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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 26-AUG-2015 to 09-FEB-2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed according to OECD 414 guideline, under GLP conditions. Test conditions and results are reported in detail.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report date:
2016

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
α,α-dimethylbenzyl hydroperoxide
EC Number:
201-254-7
EC Name:
α,α-dimethylbenzyl hydroperoxide
Cas Number:
80-15-9
Molecular formula:
C9H12O2
IUPAC Name:
1-methyl-1-phenylethyl hydroperoxide
Constituent 2
Reference substance name:
Cumene Hydroperoxide
IUPAC Name:
Cumene Hydroperoxide
Test material form:
other: liquid

Test animals

Species:
rat
Strain:
Wistar
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Germany GmbH, Sandhofer Weg 7, D-97633, from SPF colony
- Age at study initiation: young adult female rats, at least 11 weeks old at mating
- Weight at study initiation: 211-265 g.
- Fasting period before study: no
- Housing: Type II and/or III polycarbonate cages. Except during mating, successfully mated animals were housed individually.
- Diet: ssniff® SM R/M “Autoclavable Complete Feed for Rats and Mice – Breeding and Maintenance” (Ssniff Spezialdiäten GmbH, D-59494 Soest Germany), ad libitum
- Water: tap water as for human consumption, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 20.1-25.0°C (target: 22 ± 3 °C)
- Humidity (%): 31-68 % (target: 30-70%)
- Air changes: 15-20 air exchanges/hour
- Photoperiod: light 12 hours daily, from 6.00 a.m. to 6.00 p.m.

IN-LIFE DATES: From 01-SEP-2015 to 30-SEP-2015

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
propylene glycol
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The test item was formulated in the vehicle at the appropriate concentrations according to the dose level and volume selected. Formulations were prepared up to 4 days intervals based on stability assessment results when stored room temperature.

VEHICLE
- Justification for use and choice of vehicle (if other than water): the vehicle (propylene glycol) was selected in agreement with the Sponsor based on the previous experimental work including Dose Range Finding Toxicity Study.
- Concentration in vehicle: -
- Amount of vehicle (if gavage): 3 mL/kg
- Lot/batch no.: SZBE1770V
- Purity: -
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analysis of test item formulations for concentration and homogeneity was performed. using a validated HPLC method. Duplicate samples (top, middle and bottom samples) were taken from the test item formulations two times during the study (during the first and last weeks of treatment). Similarly, one sample (duplicate) was taken on each occasion from the Group 1 (control) solution for concentration measurements.
Test item content of the dosing formulations was determined twice during the treatment period. All formulations were found to be in the range of 94-101% of
nominal concentrations (5, 13.3 and 33.3 mg/mL) and were homogenous. Formulations had been shown to be of good stability. No test item was detected in the control solution.
Details on mating procedure:
- Impregnation procedure: cohoused
- M/F ratio per cage: 1/1
- Length of cohabitation: in the morning for approximately 2 hours
- Proof of pregnancy: the presence of a vaginal plug or sperm in the vaginal smear was considered as evidence of copulation (GD0).
Duration of treatment / exposure:
from Gestation Day (GD) 6 to GD19
Frequency of treatment:
once daily
Duration of test:
from Gestation Day (GD) 0 to GD20
Doses / concentrations
Remarks:
Doses / Concentrations:
15, 40 and 100 mg/kg bw/d
Basis:
other: nomimal
No. of animals per sex per dose:
24-27 mated female animals/group
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: the dose levels were set by the Sponsor based on available data including the results of a dose range finding study in the pregnant rat (see supporting study).

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least daily after the treatment
- The animals were monitored for any changes including pertinent behavioural changes and signs of toxicity including mortality, changes in skin, fur, eyes, mucous membranes, occurrence of secretions and excretions, and autonomic activity (e.g. lacrimation, piloerection, pupil size, unusual respiratory pattern), changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypies (e.g. excessive grooming, repetitive circling), bizarre behaviour (e.g. selfmutilation, walking backwards), tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on all animals at the onset of treatment (GD6), then weekly.

