DL-hexane-1,2-diol

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

September 5, 2000 to Octobor 5, 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: well documented, guideline test with GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 414

Deviations:

not specified

Principles of method if other than guideline:

the study reported here is the range finding study preceeding the developmental toxicity study

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,2-Hexanediol

IUPAC Name:

1,2-Hexanediol

Test material form:

other: liquid

Test animals

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

test animals: Rat
strain: crl:cd(SD)IGS BR VAF/Plus
supplier: Charles River Laboratories, Inc., Raleigh, North Carolina
sex: female(note: male rats were used only for the purposes of breeding and are not consered part of the test system)
number of rats: 136
date of birth: 03 Jul 2000
age at arrival: 65 days
weight on the day after arrival: 187-224
weight at study assignment: 224-250
breeder male rat data:
number of rats: 152
date of birth: 29 Feb 2000
age at arrival: 71 days
weight on the day after arrival: 245-339
weight at study assignment: 506-712
method of randomzation: computer-generated radom units, healthy mated female rats were assigned to four dosage groups using a computer-generated(weight-ordered) randomization based on body weights recorded on DG0. The mean body weights for the groups were not satistically different at the 5% level.
System of Identification: rats were permanently identified using Monel® self-piercing ear tags.
Husbandry
study rooms were independently supplied with at least ten changes per hour of 100% fresh air that has been passed through 99.97% HEPA filters. Room temperature and relative humidity were monitored constantly throughout the study and targeted at 64 °F to 79 °F ; relative humidity was targeted at 30% to 70%.
Housing: Rats were individually housed in stainless steel, wire-bottomed cages except during the cohabitation period. During cohabitation, each pair of male and female rats was housed in the male rat's cage. All cage sizes and housing conditions were in compliance with the Guide for the care and use of laboratory animals.
Lighting: 12-hours light and dark
sanitization: cage pan liners were changed approximately three times each week. Cages were changed approximately every other week.
feed and water: ad libitum

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

group I to IV:
dosage(mg/kg/day): 0(vehicle), 250, 500, 750
concentration(mg/ml): 0, 25, 50, 75
The oral(gavage) route was selected for use.
Appropriate dosages of the test substance and/or vehicle were administered once daily on DGs 6 through 19. The dosage volume was adjusted daily on the basis of the individual body weights recorded before intubation.

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

14 days

Frequency of treatment:

once daily on DGs 6 through 19

Doses / concentrations

Remarks:

Doses / Concentrations:
0(vehicle), 250, 500 and 750 mg/kg/day
Basis:
other:

No. of animals per sex per dose:

25

Control animals:

yes, concurrent vehicle

Details on study design:

After an acclimation period of at least six days, 135 virgin female rats were placed into cohabitation with 135 breeder male rats, one male rat per female rat. The cohabitation period consisted of a maximum of five days. Mating performance was evaluated daily during the cohabitation period. Female rats with spermatozoa observed in a smear of the vaginal contents and/or a copulatory plug observed in situ were considered to be at DG 0 and assigned to individual housing.

Positive control:

no data

Examinations

Observations and examinations performed and frequency:

Rats were observed for viability at least twice each day of the study. Rats were examined for clinical observations and general appearance weeky during the acclimation period and on DG0. Observations for clinical signs of effects of the test substance, abortions, premature deliveries and deaths were also made daily before dosage, approximately 60 ±10 minutes after dosage adminstration and on the day of sacrifice.
Body weights were recorded weekly during the acclimation period, on DG 0, daily during the dosage period and at sacrifice. Feed consuption values were recorded on DGs0, 6, 9,12, 15, 18 and 20.

Sacrifice and pathology:

All rats were sacrificed by carbon dioxide asphyxiation on DG 20, Caesarean-sectioned, and a gross necropsy of the thoracic, abdominal and pelvic viscera was performed. The gravid uterus was excised and weighted. Uteri of apparently nonpregnat rats were examined while being pressed between glass plates to confirm the absence of implantation sites. Tissues with gross lesions were preserved in neutral buffered 10% formalin for possible future evaluation; all other maternal tissues were discarded. Representative photographs of maternal lesions are available in the raw data.
The number of corpora lutea in each ovary was recorded. The uterus of each rat was excised and examined for pregnancy, number and distribution of implantations, liver and dead fetuses and early and later resorptions.
Each fetus was removed from the uterus, placed in an individual container and identified with a tag noting the study number, litter number, and uterine distribution. Each fetus was subsequently weighed and examined for sex and gross external alterations. Live fetuses were sacrificed by an intraperitoneal injection of sodium pentobarbital.
Approximately one-half of the fetuses in each litter were examined for soft tissue alterations using a variation of the microdissection technique of Staples. The remaining fetuses were examined for skeletal alterations after staining with aliarin red S.

