1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)propane-1,3-dione

Repeated dose toxicity: dermal

Administrative data

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1979-11-08 - 1980-06-27

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1980

Report date:

1980

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

Deviations:

yes

Remarks:

: use of intact as well as abraded skin

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)propane-1,3-dione

EC Number:

274-581-6

EC Name:

1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)propane-1,3-dione

Cas Number:

70356-09-1

Molecular formula:

C20H22O3

IUPAC Name:

1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)propane-1,3-dione

Test material form:

solid

Details on test material:

- Name of test material : BMDBM
- Substance type: light yellowish powder
- Physical state: solid

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hacking & Churchill Ltd. Wyton, Huntingdon, Cambs., England
- Age at study initiation: 11 -14 weeks
- Weight at study initiation: 2.0 - 2.8 kg
- Housing: individually
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 20 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 °C
- Humidity (%): 45 ± 10 %
- Air changes (per hr): 19

IN-LIFE DATES: From: 1979-11-08 To:1979-11-30

Administration / exposure

Type of coverage:

occlusive

Vehicle:

other: Carbitol (diethylene glycol monoethyl ether)

Details on exposure:

TEST SITE
- Area of exposure: mid dorsal
- % coverage: approx. 10 % of body surface
- Type of wrap if used: occlusive bandage consisting of a gauze covered with Elastoplast elastic adhesive dressing backed with impervious Sleek plaster.
- Time intervals for shavings or clippings: Abrasion was carried out weekly and hair clipping was repeated daily.

REMOVAL OF TEST SUBSTANCE
- Washing: with warm tap water
- Time after start of exposure: 6 h

TEST MATERIAL
- Concentration: 30, 100, and 360 mg/kg bw/day
- Constant volume used: yes
- For solids, paste formed: yes

VEHICLE
- Justification for use and choice of vehicle (if other than water): Carbinol, due to the good solubility of the test item
- Amount(s) applied: 2 mL/kg bw/day
- Lot/batch no.: 19431787 and B711019

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

6 h per day

Frequency of treatment:

21 days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

30 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

360 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10 males and 10 females per dose group. Half of the animals were tested with intact the other half was tested with abraded skin.

Control animals:

yes, concurrent no treatment

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: tested up to the highest soluble concentration

Positive control:

No positive control used.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: daily, prior to application

BODY WEIGHT: Yes
- Time schedule for examinations: at the start of dosing and then twice weekly (days 1, 5, 8, 12, 15, 19, and 22)

FOOD CONSUMPTION:
- Food consumption for each animal determined: Yes

WATER CONSUMPTION: Yes
- Time schedule for examinations: only during week 3

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: prior to treatment and then during the 3rd week of treatment
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals: prior to treatment: all animals; during the 3rd week of treatment: 5 male and 5 female rabbits with abraded skin from each group
- Parameters checked in table 1 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: prior to treatment and then during the 3rd week of treatment
- Animals fasted: Yes
- How many animals: prior to treatment: all animals; during the 3rd week of treatment: 5 male and 5 female rabbits with abraded skin from each group
- Parameters checked in table 1 were examined.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (see table)
HISTOPATHOLOGY: Yes (see table) / No / No data

Statistics:

Analysis of variance followed by Student's t-test was used to assess the significance of intergroup differences in clinical laboratory data.

Results and discussion

Results of examinations

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

No behavioural changes or signs of toxicosis were observed amongst surviving rabbits during the study period. Soft faeces and/or diarrhoea of a sporadic nature were observed in surviving rabbits from all groups, including the controls. This finding was considered to be incidental and not related to treatment with butyl methoxydibenzoylmethane (BMDBM).

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

(Tables 5a and b)
Sporadic slight erythema was observed in three negative control rabbits during week 3 of the study.
Slight dermal reactions were generally seen in all rabbits treated with Carbitol (vehicle control) during weeks 2 and 3 of the study and well-defined erythema was recorded in five rabbits of this group during week 3.
The severity of dermal reactions of rabbits receiving BMDBM was generally greater than the controls and increased in a dosage-related manner. Slight to well-defined dermal reactions were observed from Day 6 to the end of the treatment period in all rabbits treated with BMDBM 30 or 100 mg/kg/day, although well-defined reactions were more persistent in rabbits of Group 4 (BMDBM, 100 mg/kg/day). Well-defined to moderate dermal reactions were generally seen in all rabbits treated with BMDBM, 360 mg/kg/day during this period.
Dryness and sloughing of the epidermis was observed in the majority of rabbits treated with BMDBM and the incidence was seen to increase with dosage. This finding was also observed in only 3 rabbits treated with Carbitol (vehicle control) but was not observed in procedural control rabbits.
There were no apparent differences in the dermal reactions of rabbits with intact or abraded skin condition within each group.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

Five rabbits died during the study period and one rabbit was sacrificed in extremis. The distribution of the animal mortality was not dependent on test item treatment and is tabulated in table 3.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

No treatment-related trends were apparent (Table 4). Bodyweight losses on day 19 in the majority of the control and treated rabbits with abraded skin were considered to be a result of overnight food deprivation prior to removal of blood samples on day 19.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No treatment-related trends were apparent.

