Phosphorous acid, mixed 2,4-bis(1,1-dimethylpropyl)phenyl and 4-(1,1-dimethylpropyl)phenyl triesters

Acute Toxicity: dermal

Administrative data

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 20 January 2010 and 10 February 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

Due to technician error, the dermal reaction observations for four females on Day 4 and four males on Day 11 were not recorded. These deviations were considered not to affect the purpose or integrity of the study, as no evidence of dermal irritation was noted pre or post Day 4 for females or pre or post Day 11 for males.

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of GLP inspection: 15/09/09 Date of Signature on GLP certificate: 26/11/09

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

[4-(2-methylbutan-2-yl)phenyl]x [2,4-bis(2-methylbutan-2-yl)]3-x phosphite (where x = 0, 1, 2, 3)

IUPAC Name:

[4-(2-methylbutan-2-yl)phenyl]x [2,4-bis(2-methylbutan-2-yl)]3-x phosphite (where x = 0, 1, 2, 3)

Details on test material:

Sponsor's identification : DVS005u (aka Weston 705)
Description : clear colourless viscous liquid
Batch number : MW9F23A901
Date received : 05 November 2009
Expiry date : 15 June 2010
Storage conditions : approximately 4°C in the dark under nitrogen

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test Animals:

Animals: Rat, HsdRccHan: WIST

Rationale: Recognized by international guidelines as a recommended test system.

Breeder: Harlan Laboratories UK Limited, Bicester, Oxon, UK.

Number of Animals per Group: 5 males and 5 females

Total number of Animals: 5 males and 5 females

Age when treated: At the start of the study the animals weighed at least 200g, and were eight to twelve weeks of age.

Identification: After an acclimatisation period of at least five days the animals were selected at random and given a number unique within the study by indelible ink-marking on the tail and a number written on a cage card.

Acclimatization: At least 5 days under laboratory conditions, after health examination. Only animals without any visible signs of illness were used for the study.

Environmental Conditions:
Conditions:
The temperature and relative humidity were set to achieve limits of 19 to 25°C and 30 to 70% respectively. Any occasional deviations from these targets were considered not to have affected the purpose or integrity of the study. The rate of air exchange was at least fifteen changes per hour and the lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness

The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.

Accommodation:
The animals were housed in suspended solid-floor polypropylene cages furnished with woodflakes. The animals were housed individually during the 24-hour exposure period and in groups of five, by sex, for the remainder of the study.

Diet:
Free access food (2014 Teklad Global Rodent diet supplied by Harlan Teklad, Blackthorn, Bicester, Oxon, UK) was allowed throughout the study. The diet was routinely analysed and were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Water:
Free access to mains drinking water was allowed throughout the study. The drinking
water was routinely analysed and were considered not to contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study.

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

One day before treatment, the backs of the animals were clipped with an electric clipper, exposing an area of approximately 10 % of the total body surface.

UIn the absence of data suggesting the test material was toxic, one male and one female rat were initially treated with the test material at a dose level of 2000 mg/kg.

The calculated volume of test material, as received, was applied as evenly as possible to an area of shorn skin (approximately 10% of the total body
surface area) using a graduated syringe. A piece of surgical gauze, approximately 10 cm x 8 cm in size, was placed over the treatment area and semi-occluded with a piece of self adhesive bandage. The animals were caged individually for the 24 hour exposure period. Shortly after dosing the
dressings were examined to ensure that they were securely in place.

After the 24-hour contact period the bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened
with distilled water to remove any residual test material. The animals were returned to group housing for the remainder of the study period.

As no mortalities were noted a further group of animals (four males and four females) was similarly treated with the test material at a dose level of 2000 mg/kg bodyweight to give a total of five males and five females. After the 24 hour contact period the bandages were carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened with arachis oil BP to remove any residual test material. These animals were returned to group housing for the remainder of the test period.

The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for fourteen days.

