3,5,5-trimethylhexan-1-ol

Endpoint summary

Description of key information

Significantly increased liver and kidney weights were seen in male and female in rats receiving oral doses of 60 mg 3,5,5-trimethylhexan-1-ol/kg bw/d for approx. 40 days in an OECD 422 screening study. The NOAEL was 12 mg/kg bw/day for males and females.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (SIDS documents; Iuclid reference [28]; Reliability assigned: 1)

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar 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

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: no data
- Age at study initiation: 10 weeks
- Weight at study initiation: 335-399g for males,204-260g for females

Route of administration:

oral: gavage

Vehicle:

olive oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Isononanol was dissolved in olive oil to give concentrations of 0.24, 1.2, and 6 % weight/volume.
New solutions were prepared every 7 days.


DIET PREPARATION
- Rate of preparation of diet (frequency): n.a.
- Mixing appropriate amounts with (Type of food): n.a.
- Storage temperature of food: n.a.


VEHICLE
- vehicle: olive oil
- Justification for use and choice of vehicle: test substance insoluble in water
- Concentration in vehicle: 0.24, 1.2, and 6 % weight/volume
- Amount of vehicle (if gavage): 5 mL/kg bw
- Lot/batch no. Yakuhan Pharmaceutical Ltd.
- Purity: Japan Pharmacopoiea

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Males 46 days, females 14 days before mating to day 3 of lactation

Frequency of treatment:

once daily

Remarks:

Doses / Concentrations:
0 (vehicle) , 12, 60, 300 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

12

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: based on range finding study at 100, 300, and 1000 mg/kg bw using groups of 5 male and 5 female rats at each dose level, 300 mg/kg bw was selected as the top dose which was expected to be clearly toxic. Lower doses were calculated using a factor of 5.
- Rationale for animal assignment: random
- Rationale for selecting satellite groups: no satellite group
- Post-exposure recovery period in satellite groups: n.a.
- Section schedule rationale: random

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations checked in table [No.?] were included.


DETAILED CLINICAL OBSERVATIONS: No data


BODY WEIGHT: Yes
- Time schedule for examinations:
males: prior to administration of drug, on days 2, 5, 7, 10 and 14 of administration of the drug and thereafter every 7 days (including the final day of treatment) as well as on the day of the necropsies
females: on days 0, 1, 3, 5, 7, 10, 14, 17 and 20 of gestation, days 0, 1, and 4 of nursing

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: No data; Food consumption was determined weekly
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: n.a.


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: no data provided, but can easily be calculated from the body weight gain and feed intake data.


WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): n.a.
- Time schedule for examinations: water consumption was determined weekly


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes
- Time schedule for collection of blood: at termination, day 46 of exposure
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 12 per dose group
- Parameters checked in table [No. 5 of the report] were examined: erythrocyte count, mean erythrocyte capacity, platelet count, leucocyte count, hemoglobin, mean erythrocyte hemoglobin amount as well as leucocyte percentage. Coagulation time.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day 46 (males)
- Animals fasted: for 16 hours
- How many animals: 12 per dose group
- Parameters: serum GOT and GPT, γ GTP, cholinesterase, blood sugar, total cholesterol, triglycerides, phospholipids, bilirubin, urinary nitrogen, creatinine, calcium, inorganic phosphorus, total protein and albumin, sodium and potassium, chloride , A/G ration, protein fractionation

URINALYSIS: Yes
- Time schedule for collection of urine: day 43 to 44
- Animals: 6 males/group
- Parameters: pH, protein, sugar, ketones, urobilinogen, bilirubin, occult blood reaction, sediment, specific gravity and urinary volume (capacity).