Other examinations:

no data

Statistics:

Data were recorded either by hand or using the Primedica Argus Automated Data Collection and Management System and the Vivarium temperature and relative humidity monitoring system. All data were tabulated, summarized and/or statistically analyzed using the primdica Argus Automated Data Collection and Management System and the Vivarium temperature and relative humidity monitoring system, microsoft excel and/or the SAS system(version 6.12).
Clinical observation and other proportion data were analyzed using the variance test for homogneity of the binomial distribution. Continuous data were analyzed using Bartlett's test of homogeneity of variances and the analysisi of variance, when appropriate(i.e. Bartlett's test was not significant(p>0.001)).
Count data obtained at caesarean-sectioning of the dams were evaluated using the procedures described above for the Kruskal-Wallis Test.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

see details on results

Mortality:

no mortality observed

Description (incidence):

see details on results

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

see details on results

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

see details on results

Food efficiency:

not examined

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

effects observed, treatment-related

Description (incidence and severity):

see details on results

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Description (incidence and severity):

see details on results

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

see details on results

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

see details on results

Gross pathological findings:

no effects observed

Description (incidence and severity):

see details on results

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Details on results:

Mortality, Clinical and Necropsy Observations:
All rats survived until scheduled sacrifice on day 20 of gestation (DG 20).
All clinical and necropsy observations were considered unrelated to the test substance because the incidences were not dosage-dependent or the observation occurred in only one rat. Clinical observations included localized alopecia of the back or limbs, excess salivation, labored breathing, missing third digit on left forelimb and chromorhinorrhea.The only necropsy observations were a moderate dilation of the pelvis of the left kidney in one control group dam (11421) and moderate dilation for both kidneys in the one 500 mg/kg/day dosage group dam (11458).

Maternal Body Weights, Body Weight Changes and Gravid Uterine Weights:
Maternal body weight gains were significantly reduced (p#0.05) on DGs 15 to 18 in the 750 mg/kg/day dosage group. As a result of this reduction, maternal body weight gains were significantly reduced (p#0.01) in the 750 mg/kg/day dosage group for the entire dosage period (calculated as DGs 6 to 20) and for the entire gestation period (DGs 0 to 20). Maternal body weight gains in the 750 mg/kg/day dosage group were also significantly reduced (p<0.01) for the entire period after the initiation of dosing when calculated using the corrected DG 20 body weight (DG 20 body weight minus the gravid uterine weight).
Maternal body weight in the 750 mg/kg/day dosage group was significantly reduced (p<0.01) only on DG 19. Gravid uterine weights and the DG 20 body weight corrected for the gravid uterine weight (DG 20C) were not significantly reduced in the 750 mg/kg/day dosage group.
Dosages of the test substance as high as 500 mg/kg/day did not affect body weight gains or body weights.

