2,2'-methylenebis(4,6-di-tert-butyl-phenyl)-2-ethylhexyl phosphite

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 August and 7 September 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Reference

Name:

Unnamed

Type:

Constituent

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

Identity: HP-10
Chemical name: 2,4,8,10-tetrakis(1,1-dimethyl ethyl)-6-(2-ethylhexyloxy)-12H-dibenzo[d,g][1,3,2]dioxaphosphocin
Intended use: Chemical use in production of plastics (As an antioxidant and/or a stabilizer)
Appearance: White powder
Storage conditions: Room temperature in the dark
Lot number: 10549
Expiry: 6 months from date of receipt
Purity: 100%
Sample received: 3 August 1999

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

The animals chosen for this study were selected from a stock supply of healthy male and female CD rats of Sprague-Dawley origin (Hsd:Sprague-Dawley (CD)) obtained from Harlan U.K. Ltd., Bicester, Oxon, England.
They were in the weight range of 221 to 249 g and approximately eight to eleven weeks of age prior to dosing (Day 1). All the rats were acclimatised to the experimental environment for a period of five days prior to the start of the study.
The rats were allocated without conscious bias to cages within the treatment group. They were housed individually in metal cages (RS Biotech Sub-Dividable Rodent Cages- polished stainless steel (20cm high x 39cm wide x 39cm long)) until Day 3 when they were returned to group housing. The cages were fitted with grid floors to ensure rapid removal of waste material to undertrays. The cages were suspended in mobile stainless steel racks in Room 6 of Building R14.
A standard laboratory rodent diet (Special Diet Services RMI(E) SQC expanded pellet) and drinking water were provided ad libitum. The batch(es) of diet used for the study was analysed for certain nutrients, possible contaminants and micro-organisms. Results of routine physical and chemical examination of drinking water, as conducted by the supplier, are made available to Huntingdon Life Sciences Ltd. as quarterly summaries.
Thermostatic controls were set to maintain a temperature of 22 ± 3°C. Relative humidity was not fully controlled but was anticipated to be in the range 30 - 70%. Temperature and humidity were recorded continuously using a seven day recorder. Actual measurement of these parameters revealed that animal room temperature was in the range 21.5 to 24.5°C and relative humidity was in the range 37 - 63%. Permanent daily recordings of these parameters were made and these are archived with other Departmental raw data. Lighting was controlled by means of a time switch to provide 12 hours of artificial light (0700- 1900 hours) in each 24-hour period.
Each animal was identified by cage number and ear punching. Each cage was identified by a coloured label displaying the dose level, study schedule number, animal mark and the initials of the Study Director and Home Office licensee.

Administration / exposure

Type of coverage:

occlusive

Vehicle:

other: aqueous methylcellulose

Details on dermal exposure:

TEST SUBSTANCE PREPARATION: HP-10 was formulated at a maximum practical concentration of 55% w/v m 1% w/v aqueous methylcellulose and administered at a dose volume of 3.64 ml/kg bodyweight.
The test substance was prepared on the day of dosing.
ADMINISTRATION OF TEST SUBSTANCE: A group often rats (five males and five females) was treated at 2000 mg/kg bodyweight.
One day prior to treatment, hair was removed from the dorso-lumbar region of each rat with electric clippers taking care to avoid damaging the skin, exposing an area equivalent to approximately 10% of the total body surface area.
The test substance was applied by spreading it evenly over the prepared skin. The treatment area (approximately 50 mm x 50 mm) was covered with porous gauze held in place with a non irritating dressing, and further covered by a waterproof dressing encircled firmly around the trunk of the animal.
Treatment in this manner was performed on Day 1 (day of dosing) of the study only.
At the end of the 24 hours exposure period the dressings was carefully removed and the treated area of skin was washed with warm water (38°C) to remove any residual test substance. The treated area was blotted dry with absorbent paper.
Control animals: No control animals were included in this study.

Duration of exposure:

24 h

Doses:

Single dose 2000 mg/kg bw (dose volume: 3.64 mg/kg bw)

No. of animals per sex per dose:

10 animals (five males & five females).

Control animals:

no

Details on study design:

Mortality: Cages of rats were checked at least twice daily for mortalities.
Clinical signs: Animals were observed soon after dosing and at frequent intervals for the remainder of Day 1. On subsequent days animals were observed once in the morning and again at the end of the experimental day (with the exception of Day 15 - morning only). The nature and severity of the clinical signs and time were recorded at each observation.
All animals were observed for 14 days after dosing.

