1,3-diethenyl-1,1,3,3- tetramethyldisiloxane and its platinum(0) complexes

Endpoint summary

Description of key information

In a 14-day dose-range-finding study involving the gavage administration of 'karstedt concentrate', clinical signs of toxicity were seen at all dose levels (500, 750 and 1000 mg/kg bw/day). No NOAEL was determined. A dose of 750 mg/kg bw/day resulted in marked effects on body weight in males after 14 days. Dose levels of 750 and 1000 mg/kg bw/day were found to be in excess of a maximum tolerated dose (Hansen, 2016).

 

In a subsequent combined repeated-dose toxicity study with reproduction/developmental toxicity screening test, conducted according to OECD Test Guideline 422 and to GLP, 'Karstedt Concentrate’ was administered daily (in corn oil) by gavage to groups of rats (10/sex/dose) for at least 28 days at 30, 125 or 500 mg/kg bw/day. Treatment-related adverse effects were observed in the high dose animals (including reduced food consumption and growth, haematological and clinical chemistry changes, and lesions to the lungs). The NOAEL for systemic toxicity was established as 125 mg/kg bw/day (Hansen, 2017).

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

repeated dose toxicity: oral, other

Remarks:

Part of a combined repeated dose study (OECD 422) with reproductive and developmental toxicity screening.

Type of information:

experimental study

Adequacy of study:

key study

Study period:

August 2016-March 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

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:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:
Charles River Laboratories Germany, Sandhofer Weg 7, 97633 Sulzfeld, Germany.
- Females (if applicable) nulliparous and non-pregnant:
Yes.
- Age at study initiation:
Males and females were aged 81 days at first test material administration.
- Weight at study initiation:
Males: 407.0 - 474.3 g at first test material administration.
Females: 222.7 - 304.2 g at first test material administration.
- Fasting period before study:
Not specified.
- Housing:
Males and females kept in individual cages, except during mating period (see reproductive toxicity section for further details).
- Diet (e.g. ad libitum):
Standard commercial feed ad libitum.
- Water (e.g. ad libitum):
Tap water ad libitum.
- Acclimation period:
6 days.

ENVIRONMENTAL CONDITIONS
- Temperature (°C):
22°C (+/- 3°C)
- Humidity (%):
55% (+/- 15%)
- Air changes (per hr):
Not specified.
- Photoperiod (hrs dark / hrs light):
12 hrs light (150 lux)/12 hrs dark.

IN-LIFE DATES:
Males: end of the in-life period: 22 September 2016
Females: end of the in-life period: 17 October 2016.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Formulations were continuously stirred until the last animal of each group had been dosed.

VEHICLE
- Justification for use and choice of vehicle (if other than water):
Corn oil. No justification specified (standard vehicle).
- Concentration in vehicle:
Not specified.
- Amount of vehicle (if gavage):
Constant dose volume of 5 mL/kg bw/day/animal.
- Lot/batch no. (if required):
Caesar and Loretz GmbH, Germany. Batch numbers 15296404 and 15296406.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of each dose solution were analysed by ICP-OES for platinum content, at dates throughout the study period.

Duration of treatment / exposure:

Males and females were dosed from 2 weeks prior to mating and during the mating period.
Males were further dosed after the mating period for a total treatment duration of at least 28 days.
Females were dosed throughout gestation and at least up to and including day 13 post-partum (total of 49-62 days).

Frequency of treatment:

Daily

Dose / conc.:

30 mg/kg bw/day (nominal)

Dose / conc.:

125 mg/kg bw/day (nominal)

Dose / conc.:

500 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
Doses selected on the basis of a 14-day range-finding study (see Supporting study (Hansen, 2016) in this endpoint).
- Rationale for selecting satellite groups:
Satellite groups (5/sex/group) were administered vehicle only or the high dose (500 mg/kg bw/day) for 28 days. Blood samples were taken prior to the final dose, and at 3, 6, 12 and 24-hours post administration. Plasma was analysed for elemental platinum as an analytical marker for the test compound (analysis carried out by Allessa, and included as an appendix to the study report). Blood taken from these animals was also assessed for micronucleus formation (see in vivo Micronucleus ESR for full details).

Positive control:

None.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes.
- Time schedule: At least once daily.
- Cage side observations included: skin/fur, eyes, mucuous membranes, respiratory and circulatory systems, somatomotor activity and behaviour patterns.

DETAILED CLINICAL OBSERVATIONS: Yes.
- Time schedule: At least once daily.

