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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
April - July, 1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP - Guideline study, tested with the source substance 8001-79-4. In accordance to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
: no ophthalmoscopy, no neurology
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Castor Oil
- Synonyms: Ricinus Oil, oil of Palma Christi, tangantangan oil, phorboyl, Neoloid
- Composition of test material, percentage of components: Triglyceride of fatty acids. Fatty acid composition is approximately 87% ricinoleic,
7% oleic, 3% linoleic, 2% palmitic, 1% stearic, and trace amounts of dihydroxystearic.
- Analytical grade: USP AA grade
- Source: Cas Chemical, Inc. (Bayonne, NJ, USA)
- Stability: The stability of the study material during the toxicology studies was monitored by determination of peroxide content and by high performance liquid chromatography. No deterioration of the castor oil study material was observed over the course of the studies.

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Simonsen Laboratories (Gilroy, CA, USA)
- Age at study initiation: 6 weeks
- Weight at study initiation: male: 126 - 132 g; female: 107- 110 g
- Housing: rats: 5 per cage
- Diet (e.g. ad libitum): Control feed (NIH 07) or diet formulations of castor oil were available ad libitum; feeders were changed twice per week throughout the study.
- Water (e.g. ad libitum): automatic watering system
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°F): 68-76°F
- Humidity (%): 42% to 72%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:
Formulated diets were prepared by blending the appropriate amount of castor oil with a small quantity of feed to prepare a premix. The premix then was layered between the required amount of feed in a twin-shell blender and blended for 15 minutes to achieve a uniform mix. The homogeneity of castor oil in feed at 10% (100 mg/g) was determined by gravimetric analysis, and blends at 0.5% (5 mg/g) were determined by HPLC analysis. These concentrations of chemical in feed were found to be homogeneously distributed by this mixing procedure. The stability of the 0.5% dose level was determined using HPLC; it was found to be stable for at least 21 days when stored in the dark at 5°C and for 3 days when stored open to air and light in a rodent cage. During the studies, formulated diets were stored for no longer than 3 weeks at 5°C; feed hoppers in the animal cages were changed twice weekly.

Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The results of the analyses for all dose mixtures given to the animals ranged from 97% to 106% of the target concentrations.
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
daily ad libitum feeding
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 0.62, 1.25, 2.50, 5.00, 10.0 % (w/w)
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
0, 404, 809, 1583, 3067 and 5835 mg/kg bw/day
Basis:
other: actual ingested: male rats
Remarks:
Doses / Concentrations:
0, 401, 797, 1569, 3045, 5725 mg/kg bw/day
Basis:
other: actual ingested: female rats
No. of animals per sex per dose:
10; 10 additional rats/sex were included at each dose level for evaluation of hematological and clinical chemistry parameters at days 5 and 21.
Control animals:
yes, plain diet
Positive control:
none

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS/ CLINICAL OBSERVATIONS: Yes
- Time schedule: twice a day

BODY WEIGHT: Yes
- Time schedule for examinations: initially and 1 x wk thereafter.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: from additional rats at days 5 and 21, and at the end of study
- Anaesthetic used for blood collection: Yes, CO2
- Animals fasted: No data
- How many animals: 10 additional animals
- Parameters checked: red blood cell (RBC) count, red blood cell morphologic assessment, hematocrit (HCT), hemoglobin concentration (HGB), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), white blood cell count (WBC), white blood cell differential count, reticulocyte count (absolute), and platelet counts (absolute).

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: from additional rats at days 5 and 21, and at the end of study
- Animals fasted: No data
- How many animals: 10 additional animals
- Parameters checked: alkaline phosphatase activity (ALP), albumin (ALB), urea nitrogen (UN), creatinine (CREA), alanine aminotransferase activity
(ALT), total bile acids (TBA), sorbitol dehydrogenase activity (SDH), total protein (TP), and creatinine kinase (CK).


URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Complete histopathology examinations were conducted on all rats from the control and 10% dose groups. Livers were examined from male rats in all other dose groups; histologic sections of gross lesions were examined from all rats. Organ weights were determined to the nearest milligram for the liver, right kidney, right testicle, heart, thymus, and lungs. All tissues were preserved in 10% neutral buffered formalin.

