2-phenoxyethyl isobutyrate

Endpoint summary

Description of key information

Dermal NOAEL > 1000 mg/kg bw/day, 90 days rat male/female, methodolgy similar to OECD 411, Mulhern et al. (1990).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02 August 1990 to 14 November 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: A GLP study performed to sound scientific principles with a sufficient level of detail to assess the reliability of the quality of the submitted data.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 4 weeks on arrival.
- Weight at study initiation: Approximate weights on arrival; males 85 g and females 60 g.
- Housing: Individually housed in suspended polypropylene cages.
- Diet: Commercial rat and mouse food, ad libitum.
- Water: Tap water, ad libitum.
- Acclimation period: 11 days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 2 ºC
- Humidity (%): 55 ± 10%
- Air changes (per hr): 15 air changes per hour.
- Photoperiod (hrs dark / hrs light): 12 hours dark / 12 hours light.

IN-LIFE DATES: From 02 August 1990 to 14 November 1990.

Type of coverage:

occlusive

Vehicle:

other: diethyl phalate

Details on exposure:

TEST SITE
- Area of exposure: An area on the back of each animal was used as the exposure area.
- % coverage: 10% of the total body surface area.
- Type of wrap if used: An occlusive dressing consisting of a gauze patch covered by a foil backing, held in place by means of non-irritating tape
- Time intervals for shavings or clipplings: Twice weekly.

REMOVAL OF TEST SUBSTANCE
- Washing: The exposure site was cleaned of test material with diethyl phthalate immediately after removal of the dressing.
- Time after start of exposure: 6 hours

TEST MATERIAL
- Amounts applied: The test material was applied daily at 2 mL/kg.
- Concentration: 0, 100, 300 and 1000 mg/kg bw/day
- Constant volume used: yes

VEHICLE
- Amount applied: 2 mL/kg.

USE OF RESTRAINERS FOR PREVENTING INGESTION: no.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses of dosing solutions were undertaken with regard to accuracy of concentration of test material. The analyses were undertaken on samples of each dosing solution prepared during the first day of dosing and week 13 of the study. Analysis was also performed showing stability of the dosing solutions over a period of 14 days.

Duration of treatment / exposure:

13 weeks with a daily exposure time of 6 hours.

Frequency of treatment:

Daily.

Remarks:

Doses / Concentrations:
0, 100, 300 and 1000 mg/kg bw/day
Basis:

No. of animals per sex per dose:

12 animals per sex per dose.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were selected based on results obtained from preliminary studies where it was shown that the test material elicited erythema and desquamation, epidermal thickening hyperkeratosis and/or localised parakeratosis when applied to rats at a dose level of 1000 mg/kg bw/day.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Viability was checked once each morning and once as late as practicable each day. Furthermore, all animals were examined for reactions to treatment during the day. The onset, intensity and duration of all signs were recorded.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: All animals received a detailed clinical examination for evidence of systemic toxicity once each week.

DERMAL IRRITATION: Yes
- Time schedule for examinations: Twice each day (before administration and after the exposure period) the skin at the test site was inspected and assessed for reaction to treatment. Erythema, eschar, edema formation were scored according to the Draize scale. Skin thickening and desquamation were also noted.

BODY WEIGHT: Yes
- Time schedule for examinations: The weight of each animal was recorded once during the week before the start of treatment and once each week thereafter.

FOOD CONSUMPTION: Yes
- The quantity of food consumed by each animal was recorded once during the week before the start of treatment and once each week thereafter.

WATER CONSUMPTION: Yes
- Time schedule for examinations: Water consumption was monitored by visual inspection throughout the treatment period.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Week 13
- Anaesthetic used for blood collection: Yes (light ether).
- How many animals: 10 males and 10 females.
- Parameters checked in Table 1 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Week 13
- How many animals: 10 males and 10 females
- Parameters checked in Table 2 were examined.

