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Administrative data

Endpoint:
short-term repeated dose toxicity: dermal
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
Version / remarks:
May 1981
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 870.3200 (Repeated Dose Dermal Toxicity -21/28 Days)
Version / remarks:
August 1998
Deviations:
not specified
GLP compliance:
yes (incl. QA statement)
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
2-{2-chloro-4-(methylsulfonyl)-3-[(tetrahydrofuran-2-ylmethoxy)methyl]benzoyl}cyclohexane-1,3-dione
Cas Number:
473278-76-1
Molecular formula:
C20 H23 Cl O7 S
IUPAC Name:
2-{2-chloro-4-(methylsulfonyl)-3-[(tetrahydrofuran-2-ylmethoxy)methyl]benzoyl}cyclohexane-1,3-dione

Test animals

Species:
rat
Strain:
Wistar
Remarks:
Crl:WI
Details on species / strain selection:
The Wistar rats are one of the standard species and strain used on dermal toxicity studies.
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Germany
- Females (if applicable) nulliparous and non-pregnant: not specified
- Age at study initiation: approximately 8 weeks
- Weight at study initiation: males: 340 - 377 g; females: 204 - 255 g
- Fasting period before study: no
- Housing: 5 animals of the same group per cage
- Diet: ad libitum (ssniff® SM R/M “Autoclavable Complete diet for Rats and Mice – Breeding and Maintenance”)
- Water: ad libitum (tap water)
- Acclimation period: 19 - 20 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.7 - 24.1
- Humidity (%): 31 - 68
- Air changes (per hr): 15 - 20
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Type of coverage:
semiocclusive
Vehicle:
unchanged (no vehicle)
Remarks:
moistened with sterile water
Details on exposure:
TEST SITE
- Area of exposure: area starting approximately at the scapulae (shoulders) to the wing of the ileum (hipbone) and half way down the flank
- % coverage: not less than 10%
- Type of wrap if used: During the exposure period, the test substance was held in contact with the skin with a porous gauze dressing (less than or equal to 8 ply). The test site was further covered with non-irritating tape to retain the gauze dressing and the test substance and to ensure that the animals cannot ingest the test substance.
- Time intervals for shavings or clipplings: approximately 24 hours before the test and repeated as required and as practical depending upon hair growth of indiviual animals and/or effects observed.

REMOVAL OF TEST SUBSTANCE
- Washing: The test substance was gently wiped from the skin with lukewarm water after the 6-hour exposure period, to prevent ingestion.
- Time after start of exposure: 6 h

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 10, 100, 1000 mg/kg bw/day
- For solids, paste formed: yes (the test substance was moistened sufficiently with water (no more than 300 μL))


USE OF RESTRAINERS FOR PREVENTING INGESTION: yes
Analytical verification of doses or concentrations:
no
Remarks:
- No dose formulation preparation or analysis was performed during the study, as the test item powder was applied to the rat skin as provided by the Sponsor, without using any vehicle (only moistened with water).
Duration of treatment / exposure:
28 days
Frequency of treatment:
daily for 6 hours, 7 days per week
Doses / concentrationsopen allclose all
Dose / conc.:
10 mg/kg bw/day (actual dose received)
Dose / conc.:
100 mg/kg bw/day (actual dose received)
Dose / conc.:
1 000 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
10
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale: The dose levels were selected by the Sponsor in consultation with the Study Director at 10, 100 and 1000 mg/kg bw/day, based on the absence of toxicity signs following the acute rat dermal study with tefuryltrione (no deaths and no findings up to a limit dose of 2000 mg/kg/day).

