3-(methylthio)propionaldehyde

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

acute 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

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

adopted 09 Oct 2017

Deviations:

yes

Remarks:

occlusive dressing, no stepwise dosing

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: clipped dorsal trunk
- Type of wrap if used: The test material was applied to the test site and the exposed skin was covered with gauze and impervious sheeting. The materials were held in place using an elastic bandage around the trunk.

Duration of exposure:

24 h

Doses:

0.25, 0.5, 1.0 mL/kg bw (males), corresponding to 259, 518 and 1036 mg/kg bw and 0.5, 1.0 mL/kg bw (females), corresponding to 518 and 1036 mg/kg bw

No. of animals per sex per dose:

4

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: during exposure and daily thereafter
- Frequency of weighing: before dosing, at 7 and 14 days post dosing
- Necropsy of survivors performed: yes

Sex:

male

Dose descriptor:

LD50

Effect level:

736 mg/kg bw

Based on:

test mat.

95% CL:

446 - 1 191

Remarks on result:

other: dosel levels in mg/kg bw calculated with a density of 1036 mg/mL

Sex:

female

Dose descriptor:

LD50

Effect level:

818 mg/kg bw

Based on:

test mat.

95% CL:

508 - 1 347

Remarks on result:

other: dosel levels in mg/kg bw calculated with a density of 1036 mg/mL

Mortality:

0.25 mL/kg bw (corresponding to 259 mg/kg bw): 1/4 males died on Day 9.
0.5 mL/kg bw (corresponding to 518 mg/kg bw): no mortality occurred.
1.0 mL/kg bw (corresponding to 1036 mg/kg bw): 4/4 males and 3/4 females died (males: death within 3 h - 5 days; females: death within 1 day).

Clinical signs:

Local signs: Marked erythema, edema and necrosis in all animals of all dose groups, which persisted 14 days. Desquamation and fissuring were seen at 7 days in females at 1 mL/kg bw (1036 mg/kg bw).
Clinical signs: Salivation, sluggishness, and unsteady gait. Survivors recovered from these effects by 2 days.

Body weight:

Body weight gain was unaffected by treatment.

Gross pathology:

The main necropsy finding was light to dark red mottling of the lungs. Sacrificed survivors had no gross pathological changes observed.

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

CLP: Acute Dermal 3, H311 according to Regulation (EC) No. 1272/2008

Cross-reference 2

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted 17 Jul 1992

Deviations:

yes

Remarks:

no challenge control, limited information on materials and methods

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Covance, Inc., Denver, Pennsylvania, USA
- Age at study initiation: 5-7 weeks
- Housing: individually in suspended, stainless steel cages with wire mesh bottoms
- Diet: Certified Guinea Pig Diet No. 5026 (PMI Nutrition International, St. Louis, Missouri), ad libitum
- Water: tap water, ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 16-25
- Humidity (%): 20-62
- Photoperiod (hrs dark / hrs light): 12/12

Route:

intradermal and epicutaneous

Vehicle:

propylene glycol

Concentration / amount:

intradermal induction on Day 1: 5% in propylene glycol
epicutaneous induction on Day 7: 0.2 mL unchanged

Day(s)/duration:

intradermal induction: single treatment on Day 0; epicutaneous induction: 24 h exposure on Day 6

Adequacy of induction:

other: concentration chosen based on the results of a preliminary range-finding study in which 100% produced a score of 0.5 in 2/6 animals

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

unchanged (no vehicle)

Concentration / amount:

0.1 mL

Day(s)/duration:

Day 21, 48 h

Adequacy of challenge:

other: concentration chosen based on the results of a preliminary range-finding study in which 100% produced a score of 0.5 in 2/6 animals

No.:

#2

Route:

epicutaneous, occlusive

Vehicle:

propylene glycol

Concentration / amount:

25%

Day(s)/duration:

Day 21, 48 h

Adequacy of challenge:

other: The concentration was chosen due to excess irritation in the control group after the first challenge.

