Decane-1,10-diol

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

October - December 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Version / remarks:

1994

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Hexane-1,6-diol

EC Number:

211-074-0

EC Name:

Hexane-1,6-diol

Cas Number:

629-11-8

Molecular formula:

C6H14O2

IUPAC Name:

hexane-1,6-diol

Test animals

Species:

rat

Strain:

Wistar

Details on species / strain selection:

This strain was selected since extensive historical control data were available on Wistar rats and the rat is the preferred animal species for reproduction studies.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dr . K . THOMAE GmbH, Biberach an der Riss, FRG
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 84 days old
- Weight at study initiation: 394 g (males), 234 g (females)
- Housing: individually
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C):20-24 °C
- Humidity (%):30-70%
- Air changes (per hr): "full air-conditioned rooms (floor area about 18 m) in which central air conditioning guaranteed"
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on mating procedure:

At least 14 days males and females at a ratio of 1:1. (generally male no.1 with female no.101, male no.2 with female no.102).
In general, each of the male and female animals was mated overnight at a 1 : 1 ratio for a maximum of 2 weeks . Generally, throughout the mating period, each male animal was mated with a predetermined female animal from the same dose group.
Matings occurred by placing the female in the cage of the male mating partner from about 4 .00 pm until 7 .00 - 9 .00 am of the following morning. Deviations from the specified times were possible on weekends and public holidays and were reported in the raw data.
A vaginal smear was prepared after each mating and examined for sperm . If sperm was detected, pairing of the animals was discontinued . The day on which sperm were detected was denoted "day 0°' and the following day "day 1°° p .c . (post coitum).

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

Analytical verifications of the stability of the aqueous test substance solutions for a period of at least 4 hours at room temperature were carried out in a concurrent study before the beginning of this
screening study .

Duration of treatment / exposure:

The F0 adult males : at least 28 days (two week for pre-mating included)
The F0 females: during wo weeks of pre-mating, mating, gestation, lactation until Day 5 pp

Frequency of treatment:

daily

Details on study schedule:

At least 14 days males and females at a ratio of 1:1.
After this mating period, the male animals were sacrificed. The females were allowed to litter and rear their pups until day 4 after parturition (p.p.).
Thereafter, the pups and the F0 generation female parental animals were sacrificed.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Doses / concentrations 2

Dose / conc.:

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

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Positive control:

no

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes, daily

BODY WEIGHT: Yes
In general, the body weight of the male and female parental animals was determined once a week at the same time of the day (in the morning). The body weight change of the animals was calculated from these results .
The following exceptions are notable for the female animals :
a) During the mating period the parental females were weighed on the day of positive evidence of sperm (day 0 p .c .) and on days 7, 14 and 20 post coitum
b) Females showing no positive evidence of sperm in vaginal smears were weighed weekly during the mating interval . These body weight data were solely used for the calculations of the dose
c) Females with litter were weighed on the day of parturition (day 0 p .p .) and on days 4 and 7 post partum
d) Females without litter were weighed weekly. These body weight data were solely used for the calculations of the dose volume.

FOOD CONSUMPTION : yes
Generally food consumption was determined once a week (in general for a period of 7 days) for male and female animals.
The following exceptions were notable : Food consumption was not determined during the mating period. Food consumption of the females with evidence of sperm was determined for days 0- 7, 7 - 14 and 14 - 20 p .c .
Food consumption of females, which gave birth to a litter was determined for days 0- 4 and 4 - 7 p .p .

WATER CONSUMPTION : no

OTHER: Determination of implantation sites
After sacrifice of the female animals, the uteri and ovaries were removed (including the uteri of apparently non-pregnant animals) and transferred to the reproduction laboratory, for further investigations. To determine the number of implantation sites, the uteri were stained for about 5 minutes in 10 % ammonium sulfide solution according to the method of SALEWSKI (3) . Then the uteri were rinsed carefully under running water. Thereafter the implantation sites were recorded for calculation of the postimplantation loss. After these examinations, the uteri were transferred to the pathology laboratory for further investigations.