URINALYSIS: Yes
- Time schedule for collection of urine: Samples were collected over a 4 hour period of food and water deprivation.
- Parameters checked in Table 3 were examined.

Sacrifice and pathology:

GROSS PATHOLOGY/ HISTOPATHOLOGY: Yes
- All animals were sacrificed and necropsied after 13 weeks dosing. Method of killing was carbon dioxide asphyxiation followed by exsanguination.
- The following organs were weighed from all animals: adrenals, brain, heart, kidneys, liver, ovaries (with fallopian tubes), pituitary, testes (plus epididymides), thyroids.
- The following tissues from all animals were examined in situ and fixed: adrenals, aortic arch, any abnormal tissue, bladder, bone (sternum and rib), brain, ears, eyes, femur, heart, intestine (duodenum, jejunum, ileum, caecum, colon, rectum), kidneys, liver, lungs (perfused), mammary gland, thyroids, tongue, mesentric lymph node, muscle (thigh), nasal cavity, oesophagus, optic nerve, ovaries (with fallopian tubes), pancreas, pituitary, prostate, sciatic nerve, seminal vesicles, skin (normal and treated), spleen, stomach (glandular and non-glandular), spinal chord (thoracic-lumbar), submaxillary salivary gland, submandibular lymph node, testes (plus epididymides), thymus, trachea, uterus.
- Samples of the above tissues were taken from all animals and placed in 10% neutral buffered formalin (except eyes which were preserved in Davidson's fluid). The lungs were fixed in their entirety by perfusion with 10% neutral buffered formalin.
- Tissues were trimmed to a maximum thickness of 3 mm for processing. Parenchymal organs were trimmed to allow the largest surface area for examination.
- Multiple sections of the kidney were prepared with mid-transverse sections through the cortex and medulla of each being submitted for examination.
- Three cross sections of the brain were included; frontal cortex and basal ganglia, parietal cortex and thalamus, and the cerebellum and medulla oblongata. Tissues were cut into 4-6 µm thickness and stained with haematoxylin and eosin.
- All fixed tissues (with the exception of spinal chord, rectum, sternum, rib, muscle, ears, eyes, optic nerve, trachea, tongue, femur and nasal cavity) were processed and examined histologically from all animals in the Control Group and the High Dose Group. Kidneys were examined histologically from all animals from all dose groups.

Statistics:

Haematology, clinical chemistry, organ weight and body weight data were statistically analysed for homogeneity of variance using the F-max test. If the group variances appeared homogenous a parametric ANOVA was used and pairwise comparisons made via Student's t-test using Fisher's F-protected LSD. If the variances were heterogeneous log or square root transformations were used in an attempt to stabilise the variances. If the variances remained heterogeneous, then a non-parametric test such as Kruskal-Wallis ANOVA was used. Organ weights were also analysed conditional on body weight (i.e. covariance and relative analyses). Histology data were analysed using Fisher's Exact Probability test.

Clinical signs:

no effects observed

Description (incidence and severity):

No treatment related effects.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

Slight desquamation and erythema noted in all animals and the control.

Mortality:

no mortality observed

Description (incidence):

No treatment related effects.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No treatment related effects.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No treatment related effects.

Food efficiency:

not examined

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

no effects observed

Description (incidence and severity):

No treatment related effects.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No treatment related effects.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No treatment related effects.

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

No treatment related effects.

Details on results:

CLINICAL SIGNS AND MORTALITY: No deaths were observed during the course of the study. There were no clinical signs of toxicity observed which were considered to be related to treatment with the test material.

DERMAL IRRITATION: There were transient incidences of slight desquamation and erythema, observed at similar incidence and severity, and noted in all animals, with the exception of one female control.

BODY WEIGHT AND WEIGHT GAIN: Although there were slight variations evident in body weight gain they were within normal variability and did not show any relationship to dose level. There were no statistically significant differences in body weight during the dosing period.