No. of animals per dose:

20 (10 male and 10 female)

Details on study design:

RANGE FINDING TESTS:
Induction and maximum non irritant concentration for challenge was determined in a pre-test: 5% MTPA in propylene glycol administered intradermally produced local necrosis. 25% topical application produced no irritation, and up to 100% only produced a score of 0.5 in 2 of 6 animals.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneous, respectively)
- Exposure period: single injection (intradermal) and 24 h (epicutaneous)
Intradermal (3 pairs of injections):
Injection 1: 50% complete Freund's adjuvant (FCA) in distilled water
Injection 2: 5% test substance in propylene glycol
Injection 3: 5% test substance in 50% aqueous FCA
Epicutaneous: 7 days after the injections, 0.2 mL of undiluted test substance were applied on a 2 x 4 inch patch of filter paper and applied to the reclipped areas which had received the intradermal injections. The patches were covered by impermable plastic and secured with an elastic adhesive bandage wound around the animals torso. After 48 h occluded contact the skin was wiped free of excess test material with gauze soaked in 0.9% saline.
- Control group: Not included in the study.


B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day of challenge: 2 weeks after epidermal induction (Day 20)
- Exposure period: 24 h
- Test groups: test substance
- Control group: Not included in the study.
- Concentrations: 0.1 mL undiluted test item
- Evaluation (hr after challenge): 24 and 48 h

Challenge controls:

No challenge control group was included.

Positive control substance(s):

yes

Remarks:

a-hexylcinnamaldehyde

Positive control results:

Two positive control groups were included. Both groups were induced intradermally with 50% FCA in distilled water, 30% a-hexylcinnamaldehyde (HCA) in propylene glycol, and 30% HCA in 50% aqueous FCA. Epicutaneous induction was with a 48 h occluded contact with undiluted HCA. Animals were challenged with both 50% HCA in propylene glycol and undiluted HCA. Challenge with undiluted HCA induced a skin sensitisation of a score of 1 or greater in 40% of the animals. The severity indices were 0.6 (24 h) and 0.35 (48 h). Challenge with 50% HCA induced a positive response in 90% of the animals with severity indices of 1.1 (24 h) and 0.9 (48 h).

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

induction: 5% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 100% epicutaneous induction

No. with + reactions:

3

Total no. in group:

19

Remarks on result:

other: 1/10 females died on Day 10

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

induction: 5% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 100% epicutaneous induction

No. with + reactions:

5

Total no. in group:

19

Remarks on result:

other: 1/10 females died on Day 10

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

induction with vehicle, untreated during challenge

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: 4/10 animals gave a result of score 1. In view of this, a score of 2 or greater was used as basis for a positive response.

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

induction: 30% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 100% epicutaneous induction

No. with + reactions:

1

Total no. in group:

10

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

induction: 30% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 100% epicutaneous induction

No. with + reactions:

0

Total no. in group:

10

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

induction: 5% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 25% epicutaneous induction

No. with + reactions:

2

Total no. in group:

19

Remarks on result:

other: re-challenge, 1st reading

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

induction: 5% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 25% epicutaneous induction

No. with + reactions:

4

Total no. in group:

19

Remarks on result:

other: re-challenge, 2nd reading

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

induction: 30% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 50% epicutaneous induction

No. with + reactions:

2

Total no. in group:

10

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

induction: 30% intradermal and 0.2 mL unchanged epicutaneous induction, challenge with 50% epicutaneous induction

No. with + reactions:

0

Total no. in group:

10

Results of pilot study:
Intradermal injections of 5% MTPA produced local
necrosis and the concentration was considered adequate for
the main study. Topical application of 25% produced no
local irritation and 50, 70, 100% produced a score of
0.5 in 2 or 3 of 6 animals. Therefore undiluted MTPA was used for the
main study epicutaneous induction and challenge.

