Dihexadecyl peroxodicarbonate

Endpoint summary

Description of key information

Oral NOAEL is 1000 mg/kg bw/day based on the outcome of the OECD 408 study with the read-across substance.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

The study was performed between 22 March 2012 and 14 October 2012. The in-life phase of the study was conducted between 04 April 2012 (first day of treatment) and 28 May 2012 (final necropsy).

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Blackthorn, Bicester, Oxon, UK.
- Age at study initiation: approximately twelve weeks old.
- Weight at study initiation: males weighed 322 to 367g, the females weighed 198 to 224g
- Fasting period before study:
- Housing: Initially, all animals were housed in groups of five in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding (Datesand Ltd., Cheshire, UK). During the pairing phase, animals were transferred to polypropylene grid floor cages suspended over trays lined with absorbent paper on a one male: one female basis within each dose group. Following evidence of successful mating, the males were returned to their original cages. Mated females were housed individually during gestation and lactation, in solid floor polypropylene cages with stainless steel mesh lids and softwood flakes.
- Diet: ad libitum; A pelleted diet (Rodent 2018C Teklad Global Certified Diet, Harlan Laboratories U.K. Ltd., Oxon, UK)
- Water: ad libitum: Mains drinking water was supplied from polycarbonate bottles attached to the cage.
Environmental enrichment was provided in the form of wooden chew blocks and cardboard fun tunnels (Datesand Ltd., Cheshire, UK) except for mated females during gestation and lactation.
- Acclimation period: The animals were acclimatised for six days during which time their health status was assessed.

ENVIRONMENTAL CONDITIONS
The animals were housed in a single air-conditioned room within the Harlan Laboratories Ltd., Shardlow, UK, Barrier Maintained Rodent Facility.
- Temperature (°C): The temperature controls were set to achieve target values of 21 ± 2°C. Short term deviations from these targets were considered not to affect the purpose or integrity of the study. The actual range of temperature was 19.91 - 22.21°C.
- Humidity (%): The relative humidity controls were set to achieve target values of 55 ± 15%. Short term deviations from these targets were considered not to affect the purpose or integrity of the study. The actual range of relative humidity controls were 44.47 - 72.55%.
- Air changes (per hr): The rate of air exchange was at least fifteen air changes per hour.
- Photoperiod (hrs dark / hrs light): The low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness.

IN-LIFE DATES: 04 April 2012 (first day of treatment) and 28 May 2012 (final necropsy).

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
For the purpose of this study the test item was prepared at the appropriate concentrations as a suspension in Arachis oil BP.
The test item was administered daily by gavage using a stainless steel cannula attached to a disposable plastic syringe. The volume of test and control item administered was based on the most recent scheduled body weight and was adjusted at regular intervals.

VEHICLE
- Amount of vehicle (if gavage): Control: 4 mL/kg; in doses: made up to 4 mL/kg.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability and homogeneity of the test item formulations were determined. Results show the formulations to be stable for at least nineteen days. Formulations were therefore prepared weekly for the first four weeks and fortnightly thereafter and stored at approximately 4ºC in the dark.
Samples of each test item formulation were taken and analysed for concentration of Dihexadecyl Peroxodicarbonate (CAS 26322-14-5). The concentration of Dihexadecyl Peroxodicarbonate (CAS 26322-14-5) in the test item formulations was determined by gas chromatography (GC) using an external standard technique. The results indicate that the prepared formulations were within ±10% of the nominal concentration.

Duration of treatment / exposure:

Up to eight weeks.

Frequency of treatment:

The test item was administered daily by gavage using a stainless steel cannula attached to a disposable plastic syringe.

Remarks:

Doses / Concentrations:
30 mg/kg bw/day
Basis:
actual ingested

Remarks:

Doses / Concentrations:
300 mg/kg bw/day
Basis:
actual ingested

Remarks:

Doses / Concentrations:
1000 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

Ten animals per sex, per dose.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
The dose levels were chosen based on the results of previous toxicity work (14 day repeated dose oral range-finding study)

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
All animals were examined for overt signs of toxicity, ill-health and behavioural change immediately before dosing, up to thirty minutes after dosing, and one and five hours after dosing, during the working week. Animals were observed immediately before dosing, soon after dosing, and one hour after dosing at weekends and public holidays (except for females during parturition where applicable). All observations were recorded.

