Dioctyladipat

SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 57,000(SRC), determined from a structure estimation method(2), indicates that di-n-octyl adipate is expected to be immobile in soil(SRC). Volatilization of di-n-octyl adipate from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 4.34X10-7 atm-cu m/mole(3). Di-n-octyl adipate is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 8.5X10-7 mm Hg(3). Based upon analogy to biodegradation screening studies for the structurally-similar bis(2-ethylhexyl) adipate(3), biodegradation is expected to be the major degradation process for di-n-octyl adipate in soil.

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 57,000(SRC), determined from an estimation method(2), indicates that di-n-octyl adipate is expected to adsorb to suspended solids and sediment in water(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 4.34X10-7 atm-cu m/mole(5). Di-n-octyl adipate is expected to undergo hydrolysis producing octanol and adipic acid(SRC). Estimated hydrolysis half-lives are 5 years and 170 days at pH values of 7 and 8, respectively(5). Biodegradation is expected to be a major degradation process for di-n-octyl adipate in environmental waters(6). According to a classification scheme(4), a BCF of 27(5), suggests the potential for bioconcentration in aquatic organisms is low.

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), di-n-octyl adipate, which has a vapor pressure of 8.5X10-7 mm Hg at 20 °C(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase di-n-octyl adipate is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 0.67 days(SRC), calculated from its rate constant of 2.4X10-11 cu cm/molecule-sec at 25 °C(3) determined using a structure estimation method(3). Particulate-phase di-n-octyl adipate may be removed from the air by wet and dry deposition(SRC). Di-n-octyl adipate may undergo direct photolysis in the environment, since this compound contains a functional group that can absorb light >290 nm(4).

Release to the air can occur during incineration of municipal refuse, industrial rubbish and waste products from plastic production and other processes that use dioctyl adipate plasticizers(1). Leachates from municipal and industrial landfills that contain plastics may contain dioctyl adipate(1). Dioctyl adipate has been detected in wastewater effluents from the pulp and paper industry and in sewage treatment effluents(2,3). Di-n-octyl adipate was detected in effluent irrigation samples collected from Glil-Yam, 15 km north of Tel-Aviv, Israel at a concentration of 1,500 ppb from a depth of 9-10 m(4).

Using a structure estimation method based on molecular connectivity indices(1), the Koc for di-n-octyl adipate can be estimated to be 57,000(SRC). According to a classification scheme(2), this estimated Koc value suggests that di-n-octyl adipate is expected to be immobile in soil.

AEROBIC: In a semi-continuous activated sludge method used to simulate sewage treatment plant biodegradation, di-n-octyl adipate was observed to undergo primary degradation of 65-96% (at concns of 5 and 20 mg/l added/24 hr)(1); in a CO2 evolution study, di-n-octyl adipate was observed to biodegrade 94% over a 35-day incubation period which corresponds to a first-order half-life of 2.7 days(1).

A whole-fish BCF of 27 was observed for blue-gill fish exposed di-n-octyl adipate levels of 250 ug/l for a 28-day period(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low.

The estimated Henry's Law constant for di-n-octyl adipate is 4.34X10-7 atm-cu m/mole(1). This estimated Henry's Law constant indicates that di-n-octyl adipate is not expected to volatilize from water surfaces(2). Di-n-octyl adipate's estimated Henry's Law constant(1) indicates that volatilization from moist soil surfaces is not expected to occur(SRC). Di-n-octyl adipate is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 8.5X10-7 mm Hg(1).

NO ACUTE EFFECT HAS BEEN OBSERVED SOME HR AFTER ORAL ADMIN TO GUINEA PIGS OF DOSES ... EQUAL TO OR LESS THAN 14 ML/KG BODY WT. YET IN SUCCEEDING DAYS (3-21 DAYS) HALF OF ANIMALS DIED.

... DOSES OF 5 ML/KG /ADMIN TO GUINEA PIGS/ DID NOT CAUSE ANY MORTALITY, WHILE WITH 20 ML/KG, ALL ANIMALS ULTIMATELY SUCCUMBED IN ENSUING WEEKS. DEATH WAS PRECEDED BY PROGRESSIVE INFEEBLEMENT & MUSCULAR ATROPHY ... .

IN LONG-TERM TOXICITY TESTS, DAILY DOSES OF ADIPATE 0.61 MG/KG BODY WT HAVE NOT CAUSED ANY REACTION IN RATS AFTER NINETY DAYS.

Moderately toxic by intravenous route. Mildly toxic by ingestion. An eye and skin irritant.

The rate constant for the vapor-phase reaction of di-n-octyl adipate with photochemically-produced hydroxyl radicals has been estimated as 2.4X10-11 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 0.67 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Di-n-octyl adipate is expected to undergo hydrolysis producing octanol and adipic acid(SRC). A base-catalyzed second-order hydrolysis rate constant of 4.7 L/mole-sec(SRC) was estimated using a structure estimation method(2); this corresponds to half-lives of 5 years and 170 days at pH values of 7 and 8, respectively(2). Di-n-octyl adipate may undergo direct photolysis in the environment, since this compound contains a functional group that can absorb light >290 nm(3).

Occupational exposure to di-n-octyl adipate may occur through inhalation of dust particles and dermal contact with this compound at workplaces where di-n-octyl adipate is produced or used. The general population may be exposed to di-n-octyl adipate via drinking water, and dermal contact with this compound and other products containing di-n-octyl adipate. (SRC)

DRINKING WATER: Di-n-octyl adipate was detected, not quantified, in 4 of 5 raw river water samples collected from a pilot plant in Evansville, IN(1). A dioctyl adipate (isomer not reported) conc of 20 ug/l was detected in a drinking water sample collected from Miami, FL(2).

SURFACE WATER: Dioctyl adipate (isomer not reported) was detected at levels ranging from 2 to 86 ppb in 7 of 204 samples collected from 14 heavily industrialized river basins in the US between Aug 1975 and Sept 1976(1).