OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Effects on developmental toxicity

Description of key information

OECD 414 study

The potential toxic effects of TBEC on the pregnant female and on embryonic and fetal development, following daily oral administration (gavage) to pregnant female rats from implantation until the day before scheduled hysterectomy [Day 6 to Day 20 post-coitum (p.c.) inclusive] (Papineau, 2018). This GLP study was carried out according to OECD test guideline No. 414 (22 January 2001). Three groups of 24 time-mated female Sprague-Dawley rats received the test item by the oral route (gavage), at dose levels of 200, 600 or 1000 mg/kg/day, once daily from Day 6 to Day 20 p.c. inclusive. Another group of 24 time-mated female rats received the vehicle only, corn oil, under the same experimental conditions and acted as a control group. A constant dosage volume of 5 mL/kg/day was used. The test item concentrations in the dose formulations were determined. The animals were checked daily for mortality and clinical signs. Body weight and food consumption were recorded at designated intervals. On Day 21 p.c., the females were euthanized and a macroscopic post-mortem examination was performed. Hysterectomy was performed and the numbers of corpora lutea, implantation sites, uterine scars, early and late resorptions, and live and dead fetuses were recorded. The fetuses were weighed, sexed and examined for external, soft tissue and skeletal abnormalities (including cartilage). The liver and the kidneys of each dam were weighed and samples of liver, kidney and stomach were collected and preserved in 10% buffered formalin.

The concentrations of the test item in the dose formulations (-2.6% to +9.0%) remained within an acceptable range of variations (± 10%) when compared to the nominal concentrations. No test item was found in the control dose formulation. All females were pregnant with the exception of two females given 200 mg/kg/day and one female given 1000 mg/kg/day. There were no unscheduled deaths. Ptyalism was noted in 14/24 females given 600 mg/kg/day and in 24/24 females given 1000 mg/kg/day. This finding was considered to be test item treatment-related but non-adverse. There were no effects on body weight or body weight change at any dose level.  At 1000 mg/kg/day, lower food consumption (-13% vs. controls, p < 0.05) was observed between Days 6 and 9 p.c., with a return to control values thereafter. This finding was considered to be test item treatment-related but non-adverse. Brownish colored foci were observed on the stomach mucosa at the high-dose level in 1/24 females. This finding was considered to be non-adverse, and a test item treatment relationship was considered to be doubtful. There were no test item-related changes in liver or kidney weights. There were no effects on mean carcass weight, net body weight gain or gravid uterus weight. There were no effects on hysterectomy parameters (mean numbers of corpora lutea, implantation sites, pre-implantation loss, live fetuses and post-implantation loss).

From 200 mg/kg/day and when compared with controls, statistically significant lower mean fetal body weights were noted. They were mainly due to the lower body weight of female fetuses at 200 mg/kg/day (males: -3% and females: -5% with p<0.01 vs. controls), 600 mg/kg/day (males: -3% and females: -4% with p<0.05 vs. controls) and 1000 mg/kg/day (males: -5% with p<0.05 and females: -5% with p<0.01 vs. controls). As these minimal changes were within the range of the Historical Control Data and mainly resulted from control values higher than the upper limit of the Historical Control Data, a relationship with the test item is questionable. There were no toxicological effects on sex-ratio at any dose level. There were no variations and no test item treatment-related malformations at external examination. There were no test item treatment-related variations or malformations at soft tissue examination. At 600 and/or 1000 mg/kg/day and when compared with controls, there were higher litter and fetal incidences of fetuses within complete ossification of interparietal, hyoid and/or 6thsternebra and/or unossification of forepaw proximal phalanx and/or 1stmetatarsal. As incidences of these non-adverse findings (the cartilage/bone structure still present) were lower than that observed in the Historical Control Data and as control incidences were below the lower limit or in the low range of the Historical Control Data, a relationship with the test item is questionable. There were no test item-related malformations at skeletal examination.

TBEC was administered to pregnant Sprague-Dawley rats by gavage, once daily, from Day 6 to Day 20 p.c., inclusive, at the dose levels of 200, 600 and 1000 mg/kg/day. A control group received the vehicle, corn oil, under the same experimental conditions.

On the basis of the results obtained in this study:

. the No Observed Adverse Effect Level (NOAEL) for maternal parameters is considered to be 1000 mg/kg/day,

. the NOAEL for embryo-fetal development is considered to be 1000 mg/kg/day.

 

Range-finding study

The potential toxic effects of Luperox TBEC on the pregnant female and on embryonic and fetal development was evaluated, following daily oral administration (gavage) to pregnant female rats from implantation to the day before scheduled hysterectomy [Day 6 to Day 20 post-coitum (p.c.) inclusive], in order to select dose levels for a further main study (Papineau, 2017). Three groups of eight time-mated female Sprague-Dawley rats received the test item at 200, 600 or 1000 mg/kg/day, once daily from Day 6 to Day 20 p.c. by oral gavage. Another group of eight time-mated rats received the vehicle, corn oil, under the same experimental conditions and acted as a control group. All animals were checked daily for mortality and clinical signs. Body weight and food consumption were recorded regularly. After sacrifice, a macroscopicpost-mortemexamination of the females was performed on Day 21p.c.Liver and kidneys were weighed and preserved, along with stomach, in 10% buffered formalin. Hysterectomies were performed and the numbers and distribution ofcorpora lutea, implantation sites, early and late resorptions, uterine scars, and live and dead fetuses were recorded. The fetuses were sexed, weighed, examined for oral cavity and external abnormalities, and preserved for possible skeletal and soft tissues examination. 

All females were pregnant with the exception of one control female and one female given 1000 mg/kg/day. There were no unscheduled deaths. Ptyalism was transiently observed in all females given 600 or 1000 mg/kg/day. There were no relevant effects on body weight, body weight change or food consumption. At terminal sacrifice, slight increases in absolute and relative liver weights were noted at 600 and 1000 mg/kg/day. There were no test item-related macroscopic findings. There were no effects on hysterectomy parameters. There were no effects on fetal body weight or on percentage of male fetuses (sex ratio). At 1000 mg/kg/day, and when compared with controls or historical control data, there were higher litter and fetal incidences of fetuses with variations (i.e.reddish color of aminiotic fluid and protruding tongue) and/or malformations (i.e.short snout, misshapen genital tubercle, exencephaly and cleft palate).As these malformations were no longer observed in the main OECD 414 study at the same dose level of 1000 mg/kg/day and on a larger number of fetuses, there were considered of spontaneous origine.

Based on these findings and in the absence of maternal toxicity, 1000 mg/kg/day could be considered as a suitable high-dose level for the main embryo-fetal developmental study with TBEC.

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 October 2017 - 30 November 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

22 January 2001

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: breeder: Janvier, le Genest-Saint-Isle, France
- Age: at the beginning of the treatment period, the animals were 10-11 weeks old
- Mean body weight: at the beginning of the treatment period, the animals had a mean body weight of 291 g (range: 241 g to 334 g)
- Fasting period before study: no
- Housing: the animals were individually housed in polycarbonate cages (Tecniplast 2154, 940 cm2)
- Diet: SSNIFF R/M-H pelleted diet (free access)
- Water: tap water filtered with a 0.22 µm filter (free access)
- Acclimation period: for a period of 4 or 5 days before the beginning of the treatment period.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2°C
- Humidity (%): 50 ± 20%
- Air changes (per hr): about 8 to 15 cycles/hour of filtered, non-recycled air
- Photoperiod (hrs dark / hrs light): 12 h/12 h.