Oestrous cyclicity (parental animals):

no

Sperm parameters (parental animals):

no

Litter observations:

STANDARDISATION OF LITTERS: no
PARAMETERS EXAMINED: F0 pups
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities

GROSS EXAMINATION OF DEAD PUPS:
All surviving pups (after sacrifice on day 4 p.p. by means of CO2), all stillborn pups and those pups that died before schedule, were examined externally, eviscerated and their organs were assessed macroscopically.
All pups without any notable findings or abnormalities were discarded after their macroscopic evaluation.

Postmortem examinations (parental animals):

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including the cervical, thoracic, and abdominal viscera.

HISTOPATHOLOGY / ORGAN WEIGHTS yes

Postmortem examinations (offspring):

All surviving pups were sacrificed (by means of CO2) on day 4 p.p.
These pups, all stillborn pups and those that died before schedule, were subjected to a macroscopic (external and visceral) examination .

Statistics:

The data were evaluated statistically using the computer systems of the Department of Toxicology of BASF Aktiengesellschaft.

Reproductive indices:

male mating index ; male fertility index ; female mating index ; female fertility index ; gestation index ; post-implantation loss

Offspring viability indices:

Viability index ; sex ratio

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

There were no particular, dose-related findings in F0 males (whole study period) or F0 females (premating, gestation, parturition or lactation) .
One control male animal (No . 4) showed a cataract on the left eye from study day 2 until the day of scheduled sacrifice .
One 400 mg/kg female (No . 124) showed insufficient nesting activity towards the end of the gestation period . This not dose-related finding occurs also rather frequently in untreated pregnant dams and thus is regarded to be spontaneous in nature .

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Description (incidence):

None of the F0 male or F0 female parental generation animals died before schedule .

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

In the high dose F0 males statistical significant lower mean body weights were seen during the last week of the administration period (week 4) . The mean body weight of these animals was about 5 % lower than that of the corresponding control group.
Body weight gains of the high dose males were statistically significantly diminished during weeks 2 - 3 and also, if the weight gain for the total study period (wceks 0- 4) is calculated . In total, body
weight gain of the 1000 mg/kg males was about 49% lower than the concurrent control value.
The lower mean body weights and the depression in body weight gain observed in the 1000 mg/kg males have to be related to the test substance administration and are in-line with the reductions in food consumption which occurred at this dose group.
Body weights/body weight gains of the males of the 100 and 400 mg/kg groups were similar to control values . Body weights/body weight gains of all substance-treated females (100, 400 and 1000 mg/kg body weight/day) were not influenced in a dose dependent manner neither during premating nor during the gestation and lactation per iods . All differences in body weights and body weight gains observed for these rats are considered to be spontaneous in nature . This includes the statistical significant increases in dams' body weight gain at 100 mg/kg on gestation days 0- 7 and at 400 mg/kg during gestation days 14 - 20.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

The food consumption of the high dose male animals was statistically significantly reduced during study weeks 0- 1 and 3- 4, whereas the food consumption of the high dose females was not influenced by the test substance administration during premating, gestation and lactation.
If calculated for the total study period of the males (weeks 0- 4), the food consumption of the high dose group was 8 % lower than the corresponding control value. This is considered to be substance-related, because the slight reductions in food consumption are in-line with lower mean body weights and impaired body weight gains of the 1000 mg/kg males.
All other differences between the substance-treated and the concurrent control groups concerning food consumption are without any biological relevance and/or not dose-related.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Description (incidence and severity):

For all F0 males of test groups 0, 1 and 3 (0, 100 and 1000 mg/kg body weight/day) which were placed with females to generate F0 pups, mating was confirmed ; thus, the male mating index for these groups was 100% . Due to the fact that no sperm was detected in the vaginal smear of the female partner of male No . 27, the male mating index was 90 % for test group 2 (400 mg/kg body weight/day) .
For all except one (No . 27) F0 males fertility couldbe confirmed in the scheduled mating interval ; thefertility index varied between 90% and 100% with no relation to dosing .

