4-tert-pentylcyclohexanone

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Fertility based on read across from para- trans-4 -tertbutylcyclohexanol (OECD TG 408): 240 mg/kg bw.

Link to relevant study records

Reference

Endpoint:

fertility, other

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: read-across from a guideline study

Justification for type of information:

For assessing the fertility toxicity of Orivone, read-across is used from p-tert-butyl-trans-cyclohexanol. In the file attached and in the endpoint summary the full read-across is documented.

Reason / purpose for cross-reference:

read-across source

Dose descriptor:

LOEL

Effect level:

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

Based on:

test mat.

Sex:

male

Basis for effect level:

other: hyaline droplets, tubular basophilia, casts and tubular dilation

Remarks on result:

other: Result read-across source CAS No.21862-63-5; effects not relevant for humans

Remarks:

Correction for molecular weight not required

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

female

Basis for effect level:

clinical signs

body weight and weight gain

haematology

clinical biochemistry

organ weights and organ / body weight ratios

Remarks on result:

other: Result read-across source CAS No.21862-63-5

Remarks:

Correction for molecular weight not required

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male

Basis for effect level:

other: minimal focal or multifocal glandular inflammation in the prostate

Remarks on result:

other: Result read-across source CAS No.21862-63-5

Remarks:

Correction for molecular weight not required

Key result

Remarks on result:

not measured/tested

Key result

Critical effects observed:

not specified

Key result

Reproductive effects observed:

no

Effect on fertility: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

240 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

For fertility one subchronic oral study is available, conducted according to OECDTG408 in compliance with GLP. The resulting information is adequate for the endpoint

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

The effect of Orivone on fertility is derived from trans-4 -tert-butylcyclohexanol, a close analogue. First the repeated dose effects and the effects on fertility of trans-4 -tert-butylcyclohexanol will be summarised below (the same summary is presented in the repeated dose section and is repeated here to present the fertility effects seen in the context of repeated dose toxicity. Thereafter the read-across justification is presented. The accompanying files are attached in the Toxicity to reproduction Endpoint summary.

The effects on fertility including repeated dose effects (OECDTG408) of trans-4 -tert-butylcyclohexanol used for read-across to Orivone:

In a sub-chronic study according to OECD TG 408 and GLP, Wistar rats RccHanTM: WIST(SPF were orally (gavage) exposed to 0, 80, 240 and 800 mg/kg bw/day for 90 days with a 28 days recovery period. The groups comprised 10 females and 10 males which were sacrificed after 91 and 92 days of treatment, respectively. Additional 5 rats per sex and group were used in the control group (treated with corn oil only), the vehicle group (treated with 10% ethanol in corn oil) and the high-dose group (treated with 800 mg/kg/day). Recovery animals were treated for 91 days, and then allowed a 28-day recovery period after which they were sacrificed. Viability/mortality, clinical signs, food consumption and body weights were recorded periodically during acclimatization, treatment and recovery. Weekly behavioural observations were performed during treatment. Functional observational battery, locomotor activity and grip strength tests were performed during week 13. At the end of the treatment period and the recovery period, blood samples were withdrawn for haematology and plasma chemistry analyses. Urine samples were collected for urinalyses. All animals were killed, necropsied and examined post mortem. Histological examinations were performed on organs and tissues from all animals of the control group (treated with corn oil only), the vehicle group (treated with 10% ethanol in corn oil) and the high-dose group. From the animals of the low and mid dose groups (treated with 80 and 240 mg/kg/day, respectively) liver, kidneys, stomach, prostate, nasal cavities and pharynx were examined in an attempt to establish a no-effect level. 

Results:Clinical effects: No substance related mortality, (neuro)behavioural or ophthalmoscopic effects were observed. Males and females in the high dose group showed slight to moderate dyspnea (short breath) and slight to moderate salivation, which was considered treatment related. Body weight and bodyweight changes were significantly reduced in the high dose group, which was not evident during the recovery period. Haematological effects were within the range of historical control data.

Liver related parameters: The observed changes in clinical biochemistry parameters except for triglyceride levels in females treated with 800 mg/kg/day and phospholipids and globulin levels in males treated with 800 mg/kg/day, were within the range of historical control data. These alterations were not evident after the 28 day recovery period. The relative liver weights were increased in mid and high dose males and in high dose females. Accentuated lobular pattern in livers of 2 and 3 males form the mid and high dose group, respectively, were observed.                                   