IN-LIFE DATES: 06 November 2017 to 30 November 2017.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING FORMULATIONS:
- Solution in the vehicle
- Concentration in vehicle: 40, 120 and 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg/day

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Type of method: High Performance Liquid Chromatography with tandem Mass Spectrometry detection (LC/MS MS).
Test item concentrations: a sample was taken from control and test item dose formulations and analyzed using the validated method.
Homogeneity: dose formulation is a solution
Stability: the stability of dose formulation preparations was demonstrated for up to 23 days when stored in plastic vial at room temperature and protected from light.
Dose formulations ranging from 5 mg/mL to 200 mg/mL are therefore considered to be suitable for routine administration in GLP Toxicological studies within the stability period validated.

Details on mating procedure:

The females were mated at the breeder's facilities. The day of confirmed mating (detection of a vaginal plug) was designated Day 0 p.c.

Duration of treatment / exposure:

From Day 6 to Day 20 p.c., inclusive.

Frequency of treatment:

Daily

Dose / conc.:

200 mg/kg bw/day (actual dose received)

Dose / conc.:

600 mg/kg bw/day (actual dose received)

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

24 females

Control animals:

yes, concurrent vehicle

Details on study design:

- Rationale for dose selection:
The dose levels were selected by the Sponsor based on a preliminary study for effects on embryo-fetal development by the oral route in rats.
In this study, three groups of eight pregnant female Sprague-Dawley rats received the test item, daily by oral administration (gavage) throughout gestation (Day 6 to Day 20 p.c.) at dose levels of 200, 600 or 1000 mg/kg/day. An additional group of eight pregnant females received the vehicle control, corn oil, under the same experimental conditions. The dosage volume was 5 mL/kg/day.
At 1000 mg/kg/day, there was:
- ptyalism in all females,
- slight increases in the absolute and relative mean liver weights,
- no effects on pre- or post-implantation losses, number of viable fetuses and fetal body weight,
- higher litter and fetal incidences of fetuses with variations (i.e. protruding tongue and reddish color of amniotic fluid) and/or malformations (i.e. short snout, misshapen genital tubercle, exencephaly and cleft palate).

At 600 mg/kg/day, there was ptyalism in all females and slight increases in the absolute and relative mean liver weights.
At 200 mg/kg/day, there were no findings.

Based on the above data, the dose levels selected for the present study were: 200, 600 and 1000 mg/kg/day.

- Rationale for animal assignment: computerized stratification procedure.

Maternal examinations:

MORTALITY/MORBIDITY:
- Time schedule: each animal was checked for mortality and morbidity once a day before the treatment period and at least twice a day during the treatment period, including weekends and public holidays.

CLINICAL SIGNS:
- Time schedule: from arrival, each animal was observed once a day as part of the routine examinations.
From the start of the treatment period, each animal was observed at least once a day, at approximately the same time, for the recording of clinical signs.

BODY WEIGHT:
- Time schedule: the body weight of each female was recorded on Days 2, 4, 6, 9, 12, 15, 18 and 21 p.c.

FOOD CONSUMPTION:
- Time schedule: the quantity of food consumed by each female was recorded for the following intervals: days 2-4, 4-6, 6-9, 9-12, 12-15, 15-18 and 18-21 p.c.

- ORGAN WEIGHTS:
The body weight of each animal was recorded before euthanasia at the end of the treatment period. The organs specified in the Tissue Procedure Table were weighed wet as soon as possible after dissection.
The ratio of organ weight to net body weight was calculated.


POST-MORTEM MACROSCOPIC EXAMINATION:
- Sacrifice on Day 21 post-coitum.
- Examined: principal thoracic and abdominal organs

Ovaries and uterine content:

The ovaries and uterine content were examined after termination, including:
- gravid uterus weight,
- number of corpora lutea,
- number and distribution of dead and live fetuses,
- number and distribution of early and late resorptions,
- number and distribution of uterine scars,
- number and distribution of implantation sites,
- gross evaluation of placentas.

Fetal examinations:

- External examinations: Yes: all fetuses per litter
- Soft tissue examinations: Yes: half fetuses per litter
- Skeletal examinations: Yes: half fetuses per litter
- Head examinations: Yes: half fetuses per litter
- Other: body weight, sex.

Statistics:

Data were compared by one-way analysis of variances and Dunnett test (mean values being considered as normally distributed, variances being considered as homogenous) or by Fisher’s exact probability test (proportions).

Indices:

% Pre-implantation loss = 100 * (Number of corpora lutea - Number of implantation sites) / Number of corpora lutea
% Post-implantation loss = 100 * (Number of implantation sites - Number of live fetuses) / Number of implantation sites

Historical control data:

Cf attached document

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

See table 1.
Test item-related clinical signs of minor toxicological importance consisted of ptyalism, observed for 2 to 12 days in most females given 600 mg/kg/day and in all females given 1000 mg/kg/day.

Reflux at administration, noted on one occasion in 1/24 females given 1000 mg/kg/day, resulted from the gavage procedure.

The other clinical signs consisted of cutaneous lesions on the head (1/24 control females), areas of hair loss on forelimbs (2/24 females given 600 or 1000 mg/kg/day) and/or scab on the neck (1/24 control females and 1/24 females given 1000 mg/kg/day). These findings were considered to be unrelated to the test item as they were also reported in control animals, in a limited number of test item-treated animals and/or are findings commonly observed in rats of this strain and age.

Mortality:

no mortality observed

Description (incidence):

There were no unscheduled deaths.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

See table 2.
There were no effects on mean body weight.

At 1000 mg/kg/day and when compared with controls, a slightly higher mean body weight gain was noted between Days 9 and 12 p.c. (+24 g vs. +19 g in controls). As this difference was transient, of minimal amplitude and mainly due to one female that gained 40 g, a test item relationship was considered to be unlikely.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

See table 3.
At 1000 mg/kg/day, when compared with controls, a lower mean food consumption (-13%, p<0.05) was noted between Days 6 and 9 p.c., with a return towards control values thereafter. This finding was considered to be test-item treatment related but non-adverse.

At 200 and 600 mg/kg/day, there were no effects on mean food consumption.

Food efficiency:

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

There were no test item-related changes in liver or kidney weights.

Differences in organ weights were minor and reflected the usual range of individual variations.
When compared with controls, the mean absolute and relative liver weights were minimally higher (up to +8%) in females at 1000 mg/kg/day, reaching statistical significance for the relative weight only. These findings were not considered to be related to the test item given the low magnitude of the changes and as individual relative liver weights in this group were all below the highest control value.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Brownish foci were observed on the stomach mucosa only in 1/24 females given the high dose level. Given the isolated occurrence, a relationship to the test item was considered to be doubtful.

All other macroscopic observations (i.e. reddish discolored area on the lungs, adhesions between the liver and one kidney, marked dilatation of the renal pelvis, dilatation of ureters and/or enlarged placenta) were not attributed to the test item as they were of isolated occurrence, reported both in control and test item treated animals with comparable incidences, not dose-related and/or are findings commonly observed in rats of this strain and age.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Description (incidence and severity):

See table 4.
There were no effects on mean gravid uterus weight, mean carcass weight or net body weight change.

Pre- and post-implantation loss:

no effects observed

Description (incidence and severity):

See table 5.
There were no effects.

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

See table 5.
There were no effects.

Early or late resorptions:

no effects observed

Description (incidence and severity):

See table 5.
There were no effects.

Dead fetuses:

no effects observed

Description (incidence and severity):

See table 5.
There were no effects.

