, Mammal repellents. • Bactericides. • Plant growth activators. • Biopesticides. • Special • Synergists. application. 7 8 Principles of Environmental Toxicology Principles of Environmental Toxicology Pesticides, 1 Pesticides, 2 • Antibiotic insecticides. • Bacterium – Abamectin, Spinosad. – Bacillus thuringiensis (Bt) • Arsenical insecticides. • Carbamate insecticides. – Lead arsenate. – Aldicarb, Carbaryl, Carbofuran, Oxamyl. • Botanical insecticides. • Organochlorine insecticides. – Nicotine, Pyrithrins, Rotenone. – Aldrin, Dieldrin, DDT, Endrin, Methoxychlor, Pentachlorophenol. O O O HN O S N O O O O Rotenone 10 Aldicarb 9 Principles of Environmental Toxicology Principles of Environmental Toxicology Pesticides, 3 Pesticides, 4 N • Organophosphorus insecticides. • Botanical rodenticides. H – Azinphos-methyl, Dichlorvos, Chlorpyriphos, – Strychnine. H Fenthion, Diazinon, • Coumarin rodenticides. H – Malathion, Parathion. N – Brodifacoum, Bromodialone, • Pyrethroid insecticides. O Warfarin. – Fenvalerate, Permerthrin, Strychnine O • Inorganic rodenticides. Resmethrin. – Zinc Phosphide. O- • Unclassified rodenticides. N+ – Ergocalciferol, Sodium O S Fluoroacetate. P O O O Parathion 11 12 •2
Principles of Environmental Toxicology Principles of Environmental Toxicology Pesticides, 5 Pesticides, 6 • Amide herbicides. • Phenoxyacetic herbicides. OH – 2,4 D. – Metolachlor. HO OH P N • Quaternary ammonium • Dinitrophenol herbicides. N+ N+ H herbicides. – Dinoseb. O O – Diquat, Paraquat. • Imidazolinone herbicides. Glyphosate Paraquat • Thiocarbamate herbicides. – Imazethapyr. – Molinate. • Organophosphorus • Triazine herbicides herbicides. – Atrazine. – Glyphosate. • Sulfonylurea herbicides. – Metsulfuron. 13 14 Principles of Environmental Toxicology Principles of Environmental Toxicology Legal Basis for Monitoring Delaney Clause • 1958 Delaney Clause (FFDCA) • 1906 The Jungle (U. Sinclair). – Zero-risk cancer standard for residues in • 1906 Federal Meat Inspection Act; processed foods. 1906 Pure Foods and Drug Act. – 1938 Federal Food, Drug and Cosmetic Act, FFDCA. • 1910 Federal Insecticide Act, then • 1947 Federal Insecticide, Fungicide and Rodenticide Act. • Modern amendments. 15 16 Principles of Environmental Toxicology Principles of Environmental Toxicology Legal Basis for Monitoring, 2 Legal Basis for Monitoring, 3 • Federal jurisdiction. • SDWA - Safe Drinking Water Act. – EPA, FDA (HHS), FSIS (USDA), AMS (USDA) – Maximum contaminant levels. • Authority. • CWA - Clean Water Act. – FIFRA, FFDCA, FMIA, PPIA, EPIA – NPDES discharge permits. • EPA – Registration, RA, tolerance, environmental • RCRA - Resource Conservation quality. and Recovery Act. – Listed wastes. • FDA – Tolerance enforcement. • CERCLA (Superfund) • FDA, FSIS, AMS – Hazardous substances. – Food monitoring. • State primacy for FIFRA. • 1996 Food Quality Protection Act. 17 18 •3
Principles of Environmental Toxicology Principles of Environmental Toxicology Why FQPA? Motivation for Change • Years in the making: adopts most • NAS "Kids" Study: Pesticides in scientific recommendations the Diets of Infants and Children, • Delaney Paradox 1993. – Different regulations for processed • Minor crop pressure, streamlining. and raw foods • 1996 Election year opportunism. – No detectable level of carcinogens allowed in processed foods – Origins in Commerce Committee: – Court decisions requiring Consumers. enforcement of Delaney, 1993/95 – Unanimous passage, House/Senate. 19 20 Principles of Environmental Toxicology Principles of Environmental Toxicology NAS Kid's Study Results Consumed by “Kids" • The exposure of children to pesticides is Non-nursing infant subgroup substantially different from that of adults. Commodity g /kg/day • The government needs to do more to address milk 10.9 the unique risks posed to children. apples 6.3 oranges 2.7 peaches 2.1 soybeans* 1.6 pears 1.6 carrots 1.5 *component as soybean oil NAS 21 22 Principles of Environmental Toxicology Principles of Environmental Toxicology Children: Not Just Little Adults Some FQPA Changes • Kids as the dose model. • About 300 Active • Additive toxicity. Ingredients (AI) registered for top 20 commodities • Aggregate exposure. eaten by infants and • Endocrine disruption. children. • “Reasonable certainty of no harm” health standard. • Right-to-know. 23 24 •4