Kidney related parameters: Observed effects on urinalysis parameters were within the range of historical control data. The effects in the kidney in males can be contributed to alpha-hydrocarbon nephropathy. Relative kidney weights were increased in all doses in males. This increase in kidney weight in the high dose was still present after the recovery period. The effects consisted of increased incidence or incidence and severity of hyaline droplets, tubular basophilia and mononuclear cell foci along with granular casts and tubular dilation in all males. Hyaline casts were increased in incidence animals treated with 240 and 800 mg/kg/day, and tubular cysts were recorded in animals treated with 800 mg/kg/day. Some of these effects in the high dose males were still seen after the recovery period.

In high dose females an increase in incidence or incidence and severity of tubular basophilia along with minimal granular casts, tubular dilation and tubular cysts was observed. In recovery animals, increased incidences and severities of tubular basophilia, granular casts, mononuclear cell foci and tubular dilation along with increased incidence of hyaline casts were still recorded in males treated with 800 mg/kg/day.

Stomach related effects: The effects in the stomach represented a localized stomach reaction to a slightly irritant test item dosed repeatedly via gavage. There were minor incidences and/or severities of epithelial hyperplasia, hyperkeratosis, focal glandular erosion and forestomach ulceration in animals treated with 240 and 800 mg/kg/day. A number of findings recorded in the nasal cavity, nasopharyngeal duct and pharynx were deemed to be due to accidental uptake of the vehicle/test item by regurgitation.

Fertility: In the prostate, minimal focal or multifocal glandular inflammation, characterized by degenerating granulocytic cell infiltrates and inspissated colloid, were recorded in 3/10 males treated with 800 mg/kg/day.

In summary: The high dose 800 mg/kg presents systemic toxicity: decrease in body weight (gain), effects on liver, kidney and prostate. This dose seems to be the maximum tolerable dose. The kidney effects at the low and mid dose in males can be contributed toα2u-globulin nephropathy and is not relevant for human. Therefore the overall NOAEL (No-Observed-Adverse-Effect-Level) for effects relevant to human risk assessment is set at 240 mg/kg/day.

Assessing the reproductive toxicity of Orivone (CAS#16587-71-6)using read-across form p-tert-butyl-trans-cyclohexanol (CAS# 21862-63-5) and multi-constituentp-tert-butylcyclohexyl acetate(CAS# 32210-23-4)

1. Introduction and hypothesis for the analogue approach

Orivone (CAS# 16587-71-6) has a cyclohexanone backbone substituted with a (1,1)dimethyl-propyl moiety on thepara-position.For this substance no reproductive toxicity data are available.In accordance with Article 13 of REACH, lacking information should be generated whenever possible by means other than vertebrate animal tests, i.e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across. For assessment of the reproductive toxicity of Orivone,the analogue approach is selected because data on fertility is available on p-tert-butyl-trans-cyclohexanol and developmental toxicity data is available on constituentp-tert-butylcyclohexyl acetate, which can be used for read-across.

Hypothesis: Orivone (target) has similar effects on fertility compared to p-tert-butyl-trans-cyclohexanol (source) and developmental toxicity is similar top-tert-butylcyclohexyl acetate (source) resulting in a similar NOAEL for these endpoints. The structural differencesbetween Orivone and the source substances do not affect reproductive toxicity and consequently the NOAEL (see rationale below). 

Available information: For Orivone no data on reproductive toxicity is available. For p-tert-butyl-trans-cyclohexanol a well conducted oral gavage 90-day repeated dose study with a 28 days recovery element is available (according to OECD TG 408, GLP and Kl1) from which the fertility information can be derived. In this study doses up to 800 mg/kg bw/day were tested.A NOAEL of 240 mg/kg bw/day was derived based on minimal focal or multifocal glandular inflammation in the prostate in the presence of repeated dose effects such as body weight and food consumption decrease. For the second source substance,p-tert-butylcyclohexyl acetate, a developmental toxicity study (similar to OECD TG 414, GLP and Kl. 1) is available in which pregnant female rats were exposed from gestation day 7 to 21) up to 640 mg/kg bw/day. A NOAEL of 160 mg/kg bw/ day for developmental toxicity is obtained, which is based on maternal body weight decrease and food consumption which resulted in secondary body weight decrease and some delay in ossification in the pups.

2.Target chemical and source chemicals

Chemical structures and physico-chemical properties of the target source chemicals are presented in the data matrix.

3. Purity / Impurities

The reported purity of the Orivone,p-tert-butyl-trans-cyclohexanol andp-tert-butylcyclohexyl acetateis > 98%. For Orivone the major impurity identified is cis‐4‐(2‐methylbutan‐2‐yl)cyclohexanol, which is present at 1.6 % (relative peak area): the impurity contains the alcohol instead of the ketone functionality and will have the same effect on fertility and developmental toxicity as Orivone.