Table 1: Results of main study - Incidences of skin responses at challenge and in irritation control animals

Compound	Group	No. of animals	Time	Erythema Score					Edema	Necrosis
				0	0.5	1	2	3
Test item, 100%	Challenge	19	24	14	1	1	0	3	5	3
		19	48	8	5	1	0	5	11	4
Test item, 25%	Re-challenge	19	24	12	4	0	0	2	3	0
		19	48	3	8	3	0	4	13	2
Test item, 100%	Irritation	10	24	8	0	0	0	2	2	2
		10	48	6	2	0	0	0	4	1
Test item, 25%	Irritation	10	24	5	5	0	0	0	3	0
		10	48	1	5	4	0	0	6	0
HCA, 100%	Challenge	10	24	2	4	3	1	0	2	0
		10	48	5	3	2	0	0	0	0
HCA, 100%	Irritation	10	24	8	2	0	0	0	0	0
		10	48	10	0	0	0	0	0	0
HCA, 50%	Challenge	10	24	0	2	6	2	0	1	0
		10	48	0	2	8	0	0	0	0
HCA, 50%	Irritation	10	24	4	5	1	0	0	0	0
		10	48	6	4	0	0	0	0	0

HCA: a-hexylcinnamaldehyde
One female of the MTPA sensitization group died on day 10 of the study.
The irritation reaction was unexpectedly high compared to the  pre-study.

In summary, based on the scores of 2 or greater with epicutaneous challenge at 25% the test item  produced sensitization in 22% of the guinea pigs; therefore,this material was classified as a "mild sensitizer" based on the Magnusson and 

Kligman allergenicity rating criteria.

Interpretation of results:

study cannot be used for classification

Conclusions:

Based on the experimental findings, the test item causes erythema, edema and necrosis to the skin. However, due to the highly skin irritating properties, a distinct conclusion on skin sensitising effects cannot be drawn. Therefore the skin sensitisation study test result is considered to be inconclusive due to irritating effects of the test item to the skin.

Cross-reference 3

Reason / purpose for cross-reference:

reference to same study

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

adopted 28 Jul 2015

Deviations:

yes

Remarks:

no erythema and edema values for individual animals reported, only average scores given, occlusive application

GLP compliance:

not specified

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 2.0 - 3.0 kg

Type of coverage:

occlusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 0.5 mL

Duration of treatment / exposure:

4 h

Observation period:

17 days
Reading time points: 1, 24, 48 and 72 h, and 7, 10, 14 and 17 days

Number of animals:

6 (3 male and 3 female)

Details on study design:

TEST SITE
- Area of exposure: clipped dorsal trunk skin.
- Type of wrap if used: The area was covered with a gauze patch and loosely covered with impervious sheeting.

REMOVAL OF TEST SUBSTANCE
- Occlusive materials were removed and any excess sample wiped away with a moistened gauze swab.
- Time after start of exposure: 4 h

OBSERVATION TIME POINTS : 1, 24, 48 and 72 h, and 7, 10, 14 and 17 days

SCORING SYSTEM:
- Method of calculation: Draize scoring system

Irritation parameter:

erythema score

Basis:

other: average score over all animals

Time point:

24/48/72 h

Score:

2.3

Max. score:

4

Reversibility:

fully reversible within: 17 days

Irritation parameter:

edema score

Basis:

other: average score over all animals

Time point:

24/48/72 h

Score:

2.9

Max. score:

4

Reversibility:

fully reversible within: 17 days

Irritant / corrosive response data:

An hour after removal of the occlusive dressing there was mild to moderate erythema (score 1-2) and well defined to severe edema (score 3-4). On study Days 1-3 mild to severe erythema (score 1-4) was observed, which began to resolve between 3 and 7 days and had disappeared in half of the animals by Day 14 and in all animals by Day 17. Mild to severe edema (score 1-4) was observed in the animals up to study Day 3. One week after patch removal up to study Day 10 slight to moderate edema was observed (score 0-2). 14 days after patch removal, only slight edema (score 0-1) was observed, which was fully reversible until study termination. In addition, desquamation and scab formation were seen in all animals from Day 7-17.