The female mating index calculated after the mating period varied between 90% (test group 2 - 400 mg/kg body weight/day) and 100 % (test group 0,1 and 3 - 0, 100 and 1000 mg/kg body weight/day). One 400 mg/kg female (No . 127) showed no sperm in vaginal smear and/or did not give birth to a litter.
The mean duration until sperm was detected (day 0 p .c .), varied between 2 .6 and 3 .0 days and did not show a clear dose-response relationship . These values are fully within the expected range of biological variation for the rat strain used .
All mated females of test groups 0- 3 (0, 100, 400, 1000 mg/kg body weight/day) became pregnant . Therefore, a 100 % fertility index was calculated for all groups .
The mean duration of gestation was similar in all groups, the gestation index reached 100% in all groups .

The mean number of implantation sites, the postimplantation loss values and the mean number of delivered pups/dam were similar for the substance treated groups and the concurrent control group . The observable differences have no biological relevance and/or are not dose-related . The mean number of delivered pups/dam was lowest in the control group .

Effect levels (P0)

1

Key result

Dose descriptor:

NOAEL

Remarks:

(systemic toxicity)

Effect level:

400 mg/kg bw/day

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

food consumption and compound intake

2

Dose descriptor:

NOAEL

Remarks:

(systemic toxicity)

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

female

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

3

Key result

Dose descriptor:

NOAEL

Remarks:

(reproduction performance/fertility)

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

Target system / organ toxicity (P0)

Critical effects observed:

no

Results: F1 generation

General toxicity (F1)

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Filiformed tail and acaudia were the only clinical observations which occurred and both were recorded for one low dose pup (No . 17 from dam No . 113) . This pup had a filiformed tail at birth and the first day after birth . Thereafter, it lost its malformed tail completely and therefore "acaudia" was observed . These findings are considered to be spontaneous in nature, because no relation to dosing is given .

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Description (incidence and severity):

The mean number of delivered F1 pups/dam and the percentage of liveborn pups was comparable between all groups . The observable differences have no biological relevance and/or are not dose-related .
No substance-induced effects on pup viability/mortality were recorded during the lactation period. The viability index, as an indicator for the viability of the pups during the first 4 days after birth, was similar in all groups as was the mean number of live pups/litter on days 0 and 4 p .p . The observable differences have no biological relevance and/or are not dose-related .

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weights/body weight gains were not influenced by the test substance administration . On day 4 p .p ., the day of scheduled pup sacrifice, the mean pup body weights for males+females were 9 .6 g in the control group and 9 .8, 9 .4 and 9 .8 g in test groups 1-3, respectively . Pup body weight gains between days 1-4 p.p. were also very similar between the groups . The observable differences have no biological relevance and/or are not dose-related.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

Only spontaneous findings were seen at necropsy (e .g .dilated renal pelvis and acaudia) in very few of the pups examined . These findings occurred exclusively in test groups 1 and 2 (100 or 400 mg/kg body weight/day) and thus did not show any relation to dosing . The clinical finding "acaudia" of low dose pup No . 17 (from dam No . 113) was confirmed by the additional examination of the skeleton of this pup according to modified DAWSON's method. The skeletal examination revealed the absence of all caudal vertebrae .

Histopathological findings:

not examined

Other effects:

no effects observed

Description (incidence and severity):

No substance-related differences between the groups exist in respect to the sex ratios on days 0 and 4 p.p.