4. Analogue approach justification

According to REACH Annex XI 1.5 read-across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read-across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation.

Analogue selection:In absence of reproductive toxicity informationp-tert-butylcyclohexanone(CAS# 98-53-3) this substance could not be selected for read across. Based on database searches (RIFM database and OECD QSAR Toolboxp-tert-butyl-trans-cyclohexanol (CAS# 21862-63-5) andp-tert-butylcyclohexyl acetate (CAS#32210-23-4)were found as good analogues (Tanimoto index 0.77 and 0.63, respectively) since the acetate group will metabolized to an alcohol.

Structural similarities and differences:The source and target substances have a common para-tert-butyl cyclohexane backbone. Orivone has an extra methyl group attached to this tert-butyl group. Orivone has a ketone substituted on the ring, wherethe source substances have either an alcohol (p-tert-butyl-trans-cyclohexanol) or acetate (p-tert-butylcyclohexyl acetate).

Toxico-kinetic similarities and differences:AbsorptionThe molecular weight (168.3, 156.3 and 198.3 g/mol for Orivone,p-tert-butyl-trans-cyclohexanoland p-tert-butylcyclohexyl acetate respectively) and physico-chemical properties of Orivone and the source substances are all the range of full absorption (see Data matrix).Metabolism: As presented in the Toxico-kinetic section and Repeated dose toxicity read across documentation, the ketone in Orivone can be easily reduced to the alcohol functional group and then resemblesp-tert-butyl-trans-cyclohexanol. The acetate group ofp-tert-butylcyclohexyl acetatewill give the same alcohol too,after hydrolyisis or cleavage by carboxyl esterases in the gul and liver (ref). Therefore, the substance properties determined by the functional groups are interchangeable by metabolic processes. Predicted metabolites with OECD QSAR Toolbox are summarised in Fig. 1.

 

 

Fig. 1 Metabolic pathways of Orivone and its analogues.

 

Form an experimental study on structurally related tert-butyl cyclohexanones in rabbits, it appears that the resulting alcohols are extensively conjugated to glucuronic acid prior to excretion (Cheo et al. 1967). The additional methyl group at the tert-butyl group of Orivone compared to the other two target substances is not expected to be more or less prone to oxidation into an alcohol, aldehyde or acid and will not influence the toxico-kinetic aspects.

Toxico-dynamic aspects:The analogues and therefore also Orivone are expected to cause increase liver and kidney weights at high doses because of increase in metabolic demand. The alcohol metabolites will beside glucuronation also be processed in the lysosomes of the liver, bind to alpha 2u-globulins, transported to the kidneys and there these globulins precipitate at high doses, causing alpha2u-globuline nephropathy. Considering fertility and developmental toxicity the (absence) of effects will be similar between these substances, because the reactivity is similar based on the same functional groups. The receptor binding will also be similar based on the similar hydrocarbon backbone and alcohol as the similar functional group. The cis/trans configuration in the alcohol /acetate analogues is not applicable for Orivone because the ketone group has a double bond with the ring, the alcohol metabolite of Orivone can be formed in a cis or trans-configuration. Also based on this the read across is applicable.

Uncertainty of theprediction: There are no remaining uncertainties considering fertility and developmental toxicity since Orivone, p-tert butyl-trans-cyclohexanol and p-tert-butylcyclohexyl acetate are similar in molecular structure, result in similar metabolites (alcohol) and based on this will have similar toxico-kinetics and dynamic features. A NOAEL correction for fertility is not needed because Orivone has a minimal but slightly higher NOAEL due to its higher molecular weight (NOAEL correction would result in 258 mg/kg bw. For developmental toxicity such a correction is done because the NOAEL of the acetate is not conservative. The NOAEL for maternal and developmental toxicity for Orivone is 136 mg/kg bw (160 NOAEL in mg/kg bw / 198 MW (-acetate)*168 MW Orivone).

5. Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the data Matrix.

6. Conclusions per endpoint for hazard, C&L and dose descriptor

Fertility: For p-tert butyl-trans-cyclohexanol a well conducted 90-day repeated toxicity test including assessment of fertility is available (OECD TG 408, Kl. 1). At the high dose (800 mg/kg bw) repeated dose effects were seen including body weight loss, liver and kidney weight increase and alpha2u globulin nephropathy. For fertility a NOAEL of 240 mg/kg bw/day was also derived based on minimal focal or multifocal glandular inflammation in the prostate. A correction for molecular weight was not considered necessary because the present NOAEL is minimally more conservative due to the higher molecular weight of Orivone.