Interpretation of results:

study cannot be used for classification

Conclusions:

The test conditions (occlusive conditions) may have led to more detrimental skin reactions than those specified in current guidelines. Individual animal data for erythema and edema were not reported.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Cutaneous toxicology of 3-(Methylthio)propionaldehyde

Author:

Ballantyne B, Cawley TJ, Blaszcak DL , 0

Year:

2000

Bibliographic source:

J.Toxicol.-Cut. & Ocular Toxicol., 19 (2&3), 117-13

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1999

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

adopted 12 May 1981

Deviations:

yes

Remarks:

limited study duration including 9 days treatment instead of 21/28 days, treatment 5 days/week instead of daily application, test material not fully characterised

GLP compliance:

yes

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3-(methylthio)propionaldehyde

EC Number:

221-882-5

EC Name:

3-(methylthio)propionaldehyde

Cas Number:

3268-49-3

Molecular formula:

C4H8OS

IUPAC Name:

3-(methylthio)propionaldehyde

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 165.3 - 195.5 g (males) and 182.5 - 216.0 g (females)
- Housing: individually in stainless steel wire mesh cages
- Diet: Certified Rodent Diet No. 5000 (PMI Nutrition International, St. Louis, Missouri), ad libitum
- Water: tap water, ad libitum
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 26
- Humidity (%): 24 - 70

Administration / exposure

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Area of exposure: The doses were applied to the clipped dorsal trunk skin.
- Type of wrap if used: The treated areas were covered with a layer of 8-ply gauze and impervious plastic, which was secured with an adhesive elastic bandage.

REMOVAL OF TEST SUBSTANCE
- Washing: The test sites were wiped free of excess test material using gauze soaked in saline.
- Time after start of exposure: 6 h

TEST MATERIAL
- Amount applied: 0.05, 0.2 and 0.5 mL/kg bw/day, corresponding to 52.7, 210.8 and 527 mg/kg bw/day
- Constant volume or concentration used: no

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

6 h

Frequency of treatment:

6 hours/day for 9 days (5 days in first week, 4 days in second week)

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0.05 other: mL/kg bw

Remarks:

corresponding to 52.7 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

0.2 other: mL/kg bw

Remarks:

corresponding to 210.8 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

0.5 other: mL/kg bw

Remarks:

corresponding to 527 mg/kg bw/day

No. of animals per sex per dose:

Main group: 10
Recovery group: 5 (control and high dose group only)

Control animals:

yes

Details on study design:

- Dose selection rationale: Dose levels were chosen based on a preliminary range-finding study, which was performed in 3 rats/sex with treatment for 5 consecutive days. 1/3 males and 1/3 females treated at 1.0 mL/kg bw/day died on study Day 4. There were no clinical signs of toxicity and no abnormalities in the Irwin Screen. Local skin irritation, seen at 0.5 and 1.0 mL/kg bw/day, was mainly mild erythema. Body weight losses at 0.5 mL/kg bw/day and 1.0 mL/ kg bw/day were significantly greater than for the control group. Except for the 1.0 mL/kg bw/day males, all groups gained weight by the fifth day of dosing. Based on these findings, it was considered that applied doses of 0.05, 0.2, and 0.5 mL/kg bw/day were appropriate for the full 9-day study.
- Fasting period before blood sampling for clinical biochemistry: not specified
- Post-exposure recovery period in satellite groups: 28 days

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily during the exposure period, once weekly during the recovery period
- Cage side observations included: local skin lesions and signs of toxic or pharmacological effects and mortality

DERMAL IRRITATION: Yes
- Time schedule for examinations: daily during the exposure period, once weekly during the recovery period

BODY WEIGHT: Yes
- Time schedule for examinations: on study Days 1, 3, 5, 8 and 10 during the exposure period and on Day 15 and weekly thereafter during the recovery period.

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes. Food consumption was measured for a week prior to dosing, over Days 1-3, 3-5, 5-8 and 8-10 during the exposure period and for recovery animals over six daily intervals.

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: Yes

WATER CONSUMPTION: Yes
- Time schedule for examinations: Prior to dosing, over Days 1-3, 3-5, 5-8 and 8-10 during the exposure period and for recovery animals over six daily intervals.

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Blood was collected before sacrifice from the retro-orbital venous plexus and used for chemical pathological measurements.
- Anaesthetic used for blood collection: no data
- Animals fasted: no data
- How many animals: all animals
- Parameters checked: hemoglobin concentration, hematocrit, erythrocyte count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelet and reticulocyte counts, total and differential leukocyte counts, prothrombin time, and activated partial thromboplastin time.