BODY WEIGHT: Yes
Individual body weights were recorded on Day 1 (prior to dosing) and then weekly for males until termination and weekly for females until mating was evident. Body weights were then recorded for females on Days 0, 7, 14 and 20 post coitum, and on Days 1 and 4 post partum.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
During the pre-pairing period, weekly food consumption was recorded for each cage of adults. This was continued for males after the mating phase. For females showing evidence of mating, food consumption was recorded for the periods covering post coitum Days 0-7, 7-14 and 14-20. For females with live litters, food consumption was recorded on Days 1 and 4 post partum.

FOOD EFFICIENCY:
Food efficiency (the ratio of body weight change/dietary intake) was calculated retrospectively for males throughout the study period (with the exception of the mating phase) and for females during the pre-pairing phase. Due to offspring growth and milk production, food efficiency could not be accurately calculated for females during gestation and lactation.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
Water intake was measured daily throughout the study (with the exception of the pairing phase).

OPHTHALMOSCOPIC EXAMINATION: No

Laboratory Investigations:
Haematological and blood chemical investigations were performed on five males and five females selected from each test and control group prior to termination (Day 42 for males and Day 4 post partum for females). Blood samples were obtained from the lateral tail vein. Where necessary repeat samples were taken by cardiac puncture at termination. Animals were not fasted prior to sampling.

HAEMATOLOGY: Yes
The following parameters were measured on blood collected into tubes containing potassium EDTA anti-coagulant:
Haemoglobin (Hb)
Erythrocyte count (RBC)
Haematocrit (Hct)
Erythrocyte indices - mean corpuscular haemoglobin (MCH)
- mean corpuscular volume (MCV)
- mean corpuscular haemoglobin concentration (MCHC)
Total leucocyte count (WBC)
Differential leucocyte count - neutrophils (Neut)
- lymphocytes (Lymph)
- monocytes (Mono)
- eosinophils (Eos)
- basophils (Bas)
Platelet count (PLT)
Reticulocyte count (Retic) - Methylene blue stained slides were prepared but reticulocytes were not assessed
Prothrombin time (CT) was assessed by ‘Innovin’ and Activated partial thromboplastin time (APTT) was assessed by ‘Actin FS’ using samples collected into sodium citrate solution (0.11 mol/L).

CLINICAL CHEMISTRY: Yes
The following parameters were measured on plasma from blood collected into tubes containing lithium heparin anti-coagulant:
Urea, Calcium (Ca++), Glucose, Inorganic phosphorus (P), Total protein (Tot.Prot.), Aspartate aminotransferase (ASAT), Albumin, Alanine aminotransferase (ALAT), Albumin/Globulin (A/G) ratio (by calculation), Alkaline phosphatase (AP), Sodium (Na+), Creatinine (Creat), Potassium (K+), Total cholesterol (Chol), Chloride (Cl-), Total bilirubin (Bili) and Bile acids.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
Functional Observations
Prior to the start of treatment and at weekly intervals thereafter, all animals were observed for signs of functional/behavioural toxicity. Functional performance tests were also performed on five selected males and females from each dose level, prior to termination, together with an assessment of sensory reactivity to various stimuli.

Behavioural Assessments
Detailed individual clinical observations were performed for each animal using a purpose built arena. The following parameters were observed:
Gait, Hyper/Hypothermia, Tremors, Skin colour, Twitches, Respiration, Convulsions, Palpebral closure, Bizarre/Abnormal/Stereotypic behaviour, Urination, Salivation, Defecation, Pilo-erection, Transfer arousal, Exophthalmia, Tail elevation and Lachrymation.
This test was developed from the methods used by Irwin (1968) and Moser et al (1988).

Functional Performance Tests
Motor Activity.
Purpose-built 44 infra-red beam automated activity monitors were used to assess motor activity. Animals were randomly allocated to the activity monitors. The tests were performed at approximately the same time each day, under similar laboratory conditions. The evaluation period was thirty minutes for each animal. The percentage of time each animal was active and mobile was recorded for the overall thirty minute period and also during the final 20% of the period (considered to be the asymptotic period, Reiter and Macphail, 1979).

