DIIS#PR#PYL METHYLPH#SPH#NATE
(DIMP)
PROFILE OF DRINKING WATER CONTAMINANTS FOR EMERGENCY RESPONSE
GENERAL INFORMATION
Diisopropyl methylphosphonate (DIMP) is a
stable by-product or contaminant in the effluent
from the manufacture of the military nerve gas
isopropyl methylphosphonofluoridate (GB).
DIMP constitutes about 2-3% of crude GB.
In the United States, active production of GB-
containing DIMP occurred between 1953 and
1957 at the Rocky Mountain Arsenal in Colorado
where it was subsequently stored. Remaining
stockpiles of GB are mandated for destruction by
1994.
DIMP that was disposed of in surface ponds
at the Arsenal has contaminated ground water
and is known to accumulate in plants. In water,
DIMP is stable for over 2 years and is not af-
fected by photolysis, biodegradation, or volatil-
ization. In soil, it readily migrates with water.
Biotransformation in soil is slow. DIMP is not
likely to enter the atmosphere due to its low
volatility.
PHARMACOKINETICS
DIMP is readily absorbed following oral ad-
ministration to mice, rats, and dogs and is widely
distributed throughout the body. Greater than
90% of the radiolabeled compound is excreted
in urine. One major metabolite, isopropyl
methyl phosphonic acid, accounts for 95% of the
excreted compound.
HEALTH EFFECTS
Humans
No data are available on the potential systemic
human health effects of exposure to DIMP. A skin
sensitization test performed on 215 volunteers
showed no allergic dermatitis.
HEALTH EFFECTS
Experimental Animals
Acute toxicity studies in a variety of species
indicate that DIMP acts on the central nervous
system to produce ataxia, copious salivation,
lethargy, and coma. Cattle showed additional
signs of cerebral edema and encephalitis.
DIMP is a significant eye irritant in rabbits,
but upon dermal application, it produces only
minimal skin irritation. In guinea pigs, DIMP was
not found to be a skin sensitizer following dermal
application.
Studies in mink and dogs fed DIMP for 21
days or less showed no DIMP toxicity.
Blood, intestinal, and ophthalmologic?!
changes seen in rats, mice, or dogs fed DIMP for
90 days were not clearly related to DIMP toxi-
city.
In a three-generation drinking water study
with rats, decreases in the viability ratio and lac-
tation viability of pups were observed. No other
reproductive or developmental effects were
found.
Lifetime toxicity and carcinogenicity data are
not available.	\
No mutagenic effects were seen in in vitro
bacterial assays.
OTHER CRITERIA, ANALYSES, AND TREAT-
MENT TECHNOLOGIES
In 1984, the U.S. Army Medical Bioengineer-
ing Research and Development Laboratory recom-
mended an interim limit for DIMP of 26.3 mg/L in
drinking water.
Methods for the analysis of DIMP include gas
chromatography with a flame photometric phos-
phorus detector, infrared and Raman spectros-
copy, thin layer and paper chromatography,
nuclear magnetic resonance spectroscopy, and
field ionization mass spectrometry. Gas chroma-
tography using a flame photometric phosphorus
detector is considered the method of choice.
No data on treatment technologies were
found although adsorption by activated carbon
and several synthetic sorbents appear feasible.

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Physical and Chemical Properties
Empirical Formula
Synonyms
CAS Number
Physical State
Molecular Weight
Boiling Point
Liquid Density
Vapor Pressure
Solubility (at 25°C)
WV
DIMP, Diisopropyl methylphosphonate, Diisopropyl methanephosphonate,
Phosphonic acid, Methyl-, bis-( 1 -methyl-ethyl) ester, Phosphonic acid, Methyl
diisopropyl ester
1445-75-6	CH3	O	CH3
Colorless liquid	\ II /
180.18	CH-O-P-O-CH
174°C	CH3 ch3 ch3
0.976 g/cm3 at 25°C
77 mm Hg at 10°C; 122 mm Hg at 100°C
In water 1-2 g/L at 25°C and >11 g/L at >80°C.
Health Effects Data and Advisory Values
Genotoxicity
Reproductive and
Developmental Effects
Cancer Classification
DIMP did not induce genetic effects in Salmonella and Saccharomyces
cerevisiae assays with or without activation.
A significant decrease in the viability ratio of F3a rat pups and in the lactation
viability of F3b pups were observed in a three-generation drinking water study
with Sprague-Dawley rats. No other reproductive or developmental effects
were found. The results of a mink study were considered inconclusive.
EPA Group D, not classifiable as to human carcinogenicity.
Reference Dose (RfD)
0.08 mg/kg/day

Drinking Water
3 mg/L

Equivalent Level (DWEL)

Health Advisory Values
One-Day
8 mg/L

Ten-Day
8 mg/L

Longer-Term (child)
8 mg/L

Longer-Term (adult)
30 mg/L

Lifetime
0.6 mg/L
This summary was developed using information from the Drinking Water Health Advisory.
For further information contact EPA's Office of Science and Technology at (202) 260-7571.
Office of Science and Technology
Office of Water
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
June 17,1991

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