FOOD CONSUMPTION: Although there were slight intergroup differences in the total food consumed these differences did not show any relationship to dose level and were within normal variability.

WATER CONSUMPTION: There were no visual intergroup differences.

HAEMATOLOGY: There were no notable intergroup differences.

CLINICAL CHEMISTRY: There were no notable intergroup differences between the males. For females there was a slight reduction in potassium in the 300 mg/kg bw/day dose group (10%, P<0.05). Due to the magnitude of this change and the absence of a similar change at the higher dose level it is not considered to be related to treatment with test material.

URINALYSIS: There were no notable intergroup differences.

ORGAN WEIGHTS: There were no notable intergroup differences between the males. After correction for final body weight in females, (covariance analysis and after relative analyses) there was a slight decrease evident in ovaries weight in the 1000 mg/kg bw/day dose group (15%, P<0.05). This decrease in ovary weight was not reflected in any histological changes it is considered that this change is a chance

GROSS PATHOLOGY: Findings were infrequent and showed no notable intergroup differences.

HISTOPATHOLOGY NON-NEOPLASTIC: There were no notable intergroup differences. At the treatment site a very mild/minimal epidermal thickening with or without slight hyperkeratosis was present in all animals with the exception of one female in the control group. This reaction was also seen in the adjacent dorsal skin in a few animals in some groups. All other findings were typical of the usual background pathology seen in rats of this age and strain at the testing facility.

HISTOPATHOLOGY NEOPLASTIC: There were no notable intergroup differences. Necrotising papillitis (unilateral) was seen in the kidney of one male animal in the 100 mg/kg bw/day dose group but was not accompanied by pelvic dilatation. The changes seen in the kidneys of this animal, urothelial hyperplasia and papillitis, are similar to the changes which have been recorded or might be expected in the early stages of pyelone-phritis induced by urinary stasis and/or the introduction of bacterial infection into the ureters. It is possible that stasis could have arisen in this study due to the pressure exerted on the abdominal contents by the dressing used to hold the patch in place. Partial obstruction of the ureters could have permitted bacteria which are normally present in the urinary tract to spread up the ureters and cause inflammation in the papilla. It is therefore concluded that there are enough published results to show that the papillary lesion seen in this study could have been caused by repeated, partial obstruction of the ureters by the dressing used to hold the patch in place. It is not possible, however, to state that this was the definite cause.

Dose descriptor:

NOEL

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed.

Critical effects observed:

not specified

Conclusions:

Under the conditions of the test, no treatment related effects or systemic signs of toxicity were observed during the study. Slight desquamation and erythema were observed in all animals, female ovary weights were slightly lower at 1000 mg/kg bw/day, necrotising papillitis was observed in one male treated at 100 mg/kg bw/day. Since no other notable adverse effects were observed to support these findings, these effects were considered to be of no toxicological relevance.

Accordingly the NOEL is considered to be greater than the highest concentration tested, 1000 mg/kg bw/day.

Executive summary:

The subchronic dermal toxicity of the test material was investigated following a procedure in line with that noted in the standardised guideline OECD 411. During the study groups of 12 male and 12 female rats were dosed daily with test material via topical application under an occlusive dressing, for a period of 6 hours per day for 13 consecutive weeks. The groups were dosed at a constant volume of 2 mL/kg bw at concentrations of 100, 300 and 1000 mg/kg bw/day in diethyl phalate. A vehicle control was run concurrently for comparison.

Under the conditions of the study there were no notable intergroup differences or toxicologically significant effects noted when assessing changes in; body weight, food consumption, water consumption, haematology, clinical chemistry, urinalysis, organ weights, necropsy findings or histological findings. Transient incidences of slight desquamation and erythema were observed, in all animals at similar incidence and severity.

Overall, exposing rats to the test material for 13 weeks with at dose levels of up to 1000 mg/kg bw/day produced no notable findings. The NOEL was therefore taken to be > 1000 mg/kg bw/day.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

In addition to the key study, two supporting studies have been provided as evidence Owston et al. (1981) and Api (2004). Both studies were assigned a reliability score of 2 in accordance with Klimisch (1997); the quality of the overall dataset is therefore high.