Forelimb/Hindlimb Grip Strength.
An automated meter was used. Each animal was allowed to grip the proximal metal bar of the meter with its forepaws. The animal was pulled by the base of the tail until its grip was broken. The animal was drawn along the trough of the meter by the tail until its hind paws gripped the distal metal bar. The animal was pulled by the base of the tail until its grip was broken. A record of the force required to break the grip for each animal was made. Three consecutive trials were performed for each animal. The assessment was developed from the method employed by Meyer et al (1979).

Sensory Reactivity
Each animal was individually assessed for sensory reactivity to auditory, visual and proprioceptive stimuli. This assessment was developed from the methods employed by Irwin (1968) and Moser et al (1988). The following parameters were observed:
Grasp response, Touch escape, Vocalisation, Pupil reflex, Toe pinch, Blink reflex, Tail pinch, Startle reflex and Finger approach.

Sacrifice and pathology:

Adult males were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 43. Adult females were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 5 post partum. Surviving offspring were terminated via intracardiac overdose of a suitable barbiturate agent. Any females which failed to achieve pregnancy or produce a litter were killed on or after Day 25 post coitum.
All adult animals and offspring, including those dying during the study, were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.

GROSS PATHOLOGY: Yes
The following organs, removed from animals that were killed at the end of the study, were dissected free from fat and weighed before fixation:
Adrenals Prostate
Brain Seminal vesicles
Epididymides Spleen
Heart Testes
Kidneys Thymus
Liver Thyroid (weighed post-fixation with Parathyroid)
Ovaries Uterus (weighed with Cervix)

HISTOPATHOLOGY: Yes
Samples of the following tissues were removed from all animals and preserved in buffered 10% formalin, except where stated:
Adrenals, Aorta (thoracic), Bone & bone marrow (femur including stifle joint), Bone & bone marrow (sternum), Brain (including cerebrum, cerebellum and pons), Caecum, Coagulating gland+, Colon, Duodenum, Epididymides+•, Eyes*, Gross lesions, Heart, Ileum (including peyer’s patches), Jejunum, Kidneys, Liver, Lungs (with bronchi) #, Lymph nodes (mandibular and mesenteric), Mammary gland+, Muscle (skeletal), Ovaries+, Pancreas, Pituitary+, Prostate+, Oesophagus, Rectum, Salivary glands (submaxillary), Sciatic nerve, Seminal vesicles+, Skin (hind limb), Spinal cord (cervical, mid-thoracic and lumbar), Spleen, Stomach, Thyroid/parathyroid, Trachea, Testes+•, Thymus, Urinary bladder, Uterus/Cervix+ and Vagina+.

* = eyes fixed in Davidson’s fluid
• = preserved in Bouin’s fluid then transferred to 70% Industrial Methylated Spirits (IMS) approximately
forty-eight hours later
# = lungs were inflated to approximately normal inspiratory volume with buffered 10% formalin before
immersion in fixative

All tissues were despatched to the histology processing Test Site for processing. The tissues from five selected control and 1000 mg/kg bw/day dose group animals, any animals dying during the study, and any animals which failed to mate or did not achieve a pregnancy were prepared as paraffin blocks, sectioned at a nominal thickness of 5 μm and stained with haematoxylin and eosin for subsequent microscopic examination. The tissues indicated as + from the remaining control and 1000 mg/kg bw/day animals were also processed. In addition, sections of testes and epididymides from all control and 1000 mg/kg bw/day males were also stained with Periodic Acid-Schiff (PAS) stain and examined.

Statistics:

Evaluation of Data
Treatment of Data
Data were processed to give group mean values and standard deviations where appropriate.
For body weights and food consumptions during gestation, group mean values were calculated using data from females which were observed to give birth to offspring.
For body weights and food consumptions during lactation, group mean values were calculated using data from females with live young at Day 5 of lactation.