Principles of Environmental Toxicology Principles of Environmental Toxicology FIFRA FIFRA • FIFRA gives EPA strong authority • Federal Insecticide, Fungicide, and to require any data necessary to Rodenticide Act. evaluate risk to human health • FIFRA is a Licensing and the environment. Authority...labels are the license. – Registration is national in scope and • FIFRA is one of the few risk vs. authority. – Registrant-generated data benefits statutes. used to evaluate risk. EPA EPA 25 26 Principles of Environmental Toxicology Principles of Environmental Toxicology Human Health Agrichemical Registration NAS Risk Assessment Process • As many as 70 specific tests may be required (> $10M cost). 1. Hazard Identification. – Health effects and toxicology. • Toxicity testing, adverse effects. – Environmental fate. 2. Dose-Response Assessment. – Ecological effects. • Quantitative toxicity. – Residue chemistry. 3. Exposure Assessment. • Commercial development. • Food, water, home, workplace. – 10 yr cycle, $50M. 4. Risk Characterization. • Risk = Toxicity x Exposure. EPA 27 28 Principles of Environmental Toxicology Principles of Environmental Toxicology TTR: Total Toxic Residue Human Health • Prior to Food Use Registration. • Agrichemical residue plant/animal metabolism. • Ecological. • Typically with radiolabeled parent compound (AI). – Acute and chronic. • Track and identify metabolic products. – Aquatic and terrestrial. – Attempt to identify >80-90% TTR. • Human Health. • Separate toxicology trials for major – Acute and chronic. metabolites sometimes warranted. – Populations and sub-populations. • Effects of food processing and – Special protection for children. use of product as animal feed. EPA 29 30 •5
Principles of Environmental Toxicology Principles of Environmental Toxicology Risk = Toxicity x Exposure Dose - Response • Dosage - Response Experiment. • No observed effect level (NOEL). – Threshold Effect: mg/kg/day • NOEL / 100 for uncertainty is the Reference Dose, RfD. • Possible safety factors. – 10x to 100x. – Sub-population sensitivity. •No observed adverse effect level. •Lowest observed adverse effect level. NLM EPA 31 32 Principles of Environmental Toxicology Principles of Environmental Toxicology Reference Dose, RfD Reference Dose • An aggregate daily exposure to a • Derived from animal studies - best available data pesticide residue at or below the • No observable adverse effect level (NOAEL) RfD is considered generally • Uncertainty factors added to account for differences acceptable by EPA. in species (10x) and differences among individuals – Expressed as 100% or less of the (10x) = 100x RfD. • Additional mechanisms of risk assessment if carcinogenic. – Non-threshold effects. EPA 33 34 Principles of Environmental Toxicology Principles of Environmental Toxicology Reference Dose - Cancer Tolerance • The dose that will not increase cancer incidence more • Tolerance is established by review of field than 1/1,000,000 over background efficacy data, crop residue data, daily/lifetime dietary exposure and RfD. • Animal studies done at high doses and extrapolated – Maximum legal pesticide residue level. to low doses – Absence of tolerance: adulterated. • Small populations extrapolated to large populations • Required for “Emergency Exemptions” 35 36 •6
