Reaction products of 2-hydroxyethyl methacrylate and diphosphorous pentoxide and water

Endpoint summary

Description of key information

Repeated dose toxicity : target : Reaction products of 2-hydroxyethyl methacrylate and diphosphorous pentoxide and water : Oral (gavage): NOAEL (rat,systemic toxicity): male/female = 300 mg/kg bw/day, 2021

Read-Across: source data : Reaction products of 2-hydroxyethyl methacrylate and diphosphorus pentaoxide : Oral (gavage): NOAEL (rat,systemic toxicity): male/female = 300 mg/kg bw/day, OECD TG 422, 2016

Oral gavage in propylene glycol, vehicle : doses: 0, 100, 300 and 1000 mg/kg bw/day

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From January 26, 2016 to March 24, 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline study performed under GLP. All relevant validity criteria were met.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

other:

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

but considered not to adversely affect the results or integrity of the study.

Qualifier:

according to guideline

Guideline:

other: OECD guidance document 43

Version / remarks:

The guideline was designed for use with the rat, which is the preferred rodent species for reproduction toxicity testing.

Principles of method if other than guideline:

- To obtain information on the possible toxic effects of the test substance following repeated (daily) administration by oral gavage to Wistar rats at 3 dose levels. A control group received the vehicle only (propylene glycol).
- The study further included a reproductive/ developmental toxicity screening test, intended to provide initial information on possible effects on male and female reproductive performance including gonadal function, mating behaviour, conception, pregnancy, parturition and development of the F1 offspring from conception to Day 4 post-partum.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Remarks:

Crl:WI

Details on species / strain selection:

The rat is regarded as suitable species for toxicology and reproduction studies. Wistar rat was selected due to experience with this strain of rat in toxicity and reproduction toxicity studies and known fertility.

Sex:

male/female

Details on test animals or test system and environmental conditions:

Source: Charles River Laboratories, Research Models and Services, Germany GmbH (Sandhofer Weg 7, D-97633 Sulzfeld, Germany)
Housing conditions: SPF at the supplier, standard laboratory conditions during the study
Number of animals: 51 male, 51 female rats, 4 groups. 12 animals/sex/group, with the exception of the High dose group, where 15 animals/sex/group was used. Animals originated from different units, to avoid brother/sister matings
Age of animals: young adult rats, at least 10 weeks old at starting and 12 weeks at mating
Body weight at the start: males: 362-422 g, females: 218-261 g
Acclimation period: at least 5 days
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 21.2-24.3 °C (target: 22 ± 3°C)
Relative humidity: 40 - 62% (target: 30 - 70%)
Ventilation: 15-20 air exchanges/hour
Food and water supply: ssniff® SM R/M "Autoclavable complete diet for rats and mice – breeding and maintenance" and tap water, ad libitum

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Details on oral exposure:

The oral route was selected, as it is a possible route of exposure to the test substance in humans.

The test substance was formulated in the vehicle, as a clear solution at the appropriate concentrations according to the selected dose level and volume, in the Pharmacy of CiToxLAB Hungary Ltd.

Formulations were prepared in up to 6-day intervals and stored at room temperature, based on the stability assessment results. Stability of the test substance in the vehicle was assessed in the conditions employed on the study (concentration range and storage conditions of the dose formulations pending use, according to CiToxLAB study code 15/340-316AN). Analysis of PARAD substance 139 formulation samples of 1-250 mg/mL concentration range showed no decrease of concentration and can be considered as stable for 7 days at room temperature.

Analytical verification of doses or concentrations:

yes

Remarks:

HPLC

Details on analytical verification of doses or concentrations:

Analysis of test substance formulations for concentration and homogeneity was performed in the Analytical Laboratory of CiToxLAB Hungary Ltd. Top, middle and bottom duplicate samples were taken and analysed from test substance formulations and all concentrations. Sample analysis was performed on 3 occasions (with an additional occasion for the High dose (250 mg/ml) formulation) for homogeneity (top, mid and bottom) and all prepared formulations were analysed for concentration. One set was collected for analysis and one set as a back-up. Similarly, one sample was taken on each occasion in duplicate from the Group 1 (control) solution to confirm the absence of test substance. Description of the analytical method and the results of the formulation analysis are included in the Analytical report provided by the Analytical Laboratory of CiToxLAB Hungary Ltd.
Analysis of the test substance formulation samples of 1-250 mg/mL concentration range showed no decrease of concentration and can be considered as stable for 7 days at room temperature.
The measured concentrations of the test substance evaluated for each test substance-dose group varied between 94 % and 107 % of the nominal contents. No test substance was detected in the control samples. These results were within the acceptable range (85% - 115%) and are acceptable for the study purposes. All samples were found to be homogeneous.

Duration of treatment / exposure:

- Males were dosed for 28 days (14 days pre-mating and 14 days mating/post-mating), and then euthanized and subjected to necropsy examination.
- Females were dosed for 54 days (14 days pre-mating, during the mating period, through gestation and until the day before the necropsy (at least 4 days post-partum dosing). The day of birth (when parturition was complete) was defined as Day 0 post-partum.

Frequency of treatment:

Daily on a 7 days/week basis by oral gavage using a tipped gavage needle attached to a syringe. A constant volume of 4 mL/kg bw was administered to all animals. The actual volume administered was calculated and adjusted based on most recent individual body weights. (Dosing of both sexes began after at least 5 days of acclimation and 2 weeks before mating and continued up to the day before necropsy.)

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

Concentration: 0 mg/mL
Dose volume: 4 mL/kg bw

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

Concentration: 25 mg/mL
Dose volume: 4 mL/kg bw

Dose / conc.:

300 mg/kg bw/day (nominal)

Remarks:

Concentration: 75 mg/mL
Dose volume: 4 mL/kg bw

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

Concentration: 250 mg/mL
Dose volume: 4 mL/kg bw

No. of animals per sex per dose:

at least 12

Control animals:

yes, concurrent vehicle

Details on study design:

The dose levels were selected by the Sponsor in consultation with the Study Director based on available data and information from previous experimental work including the results of a repeated dose range finding study in the rat (CiToxLAB Hungary Ltd. study code 15/340-220PE). The aim was to induce toxic effects but ideally no death or suffering at the highest dose and a NOAEL at the lowest dose.
Based on the results from these preliminary studies, doses of 100, 300 and 1000 mg/kg bw/day were selected for the main study.