Developmental toxicity: For p-tert-butylcyclohexyl acetate a well conducted developmental toxicity test, similar to OECD TG 414 (Kl 1) is available. The NOAEL for maternal and developmental toxicity of this study was determined to be 160 mg/kg bw/day. The effect seen in the pups (lower body weight and delays in pup development) were due to body weight loss and lower food consumption in the dams.

Final conclusion on hazard, C&L, DNEL and risk characterization

For Orivone the NOAEL for fertility is 240 mg/kg bw and for developmental toxicity 160 mg/kg bw in the presence or systemic toxicity. This information will be forwarded for classification and labelling and risk assessment.

Data matrix for assessment of reproductive toxicity of Orivone using read-across from p-tert-butyl-trans-cyclohexanol and p-tert-butylcyclohexyl acetate.

Source/target	Target	Source	Source
Common names	Orivone	p-tert butyl-trans-cyclohexanol	p-tert-butylcyclohexyl acetate (multi constituent)
Chemical structures
CAS No.	16587-71-6	21862-63-5	32210-23-4 (generic)
EINECS	240-642-0	700-127-8	250-954-9
Tanimoto	1	0.77	0.63
Empirical formula	C11H20O	C10H20O	C12H22O2
Molecular weight	168.28	156.267	198.3
Physical state	Liquid	Solid	Liquid
Melting point °C	< -20 (IFF measured)	78 (measured) (ECHA dissemination site)	< -50(ECHA dissemination site, Kl4)
Boiling point °C	246.8 (IFF measured)	208.2 – 214.23 (estimated) (ECHA disseminated site)	243 (measured) (ECHA dissemination site)
Vapour pressure Pa	4.2 at 24°C (IFF measured)	0.74 at 20°C (measured) (ECHA dissemination site)	≤7.9 at 25°C (measured)  (ECHA dissemination site)
Water solubility mg/L	370.8 at 24°C (IFF measured)	106.1 at 20°C (measured) (ECHA dissemination site)	< 39.6 mg/L at 20°C (measured at 20 °C)/ 3.55 mg/L (QSAR estimation) (ECHA dissemination site)
Log Kow	3.9 at 25°C (IFF measured)	3.42 (estimated) (ECHA disseminated site)	4.8 at 25°C (measured) (ECHA dissemination site)
Human health
Acute oral tox mg/kg bw	LD50 = 4700 mg/kg bw	LD50 > 2000 mg/kg bw (ECHA dissemination site)	LD50 ca. 3370 mg/kg bw(ECHA dissemination site)
Acute dermal tox mg/kg bw	LD50 = 4700 mg/kg bw	No data available	LD50 > 4680 mg/kg bw (ECHA dissemination site)
NOAEL Repeated dose toxicity mg/kg bw	136 (Read-across from p-tert butyl-trans-cyclohexanol and the acetate)	240 (OECD TG 408)	160 (systemic toxicity in the OECD TG 414)
Fertility mg/kg bw	240 Read-across from p-tert butyl-trans-cyclohexanol	240 (OECD TG 408)	No data available
Developmental toxicity	136 Read-across from p-tert-butylcyclohexyl acetate (multi constituent)	160 (OECD TG 414)	160 (OECD TG 414)

 

References

Cheo 1967: Cheo, K.L., Elliott, T.H., and Tao, R.C.C., The metabolism of isomeric tert-butylcyclohexanones, Biochem. J., 104, 198-204. 1967

Effects on developmental toxicity

Description of key information

Developmental toxicity based on read across from para-4 -tert-butyl cyclohexenyl acetate (OECDTG 414): 136 mg/kg bw.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: read-across from a guideline study

Justification for type of information:

For assessing the developmental toxicity of Orivone, read-across is used from p-tert-butylcyclohexyl acetate. The read across justification is presented in the Toxicity to reproduction Endpoint summary in the fertility section. The accompanying files are also attached there.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

body weight and weight gain

clinical signs

food consumption and compound intake

mortality

Remarks on result:

other: Result read-across source CAS No. 32210-23-4

Remarks:

Corrected for molecular weight

Key result

Abnormalities:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

skeletal malformations

visceral malformations

Remarks on result:

other: Result read-across source CAS No. 32210-23-4

Remarks:

corrected for molecular weight

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

yes

Lowest effective dose / conc.:

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

Treatment related:

yes

Relation to maternal toxicity:

developmental effects as a secondary non-specific consequence of maternal toxicity effects

Dose response relationship:

yes

Relevant for humans:

not specified

Effect on developmental toxicity: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

136 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

For developmental toxicity the available study is conducted according to FDA guidelines and similar to OECDTG414 in compliance with GLP. The resulting information is adequate for the endpoint

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

The developmental toxicity of Orivone is derived from 4 -tert-butylcyclohexanol, a close analogue.The developmental toxicity of 4 -tert-butylcyclohexanyl acetate will be summarised below. The read across justification is presented at the fertility section. The accompanying files are attached in the present Toxicity to reproduction Endpoint summary.