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02 August 1990 to 14 November 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: A GLP study performed to sound scientific principles with a sufficient level of detail to assess the reliability of the quality of the submitted data.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 4 weeks on arrival.
- Weight at study initiation: Approximate weights on arrival; males 85 g and females 60 g.
- Housing: Individually housed in suspended polypropylene cages.
- Diet: Commercial rat and mouse food, ad libitum.
- Water: Tap water, ad libitum.
- Acclimation period: 11 days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 ± 2 ºC
- Humidity (%): 55 ± 10%
- Air changes (per hr): 15 air changes per hour.
- Photoperiod (hrs dark / hrs light): 12 hours dark / 12 hours light.

IN-LIFE DATES: From 02 August 1990 to 14 November 1990.

Type of coverage:

occlusive

Vehicle:

other: diethyl phalate

Details on exposure:

TEST SITE
- Area of exposure: An area on the back of each animal was used as the exposure area.
- % coverage: 10% of the total body surface area.
- Type of wrap if used: An occlusive dressing consisting of a gauze patch covered by a foil backing, held in place by means of non-irritating tape
- Time intervals for shavings or clipplings: Twice weekly.

REMOVAL OF TEST SUBSTANCE
- Washing: The exposure site was cleaned of test material with diethyl phthalate immediately after removal of the dressing.
- Time after start of exposure: 6 hours

TEST MATERIAL
- Amounts applied: The test material was applied daily at 2 mL/kg.
- Concentration: 0, 100, 300 and 1000 mg/kg bw/day
- Constant volume used: yes

VEHICLE
- Amount applied: 2 mL/kg.

USE OF RESTRAINERS FOR PREVENTING INGESTION: no.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses of dosing solutions were undertaken with regard to accuracy of concentration of test material. The analyses were undertaken on samples of each dosing solution prepared during the first day of dosing and week 13 of the study. Analysis was also performed showing stability of the dosing solutions over a period of 14 days.

Duration of treatment / exposure:

13 weeks with a daily exposure time of 6 hours.

Frequency of treatment:

Daily.

Remarks:

Doses / Concentrations:
0, 100, 300 and 1000 mg/kg bw/day
Basis:

No. of animals per sex per dose:

12 animals per sex per dose.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were selected based on results obtained from preliminary studies where it was shown that the test material elicited erythema and desquamation, epidermal thickening hyperkeratosis and/or localised parakeratosis when applied to rats at a dose level of 1000 mg/kg bw/day.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Viability was checked once each morning and once as late as practicable each day. Furthermore, all animals were examined for reactions to treatment during the day. The onset, intensity and duration of all signs were recorded.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: All animals received a detailed clinical examination for evidence of systemic toxicity once each week.

DERMAL IRRITATION: Yes
- Time schedule for examinations: Twice each day (before administration and after the exposure period) the skin at the test site was inspected and assessed for reaction to treatment. Erythema, eschar, edema formation were scored according to the Draize scale. Skin thickening and desquamation were also noted.

BODY WEIGHT: Yes
- Time schedule for examinations: The weight of each animal was recorded once during the week before the start of treatment and once each week thereafter.

FOOD CONSUMPTION: Yes
- The quantity of food consumed by each animal was recorded once during the week before the start of treatment and once each week thereafter.

WATER CONSUMPTION: Yes
- Time schedule for examinations: Water consumption was monitored by visual inspection throughout the treatment period.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Week 13
- Anaesthetic used for blood collection: Yes (light ether).
- How many animals: 10 males and 10 females.
- Parameters checked in Table 1 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Week 13
- How many animals: 10 males and 10 females
- Parameters checked in Table 2 were examined.