Changes in pregnancy duration:

not examined

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

See tables 5 and 13.
There were no effects.

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Abnormalities:

no effects observed

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

See table 6.
In controls, mean fetal body weights and mean fetal body weights of males and females were higher than the upper limit of the Historical Control Data (HCD). Therefore, from 200 mg/kg/day, lower mean body weight (-4% to -5% vs. controls) was noted. This was mainly due to female fetuses rather than male fetuses at 200 mg/kg/day (males: -3% and females: -5% with p<0.01 vs. controls), 600 mg/kg/day (males: -3% and females: -4% with p<0.05 vs. controls) and 1000 mg/kg/day (males: -5% with p<0.05 and females: -5% with p<0.01 vs. controls).
As the differences from controls in mean fetal body weights were poorly dose-related, minimal (less than 10% differences in all test-item treated groups) and within the range of the HCD, a relationship with the test item is questionable.

Changes in sex ratio:

no effects observed

Description (incidence and severity):

See table 6.
There were no effects on sex ratio (percentage of male fetuses).

External malformations:

no effects observed

Description (incidence and severity):

Variations
There were no external variations in the test item-treated groups.

Malformations
See table 7.
There were no external malformations in the test item-treated groups.
In the control group, 4 fetuses had cleft palate, together with bent tail for one of them; these findings are recorded at comparable incidence in the HCD and/or are common observations in this species and strain.

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

Cartilage
See table 10.
When compared with controls, there was a dose-related increase of delayed ossification. Cartilage of hyoid, sternebra(e), forepaw proximal phalanx and metatarsal bone were present, but there was incomplete ossification of the interparietal, hyoid and/or 6th sternebra and/or unossification of forepaw proximal phalanx and/or 1st metatarsal. As the litter and fetal incidences of controls were below the lower limit or in the low range of the HCD, and as the litter and fetal incidences of the test item-treated groups were within the range of the HCD, a relationship with the test item is questionable.
Other cartilage observations [i.e. cartilage of cervical vertebra(e) present and/or cartilage of rib present] were observed at 200 and/or at 1000 mg/kg/day. These findings were not dose-related and were noted at lower or similar incidences in the HCD, therefore a test item relationship was considered as unlikely.

Variations
See table 11.
When compared with controls, there was a dose-related increase in incomplete ossification [interparietal, hyoid and/or 6th sternebra (statistically significant at 1000 mg/kg/day)] and/or unossification [forepaw proximal phalanx (statistically significant from 600 mg/kg/day) and/or 1st metatarsal (statistically significant from 200 mg/kg/day)]. As the litter and fetal incidences of controls were below the lower limit or in the low range of the HCD, and as the litter and fetal incidences of the test item-treated groups were within the range of the HCD, a relationship with the test item is questionable.
Other skeletal variations [i.e. incomplete ossification of cervical vertebra(e) centrum, thickened rib and/or wavy rib] were observed at 200 mg/kg/day. As these findings were not dose-related and were noted with a lower incidence than that observed in the HCD, they were therefore considered to be unrelated to the test item.

Malformations
See table 12.
There were no skeletal malformations in the test item-treated groups.
In the control group, one litter had three malformed fetuses: L28862-01, -07 and -11 with split palate (cleft palate at external examination). These findings are observed with an incidence similar to the HCD and/or are commonly noted in this species and strain.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Variations
See table 8.
There were no test item treatment-related soft tissue variations.

Tissue variations (i.e. short or absent innominate artery and reddish foci on thymus) were observed in control and/or test item-treated groups, with an isolated occurrence and/or with a lower incidence than that observed in the HCD. These findings were therefore considered to be unrelated to the test item treatment.
Lower, statistically significant incidences of dilated ureter were noted at 600 and 1000 mg/kg/day. This was due to higher fetal and litter control incidences and was therefore considered to be of no relevance.

Malformations
See table 9.
There were no test item-related increases in the frequency of soft tissue malformations.

At 1000 mg/kg/day, the left ureter was markedly dilated in one fetus . This correlated with the dilatation of the left renal pelvis. As this malformation was observed with an incidence similar to HCD, it was considered to be unrelated to the test item treatment.

In the control group, one fetus had cleft palate (also observed at external examination); this finding is commonly noted in this species and strain.

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Abnormalities:

no effects observed

Developmental effects observed:

no

Table 1: Clinical signs

Dose level (mg/kg/day)	0	200	600	1000
Ptyalism			14	24
Reflux at administration				1
Number of affected animals	0/24	0/24	14/24	24/24

 

Table 2: Body weight

Dose level (mg/kg/day)	0	200	600	1000
Body weight (g)
Day 6 p.c.	290	294	291	291
	-	(+1)	(0)	(0)
Day 9 p.c.	304	310	304	303
	-	(+2)	(0)	(0)
Day 12 p.c.	323	328	326	327
	-	(+2)	(+1)	(+1)
Day 15 p.c.	347	349	347	349
	-	(+1)	(0)	(+1)
Day 18 p.c.	391	396	387	394
	-	(+1)	(-1)	(+1)
Day 21 p.c.	446	447	437	453
	-	(0)	(-2)	(+2)
Body weight change (g)
Days 6 - 9 p.c.	+14	+15	+13	+12
Days 9 - 12 p.c.	+19	+18	+22	+24*
Days 12 - 15 p.c.	+24	+21	+20	+22
Days 15- 18 p.c.	+44	+47	+40	+44
Days 18 - 21 p.c.	+54	+51	+50	+60
Days 6 - 21 p.c.	+155	+152	+146	+162
	-	(-2)	(-6)	(+5)

p.c.   : post-coitum.

-       : not applicable.

( )     : in brackets, percentage difference vs. controls. Statistical significance ^*: p<0.05.

 

Table 3: Food consumption

Dose level (mg/kg/day)	0	200	600	1000
. Days 6 - 9 p.c.	23	23	21	20*
. Days 9 - 12 p.c.	25	25	25	26
. Days 12 - 15 p.c.	28	26	26	28
. Days 15 - 18 p.c.	32	31	30	32
. Days 18 - 21 p.c.	31	29	28	31

p.c.   : post-coitum.

Statistical significance ^*: p<0.05.

Table 4: Net body weight change

Dose level (mg/kg/day)	0	200	600	1000
Gravid uterus weight	105	104 (-1)	96 (-9)	110 (+5)
Carcass weight	341	343 (+1)	341 (0)	344 (+1)
Net body weight change from Day 6 p.c.	+50	+48	+49	+52

( )     : in brackets, percentage difference vs. controls.

p.c.         : post-coitum.

^(a)         : weights are rounded values.

Table 5: Hysterectomy data

Dose level (mg/kg/day)	0	200	600	1000	HCD
Number of pregnant females at hysterectomy	24	22	24	23	407
Number of females with live fetuses at termination	24	22	24	23	388
Number of females with total resorption	0	0	0	0	0
Mean number of corpora lutea	14.0	14.0	14.3	14.8	[13.8; 16.0]
Mean number of implantation sites	13.2	13.5	13.0	14.0	[12.5; 14.5]
Mean pre-implantation loss (%)	5.5	3.8	9.0	4.9	[6.2; 14.0]
Mean number of live fetuses	12.5	12.9	11.9	13.5	[11.6; 13.8]
Dead fetuses (%)	0.0	0.0	0.0	0.0	[0.00; 0.50]
Mean number of implantation scars	0.0	0.0	0.0	0.0	/
Mean number of early resorptions	0.7	0.6	1.1	0.5	/
Mean number of late resorptions	0.0	0.0	0.0	0.0	/
Mean post-implantation loss (%)	5.4	4.3	9.0	3.7	[3.5; 11.1]

HCD     : Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014
             to July 2016), [min.; max.].