Rationale: Dermal administration was used as this is one possible route of human exposure during manufacture, handling and use of the test item.

Duration of exposure:

24 hours

Doses:

2000 mg/kg body weight

No. of animals per sex per dose:

5 males and 5 females

Control animals:

not required

Details on study design:

After the 24-hour contact period the bandage was carefully removed and the treated skin and surrounding hair wiped with cotton wool moistened
with distilled water to remove any residual test material. The animals were returned to group housing for the remainder of the study period.

The animals were observed for deaths or overt signs of toxicity ½, 1, 2 and 4 hours after dosing and subsequently once daily for fourte The animals were returned to group housing for the remainder of the study period.

After removal of the dressings and subsequently once daily for fourteen days, the test sites were examined for evidence of primary irritation and
scored according to the following scale from Draize J H (1977) "Dermal and Eye Toxicity Tests" In: Principles and Procedures for Evaluating the
Toxicity of Household Substances, National Academy of Sciences, Washington DC p.31:

EVALUATION OF SKIN REACTIONS

Erythema and Eschar Formation Value

No erythema 0
Very slight erythema (barely perceptible) 1
Well-defined erythema 2
Moderate to severe erythema 3
Severe erythema (beef redness) to slight eschar formation (injuries in depth) 4

Oedema Formation

No oedema 0
Very slight oedema (barely perceptible) 1
Slight 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

Any other skin reactions, if present were also recorded. Due to technician error, the dermal reaction observations for four females on Day 4 and four males on Day 11 were not recorded. These deviations were considered not to affect the purpose or integrity of the study, as no evidence of dermal irritation was noted pre or post Day 4 for females or pre or post Day 11 for males.

Individual bodyweights were recorded prior to application of the test material on Day 0 and on Days 7 and 14.

At the end of the study the animals were killed by cervical dislocation. All animals were subjected to gross necropsy. This consisted of an external
examination and opening of the abdominal and thoracic cavities. The appearance of any macroscopic abnormalities was recorded. No tissues were
retained.

Rationale: The dermal route was selected as the most appropriate route of exposure and the results of the study are believed to be of value in predicting the likely toxicity of the test material to man.

Statistics:

No statistical analysis was performed.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: 95% confidence limits not reported.

Mortality:

No deaths occurred during the study.

Clinical signs:

Increased respiratory rate and/or hunched posture were noted in two animals. No other signs of systemic toxicity were noted.

There were no signs of dermal irritation.

Body weight:

All animals showed expected gains in bodyweight over the study period.

Gross pathology:

No abnormalities were noted at necropsy.

Other findings:

None.

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The acute dermal median lethal dose (LD50) of the test material in the Wistar strain rat was found to be greater than 2000 mg/kg bodyweight.

Executive summary:

Introduction: The study was performed to assess the acute dermal toxicity of the test material in the Wistar strain rat. The method was designed to meet the requirements of the following:

§        OECD Guidelines for the Testing of Chemicals No. 402 “Acute Dermal Toxicity” (adopted 24 February 1987)

§        Method B3 Acute Toxicity (Dermal) of Commission Regulation (EC) No. 440/2008

Method:

Initially, two animals (one male and one female) were given a single, 24-hour, semi-occluded dermal application of the undiluted test material to intact skin at a dose level of 2000 mg/kg bodyweight. Based on the results of the initial test, a further group of eight animals (four males and four females) was similarly treated. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy.

Results:

Mortality: There were no deaths.

Clinical Observations: Increased respiratory rate and/or hunched posture were noted in two animals. No other signs of systemic toxicity were noted.

Dermal Irritation:  There were no signs of dermal irritation.

Bodyweight: All animals showed expected gains in bodyweight over the study period.

Necropsy: No abnormalities were noted at necropsy.

Conclusion: 

The acute dermal median lethal dose (LD₅₀) of the test material in the Wistar strain rat was found to be greater than 2000 mg/kg. bodyweight.

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