1-ethynylcyclohexanol

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Endpoint:

toxicity to reproduction

Remarks:

other: screening test

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-12-07 to 2012-02-02

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted in accordance with GLP.

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

Species:

rat

Strain:

other: Crl:WI(Han) (outbred, SPF-Quality)

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Source F0: Charles River Deutschland, Sulzfeld, Germany
- Age at start F0-treatment: Approximately 11 weeks old
- Weight at study initiation:
# Pre-Mating males (group 1/2/3/4): 311/310/312/310 g (means)
# Pre-Mating females (group 1/2/3/4): 196/193/196/197 g (means)
- Fasting period before study: No data
- Housing:
# Pre-mating: Animals were housed in groups of 5 animals/sex/cage in Macrolon plastic cages (MIV type, height 18 cm)
# Mating: females were caged together with males on a one-to-one-basis in Macrolon plastic cages (MIII type, height 18 cm).
# Post-mating: males were housed in their home cage (Macrolon plastic cages, MIV type, height 18 cm) with a maximum of 5 animals/cage. Females were individually housed in Macrolon plastic cages (MIII type, height 18 cm)
# Lactation: Pups were kept with the dam until termination in Macrolon plastic cages (MIII type, height 18 cm). During locomotor activity monitoring of the dams the pups were kept warm in their home cage using bottles filled with warm water. In order to avoid hypothermia of pups, pups were not left without their dam or a bottle filled with warm water for longer than 30-40 minutes.
# General: Sterilized sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France) and paper as cage-enrichment/nesting material (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom) were supplied. During locomotor activity monitoring, animals were housed individually in a Hi-temp polycarbonate cage (Ancare corp., USA; dimensions: 48.3 x 26.7 x 20.3 cm) without cage-enrichment or bedding material
- Diet: Free access to pelleted rodent diet (SM R/M-Z from SSNIFF Spezialdiäten GmbH, Soest, Germany).
- Water: Free access to tap-water
- Acclimation period F0: At least 5 days prior to start of treatment

ENVIRONMENTAL CONDITIONS
- Temperature: 21 +/- 3°C
- Humidity: 40 - 70%
(Cleaning procedures in the room might have caused the temporary fluctuations above the optimal
maximum level of 70% for relative humidity (with a maximum of 4 hours)).
- Air changes: 15 room air changes/hour
- Photoperiod: 12-hour light/12-hour dark cycle

IN-LIFE DATES: From: 2011-12-11 To: 2012-02-02

Route of administration:

oral: gavage

Vehicle:

propylene glycol

Remarks:

specific gravity 1.036 (Merck, Darmstadt, Germany)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Formulations (w/w) were prepared daily within 6 hours prior to dosing and were homogenized to a visually acceptable level. The test substance was heated before weighing (maximum temperature=49.7°C, maximum duration=4 hours and 20 minutes). Adjustment was made for the specific gravity of the vehicle and the relative density of the test substance.

VEHICLE
- Justification for use and choice of vehicle: Propylene glycol, standard vehicle for studies of this type
- Concentration in vehicle: 1.2, 6, 30 mg/mL
- Amount of vehicle (if gavage): 5 mL/kg bw (actual dose volumes were calculated according to the latest body weight)
- Lot/batch no.: No data
- Purity: No data

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation: mating period of 14 days
- Proof of pregnancy: vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged (how): individually


Mating procedures:
one female was cohabitated with one male of the same treatment group, avoiding sibling mating. Detection of mating was confirmed by evidence of sperm in the vaginal lavage or by the appearance of an intravaginal copulatory plug. This day was designated Day 0 post-coitum. Once mating occurred, the males and females were separated.

Parturition:
The females were allowed to litter normally. Day 1 of lactation was defined as the day when a litter was found completed (i.e. membranes and placentas cleaned up, nest build up and/or feeding of pups started). Females that were littering were left undisturbed.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses were conducted on a single occasion during the treatment phase, according to a validated method (NOTOX Project 498338, BASF Project 05Y0436/11X294). Samples of formulations were analyzed for homogeneity (highest and lowest concentration) and accuracy of preparation (all concentrations). Stability in vehicle over 6 hours at room temperature under normal laboratory light conditions was also determined (highest and lowest concentration). The accuracy of preparation was considered acceptable if the mean measured concentrations were 90-110% of the target concentration. Homogeneity was demonstrated if the coefficient of variation was ≤ 10%. Formulations were considered stable if the relative difference before and after storage was maximally 10%.

