United States                  Office of Prevention, Pesticides
                  Environmental Protection           and Toxic Substances
                  Agency                      (7505C)
4>EPA        Pesticide
                   Fact Sheet
                  Name of Chemical:   Phosphine
                  Reason for Issuance:  Conditional Registration
                  Date Issued:         December 1999

   Generic Name:     Phosphine

   Common Name:    Phosphine gas, Hydrogen phosphide, Phosphorus trihydride

   Trade Names:      ECO2FUME™

   EPA Chemical Code: 066500

   Chemical Abstracts
   Service (CAS)
   Number:         7803-51-2

   Year of Initial
   Registration:      1999

   Pesticide Type:     Insecticide

   Chemical Family:   Inorganic phosphine

   U.S. and Foreign
   Producers:        CYTEC Industries Inc
                  West Paterson, NJ 07424


   The end-use product, ECO2FUME™ is a cylinderized, compressed gas containing a mixture
of 2% phosphine by weight (2.6% by volume) in carbon dioxide (98% by weight).  Carbon
dioxide (in addition to being an active ingredient itself) is used as a propellant and a flame
inhibitor, making the product non-flammable in air. Phosphine is a colorless gas which is
odorless when pure, but technical grade material usually has an odor described as "fishy" or
"garlicky". The odor is believe to be due to the presence of substituted phosphines and
diphosphines (World Health Organization, 1988).  This odor cannot be relied upon as a warning
of phosphine gas exposure.

   Phosphine gas is used indoors to control a broad spectrum of insects for non-food/non-feed
commodities in sealed containers or structures. There are no homeowner or  agricultural row crop
uses for this product.  The end-use product is a poisonous liquefied gas under pressure, and is a
Restricted Use Pesticide (RUP) due to the acute inhalation toxicity of phosphine gas.  The end-
use product is withdrawn from the cylinder as a liquid, but dispensed as a gas.  In expanding
from a liquid to a gas, it increases in volume by hundreds of times. Proper dispensing equipment
and training in fumigation is necessary and required to ensure a safe  and effective fumigation.
During fumigation applicators must placard or post all entrances to the facility with signs
warning of the presence of toxic gas. This placarding must be done in accordance with the
product Application Manual.

ECO2FUME™ is used as an aid in the control of the following insects:

   Almond Moth                  Angoumois Grain Moth
   Bean Weevil                    Cadelle
   Carpet Beetle                   Cereal Leaf Beetle
   Cigarette Beetle                 Confused Flour Beetle
   Dermestid Beetle                Dried Fruit Beetle
   Dried Fruit Moth                European Grain Moth
   Flat grain Beetle                 Fruit Fly
   Granary Weevil                 Greater Wax Moth
   Hairy Fungus Beetle             Hessian Fly
   Indian Meal Moth               Khapra Beetle
   Lesser Grain Borer              Maize Weevil
   Mediterranean Flour Moth       Pink Bollworm
   Raisin Moth                    Red Flour Beetle
   Rice Weevil                    Rusty Grain Beetle
   Saw-toothed Grain Beetle        Spider Beetle
   Tobacco Moth                  Warehouse Beetle
   Yellow Meal Worm

   The following non-food/non-feed items may be treated with ECO2FUME™: Animal hide;
processed or unprocessed cotton, wool or other natural fibers or cloth; clothing, feathers, furs,
human hair, rubberized hair, vulcanized hair, mohair, leather products; tobacco (and tobacco
products); wood, cut trees, wood chips and wood and bamboo products; paper and paper
products; non-food flour; non-food starch; dried plants and flowers. There are no food or animal
feed uses registered for phosphine gas (ECO2FUME™) at this time.

   The rate at which phosphine is  dispensed using ECO2FUME™ is not dependent on
temperature or humidity, but on the dispensing equipment used. Unlike metal phosphide
fumigants, the phosphine is not generated through a chemical reaction and both the release of the
product and the termination of its administration into sealed containers or structures are

   ECO2FUME™ is applied at a concentration of 200-500 ppm, which is maintained for a period
of 2-14 days depending upon the temperature found within the immediate surroundings of the
target pest.

   The use directions and limitations for this product are lengthy and detailed for this product
and therefore the Agency is requiring the product to have a label and a separate Application
Manual.  The label and Application Manual contains numerous limitations; only the major
limitations or use restrictions are included here:

1.  Phosphine gas (ECO2FUME™) is a Restricted Use Pesticide due to the acute inhalation
toxicity of phosphine gas.  This product is for retail sale to and use only by certified applicators
for uses covered by the applicator's certification or persons trained in accordance with the
manual, working under the direct supervision and in the physical presence of the applicator.
Physical presence means on site  or on the premises. Read and follow the label and the
Application Manual which contains complete instructions for the safe use of this pesticide.

