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Toxicological information

Repeated dose toxicity: dermal

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Administrative data

Endpoint:
sub-chronic toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Acute and subchronic repeated cutaneous application of N-methyl diethanolamine in the Fischer 344 rat.
Author:
Werley, M.S. et al.
Year:
1997
Bibliographic source:
J. Toxicol. Cut. Ocular Toxicol., 16, 157-171

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
2,2'-methyliminodiethanol
EC Number:
203-312-7
EC Name:
2,2'-methyliminodiethanol
Cas Number:
105-59-9
Molecular formula:
C5H13NO2
IUPAC Name:
2,2'-(methylimino)diethanol

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Inc., Kingston, NY
- Age at study initiation: 8 weeks
- Housing: stainless steel wire mesh cages
- Diet: Ground Purina Certified Rodent Chow #5002 (Ralston Purina Co., St. Louis, MO) and ground L26 Diet (PMI Feeds, Inc.), ad libitum
- Water: tap water, ad libitum
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature: 66-77°F
- Humidity (%): 40-70
- Photoperiod: 12 hrs dark / 12 hrs light

Administration / exposure

Type of coverage:
occlusive
Vehicle:
water
Details on exposure:
TEST SITE
- Area of exposure: 2 x 2 inch
- Type of wrap if used: 12-ply NuGauze pad
- Time intervals for shavings or clipplings: A week before the first dose, prior to the first dose, and thereafter as necessary

REMOVAL OF TEST SUBSTANCE
- Washing (if done): the application site was wiped with a damp cloth and then blotted dry.
- Time after start of exposure: 6 h
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
6 hours/day; 5 days/week (total of 65 doses)
Doses / concentrationsopen allclose all
Dose / conc.:
100 mg/kg bw/day (nominal)
Dose / conc.:
250 mg/kg bw/day (nominal)
Dose / conc.:
750 mg/kg bw/day (nominal)
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
Post-exposure period: 4 weeks

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Inspection for clinical signs of toxic and/or pharmacologic effects was done daily.

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: daily

BODY WEIGHT: Yes
- Time schedule for examinations: before the first dose and weekly during the treatment and recovery period

FOOD CONSUMPTION: over weekly intervals

WATER CONSUMPTION: Yes
- Time schedule for examinations: over weekly intervals

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the study
- Anaesthetic used for blood collection: No data
- Animals fasted: No
- How many animals: 10/gender/dose
- Parameters examined: hemoglobin concentration, erythrocyte count, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), total and differential leukocyte, platelet, and reticulocyte counts.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the study
- Animals fasted: yes
- How many animals: 10/gender/dose
- Parameters examined: urea nitrogen, creatinine, bilirubin (total, conjugated, and unconjugated), calcium, sodium, potassium, chloride, phosphorus, aspartate and alanine aminotransferases, creatine kinase, creatinine, creatinine clearance, a2u-globulin, and N-acetyl-ß-glucosaminidase, lactate dehydrogenase, y-glutamyl transferase, sorbitol dehydrogenase, alkaline phosphatase, and protein electrophoresis.

URINALYSIS: Yes
- Time schedule for collection of urine:
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No
- Parameters examined: total volume, color, microscopy, pH, osmolality, protein, glucose, ketones, bilirubin, urobilinogen, and blood.

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes. A complete necropsy was performed, and the following organs weighed: liver, kidneys, brain, heart, adrenal glands, spleen, ovaries, and testes.

HISTOPATHOLOGY: Yes. A large number of tissues and organs, including skin of the dosing area.
Statistics:
Data for quantitative continuous variables were intercompared for treatment versus control groups by Levene's test, for equality of variances, analysis of variance, and t-tests.

Results and discussion

Results of examinations

Dermal irritation:
effects observed, treatment-related
Description (incidence and severity):
There were no signs indicating any systemic effect. Neither erythema nor edema was seen at any time in the mid- and low-dose groups, and no edema in the high-dose group. Erythema in the high-dose group, slight in severity, was seen at a few very limited time periods. More prominent effects seen for longer periods were desquamation, excoriation, ulceration, necrosis, and eschar. The incidence and severity of these findings were dosage-related. Low-dose findings were minimal.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
There were no significant differences in absolute body weights over the study. There were no significant effects on female body weight gain. Decreases in body weight gain of males were small, transient, and variable, and generally limited to the first 7 weeks of the study.
Food consumption and compound intake (if feeding study):
effects observed, non-treatment-related
Description (incidence and severity):
No treatment related differences in food consumption were evident for either gender.
Water consumption and compound intake (if drinking water study):
effects observed, non-treatment-related
Description (incidence and severity):
No treatment related differences in water consumption were evident for either gender.
Haematological findings:
no effects observed
Description (incidence and severity):
There were no differences from the controls with respect to hematologic results.
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
There were no differences from the controls with respect to clinical chemistry results.
Urinalysis findings:
no effects observed
Description (incidence and severity):
There were no differences from the controls with respect to urinalysis results.
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
There were no differences from the controls with respect to urinalysis results.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
Findings were limited to the area of treated skin in the MDEA animals. The most common lesions were acanthosis, hyperkeratosis, and parakeratosis. These features were most noticeable in the mid-dose females and high-dose males and females. Also present were minimal to marked dermal fibrosis, eschar, ulceration, and dermatitis. The lesions were dose-related and females were possibly more sensitive. Any lesions in the low-dose group were comparable to those of the controls, and probably a consequence of the wrapping procedure and scratching by the animals.

Effect levels

open allclose all
Key result
Dose descriptor:
NOAEL
Remarks:
local
Effect level:
100 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: dose-related irritation in the mid and high dose groups; major histopathological features were acanthosis, hyperkeratosis, parakeratosis, dermatitis, dermal fibrosis, eschar, and ulceration
Remarks on result:
other: corresponding to 0.8 mg/cm2)
Key result
Dose descriptor:
NOAEL
Remarks:
systemic
Effect level:
750 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: no systemic effects were reported

Target system / organ toxicity

Key result
Critical effects observed:
no

Applicant's summary and conclusion