BODY WEIGHT: Yes
- Time schedule for examinations: on GD 0, 3, 6, 8, 10, 12, 14, 16, 18 and 20.

FOOD CONSUMPTION: Yes
- Food was measured with precision of ±0.1 g on GD0, 3, 6, 8, 10, 12, 14, 16, 18 and 20.
- Food consumption was calculated for each interval, including GD6-20 and GD0-20.

WATER CONSUMPTION: No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: the dams’ viscera were examined macroscopically for any structural abnormalities or pathological changes; kidney and stomach and all the gross findings of all females were preserved for histopathological investigation. The ovaries and uterus were removed and the pregnancy status ascertained.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: the placentas were examined macroscopically.
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: half per litter
Statistics:
The statistical evaluation of data was performed with the program package SPSS PC+4.0 by an appropriate statistical method (Bartlett, ANOVA and Duncan, Kruskal-Wallis and Mann-Whitney U tests, Chi2) using the litter as the unit for data analysis. The homogeneity of variance between groups was checked by Bartlett`s homogeneity of variance test. Where no significant heterogeneity was detected a one-way analysis of variance (ANOVA) was made. If the obtained result was significant Duncan’s Multiple Range test was used to assess the significance of inter-group differences. Significant results with inter-group comparisons were further compared using Kruskal-Wallis, and Mann-Whitney U-tests.
Indices:
Maternal data:
- Pre-implantation loss (%, group mean): (Number of corpora lutea - Number of implantations x 100) / Number of corpora lutea
- Post-implantation loss (%, group mean): (Number of implantations - Number of live foetuses x 100) / Number of implantations

Foetal Data:
- Sex distribution (%, group mean): (Number of male (female) foetuses x 100) / Number of foetuses
- External abnormalities/litter (%, group mean) : (Number of foetuses with abnormality x 100) / Number of foetuses
- Visceral abnormalities/litter (%, group mean): (Number of foetuses with abnormality x 100) / Number of foetuses
- Skeletal abnormalities/litter (%, group mean): (Number of foetuses with abnormality x 100) / Number of foetuses
Historical control data:
Historical Control Data of Hannover Wistar Rats are presented in the report for:
- dams: body weight, body weight gain, gravid uterine weight, corrected body weight and corrected body weight gain, food consumption, placena weight.
- fetuses: intrauterine mortality, viable foetuses, sex distribution data, fetal body weight, external abnormalities, visceral abnormalities, skeletal abnormalities.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
There was no unscheduled mortality during the study.
No clinical signs considered clearly related to cumene hydroperoxide administration occurred during the study.
There were no toxicologically significant differences, or test item related-changes in the reproductive parameters examined in the conditions of this study.
The number of corpora lutea, implantation sites and pre-implantation loss mean values were comparable and there were no abortions in the Control or treated groups at any of the dose levels tested.
There were no effects considered related to cumene hydroperoxide administration under the conditions of this study, on the early and late embryonic loss, pre-implantation, post-implantation (total resorption, including the early and late embryonic loss) or total intrauterine mortality in the test item-treated dams evaluated.
There were no toxicologically significant differences in the placenta.
The necropsy data on females showed clear treatment related local effects, such as multifocal/diffuse thickness of non-glandular stomach mucosa in all dose groups (almost all at the high dose, more than half at the mid dose and one at the low dose). Test item-related multifocal/diffuse thickness of non-glandular stomach mucosa was observed in 1/24, 16/24, 26/27 rats from the Low, Mid and High Dose groups, respectively. These changes were associated with few/single red foci at the mucosa in 2/24 Mid Dose and 5/26 High Dose animals. As it is not a finding seen often in controls, the incidence of the effect is considered to be adverse due to the incidence in the high and mid dose groups.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Remarks:
systemic effects
Effect level:
100 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Remarks:
local effects
Effect level:
15 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The mean number of viable foetuses was comparable with the control mean.
There is no toxicologically significant difference in the sex distribution of foetuses between the control and treatment groups. Although, at 40 and 100 mg/kg bw/day more females than males were counted (p<0.05), however the values remaining comparable with the expected physiological range (historical controls).
The weight of foetuses at 15, 40 and 100 mg/kg bw/day did not differ significantly from the control mean, when evaluated by both litter mean and group mean.
The incidence of body weight retarded foetuses was similar in the control and test item treated groups.
There was no foetal external, visceral and skeletal malformation ascribed to the test item administration.