Where considered appropriate, quantitative data was subjected to statistical analysis to detect the significance of intergroup differences from control; statistical significance was achieved at a level of p<0.05. Statistical analysis was performed on the following parameters:
Grip Strength, Motor Activity, Body Weight, Body Weight Change, Food Consumption during gestation and lactation, Water Consumption during gestation and lactation, Pre-Coital Interval, Gestation Length, Litter Size, Litter Weight, Sex Ratio, Corpora Lutea, Implantation Sites, Implantation Losses, Viability Indices, Offspring Body Weight, Offspring Body Weight Change, Offspring Surface Righting, Haematology, Blood Chemistry, Absolute Organ Weights, Body Weight-Relative Organ Weights
Data were analysed using the decision tree from the ProvantisTM Tables and Statistics Module as detailed in "Any other information on materials and methods" below.

Clinical signs:

no effects observed

Description (incidence and severity):

There were no toxicologically significant clinical signs detected in treated animals.

Mortality:

no mortality observed

Description (incidence):

There were no toxicologically significant clinical signs detected in treated animals.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no toxicologically significant effects detected in body weight development.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No adverse effect on food consumption was detected in treated animals when compared to control animals.

Food efficiency:

not specified

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

no effects observed

Description (incidence and severity):

No toxicologically significant effect on water consumption was detected.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

No toxicologically significant effects were detected in the haematological parameters examined.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No toxicologically significant effects were detected in the blood chemical parameters examined.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

Weekly open field arena observations did not reveal any treatment-related effects for treated animals when compared to controls.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

No toxicologically significant effects were detected in the organ weights measured.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No toxicologically significant macroscopic abnormalities were detected.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No treatment related microscopic findings were detected.

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
Mortality
One female treated with 1000 mg/kg bw/day died during bleeding on Day 4 post partum. This death was considered procedure related and therefore is of no toxicological significance.
There were no further unscheduled deaths.

Clinical Observations
There were no toxicologically significant clinical signs detected in treated animals.
Animals of either sex treated with 1000 mg/kg bw/day showed episodes of increased salivation from Day 8 onwards. One female treated with 300 mg/kg bw/day also showed increased salivation on Day 33. Observations of this nature are commonly observed following the oral administration of an unpalatable or slightly irritant test item formulation and in isolation are considered not to be of toxicological importance.
One control female had mis-aligned posture characterised by the head tilting to the right from Day 35 onwards. The eyes of this animal also focussed in different directions. In the absence of treatment this was considered to be an isolated finding.

BODY WEIGHT AND WEIGHT GAIN
There were no toxicologically significant effects detected in body weight development.
Males treated with 1000 mg/kg bw/day showed a statistically significant reduction in body weight gain during Week 6. Body weight gain in the remaining treated groups during this week did not follow a true dose related response and in the absence of any significant effect on the percent of overall body weight gain, the intergroup difference was considered not to be of toxicological significance. Females treated with 1000 mg/kg bw/day showed a statistically significant reduction in body weight on Day 20 of gestation. Subsequent body weight gain during the final week of gestation was also statistically significantly reduced in these females. In isolation and in the absence of any effect on overall body weight development in females the intergroup differences were considered not to be of toxicological significance.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
No adverse effect on food consumption was detected in treated animals when compared to control animals.
Males treated with 1000 mg/kg bw/day showed a slight reduction in food efficiency during Week 6 when compared to controls. The intergroup difference was considered to be a result of the reduced body weight gain for these males during this week and in isolation was considered not to be toxicologically significant.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
No toxicologically significant effect on water consumption was detected.
Males treated with 300 and 1000 mg/kg bw/day showed an increase in overall water consumption compared to control animals. Observations of this nature are commonly observed following the oral administration of an unpalatable or slightly irritant test item formulation and in the absence of a true dose related response the intergroup differences were considered not to be of toxicological importance.
Females treated with 300 mg/kg bw/day showed a statistically significant reduction in water consumption during Week 3 of gestation. A reduction in water consumption is not generally considered to be an adverse effect of treatment and in the absence of similar findings in females treated with 1000 mg/kg bw/day, the intergroup difference was considered not to be of toxicological significance.