Positive control:

-

Observations and examinations performed and frequency:

Clinical signs and Functional observation battery:
- Animals were inspected for signs of morbidity and mortality twice daily, at the beginning and the end of the working day. General clinical observations were performed daily, after treatment at approximately the same time with minor variations, and/or in the afternoon as practical during the working day, as no peak period of effects was noted after dosing during the first few days of treatment. All animals were also monitored for pertinent behavioural changes, signs of difficult or prolonged parturition and all signs of toxicity including mortality. Any changes were recorded including their onset, degree and duration as applicable.
- Detailed examinations were performed once before the first exposure (to allow for within-subject comparisons), then at least weekly, in the morning or before treatment. These observations were performed outside the home cage in a standard arena, at similar day times as practical. The animals were monitored for changes in skin, fur, eyes, mucous membranes, occurrence of secretions and excretions, and autonomic activity (e.g. lachrymation, piloerection, pupil size, unusual respiratory pattern), or changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypies (e.g. excessive grooming, repetitive circling), difficult or prolonged parturition or bizarre behaviour (e.g. self-mutilation, walking backwards); special attention were directed towards the observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.

- Neurotoxicity (5 males and 5 females per group):
Assessment of potential test substance related neurotoxicity was performed in the morning and prior to dosing, during the last exposure week (males on Day 24; females on PPD 4). Selected animals were subjected to the functional observation battery including quantitative assessment of grip strength (manual and instrumental) and measurement of landing foot splay and fore/hind limb grip strength. Qualitative and quantitative assessments of motor activity were performed. Parameters including body position, locomotor activity, respiration rate, respiration type, piloerection, head searching compulsive biting or licking, circling, upright walking, retropulsion, jumping, exophthalmos, twitches, clonic convulsions, tonic convulsions, tremor, startle, transfer arousal, spatial locomotion, gait, posture, limb position, finger approach, finger withdrawal, touch escape response, diarrhoea, diuresis, visual placing, grip strength, body tone, corneal reflex, pinna, toe pinch, grasping reflex, positional struggle, skin, mucous membrane colour, salivation, palpebral closure, lachrymation, limb tone, abdominal tone, tail pinch, righting reflex, and/or vocalisation were evaluated using a scoring system, where score 0 was given when the behaviour or reaction of the animal was considered normal, and -1 or -2, or +1 and +2 was given if the response was less than or more than expected in an untreated animal.

- Body weight measurement:
All adult animals were weighed with an accuracy of 1 g for randomization purposes, then on Day 0, at least weekly thereafter and at termination. Parent females were weighed on gestation Days GD0, 3, 7, 14 and 20 and on post-partum Days PPD0 (within 24 hours after parturition), PPD4 and before termination. Body weights of the female animals were additionally taken on gestational Days GD10 and 17 in order to give accurate treatment volumes but these data were not evaluated statistically.

- Food consumption measurement:
Food consumption was determined by re-weighing the non-consumed diet with a precision of 1 g at least weekly (on the days of body weight measurements).

- Clinical pathology:
All animals selected for blood sampling were fasted (overnight period of food deprivation, after the litter had been culled). Blood samples were collected by cardiac puncture under pentobarbital anaesthesia, immediately prior to scheduled necropsy. For terminal blood sampling three samples were taken from each selected animal (5 males and 5 females/group), one for haematology (in tubes with K3-EDTA as anticoagulant, 1.6 mg/mL blood), one for blood clotting times (in tubes with sodium citrate as anticoagulant) and one to obtain serum (in tubes with no anticoagulant) for clinical chemistry.

- Haematology and blood clotting times: Daily or detailed weekly observation; For details on evaluated parameters see under 'any other information on material and methods incl. tables'

- Clinical chemistry: Daily or detailed weekly observation; For details on evaluated parameters see under 'any other information on material and methods incl. tables'

- Urinalysis:
Urine samples were collected for 16 hours during an overnight period of food deprivation during the last week of the study (Day 27-28 for males and PPD4-5 for female animals, respectively) from each animal by placing the animals in metabolic cages. The evaluation of the urine samples were performed by observation (e.g. appearance, colour) and test strips. For details on evaluated parameters see under 'any other information on material and methods incl. tables'

Sacrifice and pathology:

Pathology
- Gross necropsy was performed on all animals, irrespective of the date of death. After exsanguination the external appearance was examined, cranium, thoracic and abdominal cavities were opened and the appearance of the tissues and organs was observed macroscopically. Any abnormality was recorded with details of the location, colour, shape and size, as appropriate. Special attention was paid to the organs of the reproductive system. The number of implantation sites and of corpora lutea was recorded in the females as applicable.

Organ weight measurements
- At the time of termination, body weight and the weight of the following organs from all euthanized adult animals were determined.
- With a precision of 0.01 g: brain, heart, kidneys, liver, spleen and thymus
- With a precision of 0.001 g: adrenals, ovaries, thyroids with parathyroids
Paired organs were weighed together. Individual and/or paired absolute organ weights were reported for each animal and adjusted for the body and brain weights. Paired organ weights as applicable were summarised. Relative organ weight (to body and brain weight) was calculated and reported.

Tissue preservation and microscopic evaluation.
- The weighed organs and all organs showing macroscopic lesions were preserved. The eyes with the optic nerve were retained in modified Davidson’s fixative. All other organs in 10% buffered formalin solution. The retained tissues and organs were embedded in paraffin wax, sections were cut at 4-6µm by microtome and transferred to slides. Tissue sections were stained with haematoxylin-eosin/phloxine and examined by light microscope. Detailed histological examination was performed on all retained organs in the control and High dose groups and any macroscopic findings (abnormalities) observed in all animals. (Special attention was paid to the evaluation of the stages of spermatogenesis in the male gonads and histopathology of interstitial testicular cell structure. Detailed histological examination of the ovaries covered the follicular, luteal, and interstitial compartments of the ovary, as well as the epithelial capsule and ovarian stroma.).