2.  Worker exposure to phosphine  must not exceed the 8 hour TWA of 0.3 ppm during the
application or a maximum concentration of 0.3 ppm after application is  completed.  This
includes reentry into the structure. Respiratory protection must be available at the application

3.  Post "DANGER" signs on all entrances to fumigated areas.  See the Application Manual  for
the specific wording required.

4.  Notify appropriate company employees and provide relevant safety information (MSDS
sheets, first aid procedures, etc.) to local officials annually for use in the event of an emergency.

5.  Protect or remove materials containing metals such as copper, silver, gold, and their alloys
and salts from corrosive exposure to phosphine. (Thus, small electric  motors, smoke detectors,
brass sprinkle heads, batteries, fork lifts, temperature monitoring devices, etc.  Electric and


electronic equipment must be protected or removed before fumigation.)

6.  Prior to applying this product, you must inspect the structure to determine if it can be made
sufficiently gas tight.

   This product is registered as a Restricted Use Pesticide due to it's very high acute inhalation
properties.  Special training on how to operate the associated equipment to dispense the
phosphine gas is required.



   The Agency has previously based its evaluation of fumigation usage of phosphine in the U.S.
upon phosphine gas generated as the active ingredient in aluminum and magnesium phosphide.
Adequate product chemistry, lexicological, ecological effects, and environmental fate data have
been submitted and reviewed to support the conditional registration of ECO2FUME™ for the
non-food/feed uses listed above.

       ECO2FUME™ is classified in Toxicity Category I [DANGER] based on acute effects via
the inhalation route of exposure, as one would expect for a fumigation gas.  Phosphine is a
powerful respiratory poison. The 4-hour LC50 for phosphine in rats is 11 ppm.  No significant
exposure to phosphine gas is expected via the oral or dermal routes. Acute inhalation toxicity
exposure is the route of concern. Acute toxicity data for other routes of exposure were waived
with the requirement that eye protection would be required.

   In rats exposed to phosphine at 10 ppm, 6 hours/day for 3  days, there was 80% mortality in
females but no mortality in males. Both sexes of rats exhibited coagulative necrosis  in the
tubules of the kidney and pulmonary congestion was observed in the female rats that died.  A
LOEL of 10 ppm for a four-week study was based on lethality (80% deaths for females) due to
the sharp dose-response curve for acute toxicity. In a 13-week subchronic inhalation study,
Fischer 344 rats were exposed to phosphine at levels up to and including 3.0 ppm for 6
hours/day, 5 days/week. A LOEL for subchronic exposure was not established in this study; the
NOEL was 3 ppm (highest dose tested).

   In a two year combined chronic/carcinogenicity study, Charles River Fischer CDF rats were
exposed to phosphine gas in chambers at levels of 0, 0.3 ppm, 1 ppm and 3 ppm. There were no
adverse effects observed throughout the study that was relatable to the phosphine exposures. The
NOEL for this 104-week study was 3.0 ppm, the highest dose tested.  The Agency does not
believe that phosphine or a mixture of phosphine with carbon dioxide will pose a carcinogenic

   In a developmental study, pregnant CD derived Sprague Dawley female rats were exposed in

inhalation chambers to concentration of phosphine gas at levels of 0, 0.03 ppm, 0.3 ppm, 3.0
ppm, 5.0 ppm or 7.5 ppm, 6 hours per day on gestation days 6 through 15. The highest exposure
group (7.5 ppm) was terminated after 10 days due to high mortalities (14/24) The only
abnormalities were increased resorptions in liters of high dose (7.5 ppm) dams. Increased
resorptions were not observed in the 0.3, 3.0, 5.0 ppm groups.  All other observations were
comparable to those for the control females and pups. The maternal NOEL is 5 ppm and the
maternal LOEL is 7.5 ppm, based on the high incidence  of maternal death.  Although food uses
are approved for certain phosphine generating fumigants (i.e., aluminum phosphide and
magnesium phosphide), the general requirement for a reproductive toxicity study in rodents was
waived since residues of phosphine are not expected on food or drinking water and because these
developmental effects were expected to occur at doses above that at which the acute effects
would result in maternal death.

   Phosphine gas in not mutagenic in bacteria but is clastogenic in vitro. Negative results in an
Ames test and positive results in a Chinese hamster ovary cell chromosomes assay are consistent
with the in vitro test results for zinc phosphide.  Studies  conducted in vivo indicate that
phosphine is not clastogenic in mice or rats and does not cause dominant lethal mutations in mice
following exposure for up to two weeks.

