Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Administrative data

Endpoint:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16 January 2017 to 04 June 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Cross-reference
Reason / purpose for cross-reference:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report date:
2018

Materials and methods

Test guideline
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
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
1-(octyldisulfanyl)octane; 2-(octyldisulfanyl)-5-[(octylsulfanyl)disulfanyl]-1,3,4-thiadiazole; 2-(octyldisulfanyl)-5-{[5-(octyldisulfanyl)-1,3,4-thiadiazol-2-yl]sulfanyl}-1,3,4-thiadiazole; bis(octyldisulfanyl)-1,3,4-thiadiazole
EC Number:
948-020-7
Molecular formula:
N/A
IUPAC Name:
1-(octyldisulfanyl)octane; 2-(octyldisulfanyl)-5-[(octylsulfanyl)disulfanyl]-1,3,4-thiadiazole; 2-(octyldisulfanyl)-5-{[5-(octyldisulfanyl)-1,3,4-thiadiazol-2-yl]sulfanyl}-1,3,4-thiadiazole; bis(octyldisulfanyl)-1,3,4-thiadiazole
Test material form:
liquid
Details on test material:
EC Number: 948-020-7
Specific details on test material used for the study:
- Purity: > 99% (UVCB)
- Description: Amber liquid

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Sex:
male/female
Details on test animals or test system and environmental conditions:
Duration of acclimatization:
- Males: six days prior to the commencement of treatment
- Females: 20 days prior to the commencement of treatment

Age of the animals at the start of treatment:
- Males ranged from 69 to 76 days old
- Females ranged from 83 to 90 days old

Weight range of the animals at the start of treatment:
- Males 326 to 386 g
- Females 232 to 295 g

Housing: Cages comprised of a polycarbonate body with a stainless steel mesh lid; changed at appropriate intervals. Solid (polycarbonate) bottom cages were used during the acclimatization, pre-pairing, gestation, littering and lactation periods. Grid bottomed cages were used during pairing. These were suspended above absorbent paper which was changed daily during pairing.

- Diet: SDS VRF1 Certified pelleted diet, ad libitum
- Water: Tap water, ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature: 20 to 24ºC
- Humidity: 40 to 70%
- Air changes: Filtered fresh air which was passed to atmosphere and not recirculated
- Lighting: 12 hours light : 12 hours dark

Animal Replacement:
Before the commencement of treatment, study allocation was revised to reduce inter/intra group body weight variation by replacement of animals with spares and moving animals within groups. Any individuals rejected during the acclimatization period were replaced with spare animals of suitable weight from the same batch.
Replacement before treatment:
- Irregular estrous cycle: Two females

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
The required amount of test item was weighed into a suitable container and mixed, by magnetic stirring, with approximately 50% of the final volume of vehicle. Further amounts of vehicle were added and mixed to achieve the required volume. The formulation was magnetically stirred until visibly homogenous.

A series of formulations at the required concentrations were prepared in ascending order by dilution of individual weighings of the test item.

The frequency of preparation was weekly.
Details on mating procedure:
Pairing commenced: After a minimum of two weeks of treatment.

Male/female ratio: 1:1 from within the same treatment groups.

Duration of pairing: Up to two weeks.

Daily checks for evidence of mating: Ejected copulation plugs in cage tray and sperm in the vaginal smear.

Day 0 of gestation: When positive evidence of mating was detected.

Male/female separation: Day when mating evidence was detected.

Pre-coital interval: Calculated for each female as the time between first pairing and evidence of mating.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Before commencement of treatment, the suitability of the proposed mixing procedures was determined and specimen formulations at 1 and 300 mg/mL were analyzed to assess the stability and homogeneity of the test item in the liquid matrix. 15 days stability was confirmed when stored refrigerated (2 to 8°C) or 1 day when stored at room temperature (15 to 25°C).

The mean concentrations of the test material in formulations analyzed for the study were within applied limits +10/-15% for both GC and HPLC, confirming accurate formulation.
Duration of treatment / exposure:
Males: Two weeks before pairing up to necropsy after minimum of five weeks.
Females: Two weeks before pairing, then throughout pairing and gestation until Day 13 of lactation.
Frequency of treatment:
Once daily at approximately the same time each day.
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
100 mg/kg bw/day (nominal)
Dose / conc.:
330 mg/kg bw/day (nominal)
Dose / conc.:
1 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
The dose selection was based upon a range-finding study (please see RSS section 7.5.1 Supporting study, Envigo, 2018 (range-finding)).

Examinations

Parental animals: Observations and examinations:
Detailed observations were performed to establish and confirm a pattern of signs in association with dosing according to the following schedule:

F0 males Week 1 - daily
Week 2 onwards - once each week

F0 females Week 1 - daily
Week 2 - once
Gestation phase - Days 0, 7, 14 and 20
Lactation phase - Days 1, 6 and 12

Detailed observations were recorded at the following times in relation to dose administration:
Pre-dose observation
One to two hours after completion of dosing of all groups
As late as possible in the working day
Oestrous cyclicity (parental animals):
Dry and wet smears were taken as follows:

Dry smears From beginning of treatment until animals were paired for mating, using cotton swabs.