Duration of treatment / exposure:

Males were exposed for 29 days, i.e. 2 weeks prior to mating, during mating, and up to the day prior to scheduled necropsy. Females were exposed for 43 - 53 days, i.e. during 2 weeks prior to mating, during mating, during post-coitum, and during at least 4 days of lactation (up to the day prior to scheduled necropsy). Female nos. 44 (Group 1 - vehicle control), 51 (Group 2 - 6 mg/kg bw/d) and 72 (Group 4 - 100 mg/kg bw/d) were not dosed during littering.

Frequency of treatment:

Once daily for 7 days per week, approximately the same time each day with a maximum of 6 hours difference between the earliest and latest dose administration.

Remarks:

Doses / Concentrations:
6 mg/kg bw/d
Basis:
analytical conc.
low-dose level

Remarks:

Doses / Concentrations:
30 mg/kg bw/d
Basis:
analytical conc.
mid-dose level

Remarks:

Doses / Concentrations:
150 mg/kg bw/d
Basis:
analytical conc.
high-dose level

No. of animals per sex per dose:

10 animals

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
Based on results of a 14-day pilot study (NOTOX Project 498335; BASF Project 01R0436/11X204) using dose levels of 30, 100 and 300 mg/kg bw/d, and in consultation with the Sponsor. At 300 mg/kg bw/d, the most common clinical signs included uncoordinated movements and flat posture, with other clinical signs included lethargy, hunched posture, laboured respiration, rales, salivation, and piloerection noted only on 1-2 occasions. Uncoordinated movements were also commonly noted for animals at 100 mg/kg bw/d. In both cases, the clinical signs were transient, resolving by 4 hours post-dosing. No clinical signs were noted for animals at 30 mg/kg bw/d. Body weight gains were lower at 300 mg/kg bw/d in males. There were no effects on food consumption, clinical pathology, macroscopic findings or organ weights at any dose level.

- Rationale for animal assignment (F0):
Prior to commencement of treatment, by computer-generated random algorithm according to body weight, with all animals within +/- 20% of the sex mean.

Positive control:

Not applicable

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least twice daily (including observations for Mortality/Viability)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: At least once daily from start of treatment onwards

BODY WEIGHT: Yes
- Time schedule for examinations: Males and females were weighed on the first day of exposure and weekly thereafter. Mated females were weighed on Days 0, 4, 7, 11, 14, 17 and 20 post-coitum and during lactation on Days 1 and 4.

FOOD CONSUMPTION: yes
- Weekly, except for males and females which were housed together for mating and for females without evidence of mating. Food consumption of mated females was measured on Days 0, 4, 7, 11, 14, 17 and 20 postcoitum and on Days 1 and 4 of lactation.
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

WATER CONSUMPTION: Yes
- Time schedule for examinations: Subjective appraisal was maintained during the study, but no quantitative investigation was introduced as no treatment related effect was suspected.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: before necropsy
- Anaesthetic used for blood collection: Yes (isoflurane)
- Animals fasted: Yes (deprived of food overnight, with a maximum of 20 hours)
- How many animals: selected 5 animals/sex/group

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: before necropsy
- Animals fasted: Yes (deprived of food overnight, with a maximum of 20 hours)
- How many animals: selected 5 animals/sex/group

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: The selected males were tested during Week 4 of treatment and the selected females were tested towards the end of the scheduled lactation period (all before blood sampling).
- Dose groups that were examined: selected 5 animals/sex/group
- Battery of functions tested: hearing ability / pupillary reflex / static righting reflex / grip strength / locomotor activity

Sperm parameters (parental animals):

Parameters examined in F0 male parental generation:
- testis weight, epididymis weight
other: Histopathologic examination was performed on the reproductive organs from 5 selected males and females of Group 1 (control) and Group 4 (150 mg/kg bw/day), as well as all organs with macroscopic findings from all rats (i.e. testis). Of the all Group 1 and 4 males and of the males suspected to be infertile, additional slides of 3-4 micrometers of the testes were prepared and stained with PAS/hematoxylin to examine staging of spermatogenesis.