BODY WEIGHT: Yes.
- Time schedule for examinations: On the first day of dosing, weekly thereafter, and at termination. During gestation, females were weighed on days 0, 7, 14 and 20, and within 24 hours of parturition.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes.
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Not specified.

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Not specified.

OPHTHALMOSCOPIC EXAMINATION: Not specified.

HAEMATOLOGY: Yes.
- Time schedule for collection of blood: At the end of the pre-mating period.
- Anaesthetic used for blood collection: Yes (isoflurane).
- Animals fasted: Yes (overnight).
- How many animals: 5/sex, randomly selected from each group.
- Parameters checked in Table 1 were examined.

CLINICAL CHEMISTRY: Yes / No / Not specified
- Time schedule for collection of blood: At the end of the pre-mating period.
- Anaesthetic used for blood collection: Yes (isoflurane).
- Animals fasted: Yes (overnight).
- How many animals: 5/sex, randomly selected from each group.
- Parameters checked in Table 2 were examined.

URINALYSIS: Not specified.

NEUROBEHAVIOURAL EXAMINATION: Yes.
- Time schedule for examinations: Males: test day 43 or 50 (shortly before scheduled sacrifice); females: test day 65-71 (shortly before scheduled sacrifice). Screening was carried out two hours after dosing, and before any blood sampling.
- Dose groups that were examined: All.
- Battery of functions tested: sensory activity (auditory, visual, proprioceptive stimuli); grip strength; motor activity.

IMMUNOLOGY: Not specified.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes.
All tissues and organs were examined macroscopically.

The weight of the following organs was recorded before fixation (where applicable):
Adrenals, kidney (2), epididymis (2), liver, uterus (incl. cervix), ovary (2), spleen, testicle (2), thyroid, thymus, combined weight of prostate+seminal vesicles+coagulating glands. Paired organs were weighed individually and identified as left or right.

The brain and heart of 5 animals/sex/group were also weighed.

Dead pups and pups sacrificed at day 13 post-partum were carefully examined externally for gross abnormalities.

HISTOPATHOLOGY: Yes.
The following organs/parts were fixed for microscopic examination: adrenal gland (2), bone, bone marrow (os femoris), brain, epididymis (2), eye with optic nerve (2), all gross lesions observed, heart, intestine, kidney and ureter (2), liver, lungs with bronchi and bronchioles, lymph node (1 cervical and 1 mesenteric), mammary gland, skeletal muscle, sciatic nerve, oesophagus, ovary and oviduct, pituitary, prostate/seminal vesicles/coagulating gland, spinal cord (3 sections), spleen, stomach, testicle (2), thyroid, thymus, tissue masses or tumours, tongue, trachea, urinary bladder, uterus (incl. cervix), vagina.

Statistics:

Homogeneity of variances and normality of distribution were tested using the Bartlett's and Shapiro-Wilks test. In case of heterogeneity and/or non-normality of distribution, Anova and Dunnet's test were used. Non-parametrical values were evaluated using the Fisher or Chi-squared tests.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

All males of the high-dose group displayed increased salivation, considered to be treatment-related and adverse.

4/10 high-dose females also displayed increased salivation, also considered to be treatment-related and adverse.

Mortality:

mortality observed, treatment-related

Description (incidence):

Males:
500 mg/kg bw/day: no deaths.

Females:
500 mg/kg bw/day: One premature death (during lactation).

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Males:
500 mg/kg bw/day: significantly lower body weight than controls during the whole study period (e.g. 6.5%, 11.5% and 14.4% below controls on test days 22, 29 and 52, respectively).

Females:
500 mg/kg bw/day: no effects on body weights pre-mating or during lactation.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

FOOD CONSUMPTION
Males:
500 mg/kg bw/day: lower food consumption week 1 of study, approximately half control value.
125 mg/kg bw/day: lower food consumption week 1 of study, approximately 15% below control value.
Food consumption normalised between test days 22 and 28, so these observations were not considered to be adverse.

COMPOUND INTAKE (from feed):
Not applicable.

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Males:
Group mean white blood cell (WBC) counts (absolute values) were higher than the control mean for all treated groups, but the effect only achieved statistical significance at 500 mg/kg bw/day. These increases were particularly associated with dose-related elevations in mean neutrophil and lymphocyte counts (absolute values), which were themselves statistically significant at the high-dose level. For the high-dose group, statistically significant increases in monocytes and large unclassified cell means were also noted. A dose-related decrease in the mean reticulocyte (%) counts was evident for all treated groups when compared to the respective control mean. A statistically significant difference was present only at 125 and 500 mg/kg bw/day, although the effect in the mid-dose fell within historical control ranges for this effect (and, as such, was not considered by the study authors to be related to treatment).

