kresoxim-methyl (ISO);methyl (E)-2-methoxyimino-[2-(o-tolyloxymethyl)phenyl]acetate

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

other information

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPP 82-2 (Repeated Dose Dermal Toxicity -21/28 Days)

GLP compliance:

yes

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

methyl (2E)-2-methoxyimino-2-[2-[(2-methylphenoxy)methyl]phenyl]acetate

EC Number:

604-351-6

Cas Number:

143390-89-0

Molecular formula:

C18 H19 N O4

IUPAC Name:

methyl (2E)-2-methoxyimino-2-[2-[(2-methylphenoxy)methyl]phenyl]acetate

Details on test material:

- Name of test material (as cited in study report): Reg. No. 242 009 (test substance number: 91/180-2; Lab-internal abbreviation: STUR)
- Lot/batch No.: N 36 (III C1); date of manufaturing: 1991-10-23
- Storage condition of test material: room temperature, exclusion of light
- Physical state: solid (powder) / light brown
- Analytical purity: 94.3% (Reversed-Phase - HPLC with UV-Detection)
- Stability under test conditions: the storage stability was guaranteed over the study period
- Other: the homogeneity of the test substance was confirmed by analysis (Reversed-Phase - HPLC with UV-Detection)

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: CHBB: Thom (SPF); from Dr. K. Thomae GmbH, D-W7950 Biberach, FRG
- Age at study initiation: 8 - 10 weeks
- Weight at study initiation: 266 (244 - 275) g for males and 228 (220 - 237) g for females
- Fasting period before study: none specified
- Housing: singly in stainless steel wire mesh cages, Type DK-III (Becker & Co., Castrop-Rauxel, FRG; floor area about aoo cm2)
- Diet (e.g. ad libitum): ground Kliba maintenance diet rat/mouse/hamster, 343 meal, supplied by Klingentalmuhle AG; CH-4303 Kaiseraugst, Switzerland
- Water (e.g. ad libitum): drinking water
- Acclimation period: 9 days

ENVIRONMENTAL CONDITIONS
The animals were housed in fully air-conditioned rooms. There were no deviations from these ranges which influenced the results of the study.
- Temperature (°C): 20 - 24
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light): 12/12 (6:00 - 18:00 / 18:00 - 6:00 hours)

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

other: 0.5% solution of Tylose CB 30.000 (cleaned natrium carboxymethylcellulose from Hoechst AG) in aqua bidest.

Details on exposure:

TEST SITE
- Area of exposure: clipped intact dorsal skin (dorsal and dorsolateral parts of the trunk)
- % coverage: at least 10% of the body surface
- Type of wrap if used: semiocclusive dressing (4 layers of absorbent gauze and an elastic dressing)
- Time intervals for shavings or clippings: the adaptation period was followed by the daily application of the test solution to the animals for at least 6 hours. Immediately before application the fur was clipped when considered necessary and at least once a week. Only the first clipping was carried out at least 24 hours before the first application.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): yes; on removal of the dressing the application area was washed with lukewarm water.
- Time after start of exposure: after 6 hours as indicated above

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2 ml/kg; test substance was applied in a dose of 1000 mg/kg body weight by means of a 1 ml-syringe
- Concentration (if solution): 50 g/100 ml suspension in 0.5% solution of Tylose CB 30.000
- Constant volume or concentration used: yes

VEHICLE
See above

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability of the test substance in 0.5% aqueous CMC-preparation over 24 hours was confirmed by analysis (Reversed Phase - HPLC with UV-Detection) with another batch. The test substance preparation was made up daily immediately before application. For this purpose, the test substance was weighed and filled the vehicle and subsequently mixed using an Ultra-Turrax. The suspension was kept homogeneously during the applications by means of a magnetic stirrer. The mean concentrations were found to be in the range of 93.3 - 94.6% of the nominal contents for the 50 g/100 ml samples.

Duration of treatment / exposure:

21 dermal applications to the intact skin over a period of 3 weeks

Frequency of treatment:

daily; at the end of the application period, all animals were sacrificed after a fasting period (withdrawal of food of at least 16 hours).

Doses / concentrations

Remarks:

Doses / Concentrations:
0 and 1000 mg/kg per day
Basis:
nominal per unit body weight

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based upon the hitherto gained results (see acute oral toxicity, acute dermal irritation/corrosivity, acute irritation to the eye and 3 months feeding studies) for the test substance where no special toxic effects have been observed the dose 1000 mg/kg body weight was chosen. It was assumed that at this dose level when applied daily to the skin, there would be no influence on the parameters to be examined.

Positive control:

none

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes

DETAILED CLINICAL OBSERVATIONS AND SKIN FINDINGS: Yes
- Time schedule: A check for general observations was made twice a day. The animals were carefully inspected twice daily (before and after exposition).

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: A check was made twice a day for any dead or moribund animals. A check for any skin findings was carried out daily about 30 minutes after removal of the dressing.

BODY WEIGHT: Yes
- Time schedule for examinations: all animals were weighed once every week. The body weights were determined each time on the same day of week (exception: last weighing).