URINALYSIS: Yes
- Time schedule for collection of urine: Samples were collected over a 4 hour period of food and water deprivation.
- Parameters checked in Table 3 were examined.

Sacrifice and pathology:

GROSS PATHOLOGY/ HISTOPATHOLOGY: Yes
- All animals were sacrificed and necropsied after 13 weeks dosing. Method of killing was carbon dioxide asphyxiation followed by exsanguination.
- The following organs were weighed from all animals: adrenals, brain, heart, kidneys, liver, ovaries (with fallopian tubes), pituitary, testes (plus epididymides), thyroids.
- The following tissues from all animals were examined in situ and fixed: adrenals, aortic arch, any abnormal tissue, bladder, bone (sternum and rib), brain, ears, eyes, femur, heart, intestine (duodenum, jejunum, ileum, caecum, colon, rectum), kidneys, liver, lungs (perfused), mammary gland, thyroids, tongue, mesentric lymph node, muscle (thigh), nasal cavity, oesophagus, optic nerve, ovaries (with fallopian tubes), pancreas, pituitary, prostate, sciatic nerve, seminal vesicles, skin (normal and treated), spleen, stomach (glandular and non-glandular), spinal chord (thoracic-lumbar), submaxillary salivary gland, submandibular lymph node, testes (plus epididymides), thymus, trachea, uterus.
- Samples of the above tissues were taken from all animals and placed in 10% neutral buffered formalin (except eyes which were preserved in Davidson's fluid). The lungs were fixed in their entirety by perfusion with 10% neutral buffered formalin.
- Tissues were trimmed to a maximum thickness of 3 mm for processing. Parenchymal organs were trimmed to allow the largest surface area for examination.
- Multiple sections of the kidney were prepared with mid-transverse sections through the cortex and medulla of each being submitted for examination.
- Three cross sections of the brain were included; frontal cortex and basal ganglia, parietal cortex and thalamus, and the cerebellum and medulla oblongata. Tissues were cut into 4-6 µm thickness and stained with haematoxylin and eosin.
- All fixed tissues (with the exception of spinal chord, rectum, sternum, rib, muscle, ears, eyes, optic nerve, trachea, tongue, femur and nasal cavity) were processed and examined histologically from all animals in the Control Group and the High Dose Group. Kidneys were examined histologically from all animals from all dose groups.

Statistics:

Haematology, clinical chemistry, organ weight and body weight data were statistically analysed for homogeneity of variance using the F-max test. If the group variances appeared homogenous a parametric ANOVA was used and pairwise comparisons made via Student's t-test using Fisher's F-protected LSD. If the variances were heterogeneous log or square root transformations were used in an attempt to stabilise the variances. If the variances remained heterogeneous, then a non-parametric test such as Kruskal-Wallis ANOVA was used. Organ weights were also analysed conditional on body weight (i.e. covariance and relative analyses). Histology data were analysed using Fisher's Exact Probability test.

Clinical signs:

no effects observed

Description (incidence and severity):

No treatment related effects.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

Slight desquamation and erythema noted in all animals and the control.

Mortality:

no mortality observed

Description (incidence):

No treatment related effects.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No treatment related effects.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No treatment related effects.

Food efficiency:

not examined

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

no effects observed

Description (incidence and severity):

No treatment related effects.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No treatment related effects.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No treatment related effects.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No treatment related effects.

Histopathological findings: neoplastic:

no effects observed

Description (incidence and severity):

No treatment related effects.

Details on results:

CLINICAL SIGNS AND MORTALITY: No deaths were observed during the course of the study. There were no clinical signs of toxicity observed which were considered to be related to treatment with the test material.

DERMAL IRRITATION: There were transient incidences of slight desquamation and erythema, observed at similar incidence and severity, and noted in all animals, with the exception of one female control.

BODY WEIGHT AND WEIGHT GAIN: Although there were slight variations evident in body weight gain they were within normal variability and did not show any relationship to dose level. There were no statistically significant differences in body weight during the dosing period.