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Blood was collected before sacrifice from the retro-orbital venous plexus and used for chemical pathological measurements.
- Anaesthetic used for blood collection: no data
- Animals fasted: no data
- How many animals: all animals
- Parameters checked: urea nitrogen, glucose, total protein, albumin, globulin, bilirubin, sodium, potassium, calcium, chloride, inorganic phosphorus, aspartate and alanine aminotransferases, alkaline phosphate, lactate and sorbitol dehydrogenases, creatine kinase, and y-glutamyl transferase.

URINALYSIS: Yes
- Time schedule for collection of urine: Urine was collected over a 2 h interval from trays under the animal’s cage, and over 16 h from animals in metabolism cages.
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No data
- Parameters checked: Appearance, microscopy, pH, protein, ketones, bilirubin, occult blood, urobilinogen, glucose, creatinine, specific gravity, osmolality, and N-acetyl-ß-D-glucosaminidase (NAG) activity.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Before dosing, after the fifth dosing and before necropsy. Recovery animals were also evaluated the day following the cessation of dosing and prior to sacrifice.
- Dose groups that were examined: all groups
- Type of test: Irwing Screen, functional observation battery

Sacrifice and pathology:

GROSS PATHOLOGY: Yes. Necroscopic examination was conducted on all animals sacrificed by CO2 inhalation at the ends of the dosing and recovery periods to detect any indications of gross pathological change. Complete macroscopic postmortem examinations were conducted on all animals.
- The following organs were removed for weighing: brain, adrenal glands, liver, kidneys, ovaries, and testes.

HISTOPATHOLOGY: Yes. Histopathological evaluation of selected tissues (brain, kidneys, nerves, skin, spinal cord and testes) were performed on controls and high dose animals. Tissues and organs were removed, fixed in 10% neutral-buffered formalin, and then processed for light microscopic examination.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

Local signs of irritation were barely perceptible erythema in a few of the low-dose animals. Most mid- and high-dose animals showed very slight to slight erythema. By Day 18, all high-dose recovery animals were free of skin irritation.

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight gains of the high-dose males and females were lower than for the controls over the treatment period. At the end of the dosing period (Day 12) high-dose males had mean body weights 7% lower than controls, and high-dose females 5% lower. Body weights for the mid- and low-dose groups were comparable to the controls. Gains during the recovery period were comparable for control and high-dose animals.

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

The mean food consumption per bw. in all treated groups of males was 10 to 15% (p<0.01) higher than in controls from Day 5 until Day 10 but not dose-related. The effect was considered to be non-adverse.

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Treatment related histopathologic findings in the skin of the high-dose animals consisted of an occasional trace to mild inflammatory cell infiltrates in the dermis. The effect was considered adverse.

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Mild to moderate hyperkeratosis and acanthosis were observed in all animals of all dose groups at the treated skin site and acute inflammatory cell infiltration was noted in high dose-groups animals only. The effects were considered treatment-related and toxicologically relevant.

Histopathological findings: neoplastic:

not examined

Effect levels

1

Key result

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

527 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effect observed

Remarks on result:

other: corresponding to 0.5 mL/kg bw/day

2

Key result

Dose descriptor:

LOAEL

Remarks:

local

Effect level:

527 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

dermal irritation

histopathology: non-neoplastic

Remarks on result:

other: corresponding to 0.5 mL/kg bw/day

3

Key result

Dose descriptor:

NOAEL

Remarks:

local

Effect level:

210.8 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effect observed

Remarks on result:

other: corresponding to 0.2 mL/kg bw/day

Target system / organ toxicity

Key result

Critical effects observed:

no

Applicant's summary and conclusion

Conclusions:

Application of the test material to the skin of Sprague Dawley rats for a period of 9 days produced mild local skin reactions at 0.2 mL/kg bw/day (corresponding to 210.8 mg/kg bw/day) and mild to moderate local skin reactions at 0.5 mL/kg bw/day (corresponding to 527 mg/kg bw/day). The findings of the high dose group persisted until study Day 17. Based on these findings, a LOAEL for local toxicity of 527 mg/kg bw/day was derived and a NOAEL for local toxicity of 210.8 mg/kg bw/day. The NOAEL for systemic toxicity was 0.5 mL/kg bw/day (corresponding to 527 mg/kg bw/day).