Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

concentration-driven

Effects on fertility

Description of key information

There is no substance specific reproductive data available for Hydrocarbons, C5 -C7, n-alkanes, isoalkanes, n-hexane rich. However, data is available for structural analogues 2-methylbutane and commercial hexane and presented in the dossier. This data is read across to Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

 

2 -methylbutane

One-Generation Reproduction Toxicity Study (OECD TG 415)

 

NOAEL (Reproductive toxicity) >= 1000 mg/kg bw/day

 

Commercial hexane

Two-Generation Reproduction Toxicity Study (OECD TG 416)

 

NOAEC (Reproductive toxicity) = 31680 mg/m³

 

Additionally, in order to comply with standard information requirements for Annex X substances, an OECD 443 test is proposed for structural analogue, Hydrocarbon, C7-C9, isoalkanes (EC# 921-728-3). This read across is based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in Section 13.2 of the dossier. Also, an OECD Guideline 422 screening reproductive/developmental toxicity studies (oral route) in rodents is also planned with Hydrocarbons, C6-C10, n-alkanes, isoalkanes, >5% n-hexane (EC# 920-191-2). This endpoint will be updated subsequent to ECHA's approval of the testing proposal and availability of data upon completion of the studies.

Link to relevant study records

Reference

Reference 1

Endpoint:

one-generation reproductive toxicity

Type of information:

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

Adequacy of study:

key study

Study period:

2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Conducted according to OECD TG 415. GLP.

Justification for type of information:

The justification for read across is provided as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]

GLP compliance:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female 5-week-old Sprague - Dawley rats were maintained in an animal room at 22 +/- 3 deg C with a relative humidity of 30-70% under a 12 h light/dark cycle. Rats were housed 2 per cage in stainless wire caging during the premating (2 males or 2 females), mating (1 male and 1 female), and post-mating periods (2 males). Mated females were housed individually during the gestation period. Lactating animals with suckling pups were housed in the same cages. The animals were provided sterilized water, ad libitum.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

0, 100, 300, and 1000 mg/kg/day. Males were dosed for 10 weeks prior to mating and during mating. Females were dosed from 2 weeks before mating to day 21 of lactation.

Details on mating procedure:

After the 70-day premating exposure period was completed, the F0 animals were mated one male to one female, selected randomly within each dose group for 14 days. The observation of a vaginal plug or sperm in a vaginal smear was considered evidence of successful mating. The day a vaginal plug and/or sperm in a vaginal smear were observed was designated as day 0 of pregnancy. Once the vaginal plug or sperm were observed, the animals were separated and housed individually in cages. A female was re-mated with a male of proven fertility within the same experimental group if mating was not confirmed in 2 weeks. Any female that did not show evidence of successful mating after cohabitation was individually housed and euthanized on day 21 after separation. Females were examined daily during the mating period and from GD 20, females were checked two times daily for evidence of onset, progress, and completion of parturition.

All animals were allowed to litter naturally (F1 generation), and rear their own offspring until LD 21. Dams were examined daily for evidence of normal maternal behavior.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Males were dosed for 10 weeks prior to mating and during mating. Females were dosed from 2 weeks before mating to day 21 of lactation.

Frequency of treatment:

once per day

Remarks:

Doses / Concentrations:
0, 100, 300, and 1000 mg/kg/day
Basis:
nominal conc.

No. of animals per sex per dose:

24 rats/sex/dose

Control animals:

yes, concurrent vehicle

Parental animals: Observations and examinations:

All animals were observed daily for clinical signs when treated with the test chemical, and abnormal signs were recorded individually by type, observation day/time, and duration. Body weight of each male was measured twice weekly until euthanized. Female rats were weighed twice weekly during the premating period and on gestation days (GD) 0, 3, 6, 9, 12, 15, 18, and 20, as well as on lactation days (LD) 1, 4, 7, 14, and 21. In mated females that produced no litters, body weights were measured up to day 21 of the presumed gestation period. The individual amount of food consumed was recorded once a week during the premating period and on GD 0, 3, 6, 9, 12, 15, 18, and 20, as well as on lactation days (LD) 1, 4, 7, 14, and 20. Food consumption was not measured during the mating period.

Litter observations:

Pups were examined as soon as possible on the day of birth to determine the number alive and stillborn in each litter. All live pups were individually counted, sexed, weighed, and examined externally. The number of live and dead pups was noted on PND 4, 7, 14, and 21. The body weights of F1 offspring were measured by randomly selecting one pup of each sex from each litter on PND 1, 7, 14 and 21.

