listing of ECOTOX plus studies listed as fate related and salient monitoring studies are summarized in APPENDIX 1-10. Table 3-1. Chemical properties and environmental fate parameters for malathion and degradates with registrant submitted data. Property Malathion Malaoxon acid Dicarboxylic acid IUPAC Name Diethyl Diethyl ester butanedioc acid butanedioc acid Structure Chemical Formula C10H19O6PS2 C10H19O7PS C8H15O6PS2 C6H11O6PS2 Molecular Mass 330.3 g/mol 314.3 g/mol 302.3 g/mol 274.3 g/mol Vapor Pressure (25°C) 2.3*10-5 torr1 3.4*10-6 - 4.5*10-6 torr2 Law Constant 8.4*10-10 atm∙m3/mol2 8.4*10-10 atm∙m3/mol2 - 4.7*10-15 Solubility (25°C) 145 ppm1 78 ppm2 - 3218 ppm2 Hydrolysis half-life (25°C) pH 5: 107 days pH 7: 6 days pH 9: 0.5 day1 pH 5: 32 days pH 7: 9 days pH 9: 0.16 day1 - - Aqueous photolysis half-life 98 days at pH 41 - - - Soil photolysis half-life (days) 173 days1 - - - Aerobic soil metabolism range 0.3 to 11 days1 <1 day1 - - Aerobic aquatic metabolism half-life 0.5 to 10 days1 0.8 to 6 days1 - - Anaerobic aquatic metabolism half-life range 2.5 - - - Soil partition (adsorption) coefficients (Koc) 151-308 mL/g o.c. 1 81 – 327 mL/g o.c. 1 - 7 – 76 mL/g o.c.1 Terrestrial field dissipation DT50 <1 day1 - - - Octanol-water partition coefficient (Kow) 195-20001 32 5622 72 Bioconcentration factor 4.2 to 18L/kg wet-wt1 - - 3.2 L/kg Derived from registrant submitted study Derived from EPISuite 2
Soil Half-life or Aerobic Soil Metabolism Half-life (days) and Reference Temperature Malathion 1 41721701 46769501 47834301 90th% mean on seven half-lives from registrant submitted guideline studies results in 0.5 day half-life input parameter(See Table 4). However, GLN 835.4100 stipulates soil moisture at 40%-60% of water holding capacity and malathion rapidly hydrolyzes. Non-guideline studies indicate that persistence is increased in soils with low moisture and low microbial activity (Walker and Stojanovic 1973). To account for the contribution of hydrolysis to in metabolism studies, the input parameter is doubled. MWT or Molecular Weight (g/mol) Malathion 330.36 Product Chemistry Vapor Pressure (Torr) at 30oC Malathion 4 × 10-5 Product Chemistry Solubility in Water @ 25 OC, pH not reported (mg/L) Malathion 145 Product Chemistry Foliar Half-life (days) Malathion 6.1 Willis & McDowell, 1987 90th% mean on 37 malathion residue foliar persistence half-lives ranging from 0.3 to 10.9 days Heat of Henry Malathion 54,000 J/mol EPI Suite Number of Applications Malathion Malathion Use Summary Dates Malathion See Results Assumed on type of application Date selected within wettest month which malathion could be reasonably applied to a given crop. Amount Malathion Use Summary table Maximum single application rate for the crop or use pattern
3-12. Mean and upper bound dietary based EECs calculated for food items consumed by listed birds, terrestrial-phase amphibians or reptiles. Values represent potential exposures for animals feeding on the treated field or in adjacent habitat directly adjacent to the field. Food Item Model Minimum single application rate (0.5 lb a.i./A) single application rate (2.0 lb a.i./A) Multiple application scenario (3 applications of 1.5 lb a.i./A) Maximum single application rate (5.1 lb a.i./A) Mean Upper bound Mean Upper bound Mean Upper bound Mean Upper bound Terrestrial invertebrates (above ground) T-REX 33 47 130 188 172 289 332 479 Terrestrial invertebrates (soil dwelling) Earthworm fugacity NA 8.1 NA 32.3 NA 73 NA 83 Short grass T-REX 43 120 170 480 211 586 434 1224 Tall grass (surrogate for nectar and flowers) T-REX 18 55 72 220 89 273 184 561 broadleaves T-REX 23 68 90 270 111 335 230 689 Seeds and fruit T-REX 3.5 7.5 14 30 17 37 36 77 Birds (small, insectivore)*** T-HERPS 70 101 148 214 365 528 378 546 Mammals herbivore)*** 45 127 162 458 193 545 413 1167 Amphibians/reptiles (small, insectivore) T-HERPS 3.4 4.9 7.2 10.4 18 26 19 27 Aquatic plants BCF* 0.00023-2.3** Aquatic invertebrates KABAM 0.00072-7.2** Fish BCF* 0.0013-13** *Based on empirical BCFs. **Varies based on EECs in water. Higher end set to 0.1 mg/L. ***Also represent residues in carrion NA = not applicable