/          : not reported in HCD.

 

Table 6: Fetal body weight and sex ratio

Dose level (mg/kg/day)	0	200	600	1000	HCD
Mean fetal body weight (g)	5.98 -	5.75* (-4)	5.73* (-4)	5.69**(-5)	[5.5; 5.9]
Mean fetal body weight of males (g)	6.11 -	5.92 (-3)	5.90 (-3)	5.83*(-5)	[5.7; 6.1]
Mean fetal body weight of females (g)	5.85 -	5.55** (-5)	5.59* (-4)	5.53**(-5)	[5.4; 5.7]
Mean percentage of male fetuses (%)	52.3	50.9	46.3	54.1	[44.0; 55.4]

( )        : in brackets, percentage difference vs. controls.

HCD     : Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014
             to July 2016), [min.; max.].

-          : not applicable.

Statistical significance ^*: p < 0.05 and **: p<0.01.

 

Table 7: Fetal external malformations

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live fetuses, n	24	22	24	23	388
Live fetuses, n	299	283	286	311	5000
. cleft palate,L (F)	4.2 (1.3)	0.0 (0.0)	0.0 (0.0)	0.0 (0.0)	5.0 (0.4)^(a)
. bent tail,L (F)	4.2 (0.3)	0.0 (0.0)	0.0 (0.0)	0.0 (0.0)	5.0 (0.4)^(a)
Litters affected, n (%)^(c)	1 (4.2)	0 (0.0)	0 (0.0)	0 (0.0)	11 (2.8)^(b)
Fetus affected, n (%)^(c)	4 (1.3)	0 (0.0)	0 (0.0)	0 (0.0)	13 (0.3)^(b)

n: number.

HCD:Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016);(a): upper litter incidence by study; (b): mean number (percentage) of litters or fetuses affected; (c): all malformations combined.

 

Table 8: Fetal soft tissue variations

 

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live fetuses, n	24	22	24	23	387
Live fetuses, n	145	137	137	151	2404
. short innominate artery, L (F)	0 (0)	0 (0)	0 (0)	4.3 (0.7)	22.7 (3.7)^(a)
. absent innominate artery, L (F)	4.2 (0.7)	4.5 (0.7)	0 (0)	13.0 (2.0)	25.0 (5.1)^(a)
. dilated ureter, L (F)	25.0 (5.5)	9.1 (1.5)	0** (0)	4.3* (0.7)	28.0 (7.1)^(a)
. thymus: reddish foci, L (F)	0 (0)	0 (0)	0 (0)	4.3 (0.7)	0 (0)
Litters affected, n (%)^(c)	6 (25.0)	3 (13.6)	1 (4.2)	6 (26.1)	86 (22.2)^(b)
Fetus affected, n (%)^(c)	8 (5.5)	3 (2.2)	1 (0.7)	7 (4.6)	119 (5.0)^(b)

n: number.

HCD: Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016); (a): upper litter incidence by study; (b): mean number (percentage) of litters or fetuses affected; (c): all variations combined.

Statistical significance for affected fetuses/litter: *: p < 0.05 and **: p<0.01

 

Table 9: Fetal soft tissue malformations

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live fetuses, n	24	22	24	23	387
Live fetuses, n	145	137	137	151	2404
. marked dilated ureter, L(F)	0 (0)	0 (0)	0 (0)	4.3 (0.7)	4.8 (4.8)^(a)
. cleft palate, L(F)	4.2 (0.7)	0 (0)	0 (0)	0 (0)	0 (0)
Litters affected, n (%)^(c)	1 (4.2)	0 (0)	0 (0)	1 (4.3)	7 (1.8)^(b)
Fetus affected, n (%)^(c)	1 (0.7)	0 (0)	0 (0)	1 (0.7)	13 (0.5)^(b)

n: number.

HCD: Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016); (a): upper litter incidence by study; (b): mean number (percentage) of litters or fetuses affected; (c): all malformations combined

 

Table 10: Fetal skeletal examinations

Cartilage

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live foetuses, n	24	22	24	23	388
Live fetuses, n	154	146	149	160	2596
. cartilage of hyoid present, L(F)	4.2 (0.6)	18.2 (2.7)	12.5 (3.4)	26.1*(5.0)*	30.4 (7.4)^(a)
. cartilage of sternebra(e) present, L(F)	0 (0)	4.5 (0.7)	12.5 (2.0)	17.4*(2.5)	21.7 (3.8)^(a)
. forepaw: cartilage of proximal phalanx present, L(F)	33.3 (14.3)	59.1 (21.9)	70.8*(26.8)**	69.6*(33.8)^#	85.0 (50.0)^(a)
. cartilage of metatarsal bone present, L(F)	20.8 (5.2)	50.0 (13.7*)	54.2*(20.8)^#	73.9^#(28.1)^#	72.7 (36.8)^(a)
Litters affected, n (%)^(c)	21 (87.5)	18 (81.8)	23 (95.8)	23 (100.0)	236 (60.8)^(b)
Fetus affected, n (%)^(c)	65 (42.2)	79* (54.1)	75 (50.3)	104# (65.0)	990 (38.1)^(b)

n: number.

HCD: Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016); (a): upper litter incidence by study; (b): mean number (percentage) of litters or fetuses affected; (c): all cartilage findings combined.

Statistically significant ^*: p<0.05, **: p<0.01 and # :p<0.001 for the number of fetuses or litters affected.

 

Table 11: Fetal skeletal variations

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live fetuses, n	24	22	24	23	388
Live fetuses, n	154	146	149	160	2596
. interparietal: incomplete ossification, L(F)	4.2 (0.6)	22.7 (4.8*)	12.5 (2.0)	30.4*(7.5)**	45.0 (9.2)^(a^)
. hyoid: incomplete ossification, L(F)	4.2 (0.6)	18.2 (2.7)	12.5 (3.4)	26.1*(4.4)	55.0 (14.8)^(a)
. 6^thsternebra: incomplete ossification, L(F)	0 (0)	0 (0)	0 (0)	17.4*(2.5)	16.7 (2.9)^(a)
. forepaw: unossified proximal phalanx, L(F)	33.3 (14.3)	59.1 (21.9)	70.8* (26.8)**	69.6*(33.8)^#	85.0 (50.0)^(a)
. 1^stmetatarsal: unossified, L(F)	20.8 (5.2)	50.0 (13.7)*	54.2*(20.8)^#	73.9^#(28.1)^#	72.7 (36.8)^(a)
Litters affected, n (%)^(c)	21 (87.5)	19 (86.4)	23 (95.8)	23 (100.0)	345 (88.9)^(b)
Fetus affected, n (%)^(c)	68 (44.2)	82* (56.2)	76 (51.0)	104# (65.0)	1267 (48.8)^(b)

n: number.

HCD: Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016); (a): upper litter incidence by study; (b): mean number (percentage) of litters or fetuses affected; (c): all variations combined.

Statistically significant ^*: p<0.05, **: p<0.01 and #:p<0.001 for the number of fetuses or litters affected.