Principles of Environmental Toxicology Principles of Environmental Toxicology Maximum Residue Levels (MRL) TMRC • International tolerances • Theoretical Maximum Residue Contribution. EPA • Established by World Health Organization, Food and • Dietary exposures. Agriculture Organization (WHO-FAO) – Aggregate exposures: foods, water, non-occupational exposure. • 50% equivalent to US • Estimate of residues consumed daily if • US 20% more stringent, 30% less each food item contained pesticide residues equal to the tolerance. – Worst case estimate if no data. • Food contains residues at tolerance levels. • 100% of the crop is treated. • No removal by cooking. 37 38 Principles of Environmental Toxicology Principles of Environmental Toxicology Risk Cup Safety Standard • The statute establishes a strong health-based • Each new crop use of a chemical adds to the safety standard for pesticide residues in dose total. foods: • Cannot exceed 100% of RfD. – A single, safe, “reasonable certainty of no harm” • 70 yr exposure. standard for both raw & processed foods (all foods must be safe). RfD EPA 39 40 Principles of Environmental Toxicology Principles of Environmental Toxicology FQPA Tolerances Common Toxicity Mechanism • Tolerance re-evaluation. • Additive toxicity (2+2=4) • New law required review of ALL tolerances. – Neurotoxicity from organophosphorous and • 1996 Schedule: carbamate insecticides – 33% within 3 years • Risk cup (RfD) implication – 66% within 6 years – 100% within 10 years • Priority for review given to Cholinesterase Inhibition pesticides that had greatest risk to public health – OP’s, OC’s, developmental tox. 41 42 •7
Principles of Environmental Toxicology Principles of Environmental Toxicology Cholinesterase Inhibition Aggregate Exposure • Aggregate exposure to pesticides • Acetylcholine is the chemical mediator responsible used in calculation of risks. for physiological transmission of nerve impulses • Drinking water, yard/household across the synapse. chemicals, non-occupational • Acetylcholinesterase is the enzyme that modulates exposure. ACh. Cholinesterase – About 25% of all water used in the Inhibition U.S. is from groundwater. Animation – Approximately 50% of population use gw as their main supply of drinking water. • e.g. Atrazine concerns 43 44 EPA Principles of Environmental Toxicology Principles of Environmental Toxicology Endocrine Disrupters Endocrine Disrupters, 2 • Chemicals which interfere with endocrine • Hormones are biochemicals. system function. – Produced by endocrine glands. • Consists of glands and the hormones they – Travel through the bloodstream and produce. cause responses in other parts of the body. – Pituitary, thyroid, and adrenal glands, the female • Hormones of primary concern. ovaries and male testes. – Estrogen, androgen and thyroid hormones. Estradiol 45 46 Principles of Environmental Toxicology Principles of Environmental Toxicology Consumer Right-to-Know Pesticide Food Poisoning At 4 a.m., July 4, 1985, three adults who ate a solid green • FQPA required a number of new watermelon purchased in Oakland, California, had rapid actions to take place. onset of nausea, vomiting, diarrhea, profuse sweating, • “Pesticides and Food” brochure. excessive tearing, muscle fasciculations, and bradycardia. • Publication of data summaries in Aldicarb, a carbamate insecticide and potent AChE inhibitor the Federal Register (new). not registered for watermelons, was found in the samples. In the next month, 762 probable or possible cases were reported. The most severe signs and symptoms included seizures, loss of consciousness, cardiac arrhythmia, hypotension, dehydration, and anaphylaxis. Click Here 47 48 •8