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: No

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring (each litter):
- Mortality / Viability: The numbers of live and dead pups on Day 1 of lactation and daily thereafter were determined. If possible, defects or cause of death were evaluated
- Clinical signs: At least once daily, detailed clinical observations were made for all animals.
- Body weights: Live pups were weighed on Days 1 and 4 of lactation.
- Sex: Sex was determined for all pups on Days 1 and 4 of lactation.

Postmortem examinations (parental animals):

SACRIFICE
All males and the selected 5 females/group were deprived of food overnight (with a maximum of approximately 20 hours) prior to planned necropsy, but water was provided. Non-selected females were not deprived of food.
Animals surviving to scheduled necropsy were deeply anaesthetized using isoflurane and subsequently exsanguinated.
- Male animals: All surviving animals, following completion of the mating period (a minimum of 28 days of dose administration).
- Maternal animals: All surviving animals, females which delivered: Lactation Days 6-7 and females which failed to deliver* (nos. 57, 60, 63, 67 and 74): Post-coitum Days 25-28 (females with evidence of mating)
*) In case no macroscopically visible implantation sites were present, nongravid uteri were stained using the Salewski technique in order to detect any former implantation sites.


GROSS NECROPSY
- Gross necropsy consisted of macroscopic examination of the cranial, thoracic and abdominal tissues and organs, with special attention being paid to the reproductive organs. Descriptions of all macroscopic abnormalities were recorded. The numbers of former implantation sites and corpora lutea were recorded for all paired females.


ORGAN WEIGHTS
The following organ weights and terminal body weight were recorded from the following animals on the scheduled day of necropsy:

Selected 5 animals/sex/group
- Adrenal glands
- Brain
- Epididymides
- Heart
- Kidneys
- Liver
- Ovaries
- Spleen
- Testes
- Thymus
- Uterus (including cervix)
- Prostate
- Seminal vesicles including coagulating glands
- Thyroid including parathyroid

All remaining males:
- Epididymides
- Testes


HISTOPATHOLOGY
All organ and tissue samples, as defined below, were processed, embedded and cut at a thickness of 2-4 micrometers and stained with haematoxylin and eosin.
Of the all males of the control and high dose group and all males suspected to be infertile, additional slides of the testes were prepared to examine stages of spermatogenesis. The testes were processed, sectioned at 3-4 micrometers, and stained with PAS/haematoxylin.

The following slides were examined by a pathologist:
- The preserved organs and tissues of the selected 5 animals/sex of Groups 1 and 4.
- The additional slides of the testes of all males of Groups 1 and 4 and all males suspected to be infertile to examine stages of spermatogenesis.
- All gross lesions of all animals (all dose groups).
- The reproductive organs* of all animals of Groups 1 and 4, and all males that failed to sire and all females that failed to deliver healthy pups:
Group 1: --
Group 2: Female/Male nos. 51/17, 60/20: No offspring
Group 3: Female/Male nos. 63/23, 67/27: No offspring
Group 4: Female/Male nos. 74/34: No offspring

*) Reproductive organs included the cervix, clitoral gland, coagulation gland, epididymides, ovaries, preputial gland, prostate gland, seminal vesicles, testes, uterus, and vagina.

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring was sacrificed at 6-7 days of age.
- These animals were subjected to postmortem examinations (macroscopic examination).

GROSS NECROPSY
- Gross necropsy consisted of [external and internal examinations (stomach)]

NECROPSY PUPS
Pups surviving to planned termination were killed by decapitation on Days 6-7 of lactation. All pups were sexed and descriptions of all external abnormalities were recorded. The stomach was examined for the presence of milk. If possible, defects or cause of death were evaluated.

Statistics:

The following statistical methods were used to analyze the data:
- If the variables could be assumed to follow a normal distribution, the Dunnett-test (many to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex.
- The Steel-test (many-to-one rank test) was applied if the data could not be assumed to follow a normal distribution.
- The Fisher Exact-test was applied to frequency data.
The following additional methods of statistical analysis were used:
Motor activity data was subjected to the Kruskal-Wallis nonparametric ANOVA test to determine intergroup differences followed by the Wilcoxon test to compare the treated groups to the control group.
All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance.
Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables. Test statistics were calculated on the basis of exact values for means and pooled variances. Individual values, means and standard deviations may have been rounded off before printing. Therefore, two groups may display the same printed means for a given parameter, yet display different test statistics values.