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily (at the beginning and end of each day)
- Cage side observations: morbidity, mortality

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once before the first exposure (to allow for within-subject comparisons) on Day 0 and once weekly thereafter

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

BODY WEIGHT: Yes
- Time schedule for examinations: Day 0, and at least weekly during treatment period, including before necropsy on day 28 (fasted)

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Dose groups that were examined: all (pre-treatment), groups 1 (control) and 4 (high dose) on Day 27 - as no item related findings were noted, no examination was performed for groups 2 and 3.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Day 28
- Anaesthetic used for blood collection: Yes (pentobarbital)
- Animals fasted: Yes (overnight)
- How many animals: all
- Parameters examined: RBC (Red Blood Cell (erythrocyte)), Hgb (Haemoglobin concentration), Hct (Haematocrit), MCV (Mean Corpuscular (erythrocyte) Volume), MCH (Mean Corpuscular (erythrocyte) Haemoglobin), MCHC (Mean Corpuscular (erythrocyte) Haemoglobin Concentration), RDW (Red Cell (erythrocyte) volume), Plt (Platelet (thrombocyte) count), MPV (Mean Platelet (thrombocyte) volume), RETIC (Reticulocyte count), WBC (White Blood Cell (leukocyte) count), neutrophils, lymphocytes, monocytes, basophil, eosinophil, large unstained cells, APTT (Activated Partial Thromboplastin Time), PT (Prothrombin Time)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Day 28
- Animals fasted: Yes (overnight)
- How many animals: all
- Parameters examined: gucose, total bilirubin concentration, urea concentration, cholesterol concentration, triglycerides, creatinine concentration, phosphorus concentration, sodium concentration, potassium concentration, calcium concentration, chloride concentration, total protein concentration, albumin concentration, albumin/globulin ratio, aspartate aminotransferase activity, alanine aminotransferse activity, alkaline phosphatase activity, gamma glutamyltransferase activity, bile acids

URINALYSIS: Yes
- Time schedule for collection of urine: Day 28
- Metabolism cages used for collection of urine: Yes
- Animals fasted: Yes (overnight)
- Parameters examined: leukocytes, nitrite, pH, protein, glucose, urobilinogen, bilirubin, ketones, blood/erythrocytes, specific gravitiy, sediment, volume

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Day 27
- Dose groups that were examined: all
- Battery of functions tested: grip strength, landing foot splay and fore/hind grip strength, sensory reactivity (e.g. auditory, visual and proprioceptive), modified Irwin test including body position, locomotor activity, respiration rate, respiration type, piloerection, head searching compulsive biting or licking, circling, upright walking, retropulsion, jumping, exophthalmos, twitches, clonic convulsions, tonic convulsions, tremor, startle, transfer arousal, spatial locomotion, gait, posture, limb position, finger approach, finger withdrawal, touch escape response, diarrhoea, diuresis, visual placing, grip strength, body tone, corneal reflex, pinna, toe pinch, grasping reflex, positional struggle, skin, mucous membrane colour, salivation, palpebral closure, lachrymation, limb tone, abdominal tone, tail pinch, righting reflex, and/or vocalisation

OTHER: Prior to necropsy, the oestrous cycle of all females was determined by taking vaginal smears.
Sacrifice and pathology:
GROSS PATHOLOGY: Yes: After exsanguination the external appearance was examined, cranium, thoracic and abdominal cavities were opened and the appearance of the tissues and organs were observed macroscopically.

HISTOPATHOLOGY: Yes: Gross findings, Larynx, Skeletal muscle (quadriceps), Treated skin area, Liver, Skin and subcutis (inguinal), Adrenals, Lungs with bronchi, Small intestine, lymph nodes, Spinal cord, Aorta, Mammary gland (inguinal), Spleen, Brain, Nose/nasal cavity, Sternum with marrow, Epididymides, Ovaries with oviduct, Stomach, Eyes with the optic nerves, Pharynx, Testes, External lachrymal glands, Pancreas, Thymus, Oesophagus, Pituitary, Thyroid with parathyroids, Femur with marrow, Prostate, Tongue, Harderian glands, Salivary glands,
Trachea, Heart, Sciatic nerve, Urinary bladder, Kidneys, Seminal vesicles with coagulating glands, Uterus, Large intestine, Vagina

ORGAN WEIGHTS: Brain, Prostate including seminal vesicles with coagulating glands, Adrenals, Epididymides, Ovaries, Heart, Pituitary, Kidneys, Testes, Thyroids with parathyroids, Liver, Thymus, Spleen, Uterus including cervix