FOOD CONSUMPTION: Although there were slight intergroup differences in the total food consumed these differences did not show any relationship to dose level and were within normal variability.

WATER CONSUMPTION: There were no visual intergroup differences.

HAEMATOLOGY: There were no notable intergroup differences.

CLINICAL CHEMISTRY: There were no notable intergroup differences between the males. For females there was a slight reduction in potassium in the 300 mg/kg bw/day dose group (10%, P<0.05). Due to the magnitude of this change and the absence of a similar change at the higher dose level it is not considered to be related to treatment with test material.

URINALYSIS: There were no notable intergroup differences.

ORGAN WEIGHTS: There were no notable intergroup differences between the males. After correction for final body weight in females, (covariance analysis and after relative analyses) there was a slight decrease evident in ovaries weight in the 1000 mg/kg bw/day dose group (15%, P<0.05). This decrease in ovary weight was not reflected in any histological changes it is considered that this change is a chance

GROSS PATHOLOGY: Findings were infrequent and showed no notable intergroup differences.

HISTOPATHOLOGY NON-NEOPLASTIC: There were no notable intergroup differences. At the treatment site a very mild/minimal epidermal thickening with or without slight hyperkeratosis was present in all animals with the exception of one female in the control group. This reaction was also seen in the adjacent dorsal skin in a few animals in some groups. All other findings were typical of the usual background pathology seen in rats of this age and strain at the testing facility.

HISTOPATHOLOGY NEOPLASTIC: There were no notable intergroup differences. Necrotising papillitis (unilateral) was seen in the kidney of one male animal in the 100 mg/kg bw/day dose group but was not accompanied by pelvic dilatation. The changes seen in the kidneys of this animal, urothelial hyperplasia and papillitis, are similar to the changes which have been recorded or might be expected in the early stages of pyelone-phritis induced by urinary stasis and/or the introduction of bacterial infection into the ureters. It is possible that stasis could have arisen in this study due to the pressure exerted on the abdominal contents by the dressing used to hold the patch in place. Partial obstruction of the ureters could have permitted bacteria which are normally present in the urinary tract to spread up the ureters and cause inflammation in the papilla. It is therefore concluded that there are enough published results to show that the papillary lesion seen in this study could have been caused by repeated, partial obstruction of the ureters by the dressing used to hold the patch in place. It is not possible, however, to state that this was the definite cause.

Dose descriptor:

NOEL

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed.

Critical effects observed:

not specified

Conclusions:

Under the conditions of the test, no treatment related effects or systemic signs of toxicity were observed during the study. Slight desquamation and erythema were observed in all animals, female ovary weights were slightly lower at 1000 mg/kg bw/day, necrotising papillitis was observed in one male treated at 100 mg/kg bw/day. Since no other notable adverse effects were observed to support these findings, these effects were considered to be of no toxicological relevance.

Accordingly the NOEL is considered to be greater than the highest concentration tested, 1000 mg/kg bw/day.

Executive summary:

The subchronic dermal toxicity of the test material was investigated following a procedure in line with that noted in the standardised guideline OECD 411. During the study groups of 12 male and 12 female rats were dosed daily with test material via topical application under an occlusive dressing, for a period of 6 hours per day for 13 consecutive weeks. The groups were dosed at a constant volume of 2 mL/kg bw at concentrations of 100, 300 and 1000 mg/kg bw/day in diethyl phalate. A vehicle control was run concurrently for comparison.

Under the conditions of the study there were no notable intergroup differences or toxicologically significant effects noted when assessing changes in; body weight, food consumption, water consumption, haematology, clinical chemistry, urinalysis, organ weights, necropsy findings or histological findings. Transient incidences of slight desquamation and erythema were observed, in all animals at similar incidence and severity.