Food efficiency:

not examined

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

no effects observed

Description (incidence and severity):

No treatment-related trends were apparent.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

There were no changes that were considered to be related to treatment with BMDBM.
Statistical analysis of values from the week 3 investigations revealed statistical significances in comparison to the controls. These differences were not considered to be of toxicological importance and variations in values for individual rabbits were considered to bias statistical analysis in these instances.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

There were no apparent changes that were considered to be directly related to treatment with BMDBM.
Statistical analysis of values from the week 3 investigations revealed statistical significances in comparison to the controls. These differences were not considered to be of toxicological importance and variations in values for individual rabbits were considered to bias statistical analysis in these instances.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No changes were seen that were considered to be related to treatment with BMDBM.
Group mean organ weights for some groups attained statistical significance in comparison with control values. These findings were not considered to be of toxicological importance and variations in values for individual rabbits were considered to bias statistical analysis in these instances.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No changes were seen that were considered to be indicative of a treatment-related effect.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, non-treatment-related

Description (incidence and severity):

Skin: No abnormalities were seen in skin taken from procedural control group rabbits or from the untreated control sites on the animals in the treated groups. In treated skin samples from the vehicle control group and the treatment groups a minimal focal to moderate generalised increase in epidermal thickness was recorded. This was occasionally but in frequently associated with a minimal cutaneous inflammatory infiltration. No quantitative differences could be determined between animals with intact or abraded skin.
The severity of the epidermal change showed no dose-relationship in treated groups and this was considered to be similar to the severity if this change observed in the vehicle control group.
Liver: Pericholangitis characterised by occasional parenchymal or portal foci if mononuclear cell infiltration in a proportion of animals from each group. Hepatocyte necrosis in occasional rabbits.
Kidneys: Varying degrees of chronic interstitial nephritis and fibrosis in a large proportion of rabbits from both control and treatment groups. No significant differences in terms of severity are distinguishable that might be ascribed to the vehicle or the test compound.
Gastro-intestinal tract: Chronic inflammatory bowel lesions of the gastro-intestinal mucosa in a small number of rabbits at termination and in all decedents. These lesions were probably due to a localised infection and considered a contributing factor to death in the decedents in this study. This was considered to be unrelated to treatment.
Brain: Perivascular inflammatory cuffing and cerebral gliosis and granulomata in a proportion of rabbits from all groups. These lesions were probably indicative of an enzephalitozoon infestation.

Histopathological findings: neoplastic:

not examined

Effect levels

1

Key result

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

360 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

2

Key result

Dose descriptor:

LOAEL

Remarks:

systemic

Effect level:

> 360 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: As the animals showed no systemic signs of toxicity with the highest concentration used, no LOAEL for systemic toxicity could be identified.

Remarks on result:

not determinable due to absence of adverse toxic effects

3

Dose descriptor:

LOAEL

Remarks:

local

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: In this concentration, distinct local effects (formation of erythema / edema) were visible after treatment.

Target system / organ toxicity

Key result

Critical effects observed:

not specified

Any other information on results incl. tables

Table 3: Summarized mortalities after repeated dermal application of butyl methoxydibenzoylmethane (BMDBM) to rabbits.

Group		Mortalities		Total per group	Mortality
		Males	Females
1	Negative control	0	2	2/20	10 %
2	Vehicle control	2	0	2/20	10 %
3	BMDBM 30 mg/kg bw/day	0	1	1/20	5 %
4	BMDBM 100 mg/kg bw/day	0	0	0/20	0 %
5	BMDBM 360 mg/kg bw/day	1	0	1/20	5 %

 

Table 4: Group mean bodyweights (g) of rabbits after repeated dermal application of BMDBM.