Wet smears Using pipette lavage during the following phases:
For 14 days before treatment (all females including spares); animals that failed to exhibit 4-5 day cycles were not allocated to study.

After pairing until mating.

For four days before scheduled termination (nominally Days 11 to 14 of lactation). In the case of animals 54 (Group 2), 72 (Group 3) and 47(Group 4) this was for five days before scheduled termiination (Days 11 to 15 of lactation).

Sperm parameters (parental animals):
For the assessment of the testes, a detailed qualitative examination was made, taking into account the tubular stages of the spermatogenic cycle. The examination was conducted in order to identify treatment related effects such as missing germ cell layers or types, retained spermatids, multinucleate or apoptotic germ cells and sloughing of spermatogenic cells in the lumen. Any cell- or stage-specificity of testicular findings was noted.
Litter observations:
Clinical observations: Examined at approximately 24 hours after birth (Day 1 of age) and then daily thereafter for evidence of ill health or reaction to maternal treatment; these were on an individual offspring basis or for the litter as a whole, as appropriate.

Litter size: Daily records were maintained of mortality and consequent changes in litter size from Days 1-13 of age.

Sex ratio of each litter: Recorded on Days 1, 4, 7 and 13 of age.

Individual offspring body weights: Days 1, 4, 7 and 13 of age.

Ano-genital distance: Day 1 - all F1 offspring.

Nipple/areolae count: Day 13 of age - male offspring.
Postmortem examinations (parental animals):
All adult animals were subject to a detailed necropsy. After a review of the history of each animal, a full macroscopic examination of the tissues was performed. All external features and orifices were examined visually. Any abnormality in the appearance or size of any organ and tissue (external and cut surface) was recorded and the required tissue samples preserved in appropriate fixative.

Time of Necropsy:
F0 males After Week 5 investigations completed.
F0 females whose litter died before Day 13 On or after day the last offspring died.
F0 females Day 14 of lactation (following terminal blood sampling).
Day 15 of lactation (following terminal blood sampling) - animals 54 (Group 2), 72 (Group 3) and 47 (Group 4).

The organs weighed, tissue samples fixed and sections examined microscopically.
Postmortem examinations (offspring):
Premature deaths
Where possible, a fresh macroscopic examination (external and internal) with an assessment of stomach for milk content was performed.

F1 offspring on Day 4 of age
Blood sampling was required

Externally normal offspring discarded without examination.

Externally abnormal offspring examined, and retained pending possible future examination.


F1 offspring on Day 13 of age
Blood sampling was required.

All animals, except those selected for thyroid hormone analysis, were subject to an external macroscopic examination; particular attention was paid to the external genitalia. Animals possible future examination.

Thyroid glands were preserved from one male and one female in each litter.

Animals selected for thyroid hormone analysis: externally normal offspring were discarded without examination. Externally abnormal offspring were examined.
Statistics:
Statistical analyses were performed on the majority of data presented and results of these tests, whether significant or non-significant, are presented on the relevant tables. For some parameters, including gestation index and stage of estous cycle at termination the similarity of the data was such that analyses were not considered to be necessary.
Reproductive indices:
Individual data was tabulated. Group values were calculated for males and females separately for the following:

Percentage mating (%) = Number of animals mating/Animals paired X 100

Conception rate (%) = Number of animals achieving pregnancy/Animals mated x 100

Fertility index (%) = Number of animals achieving pregnancy/Animals pairing x 100

Offspring viability indices:
The following were calculated for each litter:

Post-implantation survival index (%) = (Total number of offspring born / Total number of uterine implantation sites) x 100

Post-implantation survival index was expressed as 100% where the number of offspring exceeded the number of implantation sites recorded.

Live birth index (%) = (Number of live offspring on Day 1 after littering / Total number of offspring born) x 100

Viability index (%) = (Number of live offspring on Day 4 (before blood sampling) / Number live offspring on Day 1 after littering) x 100

Lactation index (%) = (Number of live offspring on Day 13 after littering / Number of live offspring on Day 4 (after blood sampling)) x 100

Group mean values were calculated from individual litter values.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
No test item related clinical signs were apparent in the male animals at all dose levels. On Day 15 of the treatment period excessive chewing, piloerection and partially closed eyelids were evident in all females receiving 1000 mg/kg/day after the dosing procedure.
Mortality:
no mortality observed
Description (incidence):
Five adult females (1 each in the low and mid dose groups and 3 in the high dose group) were sacrificed early (4 out of 5 on post-natal day 1 or 2) during the course of the study due to pup loss according to protocol.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Effects on body weight were evident for animals receiving 1000 mg/kg/day. When compared to control, male animals receiving 1000 mg/kg/day had a reduced overall mean bodyweight gain from Week 0 to 5 (74% of Control gain). Mean bodyweight gain for females receiving 1000 mg/kg/day during Week 2 of study was reduced when compared to Controls, and this was reflected in the overall Week 0 to 2 bodyweight gain.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Male animals receiving 1000 mg/kg/day consumed less than Control in Week 1 of treatment (90% of Control). In Week 2 and 4 of treatment consumption was comparable to Control.