The following tissues were routinely processed for preparation of histologic sections and microscopic examination: adrenal
glands, brain, cecum, colon, duodenum, epididymis/seminal vesicles/prostate/testes or ovaries/uterus, esophagus, eyes (if
grossly abnormal), femur (including marrow), heart, ileum, jejunum, kidneys, liver, lungs and mainstem bronchi, mammary
gland, mandibular and mesenteric lymph nodes, nasal cavity and turbinates, pancreas, parathyroid glands, pituitary gland,
preputial or clitoral glands, rectum, salivary glands, skin, spinal cord and sciatic nerve (if neurologic signs present), spleen,
forestomach and glandular stomach, thymus, thyroid gland, trachea, urinary bladder, zymbal glands, and all gross lesions
and tissue masses including regional lymph nodes. A complete histopathologic examination was conducted on all rats from the control and 10% dose groups. Liver was examined from male rats in all other dose groups, and histologic
sections of gross lesions were examined from all rats.
Statistics:
Body weight and organ weight data were statistically analyzed within each sex by one-way Analysis of Variance tests, followed by Dunnett's t-test if pair-wise comparisons were indicated (p < 0.05)(Dunnett, 1955).

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
no adverse biologically significant effects
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
no adverse biologically significant effects
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
no adverse biologically significant effects
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY
No effects

BODY WEIGHT AND WEIGHT GAIN
Group mean body weights of rats receiving diets containing castor oil did not differ significantly from controls. Mean body weights of exposed female rats were slightly lower than the mean body weights of controls but the differences were not dose-related.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
No significant differences in average food consumption among each sex were observed, although food consumption of male and female rats receiving diets containing 10% castor oil was slightly lower than that of controls.

HAEMATOLOGY
Hematological effects of the castor oil diets among male rats included a slight decrease in MCHC at day 21 in those receiving the 10% diet; a statistically significant decrease in MCV among the 10% group; a decrease in MCH among the 5% and 10% groups; and an increase in platelets among the 1.25%, 5%, and 10% groups. The only change observed among female rats was a statistically significant decrease in reticulocyte counts at day 5 in groups receiving the 0.62% or 10% diets. None of these changes was considered biologically significant.

CLINICAL CHEMISTRY
A treatment- and dose-related increase in the activity of serum alkaline phosphatase was observed in male and female rats at days 5 and 21, and at study termination. Total bile acids were increased among males receiving the higher dietary levels at days 5 and 21 but were not increased at study termination. Other minor changes included increases in albumin observed at study termination in males receiving 5% diets and at day 5 in females receiving 10% diets, and an increase in urea nitrogen at study termination in males that received 0.62% diets and a decrease at day 5 in females that received castor oil at 10% in the diet.

ORGAN WEIGHTS
Absolute liver weights and the liver-to-body-weight ratio were increased in male rats that received diets containing 10% castor oil. Heart-to-body-weight ratios were increased in groups of male rats receiving 0.62%, 2.5%, and 10% diets; however, absolute heart weights were not increased, and the differences in body weight ratios were small and not considered treatment related. Using light microscopy, it was determined there were no morphologic changes associated with the slight differences in organ weights between groups.

In male rats, there was a slight decrease in epididymal weight (6-7%) which occurred in the middle- and high-dose groups, but this was not dose-related. There were no effects on any other male rat reproductive endpoint, or on any female rat reproductive endpoint. Although there was some variation in epididymal weights, their small magnitude and the absence of changes in other endpoints suggested that there was little or no evidence of any reproductive toxicity associated with castor oil exposure (Appendix A). Histopathologic examination revealed an absence of compound-related lesions in any organ or tissue of rats exposed to castor oil in the diet.

Effect levels

Dose descriptor:
NOAEL
Effect level:
ca. 5 000 mg/kg bw/day (actual dose received)
Based on:
other: calculated test material intake based on food consumption and body weight
Sex:
male/female
Basis for effect level:
other: rats; no effects observed based on clinical signs; mortality; body weight; food consumption; haematology; clinical chemistry; gross pathology; organ weights; histopathology;

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
After 90 days oral feeding a NOAEL of 5000 mg/kg bw/day could be identified.
Executive summary:

Castor oil is a natural oil derived from the seeds of the castor bean, Ricinus communis. It is comprised largely of triglycerides with a high ricinolin content. Toxicity studies with castor oil were performed by incorporating the material at concentrations as high as 10% in diets given to F344/N rats of both sexes for 13 weeks.

Exposure to castor oil at dietary concentrations as high as 10% in 13-week studies did not affect survival or body weight gains of rats (10 per sex and dose). There were no biologically significant effects noted in hematologic analyses in rats. Mild increases in total bile acids and in serum alkaline phosphatase were noted at various times during the studies in rats receiving the higher dietary concentrations of castor oil. Liver weights were increased in male rats receiving the 10% dietary concentration of castor oil. However, there were no histopathologic lesions associated with these liver changes, nor were there any compound-related morphologic changes in any organ. No significant changes were noted in a screening for male reproductive endpoints, including sperm count and motility, and no changes were observed in the length of estrous cycles. Thus, no adverse effects of castor oil administration were noted in these studies.