Females:
Mean white blood cell (WBC) counts (absolute values) showed minor increases at the mid- and high-dose (although neither value achieved statistical significance), and which again appeared to be primarily related to limited increases in neutrophil and lymphocyte group mean values.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Males:Increases in group mean alanine aminotransferase (ALAT) values were noted for all treated groups, which achieved statistical significance at 125 and 500 mg/kg bw/day. However, the magnitude of this effect was limited in degree (only the high-dose value approached the upper boundary of the historical control dataset). Clear treatment-related differences in other measured serum enzyme levels were not evident.
Several other statistically significant effects were detected in group mean values at 500 mg/kg bw/day: concentrations of albumin (decrease), total cholesterol (increase), protein (decrease) and calcium (decrease).

Females:
No statistically significant changes were seen in any of the clinical chemistry parameters of females.
There was a dose-related decrease in aP, but statistical significance was not achieved at any dose level.

Urinalysis findings:

not specified

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

Males:
One mid-dose animal showed slight signs of positive geotropism; another had slight diarrhoea. One low-dose and one high-dose animal showed "slight influences" during the wire manoeuvre test, and males in these two groups showed a decreased reaction to a tail pinch. All observations were considered to be spontaneous and not related to treatment.

Females:
One mid-dose female was noted with salivation and a slightly reduced urination. This was considered to be spontaneous and not related to treatment.

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Males:
Statistically significant increases in group mean liver and kidney weights relative to body weight were evident at 500 mg/kg bw/day. However, there were no differences between treated and control groups in respect of absolute liver or kidney weights, which had values residing within historical control ranges. [Note that there were changes in clinical chemistry at this dose level.]
The group mean absolute weights of the spleen, thymus and prostate/seminal vesicle were statistically significantly decreased at 500 mg/kg bw/day (although when evaluated relative to body weight, the decreases were not statistically significant).
The study investigators did not consider the above observations in males to be evidence of treatment-related adverse effects.

Females:
Dose-related increases in group mean relative and absolute adrenal weights were recorded at 125 and 500 mg/kg bw/day; the effect achieving statistical significance at the high-dose, and with the majority of the individual organ weights being outside of the historical control range. Concomitant stress hormone measurements were not conducted during this study, but the possibility exists that the basis of these changes was stress-related rather than due to organ toxicity.
Slightly elevated mean kidney weights were noted for the high-dose group (only the relative right kidney weight value being statistically significant).
A marginal, and non-statistically-significant, increase in relative and absolute mean liver weight was apparent at 500 mg/kg bw/day.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Males
500 mg/kg bw/day: one animal had lungs with multiple red foci, correlating with test-item microscopic findings, and considered to be treatment related.

Females
All doses: Haemorrhagic foci in the stomach were noted in 1/10 control females and 0/10, 3/10 and 1/10 females in the low, intermediate and high-dose groups, respectively. These findings considered to be not related to treatment, as these lesions were not seen in males, and there was no evident dose dependency.

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Males and females:
500 mg/kg bw/day: Lung - increased pigment deposition (4/5 males, 2/6 females); haemorrhages (3/5 males, 4/6 females); and granulomatous inflammation (4/5 males, 4/6 females). Incidence of pigment deposition and inflammation was statistically significant in males.
The one female that died during the study period was found to have marked granulomatous inflammation of the lungs. The investigators concluded that the pulmonary effects noted for the male and female animals were considered to be a foreign body response to test item in the lung rather a toxicological effect.

Females:
500 mg/kg bw/day: Statistically significantly increased incidence of hypertrophy of the adrenal cortex in 3/6 females. [Note that there were changes in adrenal organ weight at this dose level.] However, evidence of similar hypertrophic change was not found when tissues from mid-dose group females were examined.
No test item-related microscopic changes in the reproductive organs of high-dose males or females were detected. Qualitative evaluation of the stages of spermatogenesis in males of this treatment group revealed no abnormalities.

Histopathological findings: neoplastic:

no effects observed

Other effects:

effects observed, treatment-related

Description (incidence and severity):

A limited decrease in Thyroid Hormone T4 concentration (17.5% below the mean value of the control group, p ≤ 0.05) was noted in male animals of the high-dose group. T4 measurements for females of all treated groups were unaffected, as were those for males receiving 30 or 125 mg/kg bw/day.