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Description (incidence and severity):
Occasionally slight skin lesions (scab and scar) were observed with similar low incidence across the groups in males (1/10, 1/10, 2/10 and 1/10) and females (2/10, 2/10, 1/10 and 0/10) in the control, low, mid and high dose groups, respectively. Red discharge from eye was observed across the groups in males (3/10, 2/10, 4/10 and 0/10) in the control, low, mid and high dose groups, respectively. Thin fur was seen in one female in Mid dose group. These observations were ascribed to minor effects of friction with the restraint and not related to the test item.
Dermal irritation:
no effects observed
Description (incidence and severity):
At investigation of local effects on the treatment area, no test item related changes were observed on skin. No signs of irritation were noted.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
No adverse effects considered toxicologically significant were noted on the mean body weight and body weight gain values following daily administration of the test item at dose levels up to and including 1000 mg/kg bw/day, during the treatment period.
In Mid dose males and Low dose female, slightly lower than control body weight gain were noted, sometimes attaining statistical significance.
Based on the isolated incidence and lack of a consistent dose or gender response, these variations were regarded as incidental and without toxicological significance.
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:
no effects observed
Haematological findings:
effects observed, non-treatment-related
Description (incidence and severity):
There were no test item related adverse effects at any dose level, all parameters falling with the normal physiological and historical control ranges for the age, strain and sex of rats on test.
Variations, attaining statistical significance were noted in males in higher Mean Platelet Volume (MPV) in Mid and High dose groups (p<0.01). Significant lower levels (p<0.05 and/or 0.01) were noted for Reticulocytes, relative (Retic%) in Low and Mid dose males and for Red Cell Distribution With (RDW) in Mid dose males.
In Low and Mid dose females significantly higher (p<0.05) Red Blood Count (RBC), Haemoglobin concentration (HGB) and Heamatocrit (HCT) level were noted. Significantly higher (p<0.01) Prothrombin time (PTT) and Activated Partial Thromboplastin time (APTT) values were noted in high dose females and in Low dose females, respectively.
Based on the isolated incidence, lack of a consistent dose or gender response and that all values were in the normal historic control range, these variations were regarded as incidental and without toxicological significance.
Clinical biochemistry findings:
effects observed, non-treatment-related
Description (incidence and severity):
Albumin (Alb.) concentration was slightly higher than Control in all male dose groups and the differences reached statistical significance (p<0.01). Consequently, Total protein (Tot.Prot) and the Albumin to Globulin ratio (A/G) were also higher, reaching statistical significance (p<0.05 or p<0.01). However, there were no histopathological or other changes associated with these differences at any dose level and females do not show any changes these effects are considered to be non-adverse. As all values in the 10 mg/kg/day group were within the normal historical control range, these changes were considered to be non-adverse at this dose level.
A few other clinical chemistry parameters showed on occasion statistically significant variations, however, there was no dose or gender response and the values were within the physiological ranges. For this reason, these variations were considered not to be toxicologically significant or related to treatment.
Urinalysis findings:
effects observed, non-treatment-related
Description (incidence and severity):
No effects were noted, which could be related to the test item.
Slight differences were recorded in urine pH and specific gravity in High dose group of males and females, respectively, reaching statistical significance (p<0.01 and p<0.05, respectively). There were no statistical differences in urine volume from the control.
The degree of change seen was not sufficient to suggest a toxic effect of test item on urine parameters. In males High dose animals there were higher kidney weights and some evidence of mild histopathological changes so the small urine changes in male High dose animals may be treatment related.
Urine sediment analysis showed similar results to control in all test item treated groups.
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
There were no toxicologically significant changes in the animal behaviour, general physical condition, in the reactions to different type of stimuli, grip strength or motor activity in the control or treated groups, at the evaluation performed on Day 27.
Increased vocalization was observed on occasion throughout all the dose groups of males and control, low and high dose females at the modified Irwin test (functional observation battery). However, there were no treatment-related differences compared to the Control group, as the incidence was similar in all groups and no dose, or gender related response were noted, and these variations were considered to be without toxicological significance and within the normal biological variation with respect to behaviour, reactions to different type of stimuli or manipulations.
Slightly increased respiration rate, startle and decreased righting reflex were observed occasionally without relationship to treatment and were in the normal range for all groups, these were considered to be without any toxicologically significance.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, non-treatment-related
Description (incidence and severity):