Female animals receiving 1000 mg/kg/day consumed slightly less than Control in Week 1 of treatment (92% of Control). In Week 2 of treatment females receiving 1000 mg/kg/day consumed 8 grams more than Control (107% of Control).
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
Both males and females receiving 1000 mg/kg/day had visually consumed more water than the other treated groups and Control.
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
no effects observed
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
The microscopic examination of F0 adult animals revealed changes related to treatment with the test item in the liver, kidneys, spleen, thyroid and adrenal, but none of these changes was considered adverse.
Histopathological findings: neoplastic:
not examined
Other effects:
effects observed, treatment-related
Description (incidence and severity):
Main study adult males showed that there was a trend of increasing mean plasma TSH concentrations with increasing doses of the test item compared to the concurrent control, however the individual TSH concentration ranges overlapped among the three test item treated groups. The increase seen for adult terminal males receiving 1000 mg/kg/day was statistically significant.

The test item may affect the homeostatis of thyroid hormones.

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
effects observed, treatment-related
Description (incidence and severity):
During treatment one control female and two females receiving 1000 mg/kg/day showed an irregular cycle and one female receiving 1000 mg/kg/day presented extended oestrus, the remaining animals were regular. The animals which presented irregular cycles all positively mated and achieved pregnancy. The animal with extended oestrus was sacrificed for welfare reasons on Day 23 after mating and confirmed to be not pregnant.
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
effects observed, treatment-related
Description (incidence and severity):
Mating performance and fertility was 100% for control animals and animals receiving 100 or 330 mg/kg/day. Animals receiving 1000 mg/kg/day were 90%.

Effect levels (P0)

Key result
Dose descriptor:
NOAEL
Effect level:
330 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: general systemic toxicity

Target system / organ toxicity (P0)

Key result
Critical effects observed:
no

Results: F1 generation

Effect levels (F1)

Remarks on result:
not measured/tested

Overall reproductive toxicity

Key result
Reproductive effects observed:
no

Applicant's summary and conclusion

Conclusions:
The No Observed Adverse Effect Level (NOAEL) for general systemic toxicity (including offspring survival, growth and development) was concluded to be 330 mg/kg/day.
Executive summary:

The study was conducted in accordance with the standardized guidelines OECD 422, under GLP conditions to assess the potential systemic toxicity in rats, including a screen for reproductive/developmental effects and assessment of endocrine disruptor relevant endpoints, with administration of the test item by oral administration for at least five weeks.

 

Three groups of ten male and ten female rats received the test item at doses of 100, 330 or 1000 mg/kg/day in corn oil by oral gavage administration. Males were treated daily for two weeks before pairing, up to necropsy after a minimum of five consecutive weeks. Females were treated daily for two weeks before pairing, throughout pairing, gestation and until Day 13 of lactation or Day 14 of lactation for 3 animals. Females were allowed to litter, rear their offspring and were sacrificed on Day 14/15 of lactation. The F1 generation received no direct administration of the test item; any exposure was in utero or via the milk. A similarly constituted Control group received the vehicle, corn oil, at the same volume dose as the treated groups. During the study, clinical condition, detailed physical examination and arena observations, sensory reactivity observations, grip strength, motor activity, body weight, food consumption, water consumption, hematology (peripheral blood), blood chemistry, thyroid hormone analysis, estrous cycles, pre-coital interval, mating performance, fertility, gestation length, organ weight and macroscopic pathology and histopathology investigations were undertaken. The clinical condition, litter size and survival, sex ratio, body weight, ano-genital distance and macropathology for all offspring were also assessed. Nipple counts were performed on male offspring on Day 13 of age.

 

Administration of the test item to adult CD:Crl rats at doses ≤ 330 mg/kg/day was generally well tolerated. There were minimal dose observations, no test item-related signs observed during the detailed physical examination and arena observations, and no effects on sensory reactivity, grip strength, motor activity and food consumption.

 

Test item-related findings observed at ≤ 330 mg/kg/day were minimal and low incidence and therefore were not considered adverse. Considering the incidence, severity and significance of the test item-related clinical signs, poor body weight performance, increased water consumption, decreased serum T4 and increased plasma TSH that were evident in the adult animals receiving 1000 mg/kg/day, the No Observed Adverse Effect Level (NOAEL) for general systemic toxicity was concluded to be 330 mg/kg/day.

 

Parental test item-related reductions in post implantation survival index, live birth index, viability index, live litter size, offspring bodyweights on Day 1 of age, bodyweight gain and serum T4 were evident in the offspring from females receiving 1000 mg/kg/day. Based on these considerations, the NOAEL for offspring survival, growth and development was 330 mg/kg/day.