Group		Skin	Bodyweight [g] on day							Bodyweight change days 1 - 22	as % of controls
			0	5	8	12	15	19	22
Male
1	Negative control	Intact Abraded	2927 2968	2895 3026	2939 3068	3037 3177	3088 3262	3063 3171	3106 3270	179 302	- -
2	Vehicle control	Intact Abraded	2928 2962	2936 2980	2931 3023	2990 3162	3086 3203	2994 3134	3360 3286	432 324	241 107
3	BMDBM 30 mg/kg bw/day	Intact Abraded	2962 2947	2976 2992	3013 3046	3082 3127	3156 3201	3194 3056	3212 3216	250 269	140 89
4	BMDBM 100 mg/kg bw/day	Intact Abraded	2943 2938	2981 2935	3010 3012	3093 3100	3195 3171	3237 3130	3263 3213	320 275	179 91
5	BMDBM 360 mg/kg bw/day	Intact Abraded	2934 2942	2950 2926	2934 2981	3047 3077	3056 3157	3114 3109	3151 3252	217 310	121 103
Female
1	Negative control	Intact Abraded	2873 2854	2907 2781	2912 2910	2923 2984	2961 3085	3022 3030	3002 3080	129 226	- -
2	Vehicle control	Intact Abraded	2871 2871	2928 2910	3047 2903	3145 3028	3224 3093	3296 3105	3329 3184	458   313	355 138
3	BMDBM 30 mg/kg bw/day	Intact Abraded	2888 2866	2875 2860	2910 2897	2949 3004	3008 3120	3116 3049	3131 3189	243 323	188 143
4	BMDBM 100 mg/kg bw/day	Intact Abraded	2861 2861	2934 2917	2980 2948	3072 3007	3122 3082	3240 3114	3255 3114	394 253	305 112
5	BMDBM 360 mg/kg bw/day	Intact Abraded	2856 2785	2927 2858	2961 2908	3063 2988	3165 3084	3213 2971	3280 3128	424 343	329 152

 

Table 5a: Mean erythema (E) and oedema (O) scores after repeated dermal application of butyl methoxydibenzoylmethane (BMDBM) to 5 male rabbits (intact skin).

Day	Negative control		Vehicle control		BMDBM [mg/kg bw/day]
					30		100		360
Erythema/Oedema:	E	O	E	O	E	O	E	O	E	O
1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
2	0.0	0.0	0.0	0.0	0.0	0.0	0.2	0.0	0.0	0.0
3	0.0	0.0	0.0	0.0	0.4	0.0	0.6	0.2	0.6	0.8
4	0.0	0.0	0.2	0.0	1.0	0.0	1.2	0.8	1.0	1.2
5	0.0	0.0	0.4	0.2	1.0	0.8	1.6	1.0	1.2	1.8
6	0.0	0.0	0.0	0.0	0.8	0.8	1.8	1.8	2.0	2.0
7	0.0	0.0	0.4	0.0	1.2	0.8	1.6	2.0	2.0	2.0
8	0.0	0.0	0.6	0.2	1.0	1.0	1.6	2.0	2.0	2.0
9	0.0	0.0	0.2	0.0	1.0	0.6	1.6	1.2	2.0	1.8
10^1	0.0	0.0	0.8	0.0	1.0	0.8	1.8	1.4	2.0	2.0
11	0.0	0.0	0.5	0.0	0.8	0.6	1.6	1.4	2.0	2.0
12	0.0	0.0	1.0	0.0	1.0	0.6	1.6	1.6	2.0	2.0
13	0.0	0.0	0.8	0.0	1.0	0.6	1.6	1.2	2.0	2.2
14	0.0	0.0	0.8	1.0	1.0	0.8	1.8	1.2	2.0	2.4
15	0.0	0.0	0.8	0.3	1.2	0.8	2.0	1.6	2.0	2.0
16	0.0	0.0	0.8	0.3	1.2	0.6	2.0	1.6	2.0	1.6
17	0.0	0.0	0.8	0.3	1.2	0.8	2.0	1.6	2.0	1.8
18	0.0	0.0	0.8	0.3	1.2	0.8	2.0	1.8	2.0	1.8
19	0.4	0.4	1.3	0.5	1.2	1.0	1.6	1.8	2.0	2.2
20	0.0	0.0	1.0	0.5	1.2	1.0	1.8	1.8	2.0	2.0
21	0.0	0.0	1.3	0.5	1.2	1.0	2.0	1.8	2.0	2.0
22^2	0.0	0.0	1.3	0.3	1.2	1.0	2.0	1.8	2.0	2.2
23	0.0	0.0	1.3	1.0	1.0	1.0	2.0	2.0	2.0	2.0

¹ 1 out of 5 animals was found dead in the negative control group

² 1 out of 5 animals was found dead in the negative control group

 

Table 5b: Mean erythema (E) and oedema (O) scores after repeated dermal application of butyl methoxydibenzoylmethane (BMDBM) to 5 female rabbits (intact skin).