NEUROBEHAVIOURAL EXAMINATION: No


OPTHER
- Necropsy
- Organs examined at necropsy:
a) macroscopic: organ weight: liver, kidney, adrenal, thymus, testes,(epidymis)
b) microscopic: all animals.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes;
Organ weight: liver, kidney, adrenal glands, thymus, testes, epididymis and ovaries
HISTOPATHOLOGY: Yes; all animals
Organs: liver, kidneys, pancreas, heart, lungs, brain, pituitary gland, thymus, adrenal glands, thyroid gland, stomach (anterior stomach • glandular stomach ), duodenum, jejunum, ileum, cecum, rectum, prostate gland and ovaries, testes and epididymis

Statistics:

No data

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food efficiency:

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

effects observed, treatment-related

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
In the 300 mg/kg group one female died on day 21 of gestation, and three others had to be killed because of weakness from days 14 to 19 of
gestation. In these animals, body weights and food consumption were decreased, and histopathological examination revealed periportal fatty
change in the liver, renal epithelial fatty change and other lesions.

BODY WEIGHT AND WEIGHT GAIN
Food consumption was increased and body weights tended to be increased in males of the 300 mg/kg group, but the opposite was the case for females receiving the highest dose.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Food consumption was increased and body weights tended to be increased in males of the 300 mg/kg group, but the opposite was the case for females receiving the highest dose.

FOOD EFFICIENCY
No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
n.a.

OPHTHALMOSCOPIC EXAMINATION
Not examined

HAEMATOLOGY
Slight decreases in red blood cell counts, hematocrit, hemoglobin concentrations in males of the 300 mg/kg group.

CLINICAL CHEMISTRY
Biochemical examinations revealed slight decreases in BUN and chloride in males of the 300 mg/kg group.

URINALYSIS
Urinalysis revealed increases in urine volume and water consumption in males of the 300 mg/kg group.

NEUROBEHAVIOUR
Not examined

ORGAN WEIGHTS
Liver: absolute liver weights were increased in males and females of the 300 mg/kg group, relative liver weights were increased in males and females of the 60 and 300 mg/kg groups.
Kidney: absolute and relative weights of the right and left kidneys were increased in males of the 60 and 300 mg/kg groups, and relative weights of the right and left kidneys were increased in females of the 300 mg/kg group.

GROSS PATHOLOGY
Autopsy revealed pale discoloration of the kidneys in males of the 60 and 300 mg/kg groups, swelling of the kidneys in males of the 300 mg/kg group, and yellowish white discoloration of the liver in females of the 300 mg/kg group.

HISTOPATHOLOGY: NON-NEOPLASTIC
Histopathological examination revealed in male of the more than 12 mg/kg group, a slight or moderate degree of hyaline droplet and eosinophilic body in proximal tubular epithelium in kidney, but these findings were not observed in female (alpha2u-Globulin Nephropathy).
- In males, a slight or moderate degree of renal tubular epithelial regeneration and formation of granular casts in kidneys in males of the 60 and 300 mg/kg groups,
- - a slight degree of irregularity in the shape of follicles, columnar change of follicular epithelium and decrease in colloid in the thyroid were observed in males of the 300 mg/kg group.
- In female rats, a slight degree of renal epithelial fatty change in females of the 60 and 300 mg/kg groups, and atrophy of the thymus in the 300 mg/kg group.

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
No data

HISTORICAL CONTROL DATA (if applicable)
No data

Dose descriptor:

NOAEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: no effect noted

Dose descriptor:

LOAEL

Effect level:

60 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: males: liver and kidney weight increased; histopathological changes in liver and kidney. Females: histopathological kidney changes.

Critical effects observed:

