6,6'-di-tert-butyl-2,2'-thiodi-p-cresol

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

08 August 2017 to 22 August 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

See "Any other information" for details

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Version / remarks:

Commission Regulation (EC) No 440/2008 of 30 May 2008, B.3.Tris

Deviations:

yes

Remarks:

See "Any other information" for details

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

See "Any other information" for details

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

6,6'-di-tert-butyl-2,2'-thiodi-p-cresol

EC Number:

202-009-7

EC Name:

6,6'-di-tert-butyl-2,2'-thiodi-p-cresol

Cas Number:

90-66-4

Molecular formula:

C22H30O2S

IUPAC Name:

6,6'-di-tert-butyl-2,2'-thiodi-p-cresol

Test material form:

solid: particulate/powder

Details on test material:

Name: 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol
Other name: LOWINOX® TBP-6
CAS number: 90-66-4
Batch/Lot Number: C036K0111
Description: White powder
Purity*: 99.8%
Expiry date: 29 March 2018
Storage condition: Controlled room temperature (15-25 ºC, below 70 RH%)
Safety precautions: Routine safety precautions (gloves, goggles, face mask, lab coat) for unknown materials were applied to assure personnel health and safety.

Specific details on test material used for the study:

No further details specified in the study report.

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Crl:WI

Sex:

male/female

Details on test animals or test system and environmental conditions:

Species and strain: Crl:WI Wistar rats
Source: Charles River Laboratories, Research Models and Services, Germany GmbH, Sandhofer Weg 7, D-97633 Sulzfeld, Germany.
Hygienic level at arrival: SPF
Hygienic level during the study: Standard housing conditions
Number of animals: 5 animals/sex
Sex: Male and female, female rats were nulliparous and non-pregnant
Age of animals at dosing: Young adult rats
Body weight at treatment: Between 221 g and 255 g
Acclimatisation period: 5 days

Husbandry
Animal health: Only healthy animals were used for the test. The health status was certified by the staff Veterinarian.
Number of animal room: 242/6
Housing: Individual caging
Cage type: Type II. polypropylene/polycarbonate
Bedding and nesting: “Lignocel 3/4-S Hygienic Animal Bedding” and “Arbocel crinklets natural” nest building material produced by J. Rettenmaier & Söhne GmbH + Co.KG (D-73494 Rosenberg, Germany) was available to animals during the study.
Lighting period: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 21.1 – 28.2 °C
Relative humidity: 32 – 74 %
Ventilation: 15-20 air exchanges/hour
Enrichment: Rodents were housed with deep wood sawdust bedding to allow digging and other normal rodent activities.
The temperature and relative humidity were recorded twice daily during the acclimatisation period and throughout the study.

Food and Water Supply
Animals received ssniff® SM R/M "Autoclavable complete diet for rats and mice – breeding and maintenance" produced by ssniff Spezialdiäten GmbH, D-59494 Soest, Germany (batch number: 262 21592, expiry date: 31 January 2018), ad libitum, and tap water from the municipal supply, as for human consumption from a 500 mL bottle, ad libitum. The food is considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.
Water quality control analysis is performed once every three months and microbiological assessment is performed monthly, by Veszprém County Institute of State Public Health and Medical Officer Service (ÁNTSZ, H-8201 Veszprém, József A. u. 36., Hungary).

Animal Identification
Animals were individually identified using numbers written on the tail with an indelible marker pen. The numbers were given on the basis of CiToxLAB Hungary Ltd.' s Master File, for each animal allocated to the treatment groups. The cages were identified by cards, with information about study code, sex, dose group, cage number and individual animal numbers.

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

water

Details on dermal exposure:

Formulation
The test item was administered as a single dose. Sufficient water was used to dampen the test material to ensure good contact with the skin.

Procedure
The back of each animal was shaved (approximately 10% area of the total body surface) approximately 24 hours prior to treatment. The test item was applied as a single dose to the shaved skin and remained in contact with the skin for the 24-hour exposure period. The test material was dampened with sufficient water before application to ensure good contact with the skin. Sterile gauze pads were placed on the skin of rats to cover the test item. These gauze pads were kept in contact with the skin using a patch with adhesive hypoallergenic plaster. The entire trunk of the animal was then wrapped with semi occlusive plastic wrap for 24 hours.
At the end of the exposure period, the area of skin treated with the test item was washed with water of body temperature.

Duration of exposure:

24 hours.

Doses:

A single dermal application was made.

No. of animals per sex per dose:

10 (5 males/5 females)

Control animals:

no

Details on study design:

Clinical Observations
Clinical observations were performed on the day of treatment at 1 and 5 hours after application of the test item and once each day for 14 days thereafter. Observations included the skin and fur, eyes and mucous membranes, the respiratory, circulatory, autonomic and central nervous system, somatomotor activity and behaviour pattern.
Particular attention was directed to observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.
Skin Irritation:
Adverse skin reactions at the site of application were recorded daily following the removal of the dressing.

Body Weight Measurement
The body weights were recorded on Day 0 (before test item administration) and on Days 7 and 14 just before necropsy.

