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Chlorobenzilate (CASRN 510-15-6)

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Chlorobenzilate; CASRN 510-15-6

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 Chlorobenzilate

File First On-Line 12/01/1989

Category (section)
Last Revised
Oral RfD Assessment (I.A.) on-line 12/01/1989
Inhalation RfC Assessment (I.B.) no data 03/01/1993
Carcinogenicity Assessment (II.) no data  

_I.  Chronic Health Hazard Assessments for Noncarcinogenic Effects

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

Substance Name — Chlorobenzilate
CASRN — 510-15-6
Last Revised — 12/01/1989

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*

Decreased stool
quantity, food
consumption and body
weight gains;

Rabbit Teratology

Ciba-Geigy Corp., 1984a

NOEL: 5 mg/kg/day

LEL: 20 mg/kg/day


*Conversion Factors: Actual dose tested

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

Ciba-Geigy Corporation. 1984a. MRID No. 00144691. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Three groups of pregnant New Zealand White rabbits (19/group) were treated with technical grade chlorobenzilate as a starch suspension containing Tween 80 at doses of 5, 20, or 80 mg chlorobenzilate/kg bw/day by gastric intubation on days 7 through 19 of gestation. The control group was intubated with an equivalent volume of 3% corn starch-Tween 80 suspension on the same days. The does were observed daily and were weighed on days 0, 7, 14, 19, 21, 25, and 29 of gestation. Feed consumption was measured daily from the time of insemination until necropsy.

On gestation day 29 the does and their fetuses were evaluated for maternal and developmental toxicity effects. No developmental effects were reported at any level [NOEL=80 mg/kg/day (HDT)]; although there was an increase in the incidence of "fused sternebrae" in the high-dose level fetuses. The maternal toxicity LEL was determined to be 20 mg/kg/day based on significantly decreased feed consumption, decreased stools, decreased body weight gains, and hyperirritability. The maternal NOEL is therefore 5 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 of 3 was used to account for the lack of an acceptable chronic oral toxcity study in a second species.

MF — None

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

Data Considered for Establishing the RfD

1) Teratology - rabbit: Principal study - see previous description; core grade minimum

2) 2-Year Feeding - dog: NOEL=500 ppm (12.5 mg/kg/day); LEL=5000/3000 ppm (125/75 mg/kg/day) (increased alkaline phosphatase, reduced serum protein levels, inappetance, reduced body weights and moderate to severe anemia; extramedullary hematopoiesis of the liver and spleen and erythroid hyperplasia of the bone marrow); After week 20 the 5000 ppm dose level was reduced to 3000 ppm; core grade minimum (Ciba-Geigy Corp., 1966)

3) 2-Generation Reproduction - rat: Systemic NOEL=30 mg/kg/day; Systemic LEL=100 mg/kg/day (HDT; decreased weight gain, increased liver weight, decreased spleen weight and hypoplasia of bone marrow for 8/30 F1 parent females); Reproductive NOEL=100 mg/kg/day (HDT); core grade guideline (Ciba- Geigy Corp., 1982)

4) Teratology - rat: Maternal NOEL=20 mg/kg/day; Maternal LEL=100 mg/kg/day (salivation, lethargy); Fetotoxic NOEL=100 mg/kg/day; Fetotoxic LEL=500 mg/kg/day (HDT; increased number of resorptions and post-implantation loss); Teratogenic NOEL=500 mg/kg/day (HDT); Teratogenic LEL=none; core grade minimum (Ciba-Geigy Corp., 1984b)

Data Gap(s): None

__I.A.5. Confidence in the Oral RfD

Study — Low
Database — Medium
RfD — Medium

The critical study is given a low confidence rating since the observed GI effects are somewhat equivocal. The supporting database is of good quality; thus, confidence in the database can be considered medium to high. Confidence in the RfD can also be considered medium to high.

__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 Standard, March 1989; Pesticide Registration Files

Agency Work Group Review — 05/20/1985, 05/17/1989

Verification Date — 05/17/1989

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 Chlorobenzilate conducted in August 2003 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).

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

Substance Name — Chlorobenzilate
CASRN — 510-15-6

Not available at this time.

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_II.  Carcinogenicity Assessment for Lifetime Exposure

Substance Name — Chlorobenzilate
CASRN — 510-15-6

Not available at this time.

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

_VI.  Bibliography

Substance Name — Chlorobenzilate
CASRN — 510-15-6
Last Revised — 12/01/1989

_VI.A. Oral RfD References

Ciba-Geigy Corporation. 1966. MRID No. 00077463. Available from EPA. Write to FOI, EPA, Washington DC 20460.

Ciba-Geigy Corporation. 1982. MRID No. 00130783. Available from EPA. Write to FOI, EPA, Washington DC 20460.

Ciba-Geigy Corporation. 1984a. MRID No. 00144691. Available from EPA. Write to FOI, EPA, Washington DC 20460.

Ciba-Geigy Corporation. 1984b. MRID No. 00145908. Available from EPA. Write to FOI, EPA, Washington DC 20460.

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_VI.B. Inhalation RfC References


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_VI.C. Carcinogenicity Assessment References


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_VII.  Revision History

Substance Name — Chlorobenzilate
CASRN — 510-15-6

12/01/1989 I.A. Oral RfD summary on-line
12/01/1989 VI. Bibliography on-line
01/01/1992 IV. Regulatory Action section on-line
03/01/1993 I.B. Inhalation RfC now under review
08/01/1995 I.B. 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.
10/28/2003 I.A.6. Screening-Level Literature Review Findings message has been added.

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_VIII.  Synonyms

Substance Name — Chlorobenzilate
CASRN — 510-15-6
Last Revised — 12/01/1989

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