   Under normal environmental conditions phosphine exists as a gas.  The solubility of
phosphine in water at normal atmospheric pressure is approximately 340 ppm (World Health
Organization, 1988) and the Ostwald solubility constant (the ratio of the concentration in
solution to the concentration in the gas phase at equilibrium) is 0.201 (Fluck, 1983). Because
of its high vapor pressure (40 mm Hg at -129.4 C) and Henry's Law Constant (0.1 atm
ni3/mol), phosphine at the soil surface is expected to rapidly dissipate into the atmosphere
(World Health Organization, 1988) .

   Phosphine in the atmosphere is rapidly degraded (World Health Organization,  1988). The
half-life in air is approximately five hours with the mechanism of degradation being
photoreaction with hydroxy radicals.  The dark half-life is approximately 28 hours.   The
expected reaction products of phosphine  in air are oxyacids of phosphorous and inorganic
phosphate which are non-volatile.

   Several published laboratory studies suggest that phosphine below the soil surface is quickly
adsorbed and degraded (Hilton and Robinson,  1972; Eiseman et. al., 1997; Berck and
Gunmer, 1970). Gaseous phosphine added to soil  headspace at 1000 mg/kg dry soil in closed
containers degrades 50% after approximately five days in air dried soil and 11 days in water
saturated soil (Hilton and Robinson, 1972).  Smaller quantities of phosphine may be removed
by soil through a faster mechanism because phosphine added at a lower concentration (0.35
micrograms/kg) was undetectable in 50 minutes (Eiseman, Glindemann, Bergman and Kuschk,
1997). Diffusion through the soil environment is expected to be slow because phosphine is
sorbed in seconds when pushed through several types of soil in a nitrogen carrier (Berck and
Gunmer, 1970). The interaction of phosphine with soil appears to be mixed chemisorption

(irreversible) and physisorption (reversible), with the extent of each dependent on soil type.
Phosphine gas trapped below the surface will degrade to phosphates in a matter of days.
Phosphine has a low exposure potential for contaminating ground and surface water.

Ecological effects or potential risk to non-targeted organisms resulting from indoor use of this
fumigation gas is considered to be very minimal.  Phosphine would be highly toxic to small
mammals and birds that might remain in indoor sites (e.g., warehouses) during fumigation.





Density at
(20 °C):
PH3 (CAS #: 7803-51-2)


Liquefied gas under pressure
(Gas at ambient temperature and pressure)

-87.4 C
1.405 kg/M3; 1.5 relative to air at 20C/1 atm pressure
Flammability:     Non-flammable at concentrations equal to or less than 3% phosphine in
                 carbon dioxide (v/v). This product is 2.6% v/v.

Solubility in water: 0.04%

Storage stability:  > 1 year

Characteristics:   Corrodes copper, brass, copper alloys, silver and gold

(End-Use Product)

   Acute Inhalation
   (rats):         LC50 (4-hour) > 11 ppm (phosphine gas)

   Category:      I

   Results of studies show that phosphine gas is highly toxic by the inhalation route.
Considering the use patterns and chemical characteristics, the other acute toxicity data (81-series
guideline studies) were waived for this chemical. The Agency has based the assessment for
acute toxicity of end-use products for phosphine fumigation (i.e., ECO2FUME, Aluminum
Phosphide, Magnesium Phosphide) on exposure to the active ingredient phosphine gas, per se.
Accordingly, the acute toxicity endpoints presented below are the same as described above for

   Acute Inhalation
   (rats):            LC50 (4-hr) > 11 ppm (for phosphine gas, per se)

   Category:         I

   Primary Eye
   Irritation:         Study not required, provided eye protection required.

   Category:         Not applicable.
   Inhalation Toxicity

   inhalation (rat):           (6 hours/day) LOEL 10 ppm (lethality among females)


inhalation (rat/):
(6 hours/day, 5 days/week) NOAEL= 5 ppm (the highest concentration
inhalation (rat):
Toxicity (rat):
(6 hours/day, 5 days/week) NOEL= 3 ppm (the highest concentration
The duration of exposure was 6 hours per day on gestation days 6 through
15. Maternal Toxicity NOEL=5 ppm, Maternal Toxicity LOAEL=7.5
ppm, based on a high incidence of maternal deaths.

