Diazinon ecological information

Toxicity to fish: LC50; Species: Lepomis macrochirus (Bluegill) weight 1 g; Conditions: freshwater, static, 18 deg C, pH 7.1, hardness 44 mg/L CaCO3; Concentration: 362 ug/L for 24 hr (95% confidence interval: 270-480 ug/L) /92% purity formulation

Toxicity to daphnia and other aquatic invertebrates: EC50; Species: Daphnia magna (Water Flea) age <24 hr neonate; Conditions: freshwater, static, 21 deg C; Concentration: 6.1 ug/L for 48 hr (95% confidence interval: 4.8-7.4 ug/L); Effect: intoxication, immobilization /100% purity formualtion

Toxicity to algae: EC50; Species: Pseudokirchneriella subcapitata (Green Algae); Conditions: freshwater, static; Concentration: 3700 ug/L for 7 days; Effect: population abundance /formulation
Toxicity to microorganisms: no data available

Persistence and degradability

AEROBIC: Half-lives reported for diazinon in sterile (non-sterile) soils were 12.5 weeks (<1 week) in sandy loam and 6.5 weeks (2 weeks) in organic soil(1). Diazinon disappeared more quickly from unsterilized natural water (12 weeks) than from unsterilized distilled or sterilized natural water (>16 weeks), suggesting that degradation is both biological and chemical in nature in natural waters(2). Percent theoretical biological oxygen demand (BOD) was 16% for diazinon incubated with municipal sewage for 7.5-8.3 days(3). Diazinon, present at 100 mg/L, reached 0% of its theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test(4).

Bioaccumulative potential

BCF values were measured in the following species: topmouth gudgeon (Pseudodorasbora parva), 152, silver crucian carp (Cyprinus auratus), 36.6, carp (Cryprinus carpio), 65.1, guppy (Lebisters reticuatus) 17.5, crayfish (Procambarus clarkii), 4.9, red snail (Indoplanorbis exustus), 17.0, pond snail (Cipangopoludina malleata), 5.9(1); a fish (Fundulus heteroclutus), 10(2); species unreported, 35(3); carp, 120, rainbow trout, 63, loach, 26, shrimp, 3(4); sheepshead minnow, 200(5); eel(Anguilla anguilla) muscle and liver, 1600 and 800, respectively(6); perch 27(7); earthworm 8(8); fish from the Philipines, 12(9). According to a classification scheme(10), the range of experimental BCFs suggests the potential for bioconcentration in aquatic organisms is low to moderate(SRC).

Mobility in soil

The Koc for diazinon ranged from 40-432, and averaged 191 for 3 soils(1); in one sediment, the Koc was 250(1). For sandy loam(2.0% OM, pH 5.4), silt loam(1.4% OM, pH 7.0), silt loam(1.8% OM, pH 6.5) and sand(1.4% OM, pH 7.0), the Kocs were 1,539, 1,007, 1,653, and 1,842, respectively, with a recommended value of 1520(2). The Koc for diazinon was found to be 1589 in an Hungarian brown forest soil(3). The Koc for diazinon in two New Zealand topsoils was 165.22 and 324.49(4); the Koc in a New Zealand subsoil was 1447.47(4). According to a classification scheme(5), these experimental Koc values suggest that diazinon is expected to have moderate to low mobility in soil(SRC). Diazinon was given a leaching index of 2.0 (<20 cm movement/yr with 150 cm of annual rainfall)(6). Diazinon is reported to be fairly strongly adsorbed onto soil with low mobility(7).

Other adverse effects: no data available