Reproductive indices:

Mating index (%) = (Number of females mated/Number of females paired) x 100
Fertility index (%) = (Number of pregnant females/Number of females paired) x 100
Conception index (%) = (Number of pregnant females/Number of females mated) x 100
Gestation index (%) = (Number of females bearing live pups/Number of pregnant females) x 100

Offspring viability indices:

Percentage live males at First Litter Check = (Number of live male pups at First Litter Check/Number of live pups at First Litter Check) x 100
Percentage live females at First Litter Check = (Number of live female pups at First Litter Check/Number of live pups at First Litter Check) x 100
Percentage of postnatal loss Days 0-4 of lactation = (Number of dead pups on Day 4 of lactation/Number of live pups at First Litter Check) x 100
Viability index = (Number of live pups on Day 4 post partum/Number of pups born alive) x 100

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
No mortality occurred during the study period.
Uncoordinated movements were noted for all animals at 150 mg/kg bw/d through most of the treatment period and flat posture was also noted for all females and 7/10 males. Hunched posture was also commonly noted at this dose level, especially for females, and lethargy, rales and piloerection were noted for only a few animals on limited occasions.
Hunched posture was noted for two females at 6 mg/kg bw/d, though this was not considered to be toxicologically relevant due to the limited incidence and severity noted. Alopecia was noted for one female each at 6 and 30 mg/kg bw/d; this finding was incidental. No clinical signs were noted for control animals of either sex, nor were any signs seen for males at 6 and 30 mg/kg bw/d.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
No toxicologically relevant changes in body weights and body weight gain were noted. Females at 6 mg/kg bw/d had significantly higher absolute body weights on lactation Day 1 and lower gains on Day 4. The differences from controls were only slight, occurred in the absence of a dose related distribution, and were not considered treatment related or toxicologically relevant.
Food consumption before or after allowance for body weight was similar between treated and control animals up to 150 mg/kg bw/d. No toxicologically relevant changes were noted in food consumption.

REPRODUCTIVE FINDINGS (PARENTAL ANIMALS)
- Reproduction/developmental data: No toxicologically relevant effects on reproductive parameters were noted. The mating, fertility and conception indices, precoital time, and number of corpora lutea and implantation sites were unaffected by treatment.
- Developmental data: No toxicologically relevant effects on the gestation index and duration, parturition, maternal care and early postnatal pup development (mortality, clinical signs, body weight and macroscopy) were observed.

ORGAN WEIGHTS (PARENTAL ANIMALS)
No toxicologically relevant changes were noted in organ weights and organ to body weight ratios up to 150 mg/kg bw/d. Statistically significant changes between brain to body weight ratios of females at 6 mg/kg bw/day and control animals were not considered to be a sign of toxicity as no dose-dependency was seen and there were no corroborative findings noted at the microscopic examination.

GROSS PATHOLOGY / HISTOPATHOLOGY (PARENTAL ANIMALS)
There were no treatment-related microscopic findings; all microscopic findings recorded were considered to be within the normal range of background pathology encountered in Wistar-Han rats of this age. The assessment of the integrity of the spermatogenetic cycle did not provide any evidence of impaired spermatogenesis. Furthermore, there were no morphological findings in the reproductive organs of either sex which could be attributed to the test substance.

OTHER: NEUROBEHAVIOUR (PARENTAL ANIMALS)
One male and three females at 150 mg/kg bw/d did not have sufficient grip strength in the functional observational test. This was likely related to the uncoordinated movements seen during clinical observations, which could be indicative of a slight decrement in muscular strength. There were no toxicologically relevant effects on hearing ability, pupillary reflex, or static righting reflex up to 150 mg/kg bw/d.
The variation in motor activity did not indicate a relation with treatment. Males and females at 150 mg/kg bw/d had lower activity compared to controls in the first few blocks of testing, which was likely related to the movement-related clinical signs at this dose level. These signs were transient. Females at 6 mg/kg bw/d had significantly higher basic movements and ambulatory counts, however, the differences from controls were only slight and in the absence of a treatment related distribution, were not considered treatment-related or toxicologically relevant. All groups showed a similar habituation profile with high activity in the first interval that decreased over the duration of the test period. Males at 150 mg/kg bw/d, had a somewhat blunted habituation effect compared to controls, though they still habituated over the test session. This was also related to the clinical signs noted, as was not considered adverse.