For details on evaluated tissues and organs see under 'any other information on material and methods incl. tables'

Statistics:

Data were recorded on the appropriate forms from the relevant SOPs of CiToxLAB Hungary Ltd., and then tabulated using the Microsoft Office Word and/or Excel, or using the software PROVANTIS v.9, as appropriate. Group means and standard deviations were calculated from numerical data obtained in the study.
The statistical evaluation of appropriate data (marked † below) was performed with the statistical program package SPSS PC+4.0 (SPSS Hungary Kft, Budapest) by an appropriate statistical method (Bartlett, ANOVA/ANCOVA and Duncan, Kruskal-Wallis and Mann-Whitney U tests, T-test, Wilcoxon test, Chi2 test). The homogeneity of variance between groups was checked by Bartlett’s homogeneity of variance test. Where no significant heterogeneity was detected, a one-way analysis of variance (ANOVA/ANCOVA) was carried out. If the obtained result was significant, Duncan’s Multiple Range test or Kruskal-Wallis test was used to access the significance of inter-group differences. For a significant result at Bartlett’s test, the Kruskal-Wallis analysis of variance was used and the inter-group comparisons were performed using Mann-Whitney U-test. Chi2 test was performed as feasible. For SMART evaluation, T-test was used.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Terminally euthanised animals:
- Male animals: no clinical signs were detected in the Control, Low and Mid dose groups during the study. In the High (1000 mg/kg bw/day) dose group liquid faeces, noisy respiration and piloerection were occasionally present up to three animals during the treatment. These observations were considered to be treatment related.
- Female animals: thin fur/alopecia was observed in all groups, peaking at the end of the experiment, but is not considered to be related to test substance. No clearly adverse effects of the test substance related were noted in the Low dose groups during the study. In the Mid (300 mg/kg bw/day) dose group, piloerection and noisy respiration was observed sporadically in just 1 or 2 females. These non-specific observations seen sporadically at a low incidence is not considered to be a clear sign of an adverse effect of the test substance. In the High (1000 mg/kg bw/day) dose group, the non-specific signs of piloerection and noisy respiration was seen in a small number of male and the majority of females. Hunched back was also present in up to three female animals, which may be treatment related. A 1 to 2 cm wide crust was seen on the skin for five days in one animal, yellow coloured discharge in one animal, and discharge from vagina in one animal was observed during the treatment; these findings are of uncertain relationship with treatment.

Found dead and preterminally euthanized animals:
No common symptoms were found prior unanticipated deaths. The male animal showed slightly noisy, moderately laboured respiration one day before it was found dead. Two females showed no clinical signs before the time of death. Piloerection and slight to moderate noisy respiration and/or laboured respiration with hunched back was present in the rest of the animals, with red coloured discharge or distended abdomen prior dead or euthanasia. These symptoms were considered to be test substance related.

Excluded animals
Four females (two from the Control Dose group and two from the Mid (300 mg/kg bw/day) Dose group were excluded from certain statistical analysis (such as body weight) after being found to be sperm positive, but delivered no offspring despite detectable corpora lutea. Since body weight is affected by pregnancy, it is valid to exclude the non-pregnant animals from this data analysis. Sporadic occurrence of noisy respiration in one Control group and the two Mid dose animals, laboured respiration and piloerection in one Mid dose animal was observed, but these observations were not considered to be test item related.

Mortality:

mortality observed, treatment-related

Description (incidence):

A test substance related mortality (approximately 15% mortality) was observed in the High dose group (1000 mg/kg bw/day). One male (Day 16) and 4 females (Days 3, 6, 18 and 22 ) of the High dose group were found dead. In addition, one female (Day 17) was preterminally euthanized.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No test substance related effects were noted on the mean body weight and body weight gain values following daily administration of test substance at dose levels up to and including 1000 mg/kg bw/day

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

There were no test substance related differences in the mean daily food consumption in any test substance treated group when compared to the controls.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

When compared to the controls, there were no differences that could be considered toxicologically significant in the Low and Mid dose (100 and 300 mg/kg bw/day, respectively) groups. The High (1000 mg/kg bw/day) males only had a slightly but significantly (p<0.05) lower Mean Cell Haemoglobin Concentratin (MCHC). The female High dose group had a slightly but significantly (p<0.05) longer Activated Partial Thromboplastin Time (APTT). However the data from all animals was in the normal range and these small differences were not consistent between sexes and were not considered to be an adverse effect of treatment.
For other parameters, evaluation of the mean and individual results in comparison with the control data did not reveal any test-substance related cause of the changes noted, and/or no consistent dose or gender-related response was observed. Therefore, these differences observed between the Control and treated groups were considered incidental or individual findings, which were not related to treatment, were generally comparable with the expected physiological range and of no toxicological significance.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

In the animals evaluated at termination (on Day 28 in males and on PPD5 in females), there were no clearly toxicologically significant changes or adverse effects on the animal serum chemistry that could be ascribed to the test substance administration in the conditions of this study. Urea and chloride concentrations were statistically significantly higher in the male High (1000 mg/kg bw/day) dose group compared to the Control (p<0.05 and p<0.01, respectively). The female High dose group had statistically significantly (p<0.05) lower phosphorus values. However the data for these 3 parameters from all animals was in the normal range and these small differences were not consistent between sexes and were not considered to be an adverse effect of treatment.
Some differences in the Low and Mid treated groups also attained statistical significance; however, there was no dose or gender response or the values were within the physiological ranges. For this reason, these variations were not considered toxicologically significant or related to treatment.

Urinalysis findings:

effects observed, non-treatment-related

Description (incidence and severity):

A dose dependent decrease of pH was observed in both sexes, reaching statistical significant difference compared to the control value at the High (1000 mg/kg bw/day) dose males (p<0.05) and females (p<0.01). In the High dose only, slight but statistical significance differences were recorded with lower pH and higher urine gravity in both sexes (p<0.01) and lower urine volume in makes only (p<0.05). However, all values were in the normal control range, these findings were regarded as minor variations and were not considered to indicate an adverse effect of the test substance.

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Kidney weights were slightly higher than control in both sexes at the High dose (by 8% in males and by approximately 10% in females). This was statistically significant both in terms of absolute weight or when adjusted for body or brain weights. There were also slight differences in urine analysis at the High dose level in both sexes, so the small organ weight differences may reflect an adaptive or functional difference. A similar statistically significant difference was seen in female kidney weights in the Mid dose group but the data was all in the normal range. Therefore it was not considered to be a clear effect of the test substance. At the Mid and Low dose levels, it is considered that minor statistical differences did not reflect an effect of the test susbtance. In the absence of any histopathological or blood chemistry changes, there is no evidence of an adverse effect in the kidneys at any dose level.
In females, increased liver weights were seen in the High dose group only (by 12% absolute weight). Increased liver weights were not seen in the males of the High dose group. These liver weight changes correlate well with the centrilobular hepatocellular hypertrophy observed in High (1000 mg/kg bw/day) dose female animals.
There were no other toxicologically significant differences among groups in the weights of other organs measured when compared to controls.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

- Found dead animals: Small spleen in 2 out of 4 found dead females and small thymus in 1 out of 4 female corresponded with findings noted during microscopic examination.
- Preterminal euthanasia: Small spleen and thymus, pale foci of the left lobe in the liver were observed at necropsy and were related to the treatment. Dilatation (with gas) of the oesophagus, stomach, duodenum, jejunum, ileum, caecum and colon, and red/clear material at the perinasal fur did not have relationship to the treatment.
- Terminal animals: No treatment-related macroscopic findings were observed up to the dose level of 1000 mg/kg bw/day.

