Ecorisk Dilemma. ES/RP 532 Applied Environmental Toxicology. EPA Approach. EPA Objective. Hazard Identification. Hazard ID

Transcription

1 Ecorisk Dilemma ES/RP 53 Applied Environmental Toxicology Lecture Pesticides: Ecological Risk Assessment Too many species to protect Must accept some adverse effects (practically speaking) Habitat destruction dominates any possible effect that pesticides could have (absent a spill or other intentional misuse) Desire to know the likelihood that communities and ecosystems will be affected However, studies are largely based on examining individuals, not higher levels of hierarchy EPA Objective Choose most sensitive organism If can protect that organism, then there is a reasonable certainty of no environmental harm EPA Approach EPA findings published in the RED (Registration Eligibility Decision Document Format may vary between pesticide risk assessments, but it is typically in the format of the major RA elements Hazard ID Dose-Response Characterization Exposure Assessment Risk Characterization Deterministic Assessment Hazard Identification Hazard ID Toxicity Toxicity Sublethal Effects Reproductive potential Predator Avoidance Morphological deformities General health parameters Enzyme activities Other biomarkers of physiological effects Community Level Effects OP insecticides about an order of magnitude more toxic than herbicides and fungicides Note that pyrethroid insecticides have low mammalian and avian toxicity but very high fish and invertebrate toxicities Aquatic invertebrates more sensitive than fish

2 Toxicity (LC 5 ) of Pesticides to Coho Salmon (or closely related spp.) and Daphnia Diazinon Chlorpyrifos Azinphos-methyl Carbaryl Diuron Atrazine. LC 5 () Coho Salmon Daphnia Hazard Identification--Sublethal Effects Pesticide Effect Fish Species Effective DoseLC5 95 th Percentile (Age) () () () chlorpyrifos Impaired swimminrainbow Trout (juve permethrin Impaired swimminrainbow Trout 7 7 <.,4-DBE Impaired swimminrainbow Trout (year ~9 <.5*,4-DBE Increased predatio Sockeye Salmon 7 < <.5* (fry & smolts) carbaryl Increased predatio Rainbow trout ( gram) chlorpyrifos Schooling behavio Fathead Minnow permethrin Schooling behavio Fathead Minnow <. trifluralin Skeletal deformitieatlantic salmon 5 **. (fry to adult) atrazine Habitat modificati Blue gill (fry to adults) 4, Distribution of Species Responses to Chlorpyrifos in Water From Geisy et al. 999 A New Sublethal Hazard? Sex reversal in Chinook salmon Example of eco-epidemiology Three hypothesis Chromosomal translocation Temperature dependent sex determination Endocrine disruption Pesticides the culprit?? Nagler, Bouma, Thorgaard, Dauble.. High incidence of a male-specific genetic marker in phenotypic female Chinook salmon from the Columbia River. Environ. Health Perspectives 9:67-69 Dose-Response Assessment Electroolfactogram Studies (Moore & Waring 996 EPA chooses the most sensitive species with regard to toxicity 96-h LC5 (fish) 48-h LC5 (invertebrates) LD5 (birds/rodents) toxicity NOAEC Exposure in water during entire life cycle (invertebrates) Exposure in water during reproductive period (fish) Dietary exposure during reproductive period (birds/rodents) Atlantic Salmon Response to Female Sex Priming Pheromone Dose-Response Assessment: Sub-lethal Effects

3 Milt Production by Atlantic Salmon Post Exposure to Sex Priming Pheromone and Diazinon Exposure (Moore and Waring 996) Effect of Diazinon on Anti-Predator Behavior in Chinook Salmon Exposed to Alarm Pheromone (Scholz et al. ) Food Strikes / min Dose-Response Assessment: Sub-lethal Effects Scholz et al. Tox. Endpoints for Diazinon in EPA RED Scud LC5 =. Water flea (Daphnia) NOEC =.7 Rainbow trout LC5 = 9 Brook trout NOEC =.55 (µg/l) Exposure Assessment Effect of Half-Life on Chlorpyrifos Dissipation From Water Half-Life (Days) Days After Application.5 Modeled vs. Empirical Residues of Diazinon in Water USGS 95th Peak 6 Day Percentile. Days Post Application Apple/Pears Felsot. 3

4 Diazinon Exposure Relative to Hazard Benchmarks Peak 6 Day USGS 95th Percentile (Felsot ) Rainbow Trout (LC5=9 ) Brook Trout (NOEC=.55 ). Scud (LC5=. ). Apple/Pears Water Flea (NOEC=.7 ) RQs for Diazinon Modeled and Empirical Residue Levels Exposure Scenario Apple/Pear Apple/Pear Urban Sites Urban Sites Agric. Sites Agric. Sites Exposure Duration Fish USGS 95th%tile Invertebrates Bottom Line Adios Diazinon! Urban uses withdrawn from market--voluntarily by manufacturer (Syngenta) Probabilistic Risk Assessment Where Do Data Distributions Overlap? Deposition of Herbicides Canadian Wheat Growing Region (Waite et al. 995, ETAC 4:7) Maximum grams/ha bromoxynil,4-d dicamba 4

5 Estimate of Risk from Atmospheric Deposition of,4-d.4 g/ha (measured deposition) Guess What? We ve not really discussed ecological risk!!!! Percentile Distribution of Crop NOELs For,4-D Exposure (8 crops) Thus far, we ve only looked at effects on different species, as populations. What about the community, and by implications the ecosystem? NOEL (g/ha) Testing the Hypothesis of Ecological Hazard Field tests Mesocosm tests Examine mesocosm studies where a range of toxicant concentrations have been tested The mesocosm should have a diversity of taxa representing multiple trophic functionality Effects of Diazinon on Large Outdoor Pond Microcosms, Giddings et al., ETAC v. 5, µg/l 8 Dosing Levels + Control 8 m surface area,. m 3 water volume Parameters diaz. conc. vs. time taxa diversity taxa abundance pop n. dynamics WQ parameters Benchmarks LOEC, time weighted-7 d Algae Snails Odonata Chironomini Bluegill Survival Bluegill Biomass LOAEC LC5 Ephemeroptera Rotifers Copepods Cladocera.. Ecol. Guideline µg/l Giddings et al., ETAC v. 5, 996 Giddings et al., ETAC v. 5, 996 Summary of Effects-LOECs Zooplankton Total numbers--4.3 µg/l Taxonomic richness--.4 µ/l Insects Total numbers--9. µg/l Taxonomic richness--9. µg/l Fish Survival--54 µg/l Biomass-- µg/l Aggregate LOEC & NOECs LOEC (7-day, 9. µg/l) NOEC (7-day, 4.3 µg/l) 5