Dose descriptor:

NOAEL

Remarks:

(parental toxicity)

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on clinical signs of systemic toxicity noted at 150 mg/kg bw/d

Dose descriptor:

NOAEL

Remarks:

(developmental toxicity)

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No toxicologically relevant effects on developmental parameters

GENERAL (OFFSPRING)
Early postnatal pup development: Number of dead and living pups at first litter check, postnatal loss, viability index and sex ratio were unaffected by treatment, and clinical signs, body weight and external macroscopic examination did not reveal treatment-related findings.

VIABILITY (OFFSPRING)
Three pups of the 6 and 150 mg/kg bw/d groups were found dead or went missing during the first days of lactation. Missing pups were most likely cannibalised. No toxicological relevance was attributed to these dead/missing pups since the mortality incidence did not show a dose-related trend and remained within the range considered normal for pups of this age.

CLINICAL SIGNS (OFFSPRING)
Incidental clinical symptoms of pups consisted of no milk in the stomach, pale or lean appearance and missing tail. The nature and incidence of these clinical signs remained within the range considered normal for pups of this age, and were therefore considered to be of no toxicological relevance.

BODY WEIGHT (OFFSPRING)
Body weights of pups were unaffected by treatment up to 150 mg/kg bw/d.

SEXUAL MATURATION (OFFSPRING)
--

ORGAN WEIGHTS (OFFSPRING)
Not determined.

GROSS PATHOLOGY (OFFSPRING)
Incidental macroscopic findings of pups that were found dead included absence of milk in the stomach, insufficient milk in the stomach, cannibalism of the abdominal organs. Missing tail was the only finding noted for surviving pups, which was incidental in nature. The type and frequency of these findings remained within the range considered normal for pups of this age, and were therefore not considered to be toxicologically relevant.

HISTOPATHOLOGY (OFFSPRING)
--

OTHER FINDINGS (OFFSPRING)
--

Key result

Dose descriptor:

NOAEL

Remarks:

developmental toxicity

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No toxicologically relevant effects on developmental parameters.

Reproductive effects observed:

not specified

All rats were necropsied. Histopathologic examination was performed on an extensive list of organs and tissues from 5 selected males and females of Group 1 (control) and Group 4 (150 mg/kg bw/day), the reproductive organs from all Group 1 and Group 4 rats, as well as all organs with macroscopic findings from all rats. Of the all Group 1 and 4 males and of the males suspected to be infertile, additional slides of 3-4 micrometers of the testes were prepared and stained with PAS/hematoxylin to examine staging of spermatogenesis. There were no unscheduled deaths. There were no treatment-related macroscopic findings. There were no treatment-related microscopic findings. There were no morphological findings in the reproductive organs of either sex which could be attributed to the test substance.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

150 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Guideline study conducted in accordance with GLP

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

In a combined 28-day repeated dose toxicity study with the reproduction/developmental toxicity screening test (NOTOX, 2012; 498332) 1-Ethinyl-1-cyclohexanol was administered by daily oral gavage to male and female Wistar Han rats at dose levels of 6, 30 and 150 mg/kg bw/d; dose levels based on a 14-d range-finding study (NOTOX, 2012; 498335). Males were exposed for 29 days, i.e. 2 weeks prior to mating, during mating, and up to termination. The females were exposed for 2 weeks prior to mating, during mating, during post-coitum, and at least 4 days of lactation (for 43 - 53 days). The following observations and examinations were evaluated: mortality/viability, clinical signs (daily), functional observations and locomotor activity (Week 4 (males); end of lactation (females)), body weight and food consumption (at least at weekly intervals), clinical pathology (Week 4 (males); end of lactation (females)), macroscopy at termination, organ weights and histopathology on a selection of tissues, and reproduction/developmental parameters, consisting of mating, fertility and conception indices, precoital time, number of corpora lutea and implantation sites, gestation index and duration, parturition, maternal care, sex ratio and early postnatal pup development (mortality, clinical signs, body weights and macroscopy). Formulations of the test substance were analyzed once during the study to assess accuracy, homogeneity and stability.