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes; during the application period, the food consumption was determined once a week for a period of 7 days (exception: last week: 6 days)

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: day 21
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals: all
- Parameters examined: hematological examinations (leukocytes, erythrocytes, hemoglobin, haematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelets) and clotting analyses (prothrombin time)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day 21
- Animals fasted: Yes
- How many animals: all
- Parameters examined: enzymes (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, serum-y-glutamyltransferase) and blood chemistry (sodium, potassium, chloride, inorganic phosphate, calcium, urea, creatinine, glucose, total bilirubin, total protein, albumin, globulins, triglycerides, cholesterol and magnesium)

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes; at the end of the study and after 16 - 20 hours fasting period, the animals were sacrificed by decapitation under C02 anesthesia. The exsanguinated animals were necropsied and assessed by gross pathology. The weight of the anesthetized animals as well as the weight of liver, kidneys, adrenal glands and testes from all animals sacrificed was determined.
HISTOPATHOLOGY: Yes; subsequently to the gross-pathological examinations, the following organs or tissues were fixed in 4% formaldehyde solution: treated skin, normal skin (from other site than treated skin) liver, kidneys, adrenal glands, testes and all gross lesions. After the organs have been fixed, processing, the examination by light microscopy and the evaluation of findings was performed.

Other examinations:

none

Statistics:

(1) Clinical examinations: mean and standard deviation were calculated for the variables feed consumption, body weight and test substance intake for each group and tabulated together with the individual values for feed consumption and body weight. The statistical significance of the clinical data (body weight) was checked using the KRUSKAL-WALLIS test and the MANN-WHITNEY U-test. (2) Clinical chemistry and hematology: mean and standard deviation were calculated for each test group and tabulated together with the individual values. Except for the differential blood count, a statistic one-way analysis of variance is done via the KRUSKAL-WALLIS test. If the resulting p-value is equal or less than 0.05 a pairwise comparison of each dose group with the control group was carried out. This comparison is done using the MANN-WHITNEY U-test for the hypotheses of equal medians. (3) Pathology: mean and standard deviation were calculated for the statistical evaluation of the study for the variables of body weight and of absolute and relative organ weights (related to body weight) of the animals in each test group and tabulated together with the individual values (absolute and relative organ weights). A non-parametric one-way analysis of variance was done via the KRUSKAL-WALLIS-h test. If the resulting p-value is less than 0.05 a pairwise comparison of each dose group with the control group was carried out. This comparison was performed using the WILCOXON-Test for the hypothesis of equal medians.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Dermal irritation:

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:

no effects observed

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
No clinical signs of toxicity were observed in the test animals of both sexes. There were no deaths during the study period.

BODY WEIGHT AND WEIGHT GAIN
Body weight gain in test animals was comparable with that seen in the controls with the exception of 1 female animal of the test group (same animal with reduced food consumption; see below) which showed a transient reduced body weight.

FOOD CONSUMPTION
The food consumption rates did not appear to be affected by the treatment with the test article, with the exception of 1 female animal of the test group which showed transient reduced food consumption.

HAEMATOLOGY
No substance-related changes were observed in the results of the hematology examinations and of the clotting analyses of both sexes.

CLINICAL CHEMISTRY
No substance-related changes were observed in the results of the serum enzyme and blood chemistry examinations of both sexes.


ORGAN WEIGHTS
No significant absolute/relative weight deviations were noted.

GROSS PATHOLOGY
The only gross lesions noted was a red focus of 1 mm in diameter in the left adrenal gland of a test substance-treated female rat.

HISTOPATHOLOGY: NON-NEOPLASTIC
- The only finding noted in the treated skin of a male rat of group 1 was a sub-macroscopic, very small, superficial crust in the outer layer of the cornified epithelium. No inflammatory reaction was present underneath. Although focal crust formation was only noted microscopically in the treated skin of a treated male rat, its minuteness suggests that it was of no toxicologic significance. This is supported by the absence of any inflammatory reaction underneath the very small crust and by an otherwise unaltered architecture of the treated skin area. Moreover, its development may also be a remnant of a minimal shearing lesion or the consequence of a fortuitous scratching lesion.

- In treated male rats only, the number and the graded severity of peripheral fatty infiltration of the hepatocytes was slightly lower than in the concurrent control group. This does not represent a toxicologic alteration but are the expression of the normal variation of physiologic fat deposition in the liver parenchyma. No such difference was noted in female rats.

- Focal calcification (intratubular and interstitial) was noted in the kidneys of all treated and control female rats at comparable grades of severity. Also, only in treated and untreated female rats, minimal interstitial nephritis was encountered with the same incidences (each two rats). These and other microscopic findings noted are not related to the dermal application of the test article as their distribution over treated and control animals was comparable as well concerning their incidence as with respect to their graded severities.

- No correlate could be found in the adrenal gland of the female rat (see above, gross pathology) that may refer to the grossly reported "red focus"; this observation is, therefore also regarded to be fortuitously and not relatable to the application of the test article. It seems likely that its origin was a dilated blood vessel.


HISTOPATHOLOGY: NEOPLASTIC (if applicable)
No indication of neoplastic effects

OTHER FINDINGS
No signs of irritation on the treated skin could be observed in test or control animals. Adhesive fleece caused mechanical skin lesions beside the treated area

Effect levels

Dose descriptor:

NOAEL

Effect level:

ca. 1 000 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: see below

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

The dermal application of the test article in a concentration of 1000 mg per kilogram body weight over a period of 3 weeks to male and female rats resulted in the following observations (dose group:1000 mg/kg body weight):

- in the clinical examinations no substance-induced changes could be observed in all animals;

- the hematology and clinical chemistry examinations revealed no changes which are related to the test compound administered;

- no significantly different mean absolute or relative weight parameters and no treatment-related gross lesions or microscopic findings;

- a microscopically small and singly occurring focus of crust formation in the cornifying layer of the treated skin in one male rat was regarded to be most likely of spontaneous origin rather than treatment related;

- the slightly lower number of treated male rats showing periphero-acinar fat deposition in the liver cells as well as the less pronounced grade of severity of this observation was interpreted not to be a toxicologic phenomenon but to be the expression of the biological range of physiologic fat accumulation.