In High dose males, slightly higher liver weights (~10%) were measured, reaching statistical significance when adjusted for Body weight (p<0.01) and brain weight (p<0.05). There was a slightly higher liver weight in the Mid dose males, but as the absolute weight was only 1.6% above control, the statistical difference is considered not to reflect a test item-related effect.
In High dose males, slightly higher kidney weights (~10%) were measured, reaching statistical significance when adjusted for Body weight (p<0.01) and brain weight (p<0.05). There was a slightly higher kidney weight in the Low and Mid dose males, but as the values were all in the normal control range and there was no indication from histopathology of any changes, the statistical difference is considered not to reflect a test item-related effect.
There were no biologically significant differences among groups in the weights of other organs measured, related to body weight or brain (compared to control), although statistically significant variations without trend were noted (i.e brain, prostate, testes, epididymis, thymus, spleen). In the absence of a dose, or gender response, or a consistent correlation with histopathological results, these variations were not considered to reflect an adverse effect.
Gross pathological findings:
effects observed, non-treatment-related
Description (incidence and severity):
Incidental gross observations:
Small bilateral adrenal gland was observed in 1/10 Low dose males. In 1/10 High dose male animals, a single firm nodule was seen in right medial lobe in the liver. Small left seminal vesicle with coagulating gland was seen in 1/10 High dose males.
Single clear cyst was observed in 1/10 Control females in the ovary and oviduct and in 1/10 High dose females in the ovary bilateral single dark red focus was observed. Dilatation was observed in the uterine body and horn in 1/10 Control and 1/10 High dose females.
These findings were regarded as incidental, terminal procedure-related or reflected the physiological changes observed during the oestrous cycle in the females.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Test item-related microscopic findings were noted in the liver, kidneys and pancreas at a dose level of 1000 mg/kg bw/day. Following additional examinations, it was found that the pancreas was also altered at a dose level of 100 mg/kg bw/day.
The lesions in the liver were observed only in males. The renal changes were mostly present in the male gender with the exception of one female discussed below. The microscopic findings in the liver and kidneys were in correlation with organ weight changes in the males. While the pancreas, was proportionally altered in both sexes.
Liver (considered as adaptive response)
Minimal hepatocellular centrilobular hypertrophy was observed in 3/10 High dose males. This change was characterized by enlargement of hepatocytes with granular eosinophilic cytoplasm. No test item-related changes were noted during additional histopathological examination of males from the Mid dose group.
Kidneys
Various test item-related changes were noted in the kidneys including increased eosinophilic droplets, proteinaceous casts, tubular degeneration and pelvic dilatation.
Minimal or mild bilateral increased presence of eosinophilic droplets in the cortical tubules when compared to the Control males, was recorded in 2/10 High dose males. Although eosinophilic droplets are frequently observed in renal tubular epithelium as a common background observation in male rats, there was clear evidence of increase in both size and number of droplets in treated males. Minimal proteinaceous casts, homogeneous, eosinophilic in colour, present in the expanded lumen of tubules of the cortex/corticomedullary regions were seen in 5/10 males and 1/10 females from the High dose groups. Casts were accompanied with minimal tubular degeneration in one of these males. Also, there was increased incidence of minimal unilateral tubular basophilia (3/10) and mild unilateral/bilateral dilatation of renal pelvis (3/10) in High dose males. In Mid dose animals, there was no evidence of lesions associated with administration of the test item in the females. Minimal focal tubular proteinaceous cast at the corticomedullary area of the right kidney was only observed in 1/10 male but this observation was not accompanied with any degenerative change, therefore was considered to be within the normal range, representing a background feature rather than test item effect.
Pancreas
Minimal to moderate increase of zymogen granules of the exocrine acini when compared to untreated controls was microscopically manifested. Affected animals included 2/10 males and 2/10 females from the High dose groups. The greater severity (moderate) was seen in one female. Minimal to moderate acinar necrosis accompanied with mixed cellular inflammatory response in 1/10 High dose males and 2/10 High dose females were also recorded. Moderate degree of necrosis was only seen in one female.
There was a decrease of severity in acinar necrosis or increased zymogen granules from moderate to minimal/mild in the Mid dose groups, moderate degree was not observed. Minimal to mild necrosis was seen in 2/10 males and 2/10 females. Minimal to mild increase of zymogen granules was present in 2/10 males and 3/10 females. Minimal to mild mixed cellular inflammation was noted in 2/10 Mid dose females.
No test item-related findings were microscopically observed at a dose level of 10 mg/kg bw/day.
Histopathological findings: neoplastic:
no effects observed
Other effects:
no effects observed
Description (incidence and severity):
There were no test item related changes in the animal oestrous cycle evaluated prior to necropsy and the animals showed the normal distribution of the oestrous phases.