Accuracy, homogeneity and stability of formulations were demonstrated, i.e. formulations were stable for at least 6 hours at room temperature.

Parental toxicity, characterized by clinical signs including uncoordinated movements, flat posture and hunched posture were noted for animals of both sexes at 150 mg/kg bw/d. Reduced grip strength was noted for one male and three females at this dose level, which were considered to be likely related to the clinical signs observed at this dose level, and not to be a specific effect of the test substance. No toxicologically relevant changes were noted in any of the remaining parental parameters investigated in this study (i.e. body weight, food consumption, clinical laboratory investigations, macroscopic examination, organ weights, and microscopic examination). No reproduction/developmental toxicity was observed up to and including the highest dose level tested (150 mg/kg bw/d).

In conclusion, treatment with 1-Ethinyl-1-cyclohexanol by oral gavage in male and female Wistar Han rats at dose levels of 6, 30 and 150 mg/kg bw/d revealed parental toxicity at 150 mg/kg bw/d. No reproduction and developmental toxicity was observed for treatment up to and including 150 mg/kg bw/d.

Based on these results, the following No Observed Adverse Effect Levels (NOAEL) were derived: Parental NOAEL: 30 mg/kg bw/d, Reproduction NOAEL: 150 mg/kg bw/d, Developmental NOAEL: 150 mg/kg bw/d. This GLP-conform study is classified as acceptable and was performed according to OECD TG 422.

Short description of key information:
A combined 28-day repeated oral dose toxicity study with the reproduction/developmental toxicity screening test of 1-Ethinyl-1-cyclohexanol in rats by oral gavage (NOTOX, 2012b) demonstrated that parental toxicity, characterized by clinical signs including uncoordinated movements, flat posture and hunched posture were noted for animals of both sexes at 150 mg/kg bw/d. No toxicologically relevant changes were noted in any of the remaining parental parameters investigated in this study. Furthermore, no reproduction toxicity was observed up to the highest dose level tested (150 mg/kg bw/d). No developmental toxicity was observed up to the highest dose level tested (150 mg/kg bw/d).

Justification for selection of Effect on fertility via oral route:
The key study was selected.

Effects on developmental toxicity

Description of key information

In a prenatal toxicity study (BASF SE, 1997) the oral administration of the read-across substance 3-Methyl-1-butyn-3-ol elicited clear signs of maternal and developmental toxicity at

400 mg/kg bw/d, but was not toxic to the adult females and their fetuses at 45 or 130 mg/kg bw/d. There were no indications for substance induced teratogenicity up to and including the high dose level (400 mg/kg bw/d), as the accessory 14th and/or rudimentary cervical rib(s) in the fetuses are assessed as an embryotoxic effect representing a manifestation of a non-specific stress on the dams. Based on these results, the no observed adverse effect level (NOAEL) for the dams and the fetal organism is 130 mg/kg bw/d. Thus, developmental toxicity occurred only in the presence of maternal toxicity. Of note, no developmental toxicity was seen in a reliable study conducted according to OECD test guideline 422 with the target chemical 1-Ethinyl-1-cyclohexanol up to and including the high dose level of 150 mg/kg bw/d (NOTOX, 2012; 498332).

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study according to OECD GL 414 (“Prenatal Developmental Toxicity Study”)

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Qualifier:

according to guideline

Guideline:

EU Method B.31 (Prenatal Developmental Toxicity Study)

Version / remarks:

Cited as Directive 87/302/EEC, part B, p. 24

GLP compliance:

yes

Remarks:

Dept. of Toxicology, BASF AG

Limit test:

no

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: DR . K . THOMAE GmbH, Biberach an der Riss, Germany
- Age at study initiation: 70 days old
- Identification: ear tattoo
- Housing: singly, from day 0 - 20 p.c. in type DK III stainless steel wire mesh cages supplied by BECKER & CO ., Castrop-Rauxel, FRG (floor area about 800 cm^2). Underneath the cages, waste trays were fixed containing absorbent material (type 3/4 dustfree embedding, supplied by SSNIFF, Soest, Germany)
- Diet: ad libitum, ground Kliba 343 feed rat/mouse/hamster supplied by KLINGENTAIMOHLE AG, Kaiseraugst, Switzerland
- Water: ad libitum, drinking water of tap water quality from water bottles
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 20 - 24 °C
- Humidity: 30 - 70%
- Photoperiod (hrs dark / hrs light): 12 / 12

Food and water analysis:
- The food used in the study was assayed for chemical and for microbiological contaminants
- The drinking water is regularly assayed for chemical contaminants by the municipal authorities of Frankenthal and the Technical Services of BASF Aktiengesellschaft as well as for the presence of microorganisms by a contract laboratory.