HAEMATOLOGY
No toxicologically significant effects were detected in the haematological parameters examined.
Males from all treatment groups showed a statistically significant increase in erythrocyte count when compared to controls. Males treated with 1000 and 300 mg/kg bw/day showed a statistically significant increase in haematocrit. Males treated with 1000 mg/kg bw/day also showed a statistically significant increase in neutrophil count and a statistically significant reduction in mean corpuscular haemoglobin concentration. The majority of individual values were within normal ranges for rats of the strain and age used, and in the absence of true dose related responses the intergroup difference was considered not to be of toxicological importance.

CLINICAL CHEMISTRY
No toxicologically significant effects were detected in the blood chemical parameters examined.
Males treated with 1000 mg/kg bw/day showed a statistically significant reduction in alkaline phosphatase and cholesterol. The majority of individual values were within the normal ranges for rats of the strain and age used, and were considered not to be of toxicological importance. Females treated with 1000 mg/kg bw/day showed a statistically significant reduction in alkaline phosphatase and statistically significant increases in chloride concentration and bile acid. In the absence of any histology correlates the intergroup differences were considered not to be of toxicological importance. Females treated with 30 mg/kg bw/day showed a statistically significant reduction in cholesterol. In the absence of a true dose related response or any histology correlates the intergroup difference was considered not to be of toxicological importance.

NEUROBEHAVIOUR
Behavioural Assessments
Weekly open field arena observations did not reveal any treatment-related effects for treated animals when compared to controls.
All inter and intra group differences in behavioural scores were considered to be a result of normal variation for rats of the strain and age used, and the differences were of no toxicological importance.

Functional Performance Tests
There were no toxicologically significant changes in functional performance.
Males treated with 1000 mg/kg bw/day showed a statistically significant increase in hind limb grip strength and a statistically significant reduction in overall activity. The statistically significant difference in hind limb grip strength was confined to one out of the three tests and in the absence of any supporting clinical observations to suggest an effect of neurotoxicity, the intergroup differences were considered to be of no toxicological significance.

Sensory Reactivity Assessments
There were no treatment-related changes in sensory reactivity.

ORGAN WEIGHTS
No toxicologically significant effects were detected in the organ weights measured.
Males treated with 1000 mg/kg bw/day showed a statistically significant reduction in prostate weight, both absolute and relative to terminal body weight. Females treated with 300 mg/kg bw/day showed a statistically significant increase in absolute and relative kidney weight. In the absence of any histology correlates the intergroup differences were considered not to be of toxicological importance.

GROSS PATHOLOGY
Adults
No toxicologically significant macroscopic abnormalities were detected.
One female treated with 1000 mg/kg bw/day had an enlarged spleen at necropsy. In the absence of any histology correlates the intergroup difference was considered not to be of toxicological importance.
One control male, two control females and one female treated with 30 mg/kg bw/day had reddened lungs at necropsy. In the absence of similar findings in the 1000 mg/kg bw/day dose group and in view of this finding also being present in control animals the intergroup differences were considered not to be of toxicological significance.
Offspring
No treatment-related macroscopic abnormalities were detected for interim death or terminal kill offspring. The incidental findings observed were those occasionally observed in reproductive studies of this type and were considered to be unrelated to toxicity of the test item.

HISTOPATHOLOGY: NON-NEOPLASTIC
No treatment related microscopic findings were detected.

Dose descriptor:

NOAEL

Remarks:

systemic toxicity

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No toxicologically significant effects.

Critical effects observed:

not specified

Conclusions:

The oral administration of Dihexadecyl Peroxodicarbonate (CAS 26322-14-5) to rats by gavage, at dose levels of 30, 300 and 1000 mg/kg bw/day, did not result in any toxicologically significant effects. The ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was therefore considered to be 1000 mg/kg bw/day.
The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day.

Executive summary:

Introduction.The study was designed to investigate the systemic toxicity and potential adverse effects of the test item on reproduction (including offspring development) and is compatible with the requirements of the OECD Guidelines for Testing of Chemicals No. 422 “Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test” (adopted 22 March 1996).

This study was also designed to be compatible with Commission Regulation (EC) No 440/2008 of 30 May 2008 laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH).