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

clinical signs

haematology

histopathology: non-neoplastic

mortality

Critical effects observed:

not specified

Conclusions:

In a combined repeated-dose toxicity study with reproduction/developmental toxicity screening test, conducted according to OECD Test Guideline 422 and to GLP, 'Karstedt Concentrate’ was administered daily (in corn oil) by gavage to groups of rats (10/sex/dose) for at least 28 days (males) or 49-62 days (females) at 30, 125 or 500 mg/kg bw/day. Treatment-related adverse effects were observed in the high dose animals (including reduced food consumption and body weight, haematological and clinical chemistry changes, and lesions to the lungs). The NOAEL for systemic toxicity was established as 125 mg/kg bw/day.

Executive summary:

In a combined repeated-dose toxicity study with reproduction/developmental toxicity screening test, conducted according to OECD Test Guideline 422 and to GLP, platinum(0) 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes ('Karstedt Concentrate’) was administered daily (in corn oil) by gavage to groups of rats (10/sex/dose) for at least 28 days (males) or 49-62 days (females) at 30, 125 or 500 mg/kg bw/day. Control animals received vehicle only.

In the high-dose group, one female died, and reduced body weights were seen in males. On commencement of treatment, food consumption was transiently lower in males in the mid- and high-dose groups, but with a very marginal degree of effect evident for the former. Haematological examination revealed effects on white blood cell parameters mainly in males in the high-dose group. A statistically significant reduction in group mean reticulocyte count was also evident at the high- and mid-dose (though the value for the latter was within the historical control range for this parameter). Statistically significant effects were noted for several clinical chemistry parameters in males receiving 500 mg/kg bw/day, although effect severity was limited. A dose-related increase in absolute and relative adrenal gland weight was seen in females at 125 and 500 mg/kg bw/day (only reaching statistical significance at the higher dose, where histopathology indicated the existence of an accompanying adrenal cortical hypertrophy). Males showed a limited decrease in thyroid hormone T4 concentration at the highest tested dose.

 

On the basis of the observed treatment-related adverse effects seen in the high-dose animals, the NOAEL was considered to be 125 mg/kg bw/day.

 

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

125 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Good.

Additional information

In a 14-day dose-range-finding study involving the gavage administration of 'karstedt concentrate', clinical signs of toxicity were seen at all dose levels (500, 750 and 1000 mg/kg bw/day). No NOAEL was determined. A dose of 750 mg/kg bw/day resulted in marked effects on body weight in males after 14 days. Dose levels of 750 and 1000 mg/kg bw/day were found to be in excess of a maximum tolerated dose (Hansen, 2016).

 

In a subsequent combined repeated-dose toxicity study with reproduction/developmental toxicity screening test, conducted according to OECD Test Guideline 422 and to GLP, platinum(0) 1,3-divinyl-1,1,3,3 -tetramethyldisiloxane complexes ('Karstedt Concentrate’) was administered daily (in corn oil) by gavage to groups of rats (10/sex/dose) for at least 28 days (males) or 49-62 days (females) at 30, 125 or 500 mg/kg bw/day. Control animals received vehicle only.

 

In the high-dose group, one female died and reduced body weights were seen in males. On commencement of treatment, food consumption was transiently lower in males in the mid- and high-dose groups, but with a very marginal degree of effect evident for the former. Haematological examination revealed effects on white blood cell parameters mainly in males in the high-dose group. A statistically significant reduction in group mean reticulocyte count was also evident at the high- and mid-dose (though the value for the latter was within the historical control range for this parameter). Statistically significant effects were noted for several clinical chemistry parameters in males receiving 500 mg/kg bw/day, although effect severity was limited. A dose-related increase in absolute and relative adrenal gland weight was seen in females at 125 and 500 mg/kg bw/day (only reaching statistical significance at the higher dose, where histopathology indicated the existence of an accompanying adrenal cortical hypertrophy). Males showed a limited decrease in thyroid hormone T4 concentration at the highest tested dose.

 

On the basis of the adverse treatment-related effects seen in the high-dose animals, the NOAEL was considered to be 125 mg/kg bw/day (Hansen, 2017).

Justification for classification or non-classification

The adverse effects related to repeated oral treatment with Karstedt concentrate, including reduced growth and food consumption, haematological and clinical chemistry changes, and increased adrenal gland weights, all occurred at doses in excess of the thresholds for classification as described in Tables 3.9.2 and 3.9.3 of the CLP regulation (1272/2008). Consequently, no classification as a specific target organ toxicant after repeated exposure (STOT-RE) is required.