Table 12: Fetal skeletal malformations

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live fetuses, n	24	22	24	23	388
Live fetuses, n	154	146	149	160	2596
. palate: split, L(F)	4.2 (1.9)	0 (0)	0 (0)	0 (0)	5.0 (0.7)^(a)
Litters affected, n (%)^(c)	1 (4.2)	0 (0)	0 (0)	0 (0)	15 (3.9)^(b)
Fetus affected, n (%)^(c)	3 (1.9)	0 (0)	0 (0)	0 (0)	18 (0.7)^(b)

n: number.

HCD: Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016); (a): upper litter incidence by study; (b): mean number (percentage) of litters or fetuses affected; (c): all malformations combined. 

Table 13: Pregnancy status

Dose level(mg/kg/day)	0	200	600	1000
Number of females	24	24	24	24
Non-pregnant females	0	2	0	1
Females with live fetuses at term	24	22	24	23

 

Conclusions:

The test item was administered to pregnant Sprague-Dawley rats by gavage, once daily, from Day 6 to Day 20 p.c., inclusive, at the dose levels of 200, 600 and 1000 mg/kg/day. A control group received the vehicle, corn oil, under the same experimental conditions.
On the basis of the results obtained in this study:
- the No Observed Adverse Effect Level (NOAEL) for maternal parameters is considered to be 1000 mg/kg/day,
- the NOAEL for embryo-fetal development is considered to be 1000 mg/kg/day.

Executive summary:

The potential toxic effects of OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate (TBEC) on the pregnant female and on embryonic and fetal development, following daily oral administration (gavage) to pregnant female rats from implantation until the day before scheduled hysterectomy [Day 6 to Day 20 post-coitum (p.c.) inclusive]. This GLP study was carried out according to OECD test guideline No. 414 (22 January 2001). Three groups of 24 time-mated female Sprague-Dawley rats received the test item by the oral route (gavage), at dose levels of 200, 600 or 1000 mg/kg/day, once daily from Day 6 to Day 20 p.c. inclusive. Another group of 24 time-mated female rats received the vehicle only, corn oil, under the same experimental conditions and acted as a control group. A constant dosage volume of 5 mL/kg/day was used. The test item concentrations in the dose formulations were determined. The animals were checked daily for mortality and clinical signs. Body weight and food consumption were recorded at designated intervals. On Day 21 p.c., the females were euthanized and a macroscopic post-mortem examination was performed. Hysterectomy was performed and the numbers of corpora lutea, implantation sites, uterine scars, early and late resorptions, and live and dead fetuses were recorded. The fetuses were weighed, sexed and examined for external, soft tissue and skeletal abnormalities (including cartilage). The liver and the kidneys of each dam were weighed and samples of liver, kidney and stomach were collected and preserved in 10% buffered formalin.

The concentrations of the test item in the dose formulations (-2.6% to +9.0%) remained within an acceptable range of variations (± 10%) when compared to the nominal concentrations. No test item was found in the control dose formulation. All females were pregnant with the exception of two females given 200 mg/kg/day and one female given 1000 mg/kg/day. There were no unscheduled deaths. Ptyalism was noted in 14/24 females given 600 mg/kg/day and in 24/24 females given 1000 mg/kg/day. This finding was considered to be test item treatment-related but non-adverse. There were no effects on body weight or body weight change at any dose level.  At 1000 mg/kg/day, lower food consumption (-13% vs. controls, p < 0.05) was observed between Days 6 and 9 p.c., with a return to control values thereafter. This finding was considered to be test item treatment-related but non-adverse. Brownish colored foci were observed on the stomach mucosa at the high-dose level in 1/24 females. This finding was considered to be non-adverse, and a test item treatment relationship was considered to be doubtful. There were no test item-related changes in liver or kidney weights. There were no effects on mean carcass weight, net body weight gain or gravid uterus weight. There were no effects on hysterectomy parameters (mean numbers of corpora lutea, implantation sites, pre-implantation loss, live fetuses and post-implantation loss).

From 200 mg/kg/day and when compared with controls, statistically significant lower mean fetal body weights were noted. They were mainly due to the lower body weight of female fetuses at 200 mg/kg/day (males: -3% and females: -5% with p<0.01 vs. controls), 600 mg/kg/day (males: -3% and females: -4% with p<0.05 vs. controls) and 1000 mg/kg/day (males: -5% with p<0.05 and females: -5% with p<0.01 vs. controls). As these minimal changes were within the range of the Historical Control Data and mainly resulted from control values higher than the upper limit of the Historical Control Data, a relationship with the test item is questionable. There were no toxicological effects on sex-ratio at any dose level. There were no variations and no test item treatment-related malformations at external examination. There were no test item treatment-related variations or malformations at soft tissue examination. At 600 and/or 1000 mg/kg/day and when compared with controls, there were higher litter and fetal incidences of fetuses within complete ossification of interparietal, hyoid and/or 6^th sternebra and/or unossification of forepaw proximal phalanx and/or 1^st metatarsal. As incidences of these non-adverse findings (the cartilage/bone structure still present) were lower than that observed in the Historical Control Data and as control incidences were below the lower limit or in the low range of the Historical Control Data, a relationship with the test item is questionable. There were no test item-related malformations at skeletal examination.

TBEC was administered to pregnant Sprague-Dawley rats by gavage, once daily, from Day 6 to Day 20 p.c., inclusive, at the dose levels of 200, 600 and 1000 mg/kg/day. A control group received the vehicle, corn oil, under the same experimental conditions.

On the basis of the results obtained in this study:

. the No Observed Adverse Effect Level (NOAEL) for maternal parameters is considered to be 1000 mg/kg/day,

. the NOAEL for embryo-fetal development is considered to be 1000 mg/kg/day.

Reference 2

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

10 July 2017 - 17 August 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Principles of method if other than guideline:

Similar to an OECD 414 study with less animals per group and less fetal exams, range-finding study.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: breeder: Janvier, le Genest-Saint-Isle, France
- Age at the beginning of the treatment period: the animals were 10-11 weeks old
- Mean body weight at the beginning of the treatment period: 313 g (range: 285 g to 337 g)
- Fasting period before study: no
- Housing: The animals were individually housed in polycarbonate cages
- Diet: SSNIFF R/M-H pelleted diet (free access)
- Water: tap water filtered with a 0.22 µm filter (free access)
- Acclimation period: at least 4 days before the beginning of the treatment period

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2°C
- Humidity (%): 50 ± 20%
- Air changes (per hr): approximately 8 to 15 cycles/hour of filtered, non-recycled air
- Photoperiod (hrs dark / hrs light): 12 h/12 h

IN-LIFE DATES: 01 August 2017 to 17 August 2017

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING FORMULATIONS:
- Solution in the vehicle
- Concentration in vehicle: 40. 120. 200 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg/day

Analytical verification of doses or concentrations:

no

Details on mating procedure:

Mating: the females were mated at the breeder's facility. The day of confirmed mating (detection of a vaginal plug) was designated as Day 0 p.c.

Duration of treatment / exposure:

From Day 6 to Day 20 p.c., inclusive.

Frequency of treatment:

Daily

Dose / conc.:

0 mg/kg bw/day (actual dose received)

Dose / conc.:

40 mg/kg bw/day (actual dose received)

Dose / conc.:

120 mg/kg bw/day (actual dose received)

Dose / conc.:

200 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

8 females

Control animals:

yes, concurrent vehicle

Details on study design:

Rationale for dose level selection
The dose levels were selected in agreement with the Sponsor, based on the results of a previous OECD 407 study performed in Wistar rats.
In this study, rats received the test item daily by gavage at dose levels of 150, 550 or 1000 mg/kg/day for 28 days.
Instance of signs of abnormal systemic activity were minimal. There were no significant differences from controls in any of the parameters (i.e. Functional Observation Battery, motor activity, body weight, food consumption, hematology, blood biochemistry and organ weights). Test item-related microscopic changes were observed from 500 mg/kg/day in the kidneys of male rats (hyaline droplet formation unique to the male rat) and in the stomach in both sexes. Based on the microscopic changes, the No Observed Effect Level (NOEL) was estimated to be 150 mg/kg/day.