	Negative control		Vehicle control		BMDBM [mg/kg bw/day]
					30		100		360
Erythema/Oedema:	E	O	E	O	E	O	E	O	E	O
1	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
2	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
3	0.0	0.0	0.2	0.0	0.6	0.0	0.6	0.2	0.4	0.0
4	0.0	0.0	0.4	0.0	0.6	0.0	0.8	0.4	1.4	0.8
5	0.0	0.0	0.8	0.4	1.4	1.4	1.2	1.4	2.0	1.8
6	0.0	0.0	0.4	0.0	1.2	1.0	1.8	1.6	2.2	2.0
7	0.0	0.0	0.4	0.2	1.0	1.2	1.6	1.8	2.2	2.0
8^1	0.0	0.0	0.2	0.0	1.0	1.3	1.4	1.8	2.0	2.0
9	0.0	0.0	0.0	0.0	1.0	0.3	1.6	1.2	2.0	1.8
10	0.0	0.0	0.0	0.0	1.0	0.8	1.6	1.4	2.0	2.0
11	0.0	0.0	0.8	0.4	1.0	0.5	1.8	1.4	2.0	2.0
12^2	0.0	0.0	0.8	0.4	1.0	1.0	2.0	1.6	2.0	2.0
13	0.0	0.0	0.8	0.2	1.0	0.8	2.0	1.4	2.0	2.2
14	0.0	0.0	0.8	0.2	1.0	1.0	2.0	1.8	2.0	2.4
15	0.0	0.0	0.8	0.2	1.5	1.0	2.0	1.6	2.2	2.2
16^3	0.0	0.0	0.8	0.4	1.3	0.3	2.0	1.0	1.8	2.0
17	0.0	0.0	0.8	0.6	1.3	0.5	2.0	1.0	2.0	2.0
18	0.0	0.0	0.8	0.6	1.5	0.8	2.0	1.2	2.0	2.0
19	0.0	0.0	1.0	0.8	1.0	1.0	1.6	1.2	2.0	2.0
20	0.0	0.0	1.0	1.0	1.0	1.0	1.8	1.4	2.0	2.2
21	0.0	0.0	1.2	0.8	1.0	1.0	2.0	1.6	2.0	2.6
22	0.0	0.0	1.0	0.8	1.0	1.0	1.8	1.8	2.0	2.2
23	0.0	0.0	1.0	0.0	1.0	1.0	2.0	2.0	2.0	2.3

¹ 1 out of 5 animals was found dead in the 30 mg/kg bw group

² 1 out of 5 animals was found dead in the negative control group

³ 1 out of 5 animals was found dead in the negative control group

Applicant's summary and conclusion

Conclusions:

Repeated (21 days) dermal application of BMDBM (30, 100, and 360 mg/kg bw/day) to the intact or abraded skin of rabbits caused no deaths. Therefore, the NOAEL for systemic toxicity was set to the highest applied dose of 360 mg/kg bw/day. There was a dosage-related increase in the severity of dermal reactions of rabbits treated with BMDBM, including slight to moderate erythema and edema. The respective vehicle control exhibited only slight dermal reactions.

Executive summary:

BMDBM, a crystalline sun protection substance, was prepared freshly each day as 1.5, 5 and 18 % w/v solutions in Carbitol and applied to the skin of rabbits once daily at dosage levels of 30, 100 and 360 mg/kg bw/day, for an exposure period of six hours each day, for twenty-one consecutive days.

There was a dosage-related increase in the severity of dermal reactions of rabbits treated with BMDBM. Slight to well-defined dermal reactions were generally observed in rabbits treated with BMDBM 30 or 100 mg/kg bw/day, although well-defined reactions were more persistent in rabbits treated with BMDBM, 100 mg/kg bw/day. Well-defined to moderate dermal reactions were generally seen in rabbits treated with BMDBM, 360 mg/kg/day. Slight dermal reactions occurred in the vehicle control animals (Carbitol). Microscopic examination of the treated skin sites revealed an increased incidence of epidermal thickening in rabbits from the vehicle control and treatment groups when compared to the untreated control group. Five rabbits were found dead during the study and one rabbit was sacrificed. The death of these animals was not considered to be directly related to treatment. Histopathological examination revealed gastrointestinal infection to be a factor contributory to the death of each animal.

In all other aspects including general health, bodyweights, food consumption, water consumption, haematology, blood chemistry, organ weights macroscopic pathology, and microscopic pathology of tissues excluding skin, rabbits treated with BMDBM were similar to the procedural and vehicle controls. Therefore, the NOAEL, based on systemic effects, can be considered to be 360 mg/kg bw/day.