Effect levels (fetuses)

open allclose all
Dose descriptor:
NOAEL
Effect level:
>= 100 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: embryotoxicity
Dose descriptor:
NOAEL
Effect level:
>= 100 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: fetotoxicity
Dose descriptor:
NOAEL
Effect level:
>= 100 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: teratogenicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Table 1 : Summary of Gravid Uterine Weight, Corrected Body Weight and Corrected Body Weight Gain Data of Dams

Dose group

 

Gravid uterine weight (g)

Corrected body weight (g) (day 20)

Corrected body weight (g) (day 0-20)

Corrected body weight (g) (day 6-20)

control

Mean

SD

MIN

MAX

n

58.63

9.08

40

75

24

261.42

15.57

234

297

24

48.92

9.14

33

63

24

25.71

6.38

14

37

24

15 mg/kg bw/d

Mean

SD

MIN

MAX

n

60.04

9.07

46

77

24

2.4

259.25

12.16

234

278

24

-0.8

48.13

7.50

30

61

24

-1.6

26.04

6.19

14

40

24

1.3

40 mg/kg bw/d

Mean

SD

MIN

MAX

n

55.88

8.49

43

75

24

-4.7

258.42

13.09

233

294

24

-1.1

47.08

10.51

32

79

24

-3.7

26.83

7.14

10

42

24

4.4

100 mg/kg bw/d

Mean

SD

MIN

MAX

N

±%

58.70

11.00

34

79

27

0.1

255.93

14.94

231

303

27

-2.1

43.22

13.53

14

86

27

-11.6

23.00

9.72

6

55

27

-10.5

 

 

NS

NS

NS

NS

NS = Not Significant ; ±% = Percent Deviation Versus Control

Table 2: Summary of Intrauterine Mortality, Viable Foetuses And Their Sex Distribution

 

Dose group (mg/kg bw/d

 

Control

15

40

100

Corpora Lutea (No)

Sum:

289

289

288

317

Preimplantation Loss (1)

Sum:

%:

29

10

22 NS

8

36 NS

13

21 NS

7

Implantation (%) (1)

Sum:

%:

260

90

267 NS

92

252 NS

88

296 NS

93

Early Embryonic Loss (2)

Sum:

%:

8

3

7 NS

3

16 NS

6

12 NS

4

Late Embryonic Loss (2)

Sum:

%:

3

1

1 NS

0

3 NS

1

2 NS

1

Dead Foetuses (2)

Sum:

%:

2

1

0 NS

0

0 NS

0

0 NS

0

Total Post-implantation Loss (2)

Sum:

%:

13

5

8 NS

3

19 NS

8

14 NS

5

Total Intrauterine Mortality (1)

Sum:

%:

42

15

28 NS

10

55 NS

19

35 NS

11

Viable Foetuses (No.) (2)

Sum:

%:

247

95

259 NS

97

233 NS

92

282 NS

95

Male Foetuses (3)

Sum:

%:

129

52

117 NS

45

100 *CH

43

122 *CH

43

Female Foetuses (3)

Sum:

%:

118

48

142 NS

55

133 *CH

57

160 *CH

57

NS = Not Significant ; CH = Chi Square Test ; * = p < 0.05 ; ** = p < 0.01

1: Data compared to no. of corpora lutea – 2: Data compared to no. of implantations – 3: Data compared to no. of viable Foetuses