Neuropathological findings:

no effects observed

Description (incidence and severity):

Neurological:
There were no toxicologically significant changes in animal behaviour, general physical condition or in the reactions to different types of stimuli in the control or test groups.
There was no effect of treatment noted during the assessment of foot splay, grip strength or motor activity. Grip strengths of the forelimb were significantly (p <0.05) lower in Mid dose (300 mg/kg bw/day) females, but without dose dependency and similar results for the hindlimbs or during the modified Irwin test, this variety was not considered to be a test item related effect.
The total travelled distance in the High dose group and the shape of the curve of activity in 5 minute periods over one hour, were comparable to the control groups for both sexes; all data was within the normal expected range. Sporadic statistical significant differences were of no toxicological relevance. There was no test item related effect on locomotor activity in either sex.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

- Found dead animals:
Treatment-related slight centrilobular hepatocellular hypertrophy of the liver was observed in 1 out of 4 female. Various microscopic findings induced by stress due to treatment such as slight decrease of white pulp size/cellularity in the spleen and moderate decrease size/cellularity of the thymic cortex (correlated with gross changes), slight decrease of myeloid cellularity in the femoral and sternal bone marrows, slight diffuse vacuolation of the adrenal’s medulla were present in this found dead female. In addition, moderate decrease of white pulp size/cellularity in the spleen was also recorded in one other female rat. There were no findings that clearly indicated a cause of death.

- Preterminal euthanasia:
Treatment-related slight centrilobular hepatocellular hypertrophy of the liver was seen by light microscopy and visualized at necropsy (pale foci). The histopathological findings corresponded with stress-related responses and ascribed to the treatment included moderate decrease of white pulp size/cellularity in the spleen, moderate decrease size/cellularity of the thymic cortex and, correlated with gross changes. Additionally, decrease myeloid cellularity in the femoral (moderate severity) and sternal (slight severity) bone marrows, slight diffuse vacuolation of the adrenal’s medulla, were noted by light microscopy. There were no findings that clearly indicated a cause of a moribund state.
Other changes were regarded as incidental.

- Terminal animals:
Treatment-related centrilobular hepatocellular hypertrophy of the liver was seen at a dose level 1000 mg/kg bw/day. Minimal hypertrophy altered liver in 1 out of 5 selected male and minimal/slight hypertrophy in 4 out of 5 selected females. This change was considered to be an adaptive non-adverse response to the administration of the test substance.
Other changes were incidental or a common background.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

300 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

organ weights and organ / body weight ratios

Remarks on result:

other: for systemic effects

Key result

Critical effects observed:

no

Conclusions:

Under the study conditions, the rat NOAEL for systemic effects was established at 300 mg/kg bw/day for females and males.

Executive summary:

A study was conducted to determine the repeated dose toxicity of the test substance according to OECD guideline 422. The general systemic toxic potential of the substance to Wistar rats was assessed by daily oral administration (gavage). Males were dosed for 28 days (14 days pre-mating and 14 days mating/post-mating), and females for 14 days pre-mating, during the mating period, through gestation and until the day before the necropsy (at least 4 days post-partum dosing). Three groups each comprising at least 12 male and 12 female rats received the test substance at doses of 0, 100, 300 or 1000 mg/kg bw/day. Parameters measured during the study included signs of morbidity and mortality twice daily, daily or detailed weekly observation of clinical signs, neurological assessment, weekly body weight and food consumption, and clinical pathology evaluation, including haematology, coagulation, clinical chemistry and urinalysis. Neurological assessment including functional observation battery (FOB) and measurements of the landing foot splay, grip strength and motor activity were performed during the last week of the treatment. At termination, necropsy with macroscopic examination was performed. Weights of selected organs were recorded and representative tissues/organs were sampled and preserved in appropriate fixatives. A detailed histological examination was performed on the selected list of retained organs in the control and High dose groups. Daily administration of the test substance at dose levels of 100 or 300 mg/kg bw/day did not result in adverse changes in clinical signs, neurological assessment, body weight, food consumption, haematology, coagulation, clinical chemistry, or urinalysis parameters. Test substance related mortality (approximately 15% mortality) was observed in the High dose group (1000 mg/kg/d) and clinical adverse effects were present in High dose females. There were no effects on surviving animals on body weight or clinical pathology. Test substance related liver changes were observed in the female High dose group (1000 mg/kg bw/day) with increased weight (approximately 12%) and centrilobular hepatocellular hypertrophy. However, this observation was considered to be an adaptive change and not an adverse effect of treatment. Test substance related kidney weight changes were observed in the High dose group of both sexes (by up to about 10%), but in the absence of any histological changes, this too was considered to be an adaptive response. Under the study conditions, the rat NOAEL for systemic effects was established at 300 mg/kg bw/day for females and males (Hargitai, 2016).

Reference 2

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test

Type of information:

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

Adequacy of study:

key study

Study period:

26-01-2016 to 24-03-2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included in attachment to IUCLID section 13.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The read-across is based on the hypothesis that the source and target substances have common structural features in the same relative positions. The source and target have similar physico-chemical, toxicological properties and because of common metabolism they share common or have similar breakdown products and therefore potential mechanisms of action. Further information is included in attachment to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The source and target chemicals have comparable chemical similarity. Further information is included in attachment to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
The source substance is a chemically similar substance with common metabolism and common or similar degradants of the target substance. Further information is included in attachment to IUCLID section 13

4. DATA MATRIX
Further information is included in attachment to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

but considered not to adversely affect the results or integrity of the study.

Qualifier:

according to guideline

Guideline:

other: OECD guidance document 43

Version / remarks:

The guideline was designed for use with the rat, which is the preferred rodent species for reproduction toxicity testing.

Principles of method if other than guideline:

- To obtain information on the possible toxic effects of the test substance following repeated (daily) administration by oral gavage to Wistar rats at 3 dose levels. A control group received the vehicle only (propylene glycol).
- The study further included a reproductive/ developmental toxicity screening test, intended to provide initial information on possible effects on male and female reproductive performance including gonadal function, mating behaviour, conception, pregnancy, parturition and development of the F1 offspring from conception to Day 4 post-partum.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Remarks:

Crl:WI

Details on species / strain selection:

The rat is regarded as suitable species for toxicology and reproduction studies. Wistar rat was selected due to experience with this strain of rat in toxicity and reproduction toxicity studies and known fertility.