Developmental Toxicity NOEL=5 ppm.
This study, a requirement for a food-use pesticide, was waived since
residues of phosphine are not expected in food or drinking water.
Chronic Toxicity/

  2-Year Feeding
Acute Inhalation
Diets were fumigated at high rates with aluminum phosphide pellets.
Actual levels of phosphine in diet were unknown, due to dissipation. This
study was not considered an acceptable guideline study since toxicity,
resulting from phosphine residues, is not possible when aeration is
adequate. However, the study shows that toxic levels of residues were not
achieved even with the high fumigation treatment rates with adequate
In a two year combined chronic/carcinogenicity study, Charles River
Fischer CDF rats were exposed to phosphine gas in chambers at levels of
0, 0.3 ppm, 1 ppm and 3 ppm. The high dose of 3 ppm was selected
because higher doses would result in high mortalities from acute effects.
There were no adverse effects observed throughout the study that was
relatable to the phosphine exposures. The NOEL for this 104-week study
was 3.0 ppm, the highest dose tested.
The acute LOEL is 20 ppm based on decreased body temperatures and

                    decreased motor activity in males and females, and the NOEL is less than
                    20 ppm (the lowest concentration tested). Groups were treated at levels up
                    to and including 40 ppm of phosphine (1% a.i. in nitrogen) for 4 hours. No
                    phosphine-related neuropathological changes were observed in any
                    exposure group. Based on lack of systemic toxicity, the NOEL for
                    systemic toxicity is 40 ppm.
Animals were exposed to phosphine at levels up to and including 3 ppm
for 6 hours/day, 5 days/week.  The NOEL for systemic/neurobehavioral
effects is tentatively set at 3 ppm (the highest concentration tested);
possible effects among males in the highest exposure group were
considered slight and equivocal, and there did not appear to be any
treatment-related effects among females. [NOTE: An upgraded study
was submitted to EPA in Sept 98; however, the Agency has not yet
reviewed this study.]

Gene mutation- Ames test (Salmonella typhimurium) - Negative for
induction of reverse gene mutation in all strains up to cytotoxic

Chromosome Aberrations - Positive at 2500 and 5000 ppm without S9
activation, in an in vitro cytogenetic assay with Chinese hamster ovary
cells. Significant, but not dose-related increases in the frequency of cells
with structural  chromosome aberrations were found.  Significant
clastogenic effects were also noted at 2500 ppm with S9 activation, but not
at the highest dose tested (5000 ppm).
Unscheduled DNA Synthesis (in vivo; rat primary hepatocytes)- Negative.
This data requirement applies to food-use registrations and no food/feed
uses are being registered.
Because the route of exposure anticipated for phosphine is inhalation (the
product is a gas), the Agency does not expect significant dermal exposure.
Therefore, dermal absorption studies are not required.
Summary of Phosphide Endpoints for Risk Assessments

Short-Intermediate or
Long-Term (Dermal)
Short Term
0.007 mg/L
(ca. 5 ppm)
0.004 mg/L
(ca. 3 ppm)
0.004 mg/L
The use pattern does not indicate potential exposure via the dermal route.
Therefore, dermal risk assessments are not required.
No treatment-related effects after exposure for 15
No evidence of toxicity at the highest tested
No evidence of toxicity at the highest tested
15-Day exposure
regimen in a 90-day
inhalation - Rat
90-Day Inhalation -
Chronic Toxicity
Inhalation - Rat

There are no food/feed uses for ECO2FUME™ at this time. Tolerances are not required for this
non-food registration. Note: Carbon dioxide is exempt from the requirement for a tolerance

This registration is subject, as a condition of registration, to amending the product label to
include all label restrictions and/or other conditions that may be imposed on the metallic
phosphide registrants, to the extent that they may also be relevant to ECO2FUME™ and its uses.
The Agency, as part of reregi strati on, is currently working with this metallic phosphide Task
Force and other interested parties to mitigate phosphine exposure and risk to workers and


   ECO2FUME™ is effective at controlling a broad spectrum of economically important insect
pests on non-food commodities in sealed containers or structures. Under proper use conditions,
ECO2FUME™ appears to offer greater control of application rates as compared with metal
phosphide fumigants, and is expected to reduce the levels of peak concentrations of phosphine
necessary for satisfactory performance within fumigated areas. This product eliminates the need
for applicators to enter a closed space and dispense tablets or pellets; therefore it may greatly
reduce the exposure to fumigators. This product eliminates the need to dispose of waste pellets

and or tablets when using metal phosphide products. In addition, this product may be used as
an alternative to methyl bromide, a fumigation gas that depletes stratospheric ozone.


   Dennis McNeilly, Chemist
   Insecticide Rodenticide Branch
   Registration Division (7505C)

E-Mail Address:


Mailing Address:

   U.S. Environmental Protection Agency
   401 M St.  S.W.
   Washington DC 20460

Office Location and Telephone Number

   Room 213, Crystal Mall Building #2
   1921 Jefferson Davis Highway
   Arlington, VA 22209
DISCLAIMER: The information presented in this Pesticide Fact Sheet is for informational
purposes only and may not be used to fill data requirements for pesticide registration and
reregi strati on.