Dermal responses: Local dermal irritation at the treatment site was assessed daily using the following numerical scoring system:

Erythema and eschar formation:
No erythema 0
Slight erythema 1
Well defined erythema 2
Moderate erythema 3
Severe erythema (beet redness) to slight eschar formation (injuries in depth) 4

Oedema formation:
No oedema 0
Slight oedema 1
Well-defined oedema (edges of area well-defined by definite raising) 2
Moderate oedema (raised approximately 1 millimetre) 3
Severe oedema (raised more than 1 millimetre and extending beyond the area of exposure) 4

Bodyweight: The bodyweight of each rat was recorded on Days 1 (prior to dosing), 8 and 15. Individual weekly bodyweight changes and group mean bodyweights were calculated.

TERMINAL STUDIES
Termination: All animals were killed on Day 15 by cervical dislocation.
Macroscopic pathology: All animals were subjected to a macroscopic examination which consisted of opening the thoracic and abdominal cavities. The macroscopic appearance of all examined organs was recorded.

Statistics:

Not specified in the study report.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

dissolved

Mortality:

There were no mortalities throughout the study following a single dermal application of HP-10 to a group often rats (five males and five females) at a dose level of2000 mg/kg bodyweight.

Clinical signs:

There was no systemic response in any animal throughout the study.

Body weight:

All animals were considered to have achieved satisfactory bodyweight gains throughout the study.

Gross pathology:

No abnormalities were recorded at the macroscopic examination on Day 15.

Other findings:

Transient very slight dermal irritation (Grade 1 erythema) was seen in three females following removal of the dressings, resolving completely by Day 3. No dermal irritation was noted in any other animal during the study.

Any other information on results incl. tables

TABLE 1 – Dermal reactions

Dose (mg/kg)	Sex	Animal No	E=Erythema O=Oedema	Day
				2	3 to 15
2000	Male	1	E	0	0
			O	0	0
		2	E	0	0
			O	0	0
		3	E	0	0
			O	0	0
		4	E	0	0
			O	0	0
		5	E	0	0
			O	0	0
	Female	6	E	1	0
			O	0	0
		7	E	1	0
			O	0	0
		8	E	1	0
			O	0	0
		9	E	0	0
			O	0	0
		10	E	1	0
			O	0	0

 

TABLE 2 – Individual and group mean bodyweights (g)

Dose (mg/kg)	Sex	Animal Number	Bodyweight (g) at Day
			1	8	15
2000	Male	1	232	256	282
		2	240	278	317
		3	233	248	269
		4	240	270	298
		5	249	291	333
	Mean		239	269	300
	Female	6	221	227	236
		7	225	237	247
		8	225	238	248
		9	230	248	262
		10	224	231	237
	Mean		225	236	246

 

TABLE 3 – Individual bodyweight changes (g)

Dose (mg/kg)	Sex	Animal Number	Bodyweight change at Day (g)
			8	15
2000	Male	1	24	26
		2	38	39
		3	15	21
		4	30	28
		5	42	42
	Female	6	6	9
		7	12	10
		8	13	10
		9	18	14
		10	7	6

 

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute lethal dermal dose to rats of HP-1 0 was demonstrated to be greater than 2000 mg/kg bodyweight.

Executive summary:

A study was performed to assess the acute dermal toxicity of HP-1 0 to the rat. The method followed was based on that described in:

EEC Methods for the determination of toxicity, Annex to Directive 92/69/EEC (Official Journal No. L383A, 29.12.92), Part B, Method B.3. Acute toxicity (dermal).

OECD Guideline for Testing of Chemicals No. 402 "Acute Dermal Toxicity". Adopted: 24 February 1987.

A group of ten rats (five males and five females) received a single topical application of the test substance, formulated at a maximum practical concentration in I% w/v aqueous methylcellulose, at a dose level of 2000 mg/kg bodyweight All animals were killed and examined macroscopically on Day 15, the end of the observation period.

There was no systemic response in any animal throughout the study.

Transient very slight dermal irritation (Grade 1 erythema) was seen in three females following removal of the dressings, resolving completely by Day 3. No dermal irritation was noted in any other animal during the study.

All animals were considered to have achieved satisfactory bodyweight gains throughout the study.

No abnormalities were recorded at the macroscopic examination on Day 15.

The acute lethal dermal dose to rats of HP-1 0 was demonstrated to be greater than 2000 mg/kg bodyweight.

HP-10 will not require labelling with the risk phase R21 "Harmful in contact with skin", in accordance with Commission Directive 93/21/EEC.