Sex:

male/female

Details on test animals or test system and environmental conditions:

Source: Charles River Laboratories, Research Models and Services, Germany GmbH (Sandhofer Weg 7, D-97633 Sulzfeld, Germany)
Housing conditions: SPF at the supplier, standard laboratory conditions during the study
Number of animals: 51 male, 51 female rats, 4 groups. 12 animals/sex/group, with the exception of the High dose group, where 15 animals/sex/group was used. Animals originated from different units, to avoid brother/sister matings
Age of animals: young adult rats, at least 10 weeks old at starting and 12 weeks at mating
Body weight at the start: males: 362-422 g, females: 218-261 g
Acclimation period: at least 5 days
Light: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 21.2-24.3 °C (target: 22 ± 3°C)
Relative humidity: 40 - 62% (target: 30 - 70%)
Ventilation: 15-20 air exchanges/hour
Food and water supply: ssniff® SM R/M "Autoclavable complete diet for rats and mice – breeding and maintenance" and tap water, ad libitum

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Details on oral exposure:

The oral route was selected, as it is a possible route of exposure to the test substance in humans.

The test substance was formulated in the vehicle, as a clear solution at the appropriate concentrations according to the selected dose level and volume, in the Pharmacy of CiToxLAB Hungary Ltd.

Formulations were prepared in up to 6-day intervals and stored at room temperature, based on the stability assessment results. Stability of the test substance in the vehicle was assessed in the conditions employed on the study (concentration range and storage conditions of the dose formulations pending use, according to CiToxLAB study code 15/340-316AN). Analysis of PARAD substance 139 formulation samples of 1-250 mg/mL concentration range showed no decrease of concentration and can be considered as stable for 7 days at room temperature.

Analytical verification of doses or concentrations:

yes

Remarks:

HPLC

Details on analytical verification of doses or concentrations:

Analysis of test substance formulations for concentration and homogeneity was performed in the Analytical Laboratory of CiToxLAB Hungary Ltd. Top, middle and bottom duplicate samples were taken and analysed from test substance formulations and all concentrations. Sample analysis was performed on 3 occasions (with an additional occasion for the High dose (250 mg/ml) formulation) for homogeneity (top, mid and bottom) and all prepared formulations were analysed for concentration. One set was collected for analysis and one set as a back-up. Similarly, one sample was taken on each occasion in duplicate from the Group 1 (control) solution to confirm the absence of test substance. Description of the analytical method and the results of the formulation analysis are included in the Analytical report provided by the Analytical Laboratory of CiToxLAB Hungary Ltd.
Analysis of the test substance formulation samples of 1-250 mg/mL concentration range showed no decrease of concentration and can be considered as stable for 7 days at room temperature.
The measured concentrations of the test substance evaluated for each test substance-dose group varied between 94 % and 107 % of the nominal contents. No test substance was detected in the control samples. These results were within the acceptable range (85% - 115%) and are acceptable for the study purposes. All samples were found to be homogeneous.

Duration of treatment / exposure:

- Males were dosed for 28 days (14 days pre-mating and 14 days mating/post-mating), and then euthanized and subjected to necropsy examination.
- Females were dosed for 54 days (14 days pre-mating, during the mating period, through gestation and until the day before the necropsy (at least 4 days post-partum dosing). The day of birth (when parturition was complete) was defined as Day 0 post-partum.

Frequency of treatment:

Daily on a 7 days/week basis by oral gavage using a tipped gavage needle attached to a syringe. A constant volume of 4 mL/kg bw was administered to all animals. The actual volume administered was calculated and adjusted based on most recent individual body weights. (Dosing of both sexes began after at least 5 days of acclimation and 2 weeks before mating and continued up to the day before necropsy.)

Dose / conc.:

0 mg/kg bw/day (nominal)

Remarks:

Concentration: 0 mg/mL
Dose volume: 4 mL/kg bw

Dose / conc.:

100 mg/kg bw/day (nominal)

Remarks:

Concentration: 25 mg/mL
Dose volume: 4 mL/kg bw

Dose / conc.:

300 mg/kg bw/day (nominal)

Remarks:

Concentration: 75 mg/mL
Dose volume: 4 mL/kg bw

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

Concentration: 250 mg/mL
Dose volume: 4 mL/kg bw

No. of animals per sex per dose:

at least 12

Control animals:

yes, concurrent vehicle

Details on study design:

The dose levels were selected by the Sponsor in consultation with the Study Director based on available data and information from previous experimental work including the results of a repeated dose range finding study in the rat (CiToxLAB Hungary Ltd. study code 15/340-220PE). The aim was to induce toxic effects but ideally no death or suffering at the highest dose and a NOAEL at the lowest dose.
Based on the results from these preliminary studies, doses of 100, 300 and 1000 mg/kg bw/day were selected for the main study.

Positive control:

-

Observations and examinations performed and frequency:

Clinical signs and Functional observation battery:
- Animals were inspected for signs of morbidity and mortality twice daily, at the beginning and the end of the working day. General clinical observations were performed daily, after treatment at approximately the same time with minor variations, and/or in the afternoon as practical during the working day, as no peak period of effects was noted after dosing during the first few days of treatment. All animals were also monitored for pertinent behavioural changes, signs of difficult or prolonged parturition and all signs of toxicity including mortality. Any changes were recorded including their onset, degree and duration as applicable.
- Detailed examinations were performed once before the first exposure (to allow for within-subject comparisons), then at least weekly, in the morning or before treatment. These observations were performed outside the home cage in a standard arena, at similar day times as practical. The animals were monitored for changes in skin, fur, eyes, mucous membranes, occurrence of secretions and excretions, and autonomic activity (e.g. lachrymation, piloerection, pupil size, unusual respiratory pattern), or changes in gait, posture and response to handling as well as the presence of clonic or tonic movements, stereotypies (e.g. excessive grooming, repetitive circling), difficult or prolonged parturition or bizarre behaviour (e.g. self-mutilation, walking backwards); special attention were directed towards the observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.

- Neurotoxicity (5 males and 5 females per group):
Assessment of potential test substance related neurotoxicity was performed in the morning and prior to dosing, during the last exposure week (males on Day 24; females on PPD 4). Selected animals were subjected to the functional observation battery including quantitative assessment of grip strength (manual and instrumental) and measurement of landing foot splay and fore/hind limb grip strength. Qualitative and quantitative assessments of motor activity were performed. Parameters including body position, locomotor activity, respiration rate, respiration type, piloerection, head searching compulsive biting or licking, circling, upright walking, retropulsion, jumping, exophthalmos, twitches, clonic convulsions, tonic convulsions, tremor, startle, transfer arousal, spatial locomotion, gait, posture, limb position, finger approach, finger withdrawal, touch escape response, diarrhoea, diuresis, visual placing, grip strength, body tone, corneal reflex, pinna, toe pinch, grasping reflex, positional struggle, skin, mucous membrane colour, salivation, palpebral closure, lachrymation, limb tone, abdominal tone, tail pinch, righting reflex, and/or vocalisation were evaluated using a scoring system, where score 0 was given when the behaviour or reaction of the animal was considered normal, and -1 or -2, or +1 and +2 was given if the response was less than or more than expected in an untreated animal.