not specified

	Dose level(mg/kg/day)
Haematology	0	12	60	300
No. of animals	12	12	12	12
Hematocrit (%)	52.6 ±1.89	52.6 ±2.90	52.4 ±2.59	49.9* ±2.25
Hemoglobin (g/dl)	16.4 ±0.63	16.2 ±0.68	15.7 ±0.68	15.3** ±0.68
Blood chemical
BUN (mg/dl)	15.67 ±1.87	15.63 ±1.45	16.22 ±1.66	13.87* ±1.89
Cl(mEq/l)	107.3 ±1.3	106.5 ±2.4	106.2 ±1.6	104.8** ±0.6
Organ weights, Males absolute organ weight
Liver (g)	12.120 ±1.468	12.953 ±2.178	13.676 ±1.136	17.815** ±1.723
Kidney (right, g)	1.570 ±0.120	1.602 ±0.166	1.771* ±0.196	1.918** ±0.205
Kidney (left, g)	1.540 ±0.092	1.58 ±0.184	1.744** ±0.186	1.906** ±0.232
relative organ weight
Liver (g)	2.431 ±0.162	2.559 ±0.227	2.780** ±0.126	3.493** ±0.207
Kidney (right, g)	0.316 ±0.018	0.318 ±0.022	0.362* ±0.043	0.378** ±0.043
Kidney (left, g)	0.310 ±0.018	0.317 ±0.031	0.357** ±0.043	0.375** ±0.053
Organ weights, Females absolute organ weight
Liver (g)	13.222 ±1.105	13.470 ±1.142	14.384 ±1.673	16.032** ±1.340
relative organ weight
Liver (g)	4.011 ±0.191	4.056 ±0.219	4.408* ±0.425	5.330** ±0.390
Kidney (right, g)	0.299 ±0.050	0.299 ±0.016	0.295 ±0.022	0.330* ±0.030
Kidney (left, g)	0.295 ±0.052	0.289 ±0.019	0.291 ±0.025	0.328* ±0.036

Values are expressed as Mean±S.D.

Significantly different from 0 mg/kg bw/day group: * p=0.05 **       p=0.01

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	Dose level(mg/kg/day)
Histopathology, Males	0	12	60	300
No. of animals	12	12	12	12
Kidney
Hyaline droplet, proximal tubular epithelium	1	9**	12**	12**
Eosinophilic body, proximal tubular epithelium	0	9**	11**	12**
Regeneration, tublar epithelium	0	1	6*	7*
Cast, granular	0	0	3	6*
Thyroid Decrease, colloid	0	0	0	4
Histopathology, Females
Kidney
Hyaline droplet, proximal tubular epithelium	0	0	0	0
Eosinophilic body, proximal tubular epithelium	0	0	0	0
Degeneration, fatty, proximal tubular epithelium	0	0	0	3
Thyroid Decrease, colloid	0	0	0	0
Thymus Atrophy	0	0	0	3

Values are no. of animals with findings.

Significantly different from 0 mg/kg bw/day group: * p=0.05 **       p=0.01

Conclusions:

The NOAEL of 3,5,5-trimethylhexan-1-ol for parental animals was 12 mg/kg bw/day for males and for females in a combined repeat dose/reproduction-developmental toxicity study (OECD TG 422). The LOAEL was 60 mg/kg bw/day for males and females.

Executive summary:

3,5,5-trimethylhexan-1-ol was tested in a combined repeat dose/reproduction-developmental toxicity screening study according to OECD TG 422 and under GLP conditions using male and female rats at dose levels of 0, 12, 60, and 300 mg/kg bw/day. Key findings in parental animals by dose group were as follows:

12 mg/kg bw/day: no effects in male or female rats

60 mg/kg bw/day:

- significantly (p<0.05) increased absolute or relative organ weights (liver, kidney) in males and females

- a slight or moderate degree of hyaline droplet and eosinophilic body in proximal tubular epithelium in kidney, but these findings were not observed in female (alpha2µ-Globulin Nephropathy). However, alpha2µ-Globulin Nephropathy appears to be sex- and species -specific. That is, it occurs in male rats but not female rats and in mice, rabbit, guinea pigs or human. because they do not produce alpha2µ-Globulin.

- a slight or moderate degree of renal tubular epithelial regeneration and formation of granular casts in kidneys in males

300 mg/kg bw/day:

- one female died and 3 were moribund; deaths ocurred at gestation days 14 -21

- tendency of increased body weight in males and decreased body weight in females, compared to controls

- food consumption increased in males, decreased in females

- significant (p<0.05), yet small hematological changes; substantiated by small decreases of hematocrit and hemoglobin

- significantly increased blood urea nitrogen (p<0.05) and serum chloride (p<0.05) at termination

- increased absolute and relative liver and kidney weights in males and females (p<0.01)

- decrease of thyroid colloid in 4/12 males

- thymus atrophy in 3/12 females

Target organs:

Liver: periportal adiposis in males and females at 60 and 300 mg/kg bw/day,

Kidneys: mild fatty urethral tubular epithelium degeneration in males and females at 60 and 300 mg/kg bw/day (MHLW 1997).