Developmental neurotoxicity (F1)

Behaviour (functional findings):

not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:

not examined

Effect levels (F1)

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

> 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to adverse toxic effects at highest dose / concentration tested

Target system / organ toxicity (F1)

Critical effects observed:

no

Overall reproductive toxicity

Reproductive effects observed:

no

Lowest effective dose / conc.:

1 000 mg/kg bw/day

Applicant's summary and conclusion

Conclusions:

Thus under the conditions of this reproduction/developmental toxicity screening study, the oral administration (by gavage) of 1,6 -hexanediol resulted in marginal signs of general toxicity at 1,000 mg/kg body weight/day in the parental males ; however, no indications for general toxicity were present in the 100 and 400 mg/kg males and in the parental females at 100, 400 or 1,000 mg/kg. There were no indications for a substance-induced impairment of the reproductive function of the parental rats and no signs of developmental toxicity occurred in the progeny up to and including the highest dose level.
Therefore the NOAEL (no adverse effect level) concerning general toxicity is 1000 mg/kg bw/day for the F0 females, but only 400 mg/kg bw/day for the F0 males. The NOAELs for reproduction function and for developmental toxicity could be fixed at 1000 mg/kg bw/day.

Executive summary:

1,6 -hexanediol was administered to groups of 10 male and 10 female sexually immature rats (F0 parental generation) by stomach tube at doses of 100, 400 and 1000 mg/kg bw/day throughout the whole study period. The test substance was administered as an aqueous solution in a standard dose volume of 10 ml/kg bw. The control groups were dosed with the vehicle only (doubly distilled water). At least 14 days after the beginning of treatlment, F0 animals were mated to produce a litter. mating pairs were from the same dose group. The F0 adult males were sacrificed about 28 days after the first administration, the F0 pups were killed on day 4 post partum and the F0 females on one of the following days.

Food consumption of the F0 parents was determined regularly during premating, after the mating period and - in dams - during gestation and lactation periods. In general, body weights of F0 parents were determined once weekly. However, during gestation and lactation F0 females were weighed on days 0, 7, 14 and 20 of gestation, on the day of parturition, and on days 4 and 7 after birth. The pups were weighed on the day after birth and on day 4 post partum.

The parents' and the pups' state of health was checked each day, and parental animals were examined for their mating and reproductive performances ; this included determinations of the number of implantations and the calculation of the postimplantation loss. The pups were sexed and their viability was recorded. All pups were examined macroscopically at necropsy for external and visceral findings ; in addition, for further clarification of an external finding, the skeleton of one low dose pup had to be stained and subsequently inspected.

All F0 parental animals were assessed by gross pathology (including weight determinations of several organs). All F0 parental animals of the control and the high dose and individual animals of the 100 and 400 mg/kg groups were subjected to a histopathological examination, special attention being paid to the organs of the reproductive system.

Statistically significantly reduced food consumption in the male animals treated at 1000 mg/kg/day during study weeks 0-1 and 3-4. Statistically significantly reduced mean body weight in the males (1000 mg/kg bw/d)at the end of the study (study week 4) ; as a consequence terminal body weights of the males were also reduced with statistically significance. Moreover statistically significantly lower mean body weight gain between test weeks 2 - 3 and the total study period (test weeks 0- 4) in the male animals (1000 mg/kg bw/d). There was no substance-related effects in F0 males and females treated at 1000 mg/kg/d on organ weights, gross and histopathological findings.

There was no substance-related effects in F0 males and females treated at 100 and 400 mg/kg bw/day.

There was no substance-related adverse effects in the F0 pups (100, 400, 1000 mg/kg bw/d).

Thus under the conditions of this reproduction/developmental toxicity screening study, the oral administration (by gavage) of 1,6 -hexanediol resulted in marginal signs of general toxicity at 1,000 mg/kg body weight/day in the parental males ; however, no indications for general toxicity were present in the 100 and 400 mg/kg males and in the parental females at 100, 400 or 1,000 mg/kg. There were no indications for a substance-induced impairment of the reproductive function of the parental rats and no signs of developmental toxicity occurred in the progeny up to and including the highest dose level.

Therefore the NOAEL (no adverse effect level) concerning general toxicity is 1000 mg/kg bw/day for the F0 females, but only 400 mg/kg bw/day for the F0 males. The NOAELs for reproduction function and for developmental toxicity could be fixed at 1000 mg/kg bw/day.