Maternal Absolute (g/day) and Relative (g/kg/day) Feed Consumption Values:
Absolute (g/day) and relative (g/kg/day) feed consumption values were slightly reduced at most tabulated intervals during the dosage and postdosage periods in the 750 mg/kg/day dosage group; these reductions were significant (p#0.05) on DGs 9 to 12 (absolute only).
Dosages of the test substance as high as 500 mg/kg/day did not affect absolute or relative feed consumption values. Absolute feed consumption values were significantly reduced in the 250 mg/kg/day dosage group DG 9 to 12 and relative feed consumption values were significantly increased in the 250 mg/kg/day dosage group DG 15 to 18. These observations were considered unrelated to the test substance because they were single, nondosage dependent events.
Caesarean-Sectioning and Litter Observations
There were 22 (88%), 22 (88%), 24 (96%) and 24 (96%) pregnant rats in the 0 (vehicle),
250, 500 and 750 mg/kg/day dosage groups, respectively.
No Caesarean-sectioning or litter parameters were affected by dosages of test article as high as 750 mg/kg/day. The litter averages for corpora lutea, implantations, litter sizes, live fetuses, early and late resorptions, percent dead or resorbed conceptuses, and percent live male fetuses and fetal body weights (total, male and female) were comparable among the four dosage groups and did not significantly differ. There were no dead fetuses and no dams with all conceptuses resorbed. All placentas appeared normal.
Fetal Alterations
The number of litters with fetuses with alterations numbered 7 (31.8%), 7 (31.8%),11 (45.8%) and 9 (37.5%), in the 0 (Vehicle), 250, 500 and 750 mg/kg/day dosage groups, respectively. The number of fetuses with any alteration observed were 10 (3.0%), 10 (3.0%), 14 (3.9%) and 11 (3.2%), and the percentages of fetuses with any alteration per litter were 3.3, 3.2, 4.1 and 3.4 in these same respective dosage groups.
All fetal alterations in this study are described in the following information.
Dosages of the test substance as high as 750 mg/kg/day did not affect the incidence of gross, soft tissue or skeletal alterations or change the average number of ossification sites per fetus.
One fetus (11463-2) in the 500 mg/kg/day dosage group had exencephaly and a protruding tongue. This fetus had an irregular shaped brain at soft tissue examination.
This fetus had no additional alterations.
No other gross alterations occurred in any fetus.
Malformations
One fetus (11463-2) in the 500 mg/kg/day dosage group had an irregular shaped brain and a protruding tongue as previously described.
No other soft tissue malformations occurred in any fetus.
Variations
Vessels
One control group fetus (11406-4), two 250 mg/kg/day dosage group fetuses (11429-2;
11449-10) and three 500 mg/kg/day dosage group fetuses (11452-10; 11454-2; 11456-8) had the umbilical artery descending to the left of the urinary bladder. Only one fetus (11449-10) had an additional alteration (absent innominate artery).
No other soft tissue variations occurred in any fetus.
No skeletal fetal malformations occurred.
A cervical rib at the 7th cervical vertebra, a common variation in this strain of rat(22), was present in three control group fetuses (11407-5; 11423-9, -11) and two 750 mg/kg/day dosage group fetuses (11482-1; 11489-3). None of these fetuses had any additional alterations.
A bifid centrum in a thoracic vertebra occurred in 3(11403-16, 11424-3, 11425-3), 5 (11436-14; 11437-1; 11441-5, 7, 9), 1 (11465-7) and 1 (11487-11) fetuses from 3, 3, 1 and 1 litters in the four respective dosage groups. No additional alterations occurred in these fetuses.
Sternum
Delayed sternal ossification (incompletely ossified and/or not ossified) occurred in 2(11401-6, 11425-1), 2 (11434-1, -10), 7 (11465-5, -9; 11466-9, -13; 11468-10, 11472-1; 11474-14) and 3 (11480-3, 11485-8, 11500-7) fetuses from 2, 1, 5 and 3 litters from the 0 (Vehicle), 250, 500 and 750 mg/kg/day dosage groups, respectively. Fetus 11485-8 in the 750 mg/kg/day also had incomplete ossified pubes. No additional alterations occurred in the other fetuses.
Pelvis
The ischia and/or pubes were incompletely or not ossified in 1 (11403-5), 1 (11428-13), 2 (11451-11, 11473-7) and 6 (11479-9; 11480-5, -7; 11485-8; 11486-3; 11488-11) fetuses from 1, 1, 2 and 5 litters in the 0 (Vehicle), 250, 500 and 750 mg/kg/day dosage groups. Additional alterations occurred in one fetus (11485-8) as previously described.
Fetal Ossification Site Averages
No statistically significant or biologically important differences occurred among the four dosage groups in the average numbers of ossification sites per fetus for the hyoid, vertebrae (cervical, thoracic, lumbar, sacral and caudal), ribs, sternum (manubrium, sternal centers and xiphoid), forelimbs (carpals, metacarpals and phalanges) or hindlimbs (tarsals, metatarsals and phalanges).

Effect levels

Dose descriptor:

NOAEL

Remarks:

maternal NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: The 750 mg/kg/day dosage caused reductions in body weight gain and absolute and relative feed consumption values.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Based on the available data, the systemic no-observable-adervse-effect-level(NOAEL) is 500 mg/kg/day under the conditions of this study.

Executive summary:

This sub-acute study was performed following OECD guideline and GLP regulations. Test article was assigned to 4 groups at dose levels of 0, 250, 500, 750 mg/kg/day with SD rats. All rats survived until scheduled sacrifice on day 20 of gestation (DG 20). No clinical or necropsy observations related to the test substance occurred. Maternal body weight gains were significantly reduced on DGs 15 to 18 and body weights were significantly reduced on DG 19 in the 750 mg/kg/day dosage group. As a result of the weight gain reduction, maternal body weight gains were significantly reduced in the 750 mg/kg/day dosage group for the entire dosage period (calculated as DGs 6 to 20) and for the entire gestation period (DGs 0 to 20). Absolute (g/day) and relative (g/kg/day) feed consumption values were slightly reduced at most tabulated intervals during the dosage and postdosage periods in the 750 mg/kg/day dosage group; these reductions were significant on DGs 9 to 12 (absolute only). Therefore, the systemic no-observable-adervse-effect-level(NOAEL) is considered to be 500 mg/kg/day based on the experimental data.