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Endothall (CASRN 145-73-3)

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0155

Endothall; CASRN 145-73-3

Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data, as outlined in the IRIS assessment development process. Sections I (Health Hazard Assessments for Noncarcinogenic Effects) and II (Carcinogenicity Assessment for Lifetime Exposure) present the conclusions that were reached during the assessment development process. Supporting information and explanations of the methods used to derive the values given in IRIS are provided in the guidance documents located on the IRIS website.

STATUS OF DATA FOR Endothall

File First On-Line 03/31/1987

Category (section)
Status
Last Revised
Oral RfD Assessment (I.A.) on-line 03/01/1991
Inhalation RfC Assessment (I.B.) no data
Carcinogenicity Assessment (II.) no data 09/01/1991

_I.  Chronic Health Hazard Assessments for Noncarcinogenic Effects

_I.A. Reference Dose for Chronic Oral Exposure (RfD)



Substance Name — Endothall
CASRN — 145-73-3
Last Revised — 03/01/1991

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

Increased absolute
and relative weights
of stomach small
intestine

Two-Year Feeding
Study in Dogs

Pennwalt Agchem., 1965

NOEL: 100 ppm (diet)
mg/kg bw/day)

LEL: 300 ppm (diet)
(6 mg/kg bw/day)
100
1
2E-2
mg/kg/day

*Conversion Factors and Assumptions — Dose adjusted for assumed dog food consumption (2.5% bw/day) and expressed as endothall ion.

__I.A.2. Principal and Supporting Studies (Oral RfD)

Pennwalt Agchem. 1965. MRID No. 00101735. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Three male and 3 female dogs were administered diets that initially contained 0, 100, 300 or 800 ppm of disodium endothall. The concentration in the high- dose group was gradually increased over months 19-22 to a final concentration of 2000 ppm. The doses were calculated on the basis of the amount of endothall ion in the diet, and the standard equivalence factor for dogs (0.025 kg of diet/kg of bw/day). No effect on weight gain, hematology, BSP clearance, SGOT or urinalysis was noted. At necropsy, increased absolute and relative weights of stomach and small intestine were noted in intermediate and high-dose dogs. Increased "mucosal gland activity" was noted in the stomachs of high-dose dogs, along with slight edema of the pyloric region.

__I.A.3. Uncertainty and Modifying Factors (Oral RfD)

UF — An uncertainty factor of 100 was used to account for inter- and intraspecies differences.

MF — None

__I.A.4. Additional Studies/Comments (Oral RfD)

Data Considered for Establishing the RfD:

1) Two-Year Feeding - dog: Principal study - see previous description; no core grade

2) 3-Generation Reproduction - rat: NOEL=100 ppm (5 mg/kg/day); LEL=2500 ppm (125 mg/kg/day) [weight loss, kidney and adrenal discoloration, F2B pup mortality (dose discontinued)]; core grade minimum (Pennwalt Corp., 1965)

3) 2-Year Feeding (oncogenic) - rat: Systemic NOEL=2500 ppm (125 mg/kg/day) (HDT); no core grade (only 10 animals/sex were used) (Pennwalt Corp., 1977)

4) Teratology with postnatal phase - rat: Maternal NOEL=10 mg/kg/day; Maternal LEL=20 mg/kg/day (death); Fetotoxic NOEL=10\mg/kg/day; Fetotoxic LEL=40 mg/kg/day (increased number of skeletal variations); core grade minimum (Pennwalt Corp., 1982)

5) Teratology - mouse: Teratogenic NOEL=20 mg/kg/day; Teratogenic LEL= 40 mg/kg/day (HDT) (skeletal malformations noted at HDT with maternal toxicity); Maternal NOEL=5 mg/kg/day; Maternal LEL=20\mg/kg/day (death); Fetotoxic NOEL=20 mg/kg/day; Fetotoxic LEL=40\mg/kg/day (skeletal anomalies); core grade minimum (Pennwalt Corp., 1981)

6) 6-Week Feeding - dog: NOEL=10 mg/kg/day; LEL=20\mg/kg/day (100% mortality at this dose level and higher; congested and edematous stomachs with occasional erosion and hemorrhage); no core grade (Pennwalt Corp., 1953)

Data Gap(s): Chronic Rat Feeding Study (repeat study in progress)

__I.A.5. Confidence in the Oral RfD

Study — Medium
Database — Medium
RfD — Medium

The critical study appears to be of fair quality and is given a medium confidence rating. The database is generally supportive but since there is a data gap existing for endothall, the database is also given a medium confidence rating. Medium confidence in the RfD follows.

__I.A.6. EPA Documentation and Review of the Oral RfD

Pesticide Registration Files

Agency Work Group Review — 04/22/1986, 11/25/1986

Verification Date — 11/25/1986

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 Endothall conducted in September 2002 identified one or more significant new studies. IRIS users may request the references for those studies from 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).

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_I.B. Reference Concentration for Chronic Inhalation Exposure (RfC)

Substance Name — Endothall
CASRN — 145-73-3

Not available at this time.

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_II.  Carcinogenicity Assessment for Lifetime Exposure

Substance Name — Endothall
CASRN — 145-73-3

Not available at this time.

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_III.  [reserved]
_IV.  [reserved]
_V.  [reserved]


_VI.  Bibliography

Substance Name — Endothall
CASRN — 145-73-3
Last Revised — 07/01/1992

_VI.A. Oral RfD References

Pennwalt Agchem. 1965. MRID No. 00101735. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Pennwalt Corporation. 1953. MRID No. 00040962. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Pennwalt Corporation. 1965. MRID No. 00084610. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Pennwalt Corporation. 1977. MRID No. 00084609. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Pennwalt Corporation. 1981. MRID No. 00073371, 00085940. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Pennwalt Corporation. 1982. MRID No. 00118952. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

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_VI.B. Inhalation RfC References

None

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_VI.C. Carcinogenicity Assessment References

None

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_VII.  Revision History

Substance Name — Endothall
CASRN — 145-73-3

Date
Section
Description
03/01/1991 I.A.4. Citations added
03/01/1991 VI. Bibliography on-line
09/01/1991 II. Carcinogenicity assessment now under review
01/01/1992 IV. Regulatory Action section on-line
07/01/1992 III.A. Health Advisory on-line
07/01/1992 VI.D. Health Advisory references on-line
08/01/1992 III.A.5. Text clarified
08/01/1995 II. EPA's RfD/RfC and CRAVE workgroups were discontinued in May, 1995. Chemical substance reviews that were not completed by September 1995 were taken out of IRIS review. The IRIS Pilot Program replaced the workgroup functions beginning in September, 1995.
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.

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_VIII.  Synonyms

Substance Name — Endothall
CASRN — 145-73-3
Last Revised — 03/31/1987

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