Cyromazine (CASRN 66215-27-8)
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0220
Cyromazine;
CASRN 66215-27-8
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 Cyromazine
File First On-Line 09/30/1987
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 05/01/1991 |
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 — Cyromazine
CASRN — 66215-27-8
Last Revised — 05/01/1991
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 |
---|---|---|---|---|
Hematologic effects 6-Month Dog Study Ciba-Geigy, 1980 |
NOEL: 30 ppm diet LEL: 300 ppm diet |
100
|
1
|
7.5E-3
mg/kg/day |
*Conversion Factors: 1 ppm = 0.025 mg/kg/day (assumed dog food consumption)
__I.A.2. Principal and Supporting Studies (Oral RfD)
Ciba-Geigy Corp. 1980. MRID No. 00103193. Available from EPA. Write to FOI,
EPA, Washington, DC 20460.
Cyromazine was administered to 56 beagle dogs (7/sex/group) at 0, 30, 300, and
3000 ppm for 6 months. Pronounced effects on the hematocrit and hemoglobin
levels were noted at 300 and 3000 ppm. The systemic NOEL was established at
30 ppm (0.75 mg/kg/day).
__I.A.3. Uncertainty and Modifying Factors (Oral RfD)
UF — An uncertainty factor of 100 was used to account for the inter- and
intraspecies differences. An additional UF to account for the subchronic
values of the study was not considered necessary since the 90-day and 2-year
rat studies show that the differences between subchronic and chronic
toxicities are insignificant. Likewise, an additional UF to account for a
deficient database was not considered necessary since other studies generally
showed higher NOELs and thus the toxicologic endpoint in the 6-month dog study
is the most sensitive indicator of the toxicity of cyromazine.
MF — None
__I.A.4. Additional Comments (Oral RfD)
Data Considered for Establishing the RfD:
1) 6-Month Feeding - dog: Principal study - see previous description; core
grade minimum
2) 90-Day Feeding - rat: NOEL=30 ppm (1.5 mg/kg/day); LEL=300 ppm (15
mg/kg/day) (relative liver weight decrease for males); core grade minimum
(Ciba-Geigy, 1979a)
3) 2-Year Chronic (oncogenic) - rat: Systemic NOEL=30 ppm (1.5 mg/kg/day);
Systemic LEL=300 ppm (15 mg/kg/day)(decreased body weight); core grade minimum
(Ciba-Geigy, 1981a)
4) Teratology - rabbit: Teratogenic NOEL=5 mg/kg/day; Teratogenic LEL=10
mg/kg/day (findings of cyclopia and diaphragmatic hernia); Maternal NOEL=10
mg/kg/day; Maternal LEL=30 mg/kg/day (body weight gain depression and food
consumption reduction); core grade minimum (Ciba-Geigy, 1981b)
5) Teratology - rat: Developmental toxicity NOEL=none; LEL=l00 mg/kg/day
(LDT; increased skeletal variations); Maternal NOEL=100 mg/kg/day; Maternal
LEL=300 mg/kg/day (increased incidences of clinical observations; decreased
body weights); core grade minimum (Ciba-Geigy, 1979b)
6) 2-Generation Reproduction - rat: Reproductive NOEL=l000 ppm (50
mg/kg/day); Reproductive LEL=3000 ppm (150 mg/kg/day) (decreased pup weights
and increased pup moritality); Systemic NOEL=30 ppm (1.5 mg/kg/day); Systemic
LEL=1000 ppm (50 mg/kg/day) (body weight loss); core grade minimum (Ciba-
Geigy, 1981c)
Data Gap(s): None
__I.A.5. Confidence in the Oral RfD
Study — High
Database — High
RfD — High
The study on which the RfD is based is of high quality and of sufficient duration for the species tested (dog). Confidence in this study is high. In addition, there are generally good toxicology studies available (chronic rat and mouse studies) with cyromazine, which overall provide high confidence in the database. High confidence in the RfD follows.
__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 — Pesticide Registration Files
Agency Work Group Review — 08/5/86
Verification Date — 08/5/86
Screening-Level Literature Review Findings — A screening-level review conducted by an EPA contractor of the more recent toxicology literature pertinent to the RfD for Cyromazine conducted in November 2001 did not identify any critical new studies. IRIS users who know of important new studies may provide that information to the IRIS Hotline at hotline.iris@epa.gov or (202)566-1676.
__I.A.7. EPA Contacts (Oral RfD)
Please contact the IRIS Hotline for all questions concerning this assessment or IRIS, in general, at (202)566-1676 (phone), (202)566-1749 (FAX) or hotline.iris@epa.gov (internet address).
_I.B. Reference Concentration for Chronic Inhalation Exposure (RfC)
Substance Name — Cyromazine
CASRN — 66215-27-8
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Cyromazine
CASRN — 66215-27-8
This substance/agent has not undergone a complete evaluation and determination
under US EPA's IRIS program for evidence of human carcinogenic potential.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_VI. Bibliography
Substance Name — Cyromazine
CASRN — 66215-27-8
Last Revised — 01/01/1990
_VI.A. Oral RfD References
Ciba-Geigy Corporation. 1979a. MRID No. 00135433. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1979b. MRID No. 00027488. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1980. MRID No. 00103193. Available from EPA. Write
to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1981a. MRID No. 00103202. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1981b. MRID No. 00103196. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1981c. MRID No. 00103197. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
_VI.B. Inhalation RfD References
None
_VI.C. Carcinogenicity Assessment References
None
_VII. Revision History
Substance Name — Cyromazine
CASRN — 66215-27-8
Date |
Section |
Description |
---|---|---|
01/01/1990 | VI. | Bibliography on-line |
05/01/1991 | I.A.4. | 'Note' deleted |
04/01/1997 | III., IV., V. | Drinking Water Health Advisories, EPA Regulatory Actions, and Supplementary Data were removed from IRIS on or before April 1997. IRIS users were directed to the appropriate EPA Program Offices for this information. |
12/03/2002 | I.A.6. | Screening-Level Literature Review Findings message has been added. |
_VIII. Synonyms
Substance Name — Cyromazine
CASRN — 66215-27-8
Last Revised — 09/30/1987
- 66215-27-8
- AI3-52713 [USDA]
- Azimethiphos
- Caswell No. 167B
- CGA 72,662
- 2-cyclopropylamino-4,6-diamino-s-triazine
- Cyromazine
- Cyromazine [ANSI]
- 2,4-Diamino-6-(cyclopropylamino)-s-triazine
- EPA Pesticide Chemical Code 121301
- Larvadex
- Propanoic acid, 2-(4-((5-(trifluoromethyl)-2-pyridinyl)oxy)phenoxy)-,butyl ester
- 1,3,5-Triazine-2,4,6-triamine, N-cyclopropyl-
- Trigard
- Vetrazin