Magnesium Phosphide - Chemical Fact Sheet 4/86
CHEMICAL FACT SHEET FOR:
FACT SHEET NUMBER: 66.1
DATE ISSUED: APRIL, 1986
1. DESCRIPTION OF CHEMICAL
- Generic Name: Magnesium Phosphide
- Trade Name: Magtoxin
- EPA Shaughnessy Code: 066504
- Chemical Abstract (CAS) Number: 12057-74-8
- Year of Initial Registration: 1979
- Pesticide Type: Solid fumigant
- Chemical Family: Inorganic Phosphides
- U.S. and Foreign Producers: Degesch America, Inc.; Research Products
Company; PestCon Systems, Inc.; Bernardo Chemicals.
2. USE PATTERNS AND FORMULATIONS
- Application Sites: Indoor fumigation of agricultural commodities,
animal feeds, processed food commodities, and non-food commodities
(tobacco). Outdoor fumigation for burrowing rodent and mole control.
- Formulations: Tablets and pellets; powders in bags, envelopes and
- Application Rates: 30 tablets or 75 pellets per square feet; 1-4
tablets or 5-20 pellets for rodent burrows.
3. SCIENCE FINDINGS
- Solid, dark gray material (granules, or powder); molecular weight
134.70; material must be protected from moisture in the atmosphere
in air-tight containers; contact of the solid material with moisture
in the air, or with water, or acids release phosphine, a highly
- Requirements for acute toxicity data have been waived because of
the well known extreme inhalation toxicity of phosphine gas which it
generates. Accordingly, magnesium phosphide has been placed in
toxicity category I, the highest toxicity category.
- No chronic toxicology studies are required with respect to dietary
exposure because there is not a potential for dietary exposure
(tolerances are set at limit of detection).
- Toxicology studies on phosphine gas are required to assess the
margins of safety for exposed workers and applicators because the
Agency does not have adequate data to determine whether phosphine
may cause any long term adverse effects to humans.
Physiological and Biochemical Behavioral Characteristics
- Magnesium phosphide reacts with moisture or water to release
phosphine gas, which eventually dissipates into the atmosphere. The
resulting material from the reaction is magnesium hydroxide, a
relatively inert and innocuous material, which is a constituent of
- Exposure (monitoring data) and related information are required to
help assess the margins of safety for applicators and workers
exposed to phosphine gas.
- Phosphine is a highly toxic gas to a wide range of living organisms.
Indoor uses pose no risk to non-target organisms outside of the site
to be treated. Outdoor end use products (1.e. rodent and mole
control) must bear special precautionary labeling to protect
endangered species. Manufacturing use products must bear
environmental hazard statements for wildlife.
- Tolerances have been established for raw agricultural commodities at
a level of 0.1 ppm (40 CFR 180.377); processed foods 0.01 ppm (21
CFR 193.225); and animal feeds 0.1 ppm (40 CFR 561.268). Finished
food and feed must be held 48 hours prior to being offered to the
consumer; tobacco fumigated in hogsheads must be aerated 72 hours.
Problems Known to Have Occurred with Use of the Chemical
Summary Science Statement
- The Agency has determined that the registered uses of this chemical
will not generally cause unreasonable adverse effects to humans or
the environment if used in accordance with the approved use
directions and revised precautionary statements prescribed by this
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- Magnesium phosphide will remain a Restricted Use Pesticide due to
the extreme acute toxicity of phosphine gas which is released from
the pesticide when it is exposed to moisture in the air. Therefore,
it may be used only by certified applicators or persons under their
- This amended standard adds several new regulatory requirements to
- For retail sale to and used only by a certified applicator or by
persons trained in accordance with the product manual working
under the direct supervision and in the physical presence of the
- Respiratory protection is not required if the fumigant is applied
from outside of a site such as a railroad car or to fill an
automatic dispenser located outside of a structure. However, if
the applicator enters a confined space to apply the fumigant,
respiratory protection is required. Exposure during application
within a confined space may not exceed 0.3 ppm phosphine as an 8
hour time weighted average (TWA). Engineering controls such as
forced air ventilation are recommended as the primary means of
meeting the exposure standard. Otherwise, an approved respirator
must be worn.
- Monitoring must be conducted with a low level detector device to
assure that the exposure standard is not exceeded. If monitoring
shows that exposure is less than the standard, no respirator is
required. If more than 0.3 ppm TWA is encountered, a full face
NIOSH/MSHA approved canister respirator is required up to 15 ppm
phosphine. This type of respirator must be available during
fumigation within a confined space. If more than 15 ppm or
unknown levels of phosphine are present, a NIOSH/MSHA approved
self contained breathing apparatus (SCBA) is required. SCBA must
be available at the site or locally such as at a fire department
or rescue squad.
- After application, no person may be exposed to more than 0.3 ppm
phosphine (maximum concentration). Exposures may occur if the
fumigated site leaks into an adjacent indoor area, during transfer
of treated commodity, or during reentry into an incompletely
- All entrances to a fumigated site must be placarded (except for
railroad hopper cars which must be placarded on both sides near
the ladders and on the top hatch where fumigant was applied). A
placard may only be removed after the commodity is completely
aerated. Each fumigated site must be monitored and shown to
contain 0.3 ppm or less phosphine in the air space around and in
the mass of the commodity. If more than 0.3 ppm is detected, the
placard must be transferred with the treated commodity. Persons
must be informed of the presence of phosphine and adequate
measures taken to prevent exposure to more than 0.3 ppm.
- When fumigating from within a confined space or when reentering an
incompletely aerated space, two trained persons must be present.
5. SUMMARY OF MAJOR DATA GAPS:
- 90 day inhalation study in rats
- Teratogenicity study in one species
- Mutagenicity battery
- Exposure (monitoring data and related information for major sites)
6. CONTACT PERSON AT EPA
Product Manager 21
Registration Division (TS-767C)
401 M Street, S.W.
Washington, D.C. 20460
DISCLAIMER: THE INFORMATION PRESENTED IN THIS CHEMICAL INFORMATION FACT
SHEET IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL
DATA REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.