Tebuthiuron (CASRN 34014-18-1)
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0264
Tebuthiuron;
CASRN 34014-18-1
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 Tebuthiuron
File First On-Line 09/30/1987
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 07/01/1992 |
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 — Tebuthiuron
CASRN — 34014-18-1
Last Revised — 07/01/1992
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 |
---|---|---|---|---|
Depressed body weight 2-Generation Rat Elanco Products, 1981 |
NOEL: 100 ppm LEL: 200 ppm |
100
|
1
|
7E-2
mg/kg/day |
*Conversion Factors -- none
__I.A.2. Principal and Supporting Studies (Oral RfD)
Elanco Products Company, Division of Eli Lilly and Company. 1981. MRID No. 00090108. HED Doc. No. 001459, 002160, 005822. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
Four groups of 25 Wistar rats/sex were fed 0, 100, 200, or 400 ppm (Time- weighted average: 0, 7, 14, 28 mg/kg/day) Tebuthiuron technical (98% a.i.) in the diet (Purina mash) for 101 days (F0 rats) or 121 days (F1 rats) and then for a further period sufficient to mate, deliver, and rear two successive litters of young to 21 days of age (i.e., test diet was fed throughout mating, gestation, and lactation). F1a rats were parents of the F2 offspring. No adverse effects were reported in this study except a lower body weight gain during the pre-mating period in F1 females at dietary levels of 200 and 400 ppm (14 and 28 mg/kg/day) Tebuthiuron.
__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.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
Data Considered for Establishing the RfD
1) 2-Generation Reproduction - rat: Principal study - see previous description; core grade guideline
2) 2-Year Feeding - rat: Systemic NOEL=400 ppm (20 mg/kg/day); Systemic LEL=800 ppm (40 mg/kg/day) (growth suppression); core grade supplementary (Elanco, 1976)
3) 1-Year Feeding - dog: NOEL=25 mg/kg/day; LEL=50 mg/kg/day (increased liver-to-body weight ratios; increased alkaline phosphatase in high dose animals); core grade minimum (Eli Lilly, 1985)
4) Teratology - rat: Teratogenic NOEL=1800 ppm (90 mg/kg/day) (HDT); LEL=none; no core grade (Elanco, 1972a)
5) Teratology - rabbit: Teratogenic NOEL=25 mg/kg/day (HDT) (on gestation days 5 thru 18); LEL=none; core grade minimum (Elanco, 1975)
Other Data Reviewed:
1) 90-Day Feeding - rat: Systemic NOEL=1000 ppm (50 mg/kg/day); Systemic LEL=2500 ppm (125 mg/kg/day) (growth supression, pancreatic lesions); core grade minimum (Elanco, 1972b)
2) 90-Day Feeding - dog: Systemic NOEL=500 ppm (12.5 mg/kg/day); Systemic LEL=100 ppm (2.5 mg/kg/day) (increased relative thyroid and spleen weights); no core grade (Elanco, 1972c)
Data Gap(s): Chronic Rat Feeding Study
__I.A.5. Confidence in the Oral RfD
Study — High
Database — High
RfD — High
The critical study is of good quality and is given a high confidence rating. The supporting database is also of good quality; therefore, it is given a high confidence rating. High confidence in the RfD follows.
__I.A.6. EPA Documentation and Review of the Oral RfD
Pesticide Registration Files
Agency Work Group Review — 05/30/1986, 04/15/1987, 06/22/1988
Verification Date — 06/22/1988
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 Tebuthiuron conducted in September 2002 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 — Tebuthiuron
CASRN — 34014-18-1
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Tebuthiuron
CASRN — 34014-18-1
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 — Tebuthiuron
CASRN — 34014-18-1
Last Revised — 07/01/1992
_VI.A. Oral RfD References
Elanco Products Company, Division of Eli Lilly and Company. 1981. MRID No. 00090108. HED Doc. No. 001459, 002160, 005822. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
Elanco Products Company, Division of Eli Lilly and Company. 1976. MRID No. 00020714. HED Doc. No. 000344, 005822, 007374. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
Eli Lilly and Company. 1985. MRID No. 00146801. HED Doc. No. 005822. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
Elanco Products Company, Division of Eli Lilly and Company. 1972a. MRID No. 00020803. HED Doc. No. 000344, 000347, 005822, 006857. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
Elanco Products Company, Division of Eli Lilly and Company. 1975. MRID No. 00020644, 40485801. HED Doc. No. 000344, 007527, 007598. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
Elanco Products Company, Division of Eli Lilly and Company. 1972b. MRID No. 00020662. HED Doc. No. 000344, 000347, 005822. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
Elanco Products Company, Division of Eli Lilly and Company. 1972c. MRID No. 00020663. HED Doc. No. 000344, 000347, 005822. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
_VI.B. Inhalation RfD References
None
_VI.C. Carcinogenicity Assessment References
None
_VII. Revision History
Substance Name — Tebuthiuron
CASRN — 34014-18-1
Date |
Section |
Description |
---|---|---|
08/22/1988 | I.A.1. | NOEL corrected; RfD changed |
08/22/1988 | I.A.2. | Text changed to reflect corrected dose levels |
01/01/1992 | IV. | Regulatory Action section on-line |
07/01/1992 | I.A.1. | Short citation clarified |
07/01/1992 | I.A.2. | Principal study clarified |
07/01/1992 | I.A.4. | Citations added |
07/01/1992 | VI.A. | Oral RfD references on-line |
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 — Tebuthiuron
CASRN — 34014-18-1
Last Revised — 09/30/1987
- 34014-18-1
- EL 103
- Graslan
- Perflan
- SPIKE
- Spike 80W
- Tebuthiuron
- Urea, N-(5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl)-N,N'-dimethyl-
- Urea, 1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3-dimethyl-