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

Endpoint summary

Description of key information

Acute oral toxicity: LD50 >5000 mg/kg bodyweight male/female rats.

Acute dermal toxicity: LD50 >2000 mg/kg bodyweight in male/female rats.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

7 February 1989 to 2 March 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed in accordance with US EPA test guidelines in compliance with GLP.

Qualifier:

according to guideline

Guideline:

other: "Acute Exposure Oral Toxicity," Health Effects Test Guidelines, U. S. Environmental Protection Agency Office of Pesticide and Toxic Substances, pp. 22-31, October 1984.

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

other: Crl:CD®(SD)BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

Young adult male and female albino rats of the Crl:CD®(SD)BR strain (approximately 8 weeks of age) were procured, separated by sex, maintained in group cages in temperature- and humidity-controlled quarters, provided continuous access to Rodent Chow® 5001, Purina Mills, Inc., and water and held for an acclimation period of at least 7 days. Animal husbandry and housing at HLA comply with standards outlined in the "Guide for the Care and Use of Laboratory Animals". If variations from the prescribed environmental conditions existed, they were documented and considered to have no effect on the study outcome. No contaminants were expected to have been present in the feed or water which would have interfered with or affected the results of the study.

All animals were chosen at random, treated, and maintained during the observation period as specified for the acclimation period and were identified by animal number and corresponding ear tag. Food and water were available ad libitum throughout the study, except for an overnight period just before test material administration when food, but not water, was withheld.
Reason for Species Selection: Historically, rats have been used as a representative of a rodent species and are preferred by various regulatory agencies.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

Preparation and Administration of Test Material: For the range-finding study, the test material was mixed with corn oil to a uniform suspension at a specific concentration for each dose level. For the definitive study, the test material was mixed with corn oil to a uniform suspension at a concentration of 500 mg/ml. An individual dose was calculated for each animal based upon its fasted body weight and administered at a dose volume of 10 ml/kg by gavage. Each test material mixture was stirred with a stir plate and magnetic stir bar during dosing to maintain a uniform suspension.
Reason for Route of Administration: This is the method for administering a known quantity of test substance and has been the route of choice historically.

Doses:

Range-finding dose levels of 50, 100, 1,000, 2,500, and 5,000 mg/kg of body weight (one male and one female/dose level).
Based on the results of this range-finding study, in the definitive LD50 study animals were treated at a single level of 5,000 mg/kg of body weight.

No. of animals per sex per dose:

Range finding study - one male/one female per dose level.
Definitive study - five males & five females.

Control animals:

no

Details on study design:

Initially, five male and five female acclimated rats, weighing from 202 to 259 g, were used for five range-finding dose levels of 50, 100, 1000, 2500, and 5,000 mg/kg of body weight (one male and one female/dose level).
These range-finding animals were housed individually.
Based on the results of this range-finding study, five male and five female rats, weighing from 215 to 282 g, were used for the definitive LD50 study.
Animals were treated at a single level of 5,000 mg/kg of body weight. These definitive study animals were housed by sex in groups of five.
Observations: The range-finding study animals were observed for clinical signs and mortality at 1, 2, 4, 24, 48 and 72 hours after treatment. The definitive study animals were observed for clinical signs and mortality at 1, 2 and 4 hours after test material administration. These animals were observed daily thereafter for 14 days for clinical signs and twice daily for mortality.
All animals were weighed just before test material administration. Body weights of definitive study animals were taken again at 7 and 14 days.
Pathology: All range-finding study animals were sacrificed at termination and discarded. All definitive study animals, were sacrificed at termination, subjected to a gross necropsy examination and all abnormalities were recorded. After necropsy, animals were discarded and no tissues were saved.

Statistics:

Statistical Methods: No statistical method was performed.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Mortality:

There were no deaths during the study.

Clinical signs:

Diarrhoea was observed in three of the five female animals on the day of dosing.

