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Zinc phosphide
CASRN 1314-84-7
Contents
0203
Zinc phosphide; CASRN 1314-84-7
Health assessment information on a chemical substance is included in IRIS only
after a comprehensive review of chronic toxicity data by U.S. EPA health
scientists from several Program Offices and the Office of Research and
Development. The summaries presented in Sections I and II represent a
consensus reached in the review process. Background information and
explanations of the methods used to derive the values given in IRIS are
provided in the Background Documents.
STATUS OF DATA FOR Zinc phosphide
File On-Line 03/31/1987
Category (section) Status Last Revised
----------------------------------------- -------- ------------
Oral RfD Assessment (I.A.) on-line 01/01/1990
Inhalation RfC Assessment (I.B.) no data
Carcinogenicity Assessment (II.) no data
_I. CHRONIC HEALTH HAZARD ASSESSMENTS FOR NONCARCINOGENIC EFFECTS
__I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
Substance Name -- Zinc phosphide
CASRN -- 1314-84-7
Last Revised -- 01/01/1990
The oral Reference Dose (RfD) is based on the assumption that thresholds exist
for certain toxic effects such as cellular necrosis. It is expressed in units
of mg/kg-day. In general, the RfD is an estimate (with uncertainty spanning
perhaps an order of magnitude) of a daily exposure to the human population
(including sensitive subgroups) that is likely to be without an appreciable
risk of deleterious effects during a lifetime. Please refer to the Background
Document for an elaboration of these concepts. RfDs can also be derived for
the noncarcinogenic health effects of substances that are also carcinogens.
Therefore, it is essential to refer to other sources of information concerning
the carcinogenicity of this substance. If the U.S. EPA has evaluated this
substance for potential human carcinogenicity, a summary of that evaluation
will be contained in Section II of this file.
___I.A.1. ORAL RfD SUMMARY
Critical Effect Experimental Doses* UF MF RfD
-------------------- ----------------------- ----- --- ---------
Reduction of food NOAEL: none 10,000 1 3E-4
intake and body mg/kg/day
weight LOAEL: 50 ppm diet
(3.48 mg/kg/day)
Rat Subchronic Oral
Study
Bai et al., 1980
*Dose Conversion Factors & Assumptions: Dose conversion based on authors'
estimated intake of 317 mg/kg bw/day divided by 91 days.
___I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
Bai, K.M., M.K. Krishnakumari, H.P. Ramesh, T. Shivanandappa and S.K.
Majunder. 1980. Short-term toxicity study of zinc phosphide in albino rats.
Indian J. Exptl. Biol. 18: 854-857.
The only available subchronic oral study with zinc phosphide was the 13-week
study by Bai et al. (1980). In this study, groups of 12 female weanling rats
were fed diets containing 0, 50, 100, 200 and 500 ppm zinc phosphide. Data
from this study include several clinical, biochemical and histopathological
parameters. In rats dosed at 200 or 500 ppm, there was approximately 8 and
83% mortality. Food intake and body weight significantly decreased in all
exposed rats, indicating a dose-response susceptibility to zinc phosphide
toxicity. Histopathological lesions accompanied with increased liver, kidney
and brain weights were only observed in rats exposed with 200 or 500 ppm of
zinc phosphide. Although histopathological or hematological examinations
revealed no deleterious effects in 50 or 100 ppm dosed groups, body hair loss
was extensive in all exposed rats, except that the hair growth returned to
normal within a few weeks after week 6 in rats exposed to 50 ppm zinc
phosphide. Bai et al. (1980), therefore, concluded that zinc phosphide at the
50 ppm level was less toxic to the albino rats. Because of significant dose-
response trends in decreased food intake and body weights, the 50 ppm dose of
zinc phosphide or 3.48 mg/kg/day (based on authors' estimated intake of 317
mg/kg bw during 91 days) is considered a LOAEL. By applying an uncertainty
factor of 10,000 to this dose, an RfD of 0.0003 mg/kg/day or 24 ug/day for a
70-kg person is derived.
___I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
UF -- An uncertainty factor of 10,000 was applied; 10 for interspecies
extrapolation, 10 for providing added protection to unusually sensitive
individuals, 10 for expanding subchronic to chronic exposure, and 10 for the
lack of a NOAEL.
