E X T O X N E T
Extension Toxicology Network
A Pesticide Information Project of Cooperative Extension Offices of
Cornell University, Michigan State University, Oregon State University, and
University of California at Davis. Major support and funding was provided
by the USDA/Extension Service/National Agricultural Pesticide Impact
Assessment Program.
| |
Pesticide
Information
Profile
|
Zinc phosphide
Publication Date: 9/93
|
|
TRADE OR OTHER NAMES
Trade names for commercial products containing zinc phosphide include
Arrex, Denkarin Grains, Gopha-Rid, Phosvin, Pollux, Ridall, Ratol, Rodenticide
AG, Zinc-Tox and ZP.
INTRODUCTION
Zinc Phosphide is an inorganic chemical that is used to control rats,
mice, voles, ground squirrels, prairie dogs, nutria, muskrats, feral rabbits
and gophers. It is also uses as a tracking powder for the control of house
mice. It is used on crop areas and on non-crop areas including lawns, golf
courses, highway medians, and areas adjacent to wetlands (2). It may be
formulated as a grain based bait, as scrap bait or as a paste. Rodenticide
baits usually contain 2.0 percent of zinc phosphide.
Zinc Phosphide is a Restricted Use Pesticide (RUP). RUPs may be
purchased and used only by certified applicators.
TOXICOLOGICAL EFFECTS
ACUTE TOXICITY
Some formulations of this rodenticide are classified as highly toxic and
require the signal word DANGER-POISON on the label. Others are either
moderately toxic or only slightly toxic and thus require the signal words
WARNING or CAUTION respectively. Zinc phosphide reacts with water and acid in
the stomach and causes severe irritation (7). Symptoms of acute zinc
phosphide poisoning include nausea, shock, weak heart beat and low blood
pressure, loss of consciousness (3). Other symptoms include vomiting,
diarrhea, cyanosis, rales, restlessness and fever. There are documented
cases of adults dying from massive doses of the pesticide (4,000 to 5,000 mg)
although others have survived acute exposure of as high as 25,000 mg to
100,000 mg of zinc phosphide if vomiting occurred early and absorption was
limited (4).
The LD50 for the technical product (80-90% pure) is 45.7 mg/kg while the
LD50 values for lower concentration formulations are slightly higher (i.e.
less toxic). In sheep the LD50 ranges from 60 to 70 mg/kg (6).
The inhalation of zinc phosphide or its breakdown product phosphine gas
may result in acute toxicity (7). No specific doses were mentioned in the
reference. The compound is non-irritating to the skin and eyes (5).
CHRONIC TOXICITY
Rats fed zinc phosphide over a wide range of doses experienced toxic
effects at the lowest dose tested. Increased liver, brain and kidney weights
were noted in rats exposed to around 10 mg/kg. Body hair loss, reduction in
body weight, and reduction of food intake were all noted at 3.5 mg/kg. The
study was conducted over thirteen weeks (7).
There have been no observed symptoms of chronic poisoning due to zinc
phosphide exposure in humans (5). However another reference noted that
chronic exposure to sublethal concentrations for extended periods of time may
produce toxic symptoms (7). No specific note was made of the toxic symptoms
or the doses required to produce them. In that the available information is
inconclusive or undocumented, no definitive conclusions can be drawn to the
chronic toxic potential of zinc phosphide.
Reproductive Effects
No information currently available.
Teratogenic Effects
No information currently available.
Carcinogenic Effects
No information currently available.
Mutagenic Effects
No information currently available.
Organ Toxicity
Damage to the kidneys, to the liver and the stomach have been noted in
humans but only at high acute doses of the rodenticide. Zinc phosphide reacts
with water and stomach juices to release phosphine gas which can enter the
blood stream and adversely affect the lungs, liver, kidneys, heart and central
nervous system (7).
There is little tendency for the compound to concentrate in living
tissue.
Fate in Humans and Animals
Zinc phosphide reacts in the stomach and intestines with water and
hydrochloric acid to liberate phosphine gas. Small amounts of the rodenticide
fed to experimental animals may have produced an eighty percent absorption of
zinc as well.
