Dimethyl methylphosphonate

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SMALL SPILLS AND LEAKAGE: If you should spill this chemical, use absorbent paper to pick up all liquid spill material. Seal the absorbent paper, as well as any of your clothing which may be contaminated, in a vapor-tight plastic bag for eventual disposal. Wash any surfaces you may have contaminated with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

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.

11 [mg/m3]

120 [mg/m3]

730 [mg/m3]

DOE Protective Action Criteria (PAC): Temporary Emergency Exposure Limits (TEELs) for Dimethyl methylphosphonate: TEEL-0: 100 mg/cu m; PAC-1: 350 mg/cu m; PAC-2: 500 mg/cu m; PAC-3: 500 mg/cu m (TEEL-0: The threshold concentration below which most people will experience no adverse health effects; PAC-1: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor; PAC-2: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action; PAC-3: The maximum concentration in air below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing life-threatening health effects).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 11(SRC), determined from a log Kow of -0.61(2) and a regression-derived equation(3), indicates that dimethyl methylphosphonate is expected to have very high mobility in soil(SRC); however experiments show that dimethyl methylphosphonate adsorbs strongly to natural montmorillonite clay mineral(4). Volatilization of dimethyl methylphosphonate from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.3X10-6 atm-cu m/mole(SRC), using a fragment constant estimation method(5). Dimethyl methylphosphonate is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 0.962 mm Hg(6). In environmental chamber studies, dimethyl methylphosphonate at initial concns in soil from 100-1000 ppm exhibited half-lives ranging from 0.2-60 days; average half-life was 12.4 days(7). The transport and/or degradation process responsible for the loss of dimethyl methylphosphonate was not determined. Limited biodegradation data indicate that biodegradation is not an important fate process in soil(8).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 11(SRC), determined from a log Kow of -0.61(2) and a regression-derived equation(3), indicates that dimethyl methylphosphonate is not expected to adsorb to suspended solids and sediment(SRC); however experiments show that dimethyl methylphosphonate adsorbs strongly to natural montmorillonite clay mineral(4). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 1.3X10-6 atm-cu m/mole(SRC), developed using a fragment constant estimation method(5). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 22 and 240 days, respectively(SRC). Dimethyl methylphosphonate will hydrolyze to methanol(6). Half-lives for dimethyl methylphosphonate are calculated to be 13.2 and 43.3 yrs at 20 and 10 °C, respectively, at unspecified pH(7). Hydrolysis acid, base and neutral rates for dimethyl methylphosphonate were reported as 1.36X10-9/mole-sec, 7.5X10-3/mole-sec, and 2.5X10-10/mole-sec, respectively(8). These rates correspond to half-lives of 3.27 yrs, 124 days, 12.4 days, and 1.2 days at pH 3, 7, 9, and 11, respectively(SRC). According to a classification scheme(9), an estimated BCF of 3(SRC), from its log Kow(2) and a regression-derived equation(10), suggests the potential for bioconcentration in aquatic organisms is low(SRC). In environmental chamber studies, dimethyl methylphosphonate half-lives in muddy water ranged from 7-210 days, removal mechanism for dimethyl methylphosphonate not specified(11). Limited biodegradation data indicate that biodegradation is not an important fate process in water(12).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dimethyl methylphosphonate, which has a vapor pressure of 0.962 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase dimethyl methylphosphonate 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 2.8 days(SRC), calculated from its rate constant of 5.7X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Dimethyl methylphosphonate is not expected to be susceptible to direct photolysis by sunlight based upon data for a similar compound, diisopropyl methylphosphonate, which did not photolyze when exposed to light (>290 nm) for 232 hours in distilled or Rocky Mountain Arsenal water(4).

The following link will take the user to the National Toxicology Program (NTP) Test Agent Search Results page, which tabulates all of the "Standard Toxicology & Carcinogenesis Studies", "Developmental Studies", and "Genetic Toxicity Studies" performed with this chemical. Clicking on the "Testing Status" link will take the user to the status (i.e., in review, in progress, in preparation, on test, completed, etc.) and results of all the studies that the NTP has done on this chemical.[Available from: http://ntp-apps.niehs.nih.gov/ntp_tox/index.cfm?fuseaction=ntpsearch.searchresults&searchterm=756-79-6]

The Koc of dimethyl methylphosphonate is estimated as 11(SRC), using a log Kow of -0.61(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that dimethyl methylphosphonate is expected to have very high mobility in soil; however experiments show that dimethyl methylphosphonate adsorbs strongly to natural montmorillonite clay mineral(4).

Teratogenicity was evaluated in fertilized female Sprague Dawley rats (25/group) exposed orally by gavage to dimethyl methylphosphonate (in 2% sodium carboxymethylcellulose vehicle) at dose levels of 0, 100, 1000 or 2000 mg/kg on gestation days (GD) 6-15. Dams were sacrificed on GD 21. Significant differences were observed between treated and control animals in the following: decreased maternal body weight gain and feed consumption (high-dose group), and retarded fetal physiological growth (including decreased body weight and delay in skeletal maturation, mid- and high-dose group). No significant differences were observed between treated and control animals with respect to fetal malformations. In a supplementary study, fertilized female Sprague Dawley rats (25/group) exposed orally by gavage to dimethyl methylphosphonate (in 2% sodium carboxymethylcellulose vehicle) at dose levels of 0 or 2000 mg/kg on gestation days (GD) 6-15 and 2500 mg/kg on GD 6-10. Dams were sacrificed on GD 21. Significant differences were observed between treated and control animals in the following: decreased maternal body weight gain and feed consumption and retarded fetal physiological growth (including decreased body weight and delay in skeletal maturation) (both treatment levels). No significant differences were observed between treated and control animals in the following: gross malformations, visceral or skeletal anomalies.