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
- The test substance solutions were prepared in intervals of not more than 3 days during the administration period, because the stability of test substance solution over a period of 96 hours had been verified analytically .
- For the preparation of the solutions, an appropriate amount of the test substance was weighed in volumetric flasks, subsequently topped up with doubly distilled water and intensively shaken.


VEHICLE
- Concentration in vehicle: 4.5, 13, 40 mg/mL
- Amount of vehicle (if gavage): 10mL/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

- Analytical verifications of the stability of the test substance in Milli-Q-water for a period of 96 hours at room temperature were carried out for the same batch in a previous study (BASF Aktiengesellschaft, Project No.: 26M0231/934206).
- As the test substance preparations were true solutions, the homogeneity had not be proven analytically.
- Samples of the test substance solutions were sent to the analytical laboratories twice during the study period for verification of the concentrations

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/2
- Length of cohabitation: ca. 13.5 h
- Further matings after two unsuccessful attempts: no
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

day 6 through day 15 post coitum

Frequency of treatment:

daily, in the morning

Duration of test:

21 days

Remarks:

Doses / Concentrations:
45, 130, 400 mg/kg/day
Basis:
analytical conc.

No. of animals per sex per dose:

25 females/dose

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: The selection of doses for the present examination was based on the results of a subacute oral toxicity study in rats and a preceding range-finding prenatal toxicity study (BASF AG, 1994) in Wistar rats.
- Other: Due to technical reasons, the study was carried out in 3 sections. Each dose group was represented in each section. A treatment interval of 1 - 2 days elapsed before the next section.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day on working days or once a day (Saturday, Sunday or on public holidays) (days 0 - 20 pc).


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once a day, or more often when clinical signs of toxicity were elicited (days 0 - 20 pc).

BODY WEIGHT: Yes
- Time schedule for examinations: All animals were weighed on days 0, 1, 3, 6, 8, 10, 13, 15, 17 and 20 pc.


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- 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: No


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: uterus

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: number of dead fetuses, calculations of conception rate and pre- and postimplantation losses

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: No data

Statistics:

- two-sided Dunetts test: Food consumption, body weight, body weight changes, corrected body weight gain (net maternal body weight change), carcass weight, weight of unopened uterus, number of corpora lutea, number of implantations, number of resorptions, number of live fetuses, proportion of preimplantation loss, proportion of postimplantation loss, proportions of resorptions, proportion of live fetuses in each litter, litter mean fetal body weight, litter mean placental weight
- two-sided Kruskal-Wallis test: liver weights
one-sided Fisher's Exact test: female mortality, number of females pregnant at terminal sacrifice, number of litters with fetal findings
- one-sided Wilcoxon test: proportions of fetuses with malformations, variations and/or unclassified observations in each litter

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
400 mg/kg bw/day:
- Transient, statistically significant reduction of food consumption from day 6 to day 8 p.c. (-15% compared to control group).
- Transient, statistically significant body weight loss at beginning of treatment period (days 6 to 8 p.c.). On the following days weight gains in the highest dose group exceeded control values considerably.
- Clinical symptoms of apathy, unsteady gait and/or piloerection during entire or part of treatment period. Symptoms appeared shortly after treatment and persisted for several hours. After cessation of treatment these signs were not seen any more.

130 mg/kg bw/day: - no substance-related effects on dams, gestational parameters

45 mg/kg bw/day: - no substance-related effects on dams, gestational parameters

Dose descriptor:

NOAEL

Effect level:

130 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOAEL

Effect level:

130 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
400 mg/kg bw/day:
- Statistically significant (ca. 6%) reduction of mean fetal weights
- Statistically significant increased occurence of rudimentary cervical or accessory 14th rib(s).
- Statistically significant increased rate of affected fetuses/litter showing skeletal retardations (poor or missing ossification of skull bones, thoracic vertebral bodies and/or sternebra). Statistically or biologically relevant fetal malformations with proven dose correlation were not found.