Methods.The test item was administered by gavage to three groups, each of ten male and ten female Wistar Han™:RccHan™:WIST strain rats, for up to eight weeks (including a two week pre-pairing phase, pairing, gestation and early lactation for females), at dose levels of 30, 300 and 1000 mg/kg bw/day. A control group of ten males and ten females was dosed with vehicle alone (Arachis oil BP).

Clinical signs, behavioural assessments, body weight change and food and water consumption were monitored during the study. 

Pairing of animals within each dose group was undertaken on a one male: one female basis within each treatment group on Day 15 of the study, with females subsequently being allowed to litter and rear their offspring to Day 5 of lactation.

During the lactation phase, daily clinical observations were performed on all surviving offspring, together with litter size and offspring weights and assessment of surface righting reflex.

Extensive functional observations were performed on five selected males from each dose group after the completion of the pairing phase, and for five selected parental females from each dose group on Day 4 post partum. Haematology and blood chemistry were evaluated prior to termination on five selected males and females from each dose group. 

Adult males were terminated on Day 43, followed by the termination of all surviving females and offspring on Day 5 post partum. Any female which did not produce a pregnancy was terminated on or after Day 25 post coitum. All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

Results.

Mortality.One female treated with 1000 mg/kg bw/day died during bleeding on Day 4 post partum. There were no further unscheduled deaths. 

Clinical Observations.There were no toxicologically significant clinical signs detected in treated animals.

Behavioural Assessment.There were no treatment-related changes in the behavioural parameters measured.

Functional Performance Tests.There were no toxicologically significant changes in functional performance.

Sensory Reactivity Assessments.There were no treatment-related changes in sensory reactivity.

Body Weight.There were no toxicologically significant effects detected in body weight development.

Food Consumption.No adverse effect on food consumption or food efficiency was detected in treated animals.

Water Consumption.No toxicologically significant effect on water consumption was detected in treated animals.

Laboratory Investigations:

Haematology.No toxicologically significant effects were detected in the haematological parameters examined. 

Blood Chemistry.No toxicologically significant effects were detected in the blood chemical parameters examined. 

Pathology:

Necropsy.No toxicologically significant macroscopic abnormalities were detected.

Organ Weights.No toxicologically significant effects were detected in the organ weights measured.

Histopathology.No treatment related microscopic abnormalities were detected.

Conclusion.The oral administration of Dihexadecyl Peroxodicarbonate (CAS 26322-14-5) to rats by gavage, at dose levels of 30, 300 and 1000 mg/kg bw/day, did not result in any toxicologically significant effects. The ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was therefore considered to be 1000 mg/kg bw/day.

The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day.

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

See attached read across document.
Moreover, in ECHA´s final decision on a testing proposal, it is stated that:
"ECHA notes that, (...) read-across to the analogue substance ditetradecyl peroxydicarbonate (EC No 258-436-4) as proposed and adequately documented is plausible. Therefore, the 90-day subchronic toxicity study should not be performed with the registered substance but with the analogue substance" (TPE-D-2114453451-55-01/F).

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effects observed at the highest dose tested (limit dose)

Key result

Critical effects observed:

no

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

K1: The study was performed according to OECD guidelines and GLP.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Key study, OECD 408, Read-across:

The oral administration of the read-across substance to rats by gavage at dose levels of 100, 300, 1000 mg/kg bw/day for 90 days did not result in any toxicologically relevant effects. Therefore, the NOAEL for systemic toxicity was considered to be 1000 mg/kg bw/d.

Supporting study, OECD 422:

The oral administration of the test substance to rats by gavage, at dose levels of 30, 300 and 1000 mg/kg bw/day under the test conditions of an OECD 422 compliant study did not result in any toxicologically significant effects. The NOAEL for systemic toxicity was therefore considered to be 1000 mg/kg bw/day.

Justification for classification or non-classification

Based on the results from an OECD 408 study with the read-across substance as well as an OECD 422 study with the registered substance in rats the substance is not classified, the NOAEL is 1000 mg/kg bw/day. The data is conclusive but not sufficient for classification.