- Body weight measurement:
All adult animals were weighed with an accuracy of 1 g for randomization purposes, then on Day 0, at least weekly thereafter and at termination. Parent females were weighed on gestation Days GD0, 3, 7, 14 and 20 and on post-partum Days PPD0 (within 24 hours after parturition), PPD4 and before termination. Body weights of the female animals were additionally taken on gestational Days GD10 and 17 in order to give accurate treatment volumes but these data were not evaluated statistically.

- Food consumption measurement:
Food consumption was determined by re-weighing the non-consumed diet with a precision of 1 g at least weekly (on the days of body weight measurements).

- Clinical pathology:
All animals selected for blood sampling were fasted (overnight period of food deprivation, after the litter had been culled). Blood samples were collected by cardiac puncture under pentobarbital anaesthesia, immediately prior to scheduled necropsy. For terminal blood sampling three samples were taken from each selected animal (5 males and 5 females/group), one for haematology (in tubes with K3-EDTA as anticoagulant, 1.6 mg/mL blood), one for blood clotting times (in tubes with sodium citrate as anticoagulant) and one to obtain serum (in tubes with no anticoagulant) for clinical chemistry.

- Haematology and blood clotting times: Daily or detailed weekly observation; For details on evaluated parameters see under 'any other information on material and methods incl. tables'

- Clinical chemistry: Daily or detailed weekly observation; For details on evaluated parameters see under 'any other information on material and methods incl. tables'

- Urinalysis:
Urine samples were collected for 16 hours during an overnight period of food deprivation during the last week of the study (Day 27-28 for males and PPD4-5 for female animals, respectively) from each animal by placing the animals in metabolic cages. The evaluation of the urine samples were performed by observation (e.g. appearance, colour) and test strips. For details on evaluated parameters see under 'any other information on material and methods incl. tables'

Sacrifice and pathology:

Pathology
- Gross necropsy was performed on all animals, irrespective of the date of death. After exsanguination the external appearance was examined, cranium, thoracic and abdominal cavities were opened and the appearance of the tissues and organs was observed macroscopically. Any abnormality was recorded with details of the location, colour, shape and size, as appropriate. Special attention was paid to the organs of the reproductive system. The number of implantation sites and of corpora lutea was recorded in the females as applicable.

Organ weight measurements
- At the time of termination, body weight and the weight of the following organs from all euthanized adult animals were determined.
- With a precision of 0.01 g: brain, heart, kidneys, liver, spleen and thymus
- With a precision of 0.001 g: adrenals, ovaries, thyroids with parathyroids
Paired organs were weighed together. Individual and/or paired absolute organ weights were reported for each animal and adjusted for the body and brain weights. Paired organ weights as applicable were summarised. Relative organ weight (to body and brain weight) was calculated and reported.

Tissue preservation and microscopic evaluation.
- The weighed organs and all organs showing macroscopic lesions were preserved. The eyes with the optic nerve were retained in modified Davidson’s fixative. All other organs in 10% buffered formalin solution. The retained tissues and organs were embedded in paraffin wax, sections were cut at 4-6µm by microtome and transferred to slides. Tissue sections were stained with haematoxylin-eosin/phloxine and examined by light microscope. Detailed histological examination was performed on all retained organs in the control and High dose groups and any macroscopic findings (abnormalities) observed in all animals. (Special attention was paid to the evaluation of the stages of spermatogenesis in the male gonads and histopathology of interstitial testicular cell structure. Detailed histological examination of the ovaries covered the follicular, luteal, and interstitial compartments of the ovary, as well as the epithelial capsule and ovarian stroma.).

For details on evaluated tissues and organs see under 'any other information on material and methods incl. tables'

Statistics:

Data were recorded on the appropriate forms from the relevant SOPs of CiToxLAB Hungary Ltd., and then tabulated using the Microsoft Office Word and/or Excel, or using the software PROVANTIS v.9, as appropriate. Group means and standard deviations were calculated from numerical data obtained in the study.
The statistical evaluation of appropriate data (marked † below) was performed with the statistical program package SPSS PC+4.0 (SPSS Hungary Kft, Budapest) by an appropriate statistical method (Bartlett, ANOVA/ANCOVA and Duncan, Kruskal-Wallis and Mann-Whitney U tests, T-test, Wilcoxon test, Chi2 test). The homogeneity of variance between groups was checked by Bartlett’s homogeneity of variance test. Where no significant heterogeneity was detected, a one-way analysis of variance (ANOVA/ANCOVA) was carried out. If the obtained result was significant, Duncan’s Multiple Range test or Kruskal-Wallis test was used to access the significance of inter-group differences. For a significant result at Bartlett’s test, the Kruskal-Wallis analysis of variance was used and the inter-group comparisons were performed using Mann-Whitney U-test. Chi2 test was performed as feasible. For SMART evaluation, T-test was used.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Terminally euthanised animals:
- Male animals: no clinical signs were detected in the Control, Low and Mid dose groups during the study. In the High (1000 mg/kg bw/day) dose group liquid faeces, noisy respiration and piloerection were occasionally present up to three animals during the treatment. These observations were considered to be treatment related.
- Female animals: thin fur/alopecia was observed in all groups, peaking at the end of the experiment, but is not considered to be related to test substance. No clearly adverse effects of the test substance related were noted in the Low dose groups during the study. In the Mid (300 mg/kg bw/day) dose group, piloerection and noisy respiration was observed sporadically in just 1 or 2 females. These non-specific observations seen sporadically at a low incidence is not considered to be a clear sign of an adverse effect of the test substance. In the High (1000 mg/kg bw/day) dose group, the non-specific signs of piloerection and noisy respiration was seen in a small number of male and the majority of females. Hunched back was also present in up to three female animals, which may be treatment related. A 1 to 2 cm wide crust was seen on the skin for five days in one animal, yellow coloured discharge in one animal, and discharge from vagina in one animal was observed during the treatment; these findings are of uncertain relationship with treatment.