- Rationale for animal assignment: stratification procedure.

Maternal examinations:

MORTALITY/MORBIDITY:
- Time schedule: each animal was checked for mortality and morbidity once a day before the treatment period and at least twice a day during the treatment period, including weekends and public holidays.

CLINICAL SIGNS:
- Time schedule: from arrival, each animal was observed once a day as part of the routine examinations.
From the start of the treatment period, each animal was observed once a day, at approximately the same time, for the recording of clinical signs.

BODY WEIGHT:
- Time schedule: the body weight of each female was recorded on Days 2, 4, 6, 9, 12, 15, 18 and 21 p.c.

FOOD CONSUMPTION:
- Time schedule: the quantity of food consumed by each female was recorded for the following intervals:
- Days 2-4, 4-6, 6-9, 9-12, 12-15, 15-18 and 18-21 p.c.

POST-MORTEM MACROSCOPIC EXAMINATION:
- Sacrifice on Day 21 post-coitum.
- Examined: principal thoracic and abdominal organs and the weight of the gravid uterus, carcass and net body weight change.

Ovaries and uterine content:

The ovaries and uterine content were examined after termination, including:
- number of corpora lutea,
- number and distribution of dead and live fetuses,
- number and distribution of early and late resorptions,
- number and distribution of uterine scars,
- number and distribution of implantation sites.

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: No
- Skeletal examinations: No
- Head examinations: No
- Other: number dead and live, body weight, sex

Statistics:

Data were compared by one-way analysis of variance and Dunnett test (mean values being considered as normally distributed and variances being considered as homogeneous) or by Fisher exact probability test (proportions).
PathData software was used to perform the statistical analysis of organ weight data (level of significance of 0.05 or 0.01).

Indices:

% Pre-implantation loss = 100 * (Number of corpora lutea - Number of implantation sites) / Number of corpora lutea
% Post-implantation loss = 100 * (Number of implantation sites - Number of live fetuses) / Number of implantation sites

Historical control data:

Cf attached document

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

See Table 2.
Ptyalism was observed during the first and/or the second weeks of treatment for 1 to 11 days in some females given 600 mg/kg/day and in all females given 1000 mg/kg/day. This clinical sign was considered to be of minor toxicological significance.
Other clinical signs (i.e. scab on neck, chromodacryorrhea or chromorhinorrhea) were transiently observed in isolated animals. These signs were not considered to be test item-related as they were observed in controls, were of limited incidence, and as they are commonly observed in rats of this strain and age.

Mortality:

no mortality observed

Description (incidence):

There were no unscheduled deaths.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

See Table 3.
There were no effects of the test item on the mean body weight change or the mean body weight.
Statistically significant, higher body weight gain was noted in females given 1000 mg/kg/day between Days 9 and 12 p.c. This resulted from the lower mean body weight gain in control females (one female gained only 2 g over this time interval).

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

See Table 4.
There were no effects on mean food consumption.

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

See Table 5.
There were no effects at any dose level.
Slightly lower (not statistically significant) mean gravid uterus weight was noted in females given 200 or 1000 mg/kg/day (-17% and -12%, respectively).
As these variations were of minor amplitude and not dose related, a test item relationship was considered to be unlikely.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

There were no test item-related macroscopic findings.
The macroscopic observations (placenta fused for two fetuses:one implantation site) were not attributed to the test item as they were reported in control animals and are commonly observed in pregnant rats.

Number of abortions:

no effects observed

Description (incidence and severity):

See Tables 1 and 6.

Pre- and post-implantation loss:

effects observed, non-treatment-related

Description (incidence and severity):

See Table 6.
On Day 21 p.c., all females were pregnant with the exception of one control female and one female given 1000 mg/kg/day.
There were no effects on hysterectomy data.
At 1000 mg/kg/day, when compared with controls, there was a minimal higher mean pre-implantation loss (9.4% vs. 3.1% in controls, not statistically significant). As this effect was of low magnitude and within the range of the Historical Control Data, a relationship to the test item was considered to be unlikely.
At 200 and 1000 mg/kg/day, when compared with controls, there were a minimal lower mean numbers of live fetuses (11.3 and 11.7 vs. 13.6 in controls, respectively, not statistically significant) and a minimal lower mean post-implantation loss (9.9 and 8.4 vs. 5.1 in controls, respectively, not statistically significant) that correlated with lower mean gravid uterus weights. As these effects were not dose-related, were of low magnitude and were within or close to the range of the Historical Control Data, a relationship with the test item was considered to be unlikely.

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

See Table 6.

Early or late resorptions:

effects observed, non-treatment-related

Description (incidence and severity):

See Table 6.

Dead fetuses:

no effects observed

Description (incidence and severity):

See Table 6.

Description (incidence and severity):

See Table 6.

Changes in number of pregnant:

effects observed, non-treatment-related

Description (incidence and severity):

See Table 6.
On Day 21 p.c., all females were pregnant with the exception of one control female and one female given 1000 mg/kg/day.

Other effects:

effects observed, treatment-related

Description (incidence and severity):

Organ Weights:
See Table 7.
There was a trend toward increased mean absolute and relative-to-body liver weights in animals treated at 600 and 1000 mg/kg, and statistical significance was reached at 1000 mg/kg/day when data of non pregnant females were excluded.
Therefore, a relationship to treatment could not be excluded.

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Basis for effect level:

clinical signs

organ weights and organ / body weight ratios

Fetal body weight changes:

no effects observed

Description (incidence and severity):

See Table 8.
There were no toxicologically significant effects on mean fetal body weight or on the percentage of male fetuses.

External malformations:

effects observed, treatment-related

Description (incidence and severity):

See Tables 9 and 10.
Variations:
In the 1000 mg/kg/day group, one fetus had reddish color of amniotic fluid and protruding tongue. As these variations, that were associated with malformations (short snout, misshapen genital tubercle and exencephaly), were observed at the high-dose level only and at fetal and litter incidences higher than those observed in the Historical Control Data. As these malformations were no longer observed in the main OECD 414 study at the same dose level of 1000 mg/kg/day and on a larger number of fetuses, there were considered of spontaneous origine.
There were no external variations at 0, 200 and 600 mg/kg/day.

Malformations
In the 1000 mg/kg/day group:
- short snout, misshapen genital tubercle and exencephaly were noted in one malformed fetus from one litter,
- cleft palate was noted in four malformed fetuses from one litter.
These malformations were observed in the high-dose group only, with fetal and litter incidences higher than the upper limit of the Historical Control Data.
There were no external malformations at 0, 200 and 600 mg/kg/day.

Skeletal malformations:

not examined

Visceral malformations:

not examined

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Table 1.

Pregnancy status

Dose level (mg/kg/day)	0	200	600	1000
Number of females	8	8	8	8
Found dead females	0	0	0	0
Non-pregnant females	1	0	0	1
Females with total resorption	0	0	0	0
Females with live fetuses at term	7	8	8	7

Table 2.

Cinical signs

Dose level (mg/kg/day)	0	200	600	1000
Ptyalism			5	8
Number of affected animals	0/8	0/8	5/8	8/8

Table 3.