Body weight:

There was no significant effect on body weight gain.

Gross pathology:

No visible lesions were recorded at the time of necropsy.

Range-Finding Mortality Summary

Dose Level (mg/kg)	Hours
	0-4		24		48		72
	Male	Female	Male	Female	Male	Female	Male	Female
50	0	0	0	0	0	0	0	0
100	0	0	0	0	0	0	0	0
1000	0	0	0	0	0	0	0	0
2500	0	0	0	0	0	0	0	0
5000	0	0	0	0	0	0	0	0

 

DEFINITIVE STUDY

Sex	Dose Level (mg/kg)	Average Body Weights (g)			Mortality (Number Dead/Number Dosed)
		Initial	Day 7	Terminal
Male	5000	266	343	377	0/5
Female	5000	230	259	264	0/5

 

Clinical Signs (Number of Animals Affected)

Observation	Hours			Days
	1.0	2.0	4.0	1	2	3	4	5	6	7	8	9	10	11	12	13	14
Males (5000 mg/kg)
Appeared normal	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5	5
Females (5000 mg/kg)
Appeared normal	2	2	2	5	5	5	5	5	5	5	5	5	5	5	5	5	5
Diarrhoea	3	3	3	0	0	0	0	0	0	0	0	0	0	0	0	0	0

 

PATHOLOGY

Animal Number	Test Day
	Sex	Died	Sacrificed	Necropsy Comment
Dose Level : 5000 mg/kg of Body Weight
C30518	M	-	14	No visible lesions
C30520	M	-	14	No visible lesions
C30517	M	-	14	No visible lesions
C30516	M	-	14	No visible lesions
C30547	M	-	14	No visible lesions
C30321	F	-	14	No visible lesions
C30322	F	-	14	No visible lesions
C30323	F	-	14	No visible lesions
C30324	F	-	14	No visible lesions
C30325	F	-	14	No visible lesions

 

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The estimated oral LD50 was determined to be >5,000 mg/kg of body weight for males, females and the combined sexes.

Executive summary:

The acute oral toxicity of HP-10 was evaluated in male and female rats.

This study was conducted in accordance with the Environmental Protection Agency's Good Laboratory Practice Standards, 40 CFR 792 and"Acute Exposure Oral Toxicity," Health Effects Test Guidelines, U. S.Environmental Protection Agency Office of Pesticide and ToxicSubstances, pp. 22-31, October 1984.

 

The estimated oral LD50was determined to be >5,000 mg/kg of body weight for males, femalesandthe combined sexes. Diarrhoea was observed in three of the five female animals on the day of dosing. There was no significant effect on body weight gain. No visible lesions were recorded at the time of necropsy.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Acute toxicity: via dermal route

Link to relevant study records

Reference

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

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.

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.

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.

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

 

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.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

Acute Oral Toxicity

The acute oral toxicity of HP-10 was evaluated in male and female rats.

This study was conducted in accordance with the Environmental Protection Agency's Good Laboratory Practice Standards, 40 CFR 792 and"Acute Exposure Oral Toxicity," Health Effects Test Guidelines, U. S.Environmental Protection Agency Office of Pesticide and ToxicSubstances, pp. 22-31, October 1984.

The estimated oral LD50 was determined to be >5,000 mg/kg of body weight for males, females and the combined sexes. Diarrhoea was observed in three of the five female animals on the day of dosing. There was no significant effect on body weight gain. No visible lesions were recorded at the time of necropsy.

Acute Dermal Toxicity

A study was performed to assess the acute dermal toxicity of HP-10 to the rat. 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 1% 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.

Justification for selection of acute toxicity – oral endpoint

Effect level derived from a GLP compliance study

Justification for selection of acute toxicity – dermal endpoint

Effect level dervived using EU Method B3 and OECD guideline 402.

Justification for classification or non-classification

Based on the data available the substance does not trigger any of the requirements for classification. Therefore the substance is Not Classified.