Effect levels

Key result
Dose descriptor:
NOAEL
Effect level:
10 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
histopathology: non-neoplastic
organ weights and organ / body weight ratios

Target system / organ toxicity

Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
100 mg/kg bw/day (actual dose received)
System:
endocrine system
Organ:
pancreas
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
not specified

Any other information on results incl. tables

Table 1: Mean Total Proten, Albumin and Albumin/Globulin ratio on Day 28 with Historical control data

Males

Dose group (mg/kg bw/day)

 

control

10

100

1000

Total protein (g/L)

Mean

56.66

58.37

61.55**

62.46**

Historical control range

Min-Max. (mean)

49.60 – 63.90 (56.02)

Albumin (g/L)

Mean

29.99

31.91**

33.72**

34.45**

Historical control range

Min-Max. (mean)

26.50 – 35.40 (29.96)

Albumin/Globulin ration

Mean

1.12

1.21*

1.23**

1.24**

Historical control range

Min-Max. (mean)

0.90 – 1.40 (1.16)

* = p<0.05, ** = p< 0.01 (Duncan’s Multiple Range test)

Table 2: Mean liver weights on Day 28

 

Dose groups (mg/kg bw/day)

 

control

10

100

1000

Males

Absolute (g)

13.75

13.68

13.97

14.88

differences in %

-0.5

1.6

8.2

Body weight relative (%)

3.10

3.20

3.31*

3.39**

differences in %

3.2

6.8

9.4

Brain relative(%)

642

622

659

710*

differences in %

-3.0

2.6

10.6

Females

Absolute (g)

7.70

7.59

7.32

7.48

differences in %

-1.4

-5.0

-2.9

Body weight relative (%)

3.10

3.23

3.08

3.15

differences in %

4.2

-0.6

1.6

Brain relative(%)

384

389

370

382

differences in %

-1.3

-3.6

-0.5

* = p<0.05, ** = p< 0.01 (Duncan’s Multiple Range test)

Table 3: Mean kidney weights on Day 28

 

Dose groups (mg/kg bw/day)

 

control

10

100

1000

Males

Absolute (g)

3.07

3.16

3.26

3.34

differences in %

2.9

6.2

8.8

Body weight relative (%)

0.69

0.74*

0.77**

0.76**

differences in %

7.2

11.6

10.1

Brain relative(%)

143

144

154

159*

differences in %

0.7

7.7

11.2

Females

Absolute (g)

1.80

1.74

1.75

1.78

differences in %

-3.3

-2.8

-1.1

Body weight relative (%)

0.73

0.74

0.74

0.75

differences in %

1.4

1.4

2.7

Brain relative(%)

90

89

88

91

differences in %

-1.1

-2.2

1.1

* = p<0.05, ** = p< 0.01 (Duncan’s Multiple Range test)

Applicant's summary and conclusion