130 mg/kg bw/day: - no substance-related effects on fetuses

45 mg/kg bw/day: - no substance-related effects on fetuses

Dose descriptor:

NOAEL

Effect level:

400 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

Thus, under the conditions of this prenatal toxicity study, the oral administration (by gavage) of 3-Methyl-1 -butyn-3 -ol elicited clear signs of maternal and developmental toxicity at 400 mg/kg body weight/day, but was not toxic to the adult females and their fetuses at 45 or 130 mg/kg body weight/day. There were, however, no indications for substance induced teratogenicity up to and including the high dose level (400 mg/kg body weight/day), as the accessory 14th and/or rudimentary cervical rib(s) in the fetuses are assessed as an embryotoxic effect representing a manifestation of a non-specific stress on the dams. Based on these results, the no observed adverse effect level (NOAEL) for the dams and the fetal organism is 130 mg/kg bw/d. Thus, developmental toxicity occurred only in the presence of maternal toxicity.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

130 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Guideline study conducted in accordance with GLP

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Read across:-Methyl-1-butyn-3-ol (CAS 115-19-5)

In a developmental toxicity study (BASF AG, 1997), 3-Methyl-1-butyn-3-ol (99.6%) was administered as an aqueous solution to 25 time-mated female Wistar rats by gavage at doses of 45; 130 and 400 mg/kg bw/d on gestation days (GD) 6 through 15. The control group, consisting of 25 females, was dosed with the vehicle (drinking water) in parallel. A standard dose volume of 10 mL/kg bw was used for each test group. At terminal sacrifice on GD 20, all females (25 per group) had implantation sites.The oral administration of 400 mg/kg bw/d caused clinical symptoms of apathy, unsteady gait and/or piloerection during entire or part of treatment period. Symptoms appeared shortly after treatment and persisted for several hours. After cessation of treatment these signs were not seen any more. Additionally, transiently reduced mean food consumption and bw gain was noted at the high-dose level. No substance-related effects on dams, gestational parameters at all lower dose levels were noticed. At 400 mg/kg bw/d, fetuses showed increased incidences of rudimentary cervical or acessory 14th rib(s) and of skeletal retardation.Thus, under the conditions of this prenatal toxicity study, the oral administration of 3-Methyl-1-butyn-3-ol elicited clear signs of maternal and developmental toxicity at 400 mg/kg bw/d, but was not toxic to the adult females and their fetuses at 45 or 130 mg/kg bw/d; the maternal NOAEL was deemed as 130 mg/kg bw/d. There were, however, no indications for substance induced teratogenicity up to and including the high dose level (400 mg/kg bw/d), as the accessory 14th and/or rudimentary cervical rib(s) in the fetuses are assessed as an embryotoxic effect representing a manifestation of a non-specific stress on the dams. Based on these results, the no observed adverse effect level (NOAEL) for the dams and the fetal organism is 130 mg/kg bw/d. Thus, developmental toxicity occurred only in the presence of maternal toxicity. The developmental toxicity study is classified as acceptable and satisfies the guideline requirement for a developmental toxicity study (OECD 414) in rat.

Justification for selection of Effect on developmental toxicity: via oral route:
A study on developmental toxicity of 3-Methyl-1-butyn-3-ol was used to evaluate the developmental toxicity of the test substance 1-Ethinyl-1-cyclohexanol. The substance 3-Methyl-1-butyn-3-ol was chosen as supporting substance due to the similar composition (same number of identical functional groups) and comparable physico-chemical properties (i.e. flash point). Furthermore, with regard to the acute oral toxicity in rat, the LD50 values of both substances are above 300 mg/kg bw.

Justification for classification or non-classification

An OECD 422 guideline study gives no hint for any reprotoxic potential of 1-Ethinyl-1-cyclohexanol. No developmental (teratogenic effects) were noted in this screening study. Furthermore, read across to an OECD 414 guideline study with the structural analogue Methyl-1-butyn-3-ol (CAS 115-19-5) showed that developmental toxicity occurred only in the presence of maternal toxicity, whereas no indications for substance induced teratogenicity were found.

Therefore, classification for effects on reproduction/development is not warranted according to the criteria of EU Directive 67/548/EEC and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.