Dimethipin

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

Tolerances are established for residues for the harvest growth regulant dimethipin (2,3-dihydro-5,6-dimethyl-1,4-dithiin 1,1,4,4-tetroxide) ... in or on the following raw agricultural commodities: cottonseed 0.5 ppm; cattle, fat 0.02 ppm; cattle, meat 0.02 ppm; cattle, mbyp 0.02 ppm; goats, fat 0.02 ppm; goats, meat 0.02 ppm; goats, mbyp 0.02 ppm; hogs, fat 0.02 ppm; hogs, meat 0.02 ppm; hogs, mbyp 0.02 ppm; horses, fat 0.02 ppm; horses, meat 0.02 ppm; horses mbyp 0.02 ppm; sheep, fat 0.02 ppm; sheep, meat 0.02 ppm; and sheep, mbyp 0.02 ppm.

A tolerances is established for residues for the harvest growth regulant dimethipin (2,3-dihydro-5,6-dimethyl-1,4-dithiin 1,1,4,4-tetroxide) ... in or on the following processed feeds when present therein as a result of application fo the harvest growth regulant to the growing crops: cottonseed hulls 0.7 ppm.

LC50 Mallard duck >5,000 ppm /8-day dietary/

LC50 Bobwhite quail >5,000 ppm /8-day dietary/

LC50 Rainbow trout 52.8 mg/L/96 hr /conditions of bioassay not specified/

LC50 Bluegill sunfish = 20.9 mg/L/96 hr /conditions of bioassay not specified/

For more Ecotoxicity Values (Complete) data for DIMETHIPIN (6 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a recommended classification scheme(1), a measured Koc value of 3.3(2), indicates that dimethipin is expected to have very high mobility in soil(SRC). Volatilization of dimethipin from moist soil surfaces is not expected to be important(SRC) given a measured Henry's Law constant of 1.7X10-8 atm-cu m/mole(3). Dimethipin is not expected to volatilize from dry soil surfaces based on its measured vapor pressure(2). The half-life of dimethipin in soil is approximately 104 to 149 days(2). A photolysis half-life of 76 days was calculated for dimethipin in soil(SRC) from a measured rate constant(3,SRC).

AQUATIC FATE: Based on a recommended classification scheme(1), a measured Koc value of 3(2), indicates that dimethipin is not expected to adsorb to suspended solids and sediment in water(SRC). Dimethipin is not expected to volatilize from water surfaces(3,SRC) based on a measured Henry's Law constant of 1.7X10-8 atm-cu m/mole(3). According to a classification scheme(4), an estimated BCF of 0.44(5,SRC), from a measured log Kow of -0.17(2), suggests that bioconcentration in aquatic organisms is low(SRC). A photolysis half-life of 2.0 days was calculated for dimethipin in water at pH 5 to 9(SRC) from a measured rate constant(3). Hydrolysis is not expected to be an important process at environmental pHs(3,SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dimethipin, which has a measured vapor pressure of 3.8X10-7 mm Hg at 25 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase dimethipin is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and ozone(SRC); the half-lives for these reactions in air are estimated to be about 3.0 and 3.7 hours, respectively(3,SRC). Particulate-phase dimethipin may be physically removed from the air by wet and dry deposition(SRC).

Dimethipin

Hepatic

2 x 10 ^-2 mg/kg-day

An estimated BCF of 0.44 was calculated for dimethipin(SRC), using a measured log Kow of -0.17(1) and a recommended regression-derived equation(2). According to a classification scheme(3), this BCF suggests that bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for dimethipin is 1.7X10-8 atm-cu m/mole(1). This value indicates that dimethipin will be essentially nonvolatile from water surfaces(2,SRC). Volatilization from wet and dry soil surfaces is not expected based on dimethipin's measured Henry's Law constant(1) and vapor pressure of 3.8X10-7 mm Hg, respectively(2).

Cancer Classification: Group C Possible Human Carcinogen

CLASSIFICATION: C; possible human carcinogen. BASIS FOR CLASSIFICATION: Classification is based on an elevated combined incidence of pulmonary adenomas/carcinomas in male, but not in female, CD-1 mice. A rat study is undergoing further evaluation. HUMAN CARCINOGENICITY DATA: None. ANIMAL CARCINOGENICITY DATA: Limited.

The rate constant for the vapor-phase reaction of dimethipin with photochemically-produced hydroxyl radicals has been estimated as 1.3X10-10 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1,SRC). This corresponds to an atmospheric half-life of about 3.0 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1,SRC). The rate constant for the vapor phase reaction with ozone has been estimated as 7.4X10-17 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 3.7 hours at an average ambient ozone concentration of 7X10+11 molecules/cu cm(1,SRC). Stability of dimethipin to light is greater than or equal to 7 days at 25 °C(2). In aqueous solution, dimethipin is degraded(2); rate and method of degradation were not specified(SRC). The half-life of dimethipin in soil is approximately 104 to 149 days(2); the method of degradation was not specified(SRC). The rate constant for the hydrolysis of dimethipin has been measured to be 1.5X10-5 /day at pH 6 and 25 °C(3). This corresponds to a half-life of about 126 years(3,SRC). Rate constants for the photolysis of dimethipin in both soil and water have been measured to be 9.07X10-3 and 0.017 /day, respectively, at 25 °C(3). These correspond to photolysis half-lives of 76 days in soil and 2.0 days in water at pH 5 to 9(3,SRC).

Tolerances are established for residues for the harvest growth regulant dimethipin (2,3-dihydro-5,6-dimethyl-1,4-dithiin 1,1,4,4-tetroxide) ... in or on the following raw agricultural commodities: cottonseed; cattle, fat; cattle, meat; cattle, mbyp; goats, fat; goats, meat; goats, mbyp; hogs, fat; hogs, meat; hogs, mbyp; horses, fat; horses, meat; horses mbyp; sheep, fat; sheep, meat; and sheep, mbyp.

A tolerances is established for residues for the harvest growth regulant dimethipin (2,3-dihydro-5,6-dimethyl-1,4-dithiin 1,1,4,4-tetroxide) ... in or on the following processed feeds when present therein as a result of application of the harvest growth regulant to the growing crops: cottonseed hulls.