Overall, exposing rats to the test material for 13 weeks with at dose levels of up to 1000 mg/kg bw/day produced no notable findings. The NOEL was therefore taken to be > 1000 mg/kg bw/day.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

In addition to the key study, two supporting studies have been provided as evidence Owston et al. (1981) and Api (2004). Both studies were assigned a reliability score of 2 in accordance with Klimisch (1997); the quality of the overall dataset is therefore high.

Additional information

Repeated Dose Dermal Toxicity The key subchronic study (Mulhern et al., 1990) investigated repeated dermal toxicity following a methodology in line with that noted in the standardised guideline OECD 411. During the study groups of 12 male and 12 female rats were dosed daily with test material via topical application under an occlusive dressing, for a period of 6 hours per day for 13 consecutive weeks. The groups were dosed at a constant volume of 2 mL/kg bw at concentrations of 100, 300 and 1000 mg/kg bw/day in diethyl phalate. A vehicle control was run concurrently for comparison. Under the conditions of the study there were no notable intergroup differences or toxicologically significant effects noted when assessing changes in; body weight, food consumption, water consumption, haematology, clinical chemistry, urinalysis, organ weights, necropsy findings or histological findings. Transient incidences of slight desquamation and erythema were observed, in all animals (including the control) at similar incidence and severity. Overall, exposing rats to the test material for 13 weeks with a dose levels of up to 1000 mg/kg bw/day produced no notable findings. The NOEL was therefore taken to be > 1000 mg/kg bw/day. The study was assigned a reliability score of 1 in line with the principles for assessing data quality as defined by Klimisch (1997) and considered suitable for assessment as an accurate reflection of the test material.

 

The supporting study, Api (2004), determined the repeated dose toxicity of the test material in a study performed to sound scientific principles. Sprague-Dawley CD rats (12 per sex per dose) were exposed to the test material at 0, 100, 300 or 1000 mg/kg bw/day for 6 hours per day over thirteen consecutive weeks. Animals were observed for clinical signs, skin irritation, body weight, food consumption and water consumption. Samples were also collected from 10 males and 10 females for urinalysis, haematology and clinical blood chemistry. After 13 weeks of dosing, animals were sacrificed and necropsied. Selected organs were examined and weighed. Histopathologic examinations were performed on major tissues from all animals in the control and high-dose groups and the kidneys from all dose groups. The control and test group animals all exhibited transient, slight desquamation and erythema of the skin sporadically throughout the dosing period. Body weight and food consumption showed only normal variability. No treatment related effects were detected in the clinical observations, mortality, haematology, blood chemistry, urinalysis or findings at necropsy, and histopathological examination. Under the conditions of the test, no local skin irritation or systemic signs of toxicity were observed up to the maximum concentration tested. Therefore the NOEL was determined to be greater than 1000 mg/kg bw/day. This study was reported with a sufficient level of detail to assess the quality of the submitted data and was assigned a reliability score of 2, in accordance with Klimisch (1997).

 

Owston et al. (1981) was also provided as supporting evidence on the basis of read-across to phenyethyl alcohol.The read-across approach has been used since phenylethyl alcohol is structurally similar to the test material but is more toxicologically active. The results presented are therefore taken to be the worst case scenario.Phenethyl alcohol was administered percutaneously to groups of Sprague-Dawley rats (15 rats/sex/dose) at 0, 0.25, 0.50, 1.00 or 2.00 mL/kg bw/day for 90 days. Control animals were not shaved and did not receive any treatment. Animals were observed for clinical symptoms of toxicity and behavioural abnormalities. Body weights and food consumption were examined weekly. Ophthalmic examinations were performed on the eyes of all animals before treatment and at week 13. Blood samples were collected at weeks 6 and 13 for haematology and clinical chemistry analysis. The rats were sacrificed at week 13 and autopsied. Microscopic examination of tissues was performed. Weight gain was depressed in both sexes given 1.00 or 2.00 mL/kg bw/day. No effect on food intake was observed. Survival rate was unaffected and ophthalmological examination was unremarkable. Male rats dosed with 2.00 mL/kg bw/day revealed a decrease in haemoglobin concentration and white blood cell count at weeks 6 and 13. Organ weight measurement at all dose levels and microscopic examination of a large variety of tissues did not reveal any treatment related effects. Significant increases in the relative weights of brain, kidneys and gonads occurred in the 2.00 mL/kg bw/day, and were related to the reduced body weights. Relative liver weights were increased at all doses among the females and both absolute and relative liver weights were decreased in males given 1.00 mL/kg bw/day. The decrease in liver weights noted in the males at 1.00 mL/kg bw/day was not observed in the 2.00 mL/kg bw/day group and was not considered to be toxicological significant. The NOEL for phenyethyl alcohol was determined to be 0.50 mL/kg bw/day, which based on the read-across approach, was considered to be the worst case scenario for the substance to be registered. The study provides sufficient details on material and methods, and also a detailed description of the results, but only body weight data are presented. The study appears to have been conducted in line with good scientific principles and is in basic compliance with the standardised OECD guideline. In line with Klimisch (1997) the study was assigned a reliability score of 2.