Found dead and preterminally euthanized animals:
No common symptoms were found prior unanticipated deaths. The male animal showed slightly noisy, moderately laboured respiration one day before it was found dead. Two females showed no clinical signs before the time of death. Piloerection and slight to moderate noisy respiration and/or laboured respiration with hunched back was present in the rest of the animals, with red coloured discharge or distended abdomen prior dead or euthanasia. These symptoms were considered to be test substance related.

Excluded animals
Four females (two from the Control Dose group and two from the Mid (300 mg/kg bw/day) Dose group were excluded from certain statistical analysis (such as body weight) after being found to be sperm positive, but delivered no offspring despite detectable corpora lutea. Since body weight is affected by pregnancy, it is valid to exclude the non-pregnant animals from this data analysis. Sporadic occurrence of noisy respiration in one Control group and the two Mid dose animals, laboured respiration and piloerection in one Mid dose animal was observed, but these observations were not considered to be test item related.

Mortality:

mortality observed, treatment-related

Description (incidence):

A test substance related mortality (approximately 15% mortality) was observed in the High dose group (1000 mg/kg bw/day). One male (Day 16) and 4 females (Days 3, 6, 18 and 22 ) of the High dose group were found dead. In addition, one female (Day 17) was preterminally euthanized.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No test substance related effects were noted on the mean body weight and body weight gain values following daily administration of test substance at dose levels up to and including 1000 mg/kg bw/day

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

There were no test substance related differences in the mean daily food consumption in any test substance treated group when compared to the controls.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

When compared to the controls, there were no differences that could be considered toxicologically significant in the Low and Mid dose (100 and 300 mg/kg bw/day, respectively) groups. The High (1000 mg/kg bw/day) males only had a slightly but significantly (p<0.05) lower Mean Cell Haemoglobin Concentratin (MCHC). The female High dose group had a slightly but significantly (p<0.05) longer Activated Partial Thromboplastin Time (APTT). However the data from all animals was in the normal range and these small differences were not consistent between sexes and were not considered to be an adverse effect of treatment.
For other parameters, evaluation of the mean and individual results in comparison with the control data did not reveal any test-substance related cause of the changes noted, and/or no consistent dose or gender-related response was observed. Therefore, these differences observed between the Control and treated groups were considered incidental or individual findings, which were not related to treatment, were generally comparable with the expected physiological range and of no toxicological significance.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

In the animals evaluated at termination (on Day 28 in males and on PPD5 in females), there were no clearly toxicologically significant changes or adverse effects on the animal serum chemistry that could be ascribed to the test substance administration in the conditions of this study. Urea and chloride concentrations were statistically significantly higher in the male High (1000 mg/kg bw/day) dose group compared to the Control (p<0.05 and p<0.01, respectively). The female High dose group had statistically significantly (p<0.05) lower phosphorus values. However the data for these 3 parameters from all animals was in the normal range and these small differences were not consistent between sexes and were not considered to be an adverse effect of treatment.
Some differences in the Low and Mid treated groups also attained statistical significance; however, there was no dose or gender response or the values were within the physiological ranges. For this reason, these variations were not considered toxicologically significant or related to treatment.

Urinalysis findings:

effects observed, non-treatment-related

Description (incidence and severity):

A dose dependent decrease of pH was observed in both sexes, reaching statistical significant difference compared to the control value at the High (1000 mg/kg bw/day) dose males (p<0.05) and females (p<0.01). In the High dose only, slight but statistical significance differences were recorded with lower pH and higher urine gravity in both sexes (p<0.01) and lower urine volume in makes only (p<0.05). However, all values were in the normal control range, these findings were regarded as minor variations and were not considered to indicate an adverse effect of the test substance.

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Kidney weights were slightly higher than control in both sexes at the High dose (by 8% in males and by approximately 10% in females). This was statistically significant both in terms of absolute weight or when adjusted for body or brain weights. There were also slight differences in urine analysis at the High dose level in both sexes, so the small organ weight differences may reflect an adaptive or functional difference. A similar statistically significant difference was seen in female kidney weights in the Mid dose group but the data was all in the normal range. Therefore it was not considered to be a clear effect of the test substance. At the Mid and Low dose levels, it is considered that minor statistical differences did not reflect an effect of the test susbtance. In the absence of any histopathological or blood chemistry changes, there is no evidence of an adverse effect in the kidneys at any dose level.
In females, increased liver weights were seen in the High dose group only (by 12% absolute weight). Increased liver weights were not seen in the males of the High dose group. These liver weight changes correlate well with the centrilobular hepatocellular hypertrophy observed in High (1000 mg/kg bw/day) dose female animals.
There were no other toxicologically significant differences among groups in the weights of other organs measured when compared to controls.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

- Found dead animals: Small spleen in 2 out of 4 found dead females and small thymus in 1 out of 4 female corresponded with findings noted during microscopic examination.
- Preterminal euthanasia: Small spleen and thymus, pale foci of the left lobe in the liver were observed at necropsy and were related to the treatment. Dilatation (with gas) of the oesophagus, stomach, duodenum, jejunum, ileum, caecum and colon, and red/clear material at the perinasal fur did not have relationship to the treatment.
- Terminal animals: No treatment-related macroscopic findings were observed up to the dose level of 1000 mg/kg bw/day.

Neuropathological findings:

no effects observed

Description (incidence and severity):

Neurological:
There were no toxicologically significant changes in animal behaviour, general physical condition or in the reactions to different types of stimuli in the control or test groups.
There was no effect of treatment noted during the assessment of foot splay, grip strength or motor activity. Grip strengths of the forelimb were significantly (p <0.05) lower in Mid dose (300 mg/kg bw/day) females, but without dose dependency and similar results for the hindlimbs or during the modified Irwin test, this variety was not considered to be a test item related effect.
The total travelled distance in the High dose group and the shape of the curve of activity in 5 minute periods over one hour, were comparable to the control groups for both sexes; all data was within the normal expected range. Sporadic statistical significant differences were of no toxicological relevance. There was no test item related effect on locomotor activity in either sex.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

- Found dead animals:
Treatment-related slight centrilobular hepatocellular hypertrophy of the liver was observed in 1 out of 4 female. Various microscopic findings induced by stress due to treatment such as slight decrease of white pulp size/cellularity in the spleen and moderate decrease size/cellularity of the thymic cortex (correlated with gross changes), slight decrease of myeloid cellularity in the femoral and sternal bone marrows, slight diffuse vacuolation of the adrenal’s medulla were present in this found dead female. In addition, moderate decrease of white pulp size/cellularity in the spleen was also recorded in one other female rat. There were no findings that clearly indicated a cause of death.

