Dibutylphosphonat

Foam, carbon dioxide, dry chemical.

If material involved in fire: use water in flooding quantities as fog. Apply water from as far as distance as possible. Use dry chemical or carbon dioxide. Keep run-off water out of sewers and water sources.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

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.

If material not involved in fire: Keep material out of water sources and sewers. Build dikes to contain flow as necessary.

Personnel protection: Keep upwind. Avoid bodily contact with the material. Avoid breathing vapors. ... Do not handle broken packages unless wearing appropriate personal protective equipment. Avoid bodily contact with the material. ... .

9.6 [mg/m3]

110 [mg/m3]

630 [mg/m3]

Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]:

Respiratory protection (supplied-air respirator with full facepiece or self-contained breathing apparatus) should be available where these compounds are manufactured or used and should be worn in case of emergency and overexposure. /Phosphorus compounds/

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 33(SRC), determined from a water solubility of 7.3X10+3 mg/L(2) and a regression-derived equation(3), indicates that dibutyl hydrogen phosphite is expected to have very high mobility in soil(SRC). Volatilization of dibutyl hydrogen phosphite from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.8X10+5 atm-cu m/mole(SRC), using a fragment constant estimation method(4). Dibutyl hydrogen phosphite is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.4X10-2 mm Hg(SRC), determined from a fragment constant method(5). Biodegradation data were not available(SRC, 2006).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 33(SRC), determined from a water solubility of 7.3X10+3 mg/L(2) and a regression-derived equation(3), indicates that dibutyl hydrogen phosphite is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 1.8X10-5 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 3 and 26 days, respectively(SRC). According to a classification scheme(6), an estimated BCF of 4(SRC), from its water solubility(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Dibutyl hydrogen phosphite hydrolyzes to phosphorous acid and butanol in a base catalyzed reaction(7). Reported hydrolysis half-lives range from 2.2(8) to 60.7 days(9). Biodegradation data were not available(SRC, 2006).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dibutyl hydrogen phosphite, which has an estimated vapor pressure of 2.4X10-2 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase dibutyl hydrogen phosphite 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 7 hours(SRC), calculated from its rate constant of 5.3X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). A study on analogous diethyl hydrogen phosphite demonstrated that the ester was degraded to CO2 (half-life 28.8 hr) by UV radiation in moist air(4). Degradation in sunlight also occurred but at a slow rate. Therefore, dibutyl hydrogen phosphite could be subject to photooxidation(SRC).

The Koc of dibutyl hydrogen phosphite is estimated as 33(SRC), using a water solubility of 7.3X10+3 mg/L(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that dibutyl hydrogen phosphite is expected to have very high mobility in soil.

An estimated BCF of 4 was calculated in fish for dibutyl hydrogen phosphite(SRC), using a water solubility off 7.3X10+3 mg/L(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for dibutyl hydrogen phosphite is estimated as 1.8X10-5 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that dibutyl hydrogen phosphite is expected to volatilize from water surfaces(2). 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 3 days(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 26 days(SRC). Dibutyl hydrogen phosphite's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Dibutyl hydrogen phosphite is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.4X10-2 mm Hg(SRC), determined from a fragment constant method(3).

/LABORATORY ANIMALS: Acute Exposure/ Rated 9 on rabbit eyes. Most severe injuries have been rated 10.

/OTHER TOXICITY INFORMATION/ The toxicity of phosphites appeared to be related to their lipophilic & electronic properties. The most toxic phosphites had electronegative substituents & unsaturated alkyl chains. /Phosphites/

The rate constant for the vapor-phase reaction of dibutyl hydrogen phosphite with photochemically-produced hydroxyl radicals has been estimated as 5.3X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 7 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1).

Dibutyl hydrogen phosphite hydrolyzes to phosphorous acid and butanol in a base catalyzed reaction(2). The rate constant for the hydrolysis of dibutyl hydrogen phosphite at 50 °C is 0.26X10-5/sec and its activation energy is 22.8 kcal/mole(1). Therefore, its hydrolytic half-lives at 50 and 25 °C are 3.1 and 60.7 days, respectively(SRC). Another investigator reported a basic hydrolysis rate constant at 20 °C of 36.2 l/sec mole(3), which would indicate a hydrolytic half-life of 2.2 days at pH 7 and 32 min at pH 9(3). A study on analogous diethyl hydrogen phosphite demonstrated that the ester was degraded to CO2 (half-life 28.8 hr) by UV radiation in moist air(4). Degradation in sunlight also occurred but at a slow rate. Therefore, dibutyl hydrogen phosphite could be subject to photooxidation(SRC).

Dibutyl hydrogen phosphite's production and use as a solvent, antioxidant, and chemical intermediate may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 2.4X10-2 mm Hg at 25 °C indicates dibutyl hydrogen phosphite will exist solely as a vapor in the atmosphere. Vapor-phase dibutyl hydrogen phosphite 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 7 hours. Dibutyl hydrogen phosphite may be subject to photooxidation based on a study on analogous diethyl hydrogen phosphite which degraded to CO2 (half-life 28.8 hr) by UV radiation in moist air; degradation in sunlight also occurred but at a slow rate. If released to soil, dibutyl hydrogen phosphite is expected to have very high mobility based upon an estimated Koc of 33. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 1.8X10-5 atm-cu m/mole. Biodegradation data were not available. If released into water, dibutyl hydrogen phosphite is not expected to adsorb to suspended solids and sediment 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. Estimated volatilization half-lives for a model river and model lake are 3 days and 26 days, respectively. An estimated BCF of 4 suggests the potential for bioconcentration in aquatic organisms is low. Dibutyl hydrogen phosphite hydrolyzes to phosphorous acid and butanol with reported hydrolysis half-lives ranging from 2.2 to 60.7 days. Occupational exposure to dibutyl hydrogen phosphite may occur through inhalation and dermal contact with this compound at workplaces where dibutyl hydrogen phosphite is produced or used. (SRC)

LD50 Rat oral 3.2 g/kg /From table/

LD50 Rat dermal 2.0 g/kg /From table/