The mutagenicity of dimethyl methylphosphonate was evaluated in Salmonella tester strains TA98, TA100, TA1535 and TA1537 (Ames Test), both in the presence and absence of added metabolic activation by Aroclor-induced rat liver S9 fraction. Dimethyl methylphosphonate, diluted in DMSO, was tested at concentrations up to 2025ug/plate using the plate incorporation technique. Dimethyl methylphosphonate did not cause a positive response in any tester strain with or without metabolic activation.

The mutagenicity of dimethyl methylphosphonate was evaluated in Salmonella tester strains TA1535 and TA1538 (Ames Test), both in the presence and absence of added metabolic activation by rat liver S9 fraction. Based on preliminary toxicity determinations, dimethyl methylphosphonate, diluted in DMSO, was tested at concentrations up to 50mg/plate using the plate incorporation technique. Dimethyl methylphosphonate did not cause a positive response in any tester strain with or without metabolic activation.

SOURCE DOMINATED: Dimethyl methylphosphonate ambient air concns at three different locations near the edge of a hazardous liquid waste lagoon were 109,000, 10,600 and 2450 ng/cu m(1). Concns at two sites approximately 1 mile from this lagoon were 31 and 20 ng/cu m(1).

Dimethyl methylphosphonate's production and use as a flame retardant, simulants for nerve agents, antifoam agent, plasticizer and stabilizer, textile conditioner and antistatic agent, a preignition additive for gasoline, and as an additive for solvents and low-temperature hydraulic fluid(1) may result in its release to the environment through various waste streams(SRC). The compound is listed as a chemical weapons precursor and is regulated by the Chemical Waepons Convention.

Dimethyl Methylphosphonate

TR-323: Toxicology and Carcinogenesis Studies of Dimethyl Methylphosphonate (CASRN 756-79-6) in F344/N Rats and B6C3F1 Mice (Gavage Studies) (1987 )

08/19/86

Some Evidence

No Evidence

Inadequate Experiment

An estimated BCF of 3 was calculated in fish for dimethyl methylphosphonate(SRC), using a log Kow of -0.61(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 dimethyl methylphosphonate is estimated as 1.3X10-6 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that dimethyl methylphosphonate 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 22 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 240 days(SRC). Dimethyl methylphosphonate's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Dimethyl methylphosphonate is not expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 0.962 mm Hg(3).

/LABORATORY ANIMALS: Acute Exposure/ ... To investigate alpha(2u)-globulin accumulation in the kidney after dimethyl methylphosphonate (DMMP) and diethyl ethylphosphonate (DEEP), male and female Fischer-344 rats were administered DMMP or DEEP daily for five consecutive days by gavage. DMMP doses were 500- and 1,000-mg/kg body weight (bw); due to marked toxicity, daily DEEP dose of 50 and 100 mg/kg had to be used. Control rats received corn oil only and positive controls received five doses of 500-mg/kg bw trimethylpentane (TMP). Relative kidney weights were increased in male rats dosed with DMMP, DEEP, and TMP. Alpha(2u)-globulin in kidney cytosol was separated and quantified by capillary electrophoresis and by SDS-PAGE and Western blotting. In DMMP-, DEEP-, and TMP-treated rats, dose-dependent increases in the alpha(2u)-globulin content were observed by both methods in male, but not female rats. The increase of alpha(2u)-globulin accumulation was accompanied by the formation of protein droplets in the proximal tubules of male rats...

/LABORATORY ANIMALS: Acute Exposure/ Four male and four female albino rabbits received a dermal application of 2000 mg/kg Fyrol DMMP to their abdominal skin, which was then wrapped for 24 hours. The skin at the application site was abraded on half the animals. After 24 hours, the binding was removed. The animals were observed for 14 days after which they underwent necropsy. There was no mortality in this study. All rabbits appeared normal thoughout the study, with no clinical signs of toxicity. At necropsy one rabbit showed pale lungs but the other nine animals appeared normal.

/LABORATORY ANIMALS: Acute Exposure/ Six albino rabbits received a dermal application of 0.5 mg of dimethyl methylphosphonate to one abraded and one nonabraded skin site. The application sites were then covered for 24 hours. When unwrapped, the sites were examined at 24 and 72 hours for irritation. If irritation was present, it was scored according to Draize. Very slight irritation was observed at 24 and 72 hours.

/LABORATORY ANIMALS: Acute Exposure/ Six albino rabbits received 0.5 mL of Fyrol DMMP applied to a previously shaven area of their skin. The skin at the application sites of the rabbits was abraded prior to the administration of the test substance. The sites were covered for 24 hours, after which they were uncovered and examined for irritation. The sites were scored for irritation according to Draize. ...There was no irritation at any of the application sites.

For more Non-Human Toxicity Excerpts (Complete) data for DIMETHYL METHYLPHOSPHONATE (30 total), please visit the HSDB record page.