On the basis of these findings, the NOAEL of 3,5,5-trimethylhexan-1-ol for repeat dose toxicity was considered to be 12 mg/kg/day for males and for females; the LOAEL was 60 mg/kg bw/day (MHLW, 1997, Yoshimura 2007).

The study is considered to be suitable for assessment. It should, however, be noted that compared to the more specific guideline studies for this endpoint (e.g. OECD 408) the list of parameters to be examined is reduced. Further, the animal number is relatively low in screening studies and the statistical power is therefore reduced compared to an OECD 408 study. In some instances borderline effects may therefore fail to gain a level of statistical significance, making it difficult to assign correctly NOAEL-values.

Endpoint conclusion

Dose descriptor:

NOAEL

12 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

3,5,5-trimethylhexan-1-ol was tested in a combined oral repeat dose/reproduction-developmental toxicity study (according to OECD TG 422 and under GLP) using male and female rats at dose levels of 0, 12, 60, and 300 mg/kg bw/day. Key findings in parental animals by dose group were as follows:

12 mg/kg bw/day: no effects in male or female rats

60 mg/kg bw/day:

- significantly (p<0.05) increased absolute or relative organ weights (liver, kidney) in males, and females (relative liver weight)

- a slight or moderate degree of hyaline droplet and eosinophilic body in proximal tubular epithelium in kidney, but these findings were not observed in female (alpha2µ-Globulin Nephropathy). However, alpha2µ-Globulin Nephropathy appears to be sex- and species -specific. That is, it occurs in male rats but not female rats and in mice, rabbit, guinea pigs or human, because they do not produce alpha2µ-Globulin.

- a slight or moderate degree of renal tubular epithelial regeneration and formation of granular casts in kidneys in males

300 mg/kg bw/day:

- one female died and 3 were moribund; deaths ocurred at gestation days 14 -21

- tendency of increased body weight in males and decreased body weight in females, compared to controls

- food consumption increased in males, decreased in females

- significant (p<0.05), yet small hematological changes; substantiated by small decreases of hematocrit and hemoglobin

- significantly increased blood urea nitogen (p<0.05) and serum chloride (p<0.05) at termination

- increased absolute and relative liver and kidney weights in males and females (p<0.01)

- decrease of thyroid colloid in 4/12 males

- athrophy of the thymus in 3/12 females

Target organs:

Liver: periportal adiposis in males and females at 60 and 300 mg/kg bw/day,

Kidneys: mild fatty urethral tubular epithelium degeneration in males and females at 60 and 300 mg/kg bw/day (MHLW 1997).

The NOAEL of 3,5,5-trimethylhexan-1-ol for repeat dose toxicity was considered to be 12 mg/kg/day for males and for females; the LOAEL was 60 mg/kg bw/day (MHLW, 1997).

The NOAEL is based on the effects seen in males at 60 mg/kg bw/day, i.e. fatty liver changes which are associated with liver weight increase. The changes seen in the male kidney appears to be related to effects that are specific for the male rat (alpha2 microglobulin nephropathy), and which, therefore, is not relevant for the purpose of risk assesment, while fatty degeneration of the renal tubular epithelium was seen (no statistical significance) in females at 60 mg/k bw/day.

The conduct of acute or repeated inhalation studies is technically not feasible because the vapour pressure of long chain alcohols (carbon chain length C5 or more) is too low to produce toxic atmospheres (Nelson et al., Tox Ind Health 6:373 -387, 1990; Nelson et al., J Am Coll Tox 9:93 -97, 1990).

As to the dermal route, data from a similar chemical (n-nonanol) suggest low dermal absorption and lack of dermal toxicity for 3,5,5-trimethylhexan-1-ol. The conduct of a dermal study is therefore not justified (Fassett, 1963).

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: liver; urogenital: kidneys

Justification for classification or non-classification

Regulation 67/548/EEC: classification criteria not met

Regulation 1272/2007/EC: specific target organ following repeated exposure: category 2 (liver, kidneys) . Based on the findings in males and females at 60 and 300 mg/kg bw and day.