NECROPSY
Macroscopic examination was performed on all animals. The animals were sacrificed by exsanguination under pentobarbital anaesthesia (Release, 300 mg/mL pentobarbital sodium; Lot number: 106075, Expiry date: 31 July 2018, Produced by: Wirtschaftsgenossenschaft deutscher Tierärzte eG, Germany). After examination of the external appearance, the cranial, thoracic and the abdominal cavities were opened and the organs and the tissues were observed. Macroscopic abnormalities were recorded.

Statistics:

Not specified.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

6,6’-di-tert-butyl-2,2’-thiodi-p-cresol did not cause mortality at the dose level of 2000 mg/kg bw.

Clinical signs:

There were no systemic clinical signs noted in any animal throughout the study.

Body weight:

Body weight gains of 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol treated animals during the study showed no indication of a test item-related effect.

Gross pathology:

There was no evidence of the macroscopic observations at a dose level of 2000 mg/kg bw.

Other findings:

No local dermal signs were observed after treatment with the test item during the 14 days observation period.

Any other information on results incl. tables

CLINICAL OBSERVATIONS

DOSE LEVEL: 2000 mg/kg bw

SEX: MALE

Cage No.

Animal No.

Observations

Observation days

Frequency

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

1h

5h

1

357

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

2

358

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

3

359

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

4

360

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

5

361

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

DOSE LEVEL: 2000 mg/kg bw

SEX: FEMALE

Cage No.

Animal No.

Observations

Observations days

Frequency

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

1h

5h

6

362

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

7

363

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

8

364

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

9

365

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

10

366

Symptom Free

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

+

16/16

Remarks:             + = present

                         h = hour (s)          Treatment day = Day 0

                          Frequency of observation = number of occurrence of observations / total number of observations

 

BODY WEIGHT DATA

DOSE LEVEL: 2000 mg/kg bw						SEX: MALE
Cage No.	Animal No.	Body weight (g)			Body Weight Gain (g)
		Days
		0	7	14	0-7	7-14	0-14
1	357	233	297	349	64	52	116
2	358	243	285	319	42	34	76
3	359	247	309	366	62	57	119
4	360	229	288	358	59	70	129
5	361	222	289	247	67	58	125
Mean:		234.8	293.6	347.8	58.8	54.25	113.0
Standard deviation:		10.2	9.7	17.8	9.8	13.1	21.3
DOSE LEVEL: 2000 mg/kg bw						SEX: FEMALE
Cage No.	Animal No.	Body weight (g)			Body Weight Gain (g)
		Days
		0	7	14	0-7	7-14	0-14
6	362	225	264	279	39	15	54
7	363	242	261	276	19	15	34
8	364	255	317	338	62	21	83
9	365	221	240	251	19	11	30
10	366	232	252	257	20	5	25
Mean:		235.0	266.8	280.2	31.8	143.4	45.2
Standard deviation:		13.7	29.6	34.5	18.9	5.9	23.8

 

NECROPSY FINDINGS

DOSE LEVEL: 2000 mg/kg bw					SEX: MALE
Cage No.	Animal No.	Necropsy Date/ Necropsy Day	External Observations	Internal Observations	Organ/ Tissue
1	357	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
2	358	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
3	359	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
4	360	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
5	361	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
DOSE LEVEL: 2000 mg/kg bw					SEX: FEMALE
Cage No.	Animal No.	Necropsy Date/ Necropsy Day	External Observations	Internal Observations	Organ/ Tissue
6	362	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
7	363	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
8	364	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
9	365	22 August 2017 Day 14	No external observations	No internal observations	Not applicable
10	366	22 August 2017 Day 14	No external observations	No internal observations	Not applicable

 

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of this study, the acute dermal median lethal dose (LD50 value) of the test item 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol was found to be above 2000 mg/kg bw in male and female Crl:WI rats.
According to the GHS criteria, 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol can be ranked as "Category 5 or Unclassified" for acute dermal exposure.

Executive summary:

An acute dermal toxicity study was performed with test item 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol in Crl:WI rats, in compliance with OECD Guideline No. 402.

 

A limit test was carried out at 2000 mg/kg body weight (bw) in both sexes (5 rats/sex). The test item was applied as a single dermal 24-hour exposure followed by a 14-day observation period.

 

Clinical observations were performed on all animals at 1 and 5 hours after dosing and daily for 14 days thereafter. Body weight was measured prior to dosing on Day 0 and on Days 7 and 14. Gross macroscopic examination was performed on all animals at the end of the 2-week observation period (Day 14).

 

RESULTS

Mortality

6,6’-di-tert-butyl-2,2’-thiodi-p-cresol did not cause mortality at the dose level of 2000 mg/kg bw.

 

Clinical Observations

There were no systemic clinical signs noted in any animal throughout the study.

 

Local dermal signs

No local dermal signs were observed after treatment with the test item during the 14 days observation period.

 

Body weight and body weight gain

Body weight gains of 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol treated animals during the study showed no indication of a test item-related effect.

 

Macroscopic Findings

There was no evidence of the macroscopic observations at a dose level of 2000 mg/kg bw.

 

CONCLUSIONS

Under the conditions of this study, the acute dermal median lethal dose (LD50 value) of the test item 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol was found to be above 2000 mg/kg bw in male and female Crl:WI rats.

 

According to the GHS criteria, 6,6’-di-tert-butyl-2,2’-thiodi-p-cresol can be ranked as "Category 5 or Unclassified" for acute dermal exposure.