Dibutyl azelate

Using a structure estimation method based on molecular connectivity indices(1), the Koc for dibutyl azelate can be estimated to be 2,700(SRC). According to a classification scheme(2), this estimated Koc value suggests that dibutyl azelate is expected to have slight mobility in soil(SRC).

An estimated BCF of 590 was calculated for dibutyl azelate(SRC), using an estimated log Kow of 5.8(1,SRC) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is high(SRC).

The Henry's Law constant for dibutyl azelate is estimated as 1.2X10-5 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that dibutyl azelate is expected to volatilize from water surfaces(2); however, adsorption may attenuate this process(SRC). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 16 days if adsorption is ignored(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 183 days if adsorption is ignored(SRC). The estimated volatilization half-life of dibutyl azelate from a model pond is 600 days if adsorption is considered(3). Dibutyl azelate's Henry's Law constant(1) indicates that volatilization from moist soil surfaces may occur(SRC); however, adsorption may attenuate this process(SRC). Dibutyl azelate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 3X10-4 mm Hg(SRC), determined from a fragment constant method(4).

The rate constant for the vapor-phase reaction of dibutyl azelate with photochemically-produced hydroxyl radicals has been estimated as 1.6X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 1 day at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). A base-catalyzed second-order hydrolysis rate constant of 0.11 L/mole-sec(SRC) was estimated using a structure estimation method(2); this corresponds to half-lives of 2 years and 75 days at pH values of 7 and 8, respectively(2). The expected hydrolysis products are butanol and azelaic acid. Dibutyl azelate may undergo photolysis in the environment since this compound contains a functional group that can absorb light greater than 290 nm(3).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 20,145 workers (7,808 of these are female) are potentially exposed to dibutyl azelate in the US(1). Occupational exposure to dibutyl azelate may occur through inhalation and dermal contact with this compound at workplaces where dibutyl azelate is produced or used(SRC). The general population may be exposed to dibutyl azelate through the use of consumer products, such as contact lenses, that contain this compound(SRC).

Dibutyl azelate's production and use as a plasticizer and contact lens constituent may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 3X10-4 mm Hg at 25 °C indicates dibutyl azelate will exist solely as a vapor in the ambient atmosphere. Vapor-phase dibutyl azelate will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 1 day. Dibutyl azelate may also undergo direct photolysis since it contains a functional group that can absorb light greater than 290 nm, but the kinetics of this reaction are unknown. If released to soil, dibutyl azelate is expected to have slight mobility based upon an estimated Koc of 2,700. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 1.2X10-5 atm-cu m/mole; however adsorption may attenuate this process. Dibutyl azelate is not expected to volatilize from dry soil surfaces based on its vapor pressure. If released into water, dibutyl azelate is expected to adsorb to suspended solids and sediment in water based upon the estimated Koc. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. Estimated volatilization half-lives for a model river and model lake are 16 and 183 days, respectively if adsorption is ignored. The volatilization half-life from a model pond is 600 days if adsorption is considered. Hydrolysis is expected to occur slowly in the environment based on estimated hydrolysis half-lives of 75 days and 2 years at pH 8 and 7, respectively. An estimated BCF of 590 suggests the potential for bioconcentration in aquatic organisms is high. Occupational exposure to dibutyl azelate may occur through inhalation and dermal contact with this compound at workplaces where dibutyl azelate is produced or used. The general population may be exposed to dibutyl azelate through the use of consumer products, such as contact lenses, that contain this compound. (SRC)

LD50 Mouse oral >12.8 g/kg

LD50 Mouse ip >12.8 g/kg

LD50 Guinea pig oral >10.0 g/kg