Pollutants of Emerging Concern in Orange County Stormwater Synthetic Pyrethroid Pesticides Fipronil Pesticide
Regulatory Drivers Basin Plan narrative objective The concentration of toxic pollutants in the water column, sediments or biota shall not adversely affect beneficial uses Region 8 Pesticide toxicity has been identified as a pollutant of concern in stormwater and a number of waterbodies have been listed as impaired due to unknown toxicity or sediment toxicity A TMDL for toxic pollutants has been promulgated in San Diego Creek and Newport Bay TMDL requirements are being implemented into municipal stormwater permits
Synthetic Pyrethroid Pesticides Light-stable synthetic derivatives of pyrethrin, natural insecticidal extracts of the chrysanthemum flower. Sodium channel toxin Includes Bifenthrin, Permethrin, Cyfluthrin, Cypermethrin, Deltamethrin, Cyhalothrin, etc. In animals, toxicity enhanced by simultaneous high-dose exposure to organophosphates
Synthetic Pyrethroid Pesticides (cont.) Bifenthrin used extensively in the San Diego Creek watershed (ornamental nurseries) for Red Imported Fire Ant (RIFA) control Binds to soil particulates Half-life (days) in soils Aerobic Anaerobic Bifenthrin 96.3 425 Cyfluthrin 11.5 33.6 Permethrin 39.5 197
Malathion Diazinon Chlorpyrifos Bifenthrin Permethrin Carbaryl ug/l Relative Aquatic Toxicities of Pesticides Analyzed in the OC Program 10 LC 50 s for 96-hr Americamysis Survival Test 1 0.1 0.01 0.001 Organophosphates - Synthetic Pyrethroids - Carbamates Source: Average values from USEPA Ecotox database
Malathion Diazinon Bifenthrin Permethrin ug/l Relative Aquatic Toxicities of Pesticides Analyzed in the OC Program 10 LC 50 s for 48-hr Ceriodaphnia Survival Test 1 0.1 0.01 0.001
Malathion Diazinon Chlorpyrifos Bifenthrin Permethrin Carbaryl ug/l Relative Aquatic Toxicities of Pesticides Analyzed in the OC Program 10000 LC 50 s for 96-hr Fathead Minnow Survival Test 1000 100 10 1 0.1
Fipronil Pesticide Not yet analyzed in OC Program Neurotoxin in the phenyl pyrazole class of pesticides Registered for use in CA in late 1990s Popular usage for flea control (Frontlinetopically applied to dogs and cats); termite, roach, and ant control (Combat - baits) Only slightly soluble in water; binds to soil particulates
Fipronil Pesticide (cont.) Half-life in oxygenated soils = 188 days; 18-22 days in anaerobic soils; 1-5 days in aerobic aquatic conditions Forms metabolites much more toxic (to fish) than the parent compound Fipronil: Degrades in anaerobic soils to Fipronil Sulfide Degrades in aerobic soils to Fipronil Sulfone Photodegrades in water quickly to Fipronil Disulfinyl (1/2 life - 0.33 days)
Aquatic Toxicity of Fipronil and Metabolites ( g/l) Organism Test Fipronil Fipronil Desulfinyl Ceriodaphnia dubia 48-hr 17.7 355 LC 50 Fipronil Sulfone Fipronil Sulfide Americamysis bahia 96-hr 0.14 1.5 LC 50 Rainbow Trout 96-hr 250 31 39 LC 50 Bluegill 96-hr 83 20 25 LC 50 Source - DPR
Fipronil Sales in California 35000 30000 25000 20000 15000 10000 5000 0 2000 2001 2002 2003 2004 2005 Pounds of Active Ingredient
Current Issues Finding a laboratory which can analyze Fipronil in stormwater at a reasonable price Attaining laboratory reporting limits for synthetic pyrethroids below literature values of LC 50 s for common toxicity testing organisms Finding consistency between toxicity testing results and concentrations of pyrethroid pesticides in water and sediment
Control Adj Surv / ug/kg Example of Inconsistency between Toxicity Testing and Chemistry 120 Amphipod Survival and Pyrethroid Pesticides in Sediment Upper Newport Bay - UNBJAM 100 80 60 40 20 0 4/19/06 6/20/06 9/14/06 11/15/06 3/8/07 6/21/07 9/19/07 4/9/08 6/10/08 5/7/09 6/17/09 % Survival Bifenthrin Permethrin LC 50 s for Eohaustorius estuarius - Source: Dr. Brian Anderson UC Davis Bifenthrin - 7.9 ug/kg ; Permethrin -140.1 ug/kg
Additional Data 100 TOC, Particle Size, and BRI Scores Upper Newport Bay - UNBJAM 81.8 61.7 64.2 10 1 0.1 Apr06 Jun06 Sep06 Nov06 Mar07 Jun07 Sep07 Apr08 Jun08 Sep08 May09 Jun09 %C % Clay BRI Score