Developmental toxicity (OECDTG414) of 4-tert-butylcyclohexanol used for read-across to Orivone:

A FDA guideline developmental toxicity study similar to OECDTG414 and GLP was performed. 25 pregnant Crl:CD(SD) rats were exposed orally (gavage) to 0 (vehicle), 40, 160 and 640 mg/kg/day during gestation days 7 through 20. The dosage volume (10 mL/kg) was adjusted daily on the basis of the individual body weights recorded before intubation. All rats were examined for clinical observations of effects of the test substance, abortions, premature deliveries and deaths before dosage, between one and two hours after dosage and once daily during the post dosage period. Body weights were recorded on DG 0 and daily during the dosage and post dosage periods. Feed consumption values were recorded on DGs 0, 7, 10, 12, 15, 18, 20 and 21. All surviving rats were sacrificed on DG 21, Caesarean-sectioned and a gross necropsy of the thoracic, abdominal and pelvic viscera performed. All fetuses were weighed and examined for sex and gross external alterations. Approximately ½ of the fetuses in each litter were evaluated for soft tissue or skeletal alterations.

Results:Mortality: Except one, all 25 other rats in this study survived to scheduled sacrifice.

One rat in the 640 mg/kg/day dosage group had severe adverse clinical observations attributable to the test substance and was sacrificed on DG 20. Additional clinical signs observed only in the 640 mg/kg/day dosage group rat that was sacrificed on DG 20 included extreme excess salivation, scant feces, decreased motor activity, ptosis, coldness to touch and apparent dehydration. This rat also had the only necropsy observations associated with treatment with the test substance, distention of the stomach with gas and yellow fluid and a litter of 17 dead fetuses (average is 14 +/- 3). These dead fetuses were otherwise normal for their developmental ages.

Clinical signs: The 160 and 640 mg/kg/day dosages of the test substance were associated with dosage dependent, statistically significant increases in clinical observations the incidences of excess salivation (total) and slight excess salivation (1 and 2 hours after intubation), as compared with the vehicle control group values. The 640 mg/kg/day dosage of the test substance also resulted in statistically significant increases in the incidences of moderate excess salivation, red perioral area and sparse hair coat on the limbs and increased incidences of extreme excess salivation, ungroomed coat, sparse hair coat and localized alopecia of the limbs and/or neck. 

Body weight:Maternal body weightswere significantly reduced in the 640 mg/kg/day dosage group on DGs 9 through 21, with the exception of DG 11, as compared with the vehicle control group values. The one dam that was sacrificed showed similar body weight as others in this high dose group up to day 18. At day 19 and 20 this dam had the lowest body weight of this group. The 640 mg/kg/day dosage group also had significantly reduced absolute and relative feed consumption values for the entire dosage period. Pregnancy occurred in 24 to 25 rats in each dosage group. Fetal body weightswere significantly reduced at the 640 mg/kg/day dosage group, as compared with the vehicle control group values. No other Caesarean-sectioning or litter parameters were affected by dosages of as high as 640 mg/kg/day. The 640 mg/kg/day dosage of the test substance was associated with transient delays in fetal development including statistically significant increases in the fetal (but not the litter) incidences of moderate enlargement of the renal pelvis of one or both kidneys and reversible delays in ossification of the caudal vertebrae, fore- and hind-limb phalanges and hind-limb metarsals. The delays in fetal development were considered to be associated with the significant reductions in fetal body weight that also occurred at the 640 mg/kg/day dosage level and are frequent observations at dosages that produced reductions in maternal body weight gain and feed consumption, as occurred in this study. 

Overall: At the high dose of 640 mg/kg bw after dosing p-tert-butyl cyclohexyl acetate quite severe clinical signs, body weight and food reduction was seen in the dams at 640 mg/kg bw was seen with one dam that needed to be sacrificed on day 20. The next lower dose no such effects were seen. The maternal and developmental NOAEL were both 160 mg/kg bw/day. The maternal decrease in body weight and food consumption at the high dose resulted in transient delay of fetal development. These effects are therefore not considered to be selectively toxic to embryo-fetal development and did not result in teratogenicity. 

Justification for classification or non-classification

Based on the information above the substance does not need to be classified for reproductive toxicity according to EU CLP (EC No. 1272/2008 and its updates.