- Preterminal euthanasia:
Treatment-related slight centrilobular hepatocellular hypertrophy of the liver was seen by light microscopy and visualized at necropsy (pale foci). The histopathological findings corresponded with stress-related responses and ascribed to the treatment included moderate decrease of white pulp size/cellularity in the spleen, moderate decrease size/cellularity of the thymic cortex and, correlated with gross changes. Additionally, decrease myeloid cellularity in the femoral (moderate severity) and sternal (slight severity) bone marrows, slight diffuse vacuolation of the adrenal’s medulla, were noted by light microscopy. There were no findings that clearly indicated a cause of a moribund state.
Other changes were regarded as incidental.

- Terminal animals:
Treatment-related centrilobular hepatocellular hypertrophy of the liver was seen at a dose level 1000 mg/kg bw/day. Minimal hypertrophy altered liver in 1 out of 5 selected male and minimal/slight hypertrophy in 4 out of 5 selected females. This change was considered to be an adaptive non-adverse response to the administration of the test substance.
Other changes were incidental or a common background.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEL

Remarks:

systemic effects

Effect level:

>= 300 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

Key result

Critical effects observed:

no

Conclusions:

For the target substance: the rat NOAEL for general systemic toxicity is considered to be 300 mg/kg bw/day for male/female rats.

Executive summary:

The study was performed on a source substance according the requirements of OECD TG 422 guideline under GLP conditions. Following a previously conducted 14-day sighting study, the systemic toxic potential of the test item in Wistar rats, including a screen for reproductive/developmental effects was conducted by oral gavage administration. Males were dosed for 28 days (14 days pre-mating and 14 days mating/post-mating), and females for 14 days pre-mating, during the mating period, through gestation and until the day before the necropsy (at least 4 days post-partum dosing). Three groups each comprising at least 12 male and 12 female rats received the test substance at doses of 0, 100, 300 or 1000 mg/kg bw/day. Parameters measured during the study included signs of morbidity and mortality twice daily, daily or detailed weekly observation of clinical signs, neurological assessment, weekly body weight and food consumption, and clinical pathology evaluation, including haematology, coagulation, clinical chemistry and urinalysis. Neurological assessment including functional observation battery (FOB) and measurements of the landing foot splay, grip strength and motor activity were performed during the last week of the treatment. At termination, necropsy with macroscopic examination was performed. Weights of selected organs were recorded and representative tissues/organs were sampled and preserved in appropriate fixatives. A detailed histological examination was performed on the selected list of retained organs in the control and High dose groups. Daily administration of the test substance at dose levels of 100 mg/kg bw/day or 300 mg/kg bw/day did not result in adverse changes in clinical signs, neurological assessment, body weight, food consumption, haematology, coagulation, clinical chemistry, or urinalysis parameters. Test item related mortality (approximately 15%) was observed in the High dose group (1000 mg/kg bw/day) and clinical adverse effects were present in High dose females. There were no effects on surviving males/females on body weight or clinical pathology. Test item related liver changes were observed in the female High dose group (1000 mg/kg bw/day) with increased weight (approximately 12%) and centrilobular hepatocellular hypertrophy. However, this observation was considered to be an adaptive change and not an adverse effect of treatment. Test item related kidney weight changes were observed in the High dose group (1000 mg/kg bw/day) of both sexes (approximately 10%), but in the absence of any correlating histopathological changes, this was considered to be an adaptive response. Under the study conditions, the rat NOAEL for general systemic toxicity was considered to be 300 mg/kg bw/day for male/female rats.

The target substance is expected to have a no-observed-adverse-effect level (NOAEL) of greater than or equal to 300 mg/kg bw/day in male/female rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

300 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The key study is GLP compliant and of a high quality (Klimisch 1); The available information as a whole meets the tonnage driven information requirements of REACH.

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

Mode of Action Analysis / Human Relevance Framework

Not applicable.

Additional information

Repeated dose - Oral:

Key Study : OECD TG 422, 2016 : Read-Across SOURCE ( Reaction products of 2-hydroxyethyl methacrylate and diphosphorus pentaoxide ) : The study was performed according the requirements of OECD TG 422 guideline under GLP conditions. Following a previously conducted 14-day sighting study, the systemic toxic potential of the test item in Wistar rats, including a screen for reproductive/developmental effects was conducted by oral gavage administration. Males were dosed for 28 days (14 days pre-mating and 14 days mating/post-mating), and females for 14 days pre-mating, during the mating period, through gestation and until the day before the necropsy (at least 4 days post-partum dosing). Three groups each comprising at least 12 male and 12 female rats received the test substance at doses of 0, 100, 300 or 1000 mg/kg bw/day. Parameters measured during the study included signs of morbidity and mortality twice daily, daily or detailed weekly observation of clinical signs, neurological assessment, weekly body weight and food consumption, and clinical pathology evaluation, including haematology, coagulation, clinical chemistry and urinalysis. Neurological assessment including functional observation battery (FOB) and measurements of the landing foot splay, grip strength and motor activity were performed during the last week of the treatment. At termination, necropsy with macroscopic examination was performed. Weights of selected organs were recorded and representative tissues/organs were sampled and preserved in appropriate fixatives. A detailed histological examination was performed on the selected list of retained organs in the control and High dose groups. Daily administration of the test substance at dose levels of 100 mg/kg bw/day or 300 mg/kg bw/day did not result in adverse changes in clinical signs, neurological assessment, body weight, food consumption, haematology, coagulation, clinical chemistry, or urinalysis parameters. Test item related mortality (approximately 15%) was observed in the High dose group (1000 mg/kg bw/day) and clinical adverse effects were present in High dose females. There were no effects on surviving males/females on body weight or clinical pathology. Test item related liver changes were observed in the female High dose group (1000 mg/kg bw/day) with increased weight (approximately 12%) and centrilobular hepatocellular hypertrophy. However, this observation was considered to be an adaptive change and not an adverse effect of treatment. Test item related kidney weight changes were observed in the High dose group (1000 mg/kg bw/day) of both sexes (approximately 10%), but in the absence of any correlating histopathological changes, this was considered to be an adaptive response. Under the study conditions, the rat NOAEL for general systemic toxicity was considered to be 300 mg/kg bw/day for male/female rats.

Justification for classification or non-classification

The substance does not meet classification criteria under Regulation (EC) No 1272/2008 for specific organ toxicity repeated exposure (STOT-RE).

Since there was no reported significant effects relevant to humans reported at guidance related levels (ORAL ≤ 300 mg/kg bw/day) then there is no requirement to classify STOT-RE.

References:

1. ECHA Guidance on Application on the CLP Criteria, (v5.0, July 2017), Section 3.9.2 : Table 3.16 - Equivalent guidance values for 28-day and 90-day studies