Body weights and body weight changes

Dose level (mg/kg/day)	0	200	600	1000
Body weight (g)
. Day 6 p.c.	312	313	313	315
	-	(0)	(0)	(+1)
. Day 9 p.c.	326	328	323	325
	-	(+1)	(-1)	(0)
. Day 12 p.c.	339	345	341	346
	-	(+2)	(+1)	(+2)
. Day 15 p.c.	362	365	365	366
	-	(+1)	(+1)	(+1)
. Day 18 p.c.	408	408	408	405
	-	(0)	(0)	(-1)
. Day 21 p.c.	460	453	465	458
	-	(-2)	(+1)	(0)
Body weight change (g)
. Days 6-9 p.c.	+14	+15	+10	+9
. Days 9-12 p.c.	+13	+17	+18	+22**
. Days 12-15 p.c.	+23	+20	+23	+19
. Days 15-18 p.c.	+46	+43	+43	+39
. Days 18-21 p.c.	+52	+46	+57	+53
. Days 6 - 21 p.c.	+148	+140	+153	+142

Statistical significance: **: p < 0.01.

p.c.  : post-coitum.

-       : not applicable.

( )     : in brackets, percentage difference vs.controls.

Table 4.

Food consumption (g/animal/day)

Dose level (mg/kg/day)	0	200	600	1000
Days 6-9p.c.	21	22	21	20
Days 9-12p.c.	24	24	25	26
Days 12-15p.c.	25	24	26	27
Days 15-18p.c.	30	28	30	30
Days 18-21p.c.	29	28	30	31

p.c.        : post-coitum.

Table 5.

Mean carcass weight, net body weight change and gravid uterus weight (a) (expressed in g)

Dose level (mg/kg/day)	0	200	600	1000
Gravid uterus weight	109	91	105	96
	-	(-17)	(-4)	(-12)
Carcass weight	351	362	360	362
	-	(+3)	(+3)	(+3)
Net body weight change from Day 6 p.c.	38.8	48.9	47.3	46.3

( )  : in brackets, percentage differencevs.controls.

(a): weights are rounded values.

-    : not applicable.

Table 6.

Hysterectomy data

Dose level (mg/kg/day)	0	200	600	1000	HCD
Number of pregnant females at hysterectomy	7	8	8	7	407
Number of females with live fetuses at termination	7	8	8	7	388
Number of females with total resorption	0	0	0	0	0
Mean number ofcorpora lutea	14.7	13.5	13.9	14.3	[13.8; 16.0]
Mean number of implantation sites	14.3	12.4	13.0	12.9	[12.5; 14.5]
Mean pre-implantation loss (%)	3.1	6.7	6.8	9.4	[6.2; 14.0]
Mean number of live fetuses	13.6	11.3	12.5	11.7	[11.6; 13.8]
Dead fetuses (%)	0.0	0.0	0.0	0.0	[0.00; 0.50]
Mean number of implantation scars	0.0	0.0	0.0	0.0	/
Mean number of early resorptions	0.4	1.0	0.3	1.0	/
Mean number of late resorptions	0.3	0.1	0.3	0.1	/
Mean post-implantation loss (%)	5.1	9.9	3.9	8.4	[3.5; 11.1]

HCD      : Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016), [min.; max.].

/     : not reported in HCD.

Table 7.

Changes in the mean liver weights (expressed in percent changes from controls)

Group	2	3	4
Dose level (mg/kg/day)	200	600	1000
Exam. animals / Num. of animals	8/8	8/8	8/8
- Final body weight	+4 (+3)	+3 (+3)	+2 (+3)
- Liver
. absolute	+5 (+2)	+14 (+10)	+15 (+17*)
. relative to body weight	+1 (+1)	+10 (+8)	+13 (+14)
- Kidney
. absolute	+6 (+6)	+7 (+8)	+8 (+9)
. relative to body weight	+2 (+3)	+4 (+5)	+7 (+6)

Statistical significance: *: p < 0.05.

 ( ): in brackets, data of non-pregnant females excluded.

Table 8.

Fetal data

Dose level (mg/kg/day)	0	200	600	1000
Mean fetal body weight (g)	5.76 -	5.86 (+1.7)	5.96 (+3.5)	5.63 (-2.3)
Mean percentage of male fetuses (%)	52.5	52.6	47.9	42.4

( )  : in brackets, percentage difference vs. controls.

-    : not applicable.

Table 9.

Fetal (litter) incidences (%) of external variations 

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live fetuses	7	8	8	7	388
Number of live fetuses	95	90	100	82	5000
Litters affected, n (%)	0 (0)	0 (0)	0 (0)	1 (14.3)	6 (1.5)^(b)
Fetuses affected, n (%)	0 (0)	0 (0)	0 (0)	1 (1.2)	7 (0.1)^(b)
Reddish color of amniotic fluid, F (L)	0 (0)	0 (0)	0 (0)	1.2 (14.3)	/
Protruding tongue, F(L)	0 (0)	0 (0)	0 (0)	1.2 (14.3)	0.4 (4.8)^(a)

F      : fetal incidence.

L      : litter incidence.

HCD : Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016).

/       : not reported in HCD.

^(a)        : maximum incidence.

^(b)        : mean incidence.

Table 10.

Fetal (litter) incidences (%) of external malformations

Dose level (mg/kg/day)	0	200	600	1000	HCD
Dams with live fetuses	7	8	8	7	388
Number of live fetuses	95	90	100	82	5000
Litters affected, n (%)	0 (0)	0 (0)	0 (0)	2 (28.6)	11 (2.8)^(b)
Fetuses affected, n (%)	0 (0)	0 (0)	0 (0)	5* (6.1)	13 (0.3)^(b)
Short snout, F (L)	0 (0)	0 (0)	0 (0)	1.2 (14.3)	0.4 (5.0)^(a)
Cleft palate, F(L)	0 (0)	0 (0)	0 (0)	4.9* (14.3)	0.4 (5.0)^(a)
Genital tubercle: misshapen, F(L)	0 (0)	0 (0)	0 (0)	1.2 (14.3)	/
Exencephaly, F (L)	0 (0)	0 (0)	0 (0)	1.2 (14.3)	0.4 (4.8)^(a)

F      : fetal incidence.

L      : litter incidence.

HCD : Historical Control Data (control data collected from 18 studies covering a period ranging from March 2014 to July 2016).

/       : not reported in HCD.

^(a)        : maximum incidence.

^(b)        : mean incidence.

Statistically significant from controls: *: p < 0.05 for fetal incidence.

Conclusions:

The test item was administered by gavage once daily from Days 6 to 20 p.c., inclusive, to pregnant Sprague-Dawley rats at the dose levels of 200, 600 and 1000 mg/kg/day. The control group received the vehicle, corn oil, under the same experimental conditions.
The dose level of 1000 mg/kg/day was associated with ptyalism and higher litter and fetal incidences of variations and malformations, mainly affecting the head region, along with slight increases in the absolute and relative liver weights.
The dose level of 600 mg/kg/day was associated with ptyalism in some females and slight increases in absolute and relative liver weights.
The dose level of 200 mg/kg/day was not associated with test item-related effects.
Based on these findings and in the absence of maternal toxicity, 1000 mg/kg/day could be considered as a suitable high-dose level for the main embryo-fetal developmental study with the test item.