Table 3: Summary of Foetal Body Weight Data - Litter Means and All Foetus (g)

 

control

15 mg/kg bw/d

40 mg/kg bw/d

100 mg/kg bw/d

 

Body weight: male and female (g)

MEAN

SD

MAX

MIN

N

±%

3.406

0.32

4.13

1.91

247

3.376

0.29

4.16

2.12

259

-0.9

3.439

0.34

4.37

2.07

233

1.0

3.384 NS

0.30

4.01

1.92

282

-0.7

 

Foetus Mean Weight/Litter (g)

MEAN

SD

MAX

MIN

N

±%

3.405

0.20

3.66

2.82

24

3.379

0.16

3.63

3.09

24

-0.8

3.443

0.23

3.87

3.09

24

1.1

3.374 NS

0.19

3.73

3.02

27

-0.9

 

Retarded In Bodyweight

N

±%

8

3.2

7 NS

2.7

11 NS

4.7

9 NS

3.2

NS = Not Significant

Applicant's summary and conclusion

Conclusions:
Cumene Hydroperoxide administered to pregnant Hannover Wistar rats by oral gavage at dose levels of 15, 40 and 100 mg/kg bw/day, daily from gestation
days GD 6 to 19, was not associated with a developmental toxicity. The NOAEL developmental toxicity is ≥ 100 mg/kg bw/day.
Executive summary:

A developmental toxicity study (according to OECD TG 414, GLP) was performed to assess the effects of Cumene Hydroperoxide on the embryonic and foetal development (including the organogenesis period) of Hannover Wistar rats. The dams (one control and 3-treated groups) were treated daily by oral (gavage) administration, from gestation day GD6 up to and including GD19. Caesarean sections, necropsy of dams and examination of uterine contents were performed on GD20.

The dose levels were 15, 40 and 100 mg/kg bw/day. All formulations were within the range of 94 to 101% of nominal concentration and were homogenous. Control dams were treated with a vehicle (propylene glycol) only.

NOAELmaternal systemic toxicity: 100 mg/kg bw/day

NOAELmaternal local toxicity: 15 mg/kg bw/day

NOAELembryotoxicity: ≥ 100 mg/kg bw/day

NOAELfoetotoxicity: ≥ 100 mg/kg bw/day

NOAELteratogenecity: ≥ 100 mg/kg bw/day

There was no unscheduled mortality, test item related clinical signs or changes in the body weight, body weight gain or animal food consumption during the study.

There were no toxicologically significant differences, or test item related-changes in the reproductive parameters examined in the conditions of this study.

The number of corpora lutea, implantation sites and pre-implantation loss mean values were comparable and there were no abortions in the Control or treated groups at any of the dose levels tested.

There were no effects considered related to Cumene Hydroperoxide administration under the conditions of this study, on the early and late embryonic loss, pre-implantation, post-implantation (total resorption, including the early and late embryonic loss) or total intrauterine mortality in the test item-treated dams evaluated.

The necropsy data on females showed clear treatment related local effects, such as multifocal/diffuse thickness of non-glandular stomach mucosa in all dose groups (almost all at the high dose, more than half at the mid dose and one at the low dose). These changes were associated with few/single red foci at the mucosa in the mid and high dose animals. The toxicological significance of these observations cannot be evaluated in the absence of histopathology examination, however as this finding is not seen often in controls, the incidence of this effect is considered to be adverse in the high and mid dose groups.

The mean number of viable foetuses was comparable with the control mean.

The sex distribution of foetuses did not differ significantly between the control and treatment groups both for mean and absolute numbers.

There were no toxicologically significant differences in the placenta.

The weight of foetuses at 15, 40 and 100 mg/kg bw/day did not differ significantly from the control mean, when evaluated by both litter mean and group mean.

The incidence of body weight retarded foetuses was similar in the control and test item treated groups.

There was no foetal external, visceral and skeletal malformation ascribed to the test item administration.