ECOLOGICAL EFFECTS
Zinc Phosphide is highly toxic to wild birds and freshwater fish. It is
also toxic to non-target mammals. Nearly sixty studies have been conducted on
the toxicity of this rodenticide to wild animals. The most sensitive bird
species which have been evaluated are geese (LD50 of 7.5 mg/kg for the White-
fronted Goose). Pheasants, morning doves, quail, mallard ducks and the horned
lark are also very susceptible to this compound. Blackbirds are less
sensitive (2).
The fish species which have been evaluated include bluegill sunfish (LC50
= 0.8 mg/l) and rainbow trout (0.5 mg/l) (5). Carp were also found to be
susceptible to zinc phosphide, especially in weakly acidic water.
Secondary toxicity to mammalian predators from zinc phosphide is rather
low (2) primarily because the compound does not significantly accumulate in
the muscles of target species. Some of the toxic effects to predators have
been due to the ingestion of zinc phosphide that was in the digestive tract of
the target organism (the prey). However, most predators will not eat the
digestive tract. Studies on secondary organisms have focused on coyotes, fox,
mink, weasels and birds of prey. Under field conditions most of the toxic
effects to non-target wildlife are due to misuse or misapplication of this
rodenticide (2).
ENVIRONMENTAL FATE
Zinc phosphide may be applied as an active ingredient in either bait or a
dust. Soil acidity tends to break the compound down liberating phosphine a
highly toxic gas. There is a potential for movement of this compound into
adjacent, slightly acidic waters, where it can endanger fish populations (7).
PHYSICAL PROPERTIES AND GUIDELINES
Exposure Guidelines:
| TLV: | 0.3 ppm (7) |
| RfD: | 0.0003 mg/kg |
Physical Properties:
| CAS #: | 1314-84-7 |
| Chemical name: | Zinc phosphide |
| Chemical class/use: | inorganic rodenticide |
| Solubility in water: | practically insoluble |
| Solubility in other solvents: | practically insoluble in alcohol; slightly soluble in benzene |
| Melting Point: | >420 degrees C |
| Vapor Pressure: | Negligible in the dry state |
BASIC MANUFACTURER
Bell Laboratories, Inc.
3699 Kinsman Blvd.
Madison, WI 53704
Review by Basic Manufacturer:
Comments solicited: December, 1992
Comments received:
HACCO, Inc.
537 Atlas Ave.
Madison, WI 53714
Review by Basic Manufacturer:
Comments solicited: December, 1992
Comments received:
REFERENCES
Briggs, S.A. 1992. Basic Guide to Pesticides: Their Characteristics
and Hazards. Hemisphere Publishing Corp., WA.
Johnson, G.D. and K.A. Fagerstone. 1992. Primary and Secondary
Hazards of Zinc Phosphide to Nontarget Wildlife: A Review of the Literature.
Denver Wildlife Research Center, USDA/APHIS, Denver, CO.
Clarkson, T.W. 1991. Inorganic and Organometal Pesticides. In
Handbook of Pesticide Toxicology, Volume 2, Classes of Pesticides. W.J. Hayes
and E.R. Laws (eds.). Academic Press, NY.
Ecobichon, D.J. 1991. Toxic Effects of Pesticides. In Casarett and
Doull's Toxicology: The Basic Science of Pesticides, Fourth Edition. M.O.
Amdur, J. Doull and C.D. Klassen (eds.). Pergamon Press, NY.
The Agrochemicals Handbook. 1991. The Royal Society of Chemistry.
Cambridge, England.
Worthing, C.R. (ed.). 1991. The Pesticide Manual: A World
Compendium. The British Crop Protection Council.
TOXNET. 1992. Hazardous Substance Database. Zinc Phosphide.
National Library of Medicine. Hazardous Substance Data Base.
Disclaimer: Please read
the pesticide label prior to use. The information contained at this web
site is not a substitute for a pesticide label. Trade names used herein
are for convenience only; no endorsement of products is intended, nor is
criticism of unnamed products implied. Most of this information is historical
in nature and may no longer be applicable.
To Top
For more information relative to pesticides and their use in New York State, please contact the PMEP staff at:
| |
5123 Comstock Hall
Cornell University
Ithaca, NY 14853-0901
(607) 255-1866
|
|
 |
This site is supported, in part, by funding from the
 |
Questions regarding the development of this web site should be directed to the
PMEP Webmaster