Executive summary:

The potential toxic effects of Luperox TBEC (OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate) on the pregnant female and on embryonic and fetal development was evaluated, following daily oral administration (gavage) to pregnant female rats from implantation to the day before scheduled hysterectomy [Day 6 to Day 20 post-coitum (p.c.) inclusive], in order to select dose levels for a further main study. Three groups of eight time-mated female Sprague-Dawley rats received the test item at 200, 600 or 1000 mg/kg/day, once daily from Day 6 to Day 20 p.c. by oral gavage. Another group of eight time-mated rats received the vehicle, corn oil, under the same experimental conditions and acted as a control group. All animals were checked daily for mortality and clinical signs. Body weight and food consumption were recorded regularly. After sacrifice, a macroscopic post-mortem examination of the females was performed on Day 21 p.c. Liver and kidneys were weighed and preserved, along with stomach, in 10% buffered formalin. Hysterectomies were performed and the numbers and distribution of corpora lutea, implantation sites, early and late resorptions, uterine scars, and live and dead fetuses were recorded. The fetuses were sexed, weighed, examined for oral cavity and external abnormalities, and preserved for possible skeletal and soft tissues examination. 

All females were pregnant with the exception of one control female and one female given 1000 mg/kg/day. There were no unscheduled deaths. Ptyalism was transiently observed in all females given 600 or 1000 mg/kg/day. There were no relevant effects on body weight, body weight change or food consumption. At terminal sacrifice, slight increases in absolute and relative liver weights were noted at 600 and 1000 mg/kg/day. There were no test item-related macroscopic findings. There were no effects on hysterectomy parameters. There were no effects on fetal body weight or on percentage of male fetuses (sex ratio). At 1000 mg/kg/day, and when compared with controls or historical control data, there were higher litter and fetal incidences of fetuses with variations (i.e. reddish color of aminiotic fluid and protruding tongue) and/or malformations (i.e. short snout, misshapen genital tubercle, exencephaly and cleft palate). As these malformations were no longer observed in the main OECD 414 study at the same dose level of 1000 mg/kg/day and on a larger number of fetuses, there were considered of spontaneous origine.

Based on these findings and in the absence of maternal toxicity, 1000 mg/kg/day could be considered as a suitable high-dose level for the main embryo-fetal developmental study with Luperox TBEC (OO-tert-butyl O-(2-ethylhexyl) peroxycarbonate).

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Experimental exposure time per week (hours/week):

7

Species:

rat

Quality of whole database:

Key study

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Toxicity to reproduction: other studies

Description of key information

In the OECD 408 study (Papineau, 2018), the estrous cycle was determined over 21 or 14 consecutive days for all females at the end of the treatment or treatment-free period, respectively. At the end of the treatment period, seminological investigations (count and motility) were performed on all males, and sperm morphology was determined in control and high-dose males. On completion of the treatment, epididymides, ovaries (including oviducts), testes and uterus (horns and cervix) were weighed. A microscopic examination was performed on epididymides, ovaries, prostate , seminal vesicles (including coagulation gland), testes, uterus and vagina from control and high-dose animals euthanized at the end of the treatment period.

A non-adverse slight increase in the length of diestrus was observed in females given 600 mg/kg/day at the end of the treatment period. No variations were observed at the end of the treatment-free period. The epididymal sperm motility and morphology, and the testicular and epididymal spermatozoa count were unaffected by the test item treatment. At pathology investigations, there was no adverse effect on the male and female reproductive organs.

Link to relevant study records

Reference

Endpoint:

toxicity to reproduction: other studies

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)

GLP compliance:

yes (incl. QA statement)

Type of method:

in vivo

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

daily

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Dose / conc.:

300 mg/kg bw/day (actual dose received)

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

Control animals:

yes, concurrent vehicle

Details on study design:

SPERM PARAMETERS:
Before euthanasia at the end of the treatment period, each male was anesthetized by an intraperitoneal injection of sodium pentobarbital.
As no relevant changes were observed at the end of the treatment period, these examinations were not carried out at the end of the treatment-free period.

Epididymal sperm
Under deep anesthesia and after weighing the epididymis, sperm from the cauda of the left epididymis was collected for motility and morphology investigations. Animals were then euthanized.
The cauda of the left epididymis was separated from the corpus using a scalpel and subsequently kept at 20°C pending further investigation.

Epididymal sperm motility
The sperm was evaluated on a slide, after appropriate dilution if required. The numbers of motile and immotile spermatozoa in a sample of 200 spermatozoa were evaluated under a microscope using a 40 fold magnification. Results were expressed as the proportions of motile and non-motile spermatozoa.

Epididymal sperm morphology
Morphology was determined from a sperm smear, after eosin staining and counting of 100 spermatozoa per slide. This was evaluated for groups 1 and 4 in the first instance.
In view of the findings observed in these groups at the end of the treatment period, this determination was not extended to groups 2 and 3 or recovery animals.

Results were expressed as the proportion of spermatozoa in each of the following categories:
- normal,
- normally shaped head separated from flagellum,
- abnormal head separated from flagellum,
- abnormal head with normal flagellum,
- abnormal head with abnormal flagellum,
- normally shaped head with abnormal flagellum.

Epididymal sperm count
After thawing, the left cauda epididymis was weighed, minced and homogenized in a saline-triton solution using a Polytron.
An aliquot of the suspension was collected and the number of spermatozoa was counted in a microscope slide counting chamber.
Results were expressed as the numbers of spermatozoa per cauda and per gram of cauda.

Testicular sperm
The left testis was collected and kept at -20°C for further sperm count investigation. After thawing, the left testis was weighed and ground. The resulting preparation was diluted and sperm heads resistant to homogeneization (i.e. elongated spermatids and mature spermatozoa) were counted in a microscope slide counting chamber.
Results were expressed as the number of sperm heads per gram of testis, and the daily sperm production rate was calculated (using a time divisor of 6.10).

MONITORING OF ESTROUS CYCLE:
The estrus cycle stage was determined for each female euthanized at the end of the treatment period, from a fresh vaginal lavage (stained with methylene blue), daily for 21 consecutive days before the end of the treatment period.
In view of the findings observed at the end of the treatment period, this examination was carried out daily for 14 consecutive days before the end of the treatment-free period.

ORGAN WEIGHTS:
Epididymides, Ovaries (including oviducts), Testes, Uterus (horns and cervix).

HISTOPATHOLOGY:
Epididymides, Ovaries (including oviducts), Prostate (dorso-lateral, and ventral), Seminal vesicles (including coagulation gland), Testes, Uterus (horns and cervix), Vagina.

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Executive summary:

In the OECD 408 study (Papineau, 2018), the estrous cycle was determined over 21 or 14 consecutive days for all females at the end of the treatment or treatment-free period, respectively. At the end of the treatment period, seminological investigations (count and motility) were performed on all males, and sperm morphology was determined in control and high-dose males. On completion of the treatment, epididymides, ovaries (including oviducts), testes and uterus (horns and cervix) were weighed. A microscopic examination was performed on epididymides, ovaries, prostate , seminal vesicles (including coagulation gland), testes, uterus and vagina from control and high-dose animals euthanized at the end of the treatment period.

A non-adverse slight increase in the length of diestrus was observed in females given 600 mg/kg/day at the end of the treatment period. No variations were observed at the end of the treatment-free period. The epididymal sperm motility and morphology, and the testicular and epididymal spermatozoa count were unaffected by the test item treatment. At pathology investigations, there was no adverse effect on the male and female reproductive organs.

Justification for classification or non-classification

According to EU Regulation (EC) N0. 1272/2008 (CLP), TBEC is not classified for reprotoxicity.