MF -- None
___I.A.4. ADDITIONAL COMMENTS (ORAL RfD)
Zinc phosphide is a rodenticide (Worthing, 1983) that is insoluble in water,
but reacts with HCL and sulfuric acid with the evolution of spontaneously
flammable phosphine (Windholz, 1983). The toxicity of ingested zinc phosphide
is due to the formation of phosphine gas in the acid environment of the
stomach (U.S. EPA, 1983; Bai et al., 1980). Chronic data for phosphine do not
suggest a lower RfD for zinc phosphide. An RfD of 0.0003 mg/kg/day can be
derived for zinc phosphide based on analogy to phosphine (assuming the release
of two equivalents of phosphine for each molecule of zinc phosphide in stomach
acid). Information on the toxicity of phosphine can be found in the IRIS file
for phosphine.
___I.A.5. CONFIDENCE IN THE ORAL RfD
Study -- Medium
Data Base -- Low
RfD -- Low
The referenced study was well-designed and incorporated several biological and
biochemical endpoints, however, only females were tested; thus, the study was
given a medium level of confidence. The data base did not provide supportive
chronic studies and was given a low confidence rating. The RfD was assigned a
low level of confidence because of the poor data base and lack of a NOAEL.
___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
Source Document -- This assessment is not presented in any existing U.S. EPA
document.
Other EPA Documentation -- U.S. EPA, 1983
Agency Work Group Review -- 02/26/1986, 05/14/1986
Verification Date -- 05/14/1986
___I.A.7. EPA CONTACTS (ORAL RfD)
Please contact the Risk Information Hotline for all questions concerning this
assessment or IRIS, in general, at (513)569-7254 (phone), (513)569-7159 (FAX)
or RIH.IRIS@EPAMAIL.EPA.GOV (internet address).
__I.B. REFERENCE CONCENTRATION FOR CHRONIC INHALATION EXPOSURE (RfC)
Substance Name -- Zinc phosphide
CASRN -- 1314-84-7
Not available at this time.
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE
Substance Name -- Zinc phosphide
CASRN -- 1314-84-7
This substance/agent has not undergone a complete evaluation and determination
under US EPA's IRIS program for evidence of human carcinogenic potential.
_VI. BIBLIOGRAPHY
Substance Name -- Zinc phosphide
CASRN -- 1314-84-7
Last Revised -- 01/01/1990
__VI.A. ORAL RfD REFERENCES
Bai, K.M., M.K. Krishnakumari, H.P. Ramesh, T. Shivanandappa and S.K.
Majunder. 1980. Short-term toxicity study of zinc phosphide in albino rats.
Ind. J. Exptl. Biol. 18: 854-857.
U.S. EPA. 1983. Reportable Quantity for Zinc Phosphide. Prepared by the
Office of Health and Environmental Assessment, Environmental Criteria and
Assessment Office, Cincinnati, OH for the Office of Solid Waste and Emergency
Response, Washington, DC.
Windholz, M. 1983. The Merck Index. Merck and Company, Inc., Rahway, NJ.
Worthing, C.R. 1983. The Pesticide Manual, 7th ed. British Crop Protection
Council. p. 563.
__VI.B. INHALATION RfD REFERENCES
None
__VI.C. CARCINOGENICITY ASSESSMENT REFERENCES
None
_VII. REVISION HISTORY
Substance Name -- Zinc phosphide
CASRN -- 1314-84-7
-------- -------- --------------------------------------------------------
Date Section Description
-------- -------- --------------------------------------------------------
03/01/1988 I.A.1. Dose conversion clarified
06/30/1988 I.A.6. Work Group review date added
06/30/1988 I.A.6. Verification date revised
01/01/1990 I.A.4. Corrected Colman, 1983 citation to U.S. EPA, 1983
01/01/1992 I.A.7. Primary contact changed
01/01/1992 IV. Regulatory actions updated
VIII. SYNONYMS
Substance Name -- Zinc phosphide
CASRN -- 1314-84-7
Last Revised -- 03/31/1987
1314-84-7
BLUE-OX
KILRAT
MOUS-CON
PHOSPHURE DE ZINC
PHOSVIN
RCRA WASTE NUMBER P122
RUMETAN
UN 1714
ZINCO(FOSFURO DI)
Zinc phosphide
ZINC(PHOSPHURE DE)
ZINC-TOX
ZINKFOSFIDE
ZINKPHOSPHID
ZP
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0203.HTM
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