 

Repeated Dose Inhalation Toxicity

Exposure via the dermal route is the most appropriate route of exposure for the submitted substance. Further testing either via inhalation route is considered less appropriate and has been omitted on this basis.

 

Repeated Dose Oral Toxicity Supporting Study

The dose range-finder study was conducted according to OECD Test Guideline 407 and in compliance with GLP to evaluate the potential toxicity and to determine the dose levels for repeated dose study of the test material to Sprague-Dawley rats of both sexes for 2 weeks. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Test groups consisted of a dose group at a dose level of 0.17, 0.5 and 1.5 % groups and a control group (10 mL of Corn oil for 1 kg of powder feed containing test material) with 5 animals of each sex per group. All animals were dosed daily for 2 weeks by orally (dietary).

During the observation period, observation of clinical signs, measurement of body weights and food consumption were performed, and after the observation period, haematology and clinical chemistry, organ weight, gross post mortem examinations were performed.

No abnormal clinical signs or mortality were observed during the duration of the study.

There were no test material-related differences in body weight, food consumption, haematology, clinical chemistry, organ weights and necropsy in the animals of both sexes in the 0.17, 0.5 and 1.5 % dosing groups.

The mean total test material intakes at 0.17, 0.5 and 1.5% were 182.9, 543.7 and 1 687.1 mg/kg/day for males, and 191.7, 531.3 and 1 512.4 mg/kg/day for females, respectively.

Under the conditions of the study, the high dose level for the subsequent DRF prenatal development toxicity study should be selected at 1.5 %.

 

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:

Exposure via the dermal route is an appropriate route of exposure for the submitted substance. Further testing via the oral route is considered less appropriate and has been omitted on this basis.

 

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:

Exposure via the dermal route is an appropriate route of exposure for the submitted substance. Further testing via inhalation is considered less appropriate and has been omitted on this basis.

 

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:

Exposure via the dermal route is an appropriate route of exposure for the submitted substance. Further testing via inhalation is considered less appropriate and has been omitted on this basis.

 

Justification for selection of repeated dose toxicity dermal - systemic effects endpoint:

This study was performed to GLP and following sound scientific principles, with a sufficient level of reporting to assess the quality of the data submitted. The study was thus assigned a reliability score of 1 in line with the principles for assessing data quality as defined by Klimisch (1997).

 

Justification for selection of repeated dose toxicity dermal - local effects endpoint:

This study was performed to GLP and following sound scientific principles, with a sufficient level of reporting to assess the quality of the data submitted. The study was thus assigned a reliability score of 1 in line with the principles for assessing data quality as defined by Klimisch (1997).

Justification for classification or non-classification

According to the criteria outlined in Regulation (EC) No. 1272/2008 and Directive 67/548/EEC, the substance does not meet the criteria for classification as under repeat dose toxicity and specific organ toxicity.