Postmortem examinations (parental animals):

Males were euthanized at the end of the 14-day mating period; females that delivered were euthanized on day 22 after parturition. All adult animals were subjected to a full and detailed gross necropsy, which included a careful examination of the external surface of the body, the cranial, thoracic, abdominal cavities, and their contents. Special attention was paid to the reproductive organs. At necropsy the following organs were obtained and weighed from all animals: brain, pituitary gland, thymus, heart, lung, liver, kidneys, adrenal glands, spleen, testes, epididymides, prostates, seminal vesicles, ovaries, uterus and abnormal lesions. Testes and epididymides were preserved in Bouin’s fixative. Other tissues were fixed with a 10% neutral buffered formalin solution. The tissues were routinely processed, embedded in paraffin and sectioned at 3-5 um. These sections were stained with hematoxylin-eosin (H&E) for microscopic examination. All tissues taken from the control and high dose groups, and testis and epididymis from the low and middle dose groups were examined microscopically.

Postmortem examinations (offspring):

Culled pups and dead pups found during the study were examined macroscopically for structural abnormalities or pathological changes. On PND 22, one male and one female per litter were euthanized and subjected to external and internal macroscopic examination.

Statistics:

The data are expressed as mean ± standard deviation (SD). Parametric data were subjected to one-way analysis of variance (ANOVA). Other data were analyzed using Kruskal-Wallis nonparametric ANOVA. If either test showed statistical significance, the data were analyzed using the Dunnett multiple comparison procedure.

Precoital time, duration of gestation, and the numbers of live and dead pups were statistically evaluated using the
Kruskal–Wallis nonparametric ANOVA, followed by the Mann- Whitney U-test when appropriate. Incidence data (e.g. clinical signs and histopathological findings) were compared using Fisher’s exact probability test.

Reproductive indices:

copulation index, fecundity index, fertility index, delivery index, precoital time, and duration of gestation

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Other effects:

no effects observed

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)

Post-dosing salivation was noted in the dosed groups and was observed only immediately after treatment. This is likely due to the irritating effects of the test article rather than an indication of toxicity. Other clinical signs found in the treatment groups, such as loss of fur, scratch wounds, and scabs, were not considered to be related to treatment of 2-methylbutane since they occurred at a very low incidence and did not exhibit a dose-response relationship.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)

A statistical significant suppression of body weight gain observed in the male 1000 mg/kg group which was attributed to the administration to the test chemical, which is consistent with the slightly decreased food consumption observed in the group during the study period. this change did not exhibit a dose-response relationship and was not accompanied by changes in body weight; therefore, it was not considered to be a treatment related effect.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)

Treatment with 2-methylbutane did not affect any of the fertility and reproductive performance parameters evaluated.

ORGAN WEIGHTS (PARENTAL ANIMALS)

In males, absolute heart weight in the 1000 mg/kg group was significantly decreased in comparison to that of the control group. The relative weight of adrenal glands was significantly increased without a dose-response relationship in comparison to the control group. Relative weights of brain, liver, kidneys, and testes in the 1000 mg/kg group were also significantly increased in comparison to the control group.

2-methylbutane to rats caused a statistically significant suppression in body weight gain in the male 1000 mg/
kg group. The suppressed body weight affected the weights of the heart, brain, liver, and testes in the high dose group. However, the weight changes in these organs were within the limits of normal biological variations and there were no corresponding pathological changes. Previous studies have demonstrated that the function and weight of adrenal glands are adversely affected by various stressful factors. Therefore, these changes are not considered toxicologically significant.

GROSS PATHOLOGY (PARENTAL ANIMALS)
No abnormal gross pathological findings were observed

HISTOPATHOLOGY (PARENTAL ANIMALS)
Renal tubular degeneration/regeneration was observed in 13, 10, 11, and 18 males at 0, 100, 300, and 1000 mg/kg, respectively. These effects were the only treatment related finding and are related to the male rat specific a2u-globulin nephropathy. This finding is not relevant to human health.

Key result

Dose descriptor:

NOAEL

Remarks:

reproductive toxicity

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: highest dose given

Key result

Dose descriptor:

NOAEL

Remarks:

systemic toxicity

Effect level:

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

Based on:

test mat.

Sex:

female

Basis for effect level:

other: highest dose given

Key result

Dose descriptor:

NOAEL

Remarks:

systemic toxicity

Effect level:

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

Based on:

test mat.

Sex:

male

Basis for effect level:

other: a2u-globulin nephropathy observed in male rats. This effect is not relevant to human health.

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Litter size and sex, number of live and stillborn at birth and pup mortality from PND 1 to weaning were comparable among all groups. No significant differences in clinical observations or body weight changes were noted for both dams and pups during the lactation period. Macroscopic examination of pups did not reveal gross malformations or findings that would indicate abnormal development.

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: pup development

Key result

Reproductive effects observed:

no

Conclusions:

The reproductive and developmental NOAEL >= 1000 mg/kg/day, the highest dose tested. The systemic NOAEL for male rats the NOAEL = 300 mg/kg/day based on the a2u-globulin nephropathy observed that is not relevant to human health. The systemic NOAEL for female rats was NOAEL >= 1000 mg/kg/day, the highest dose tested.

Executive summary:

A one-generation reproductive toxicity study using Sprague-Dawley rats was conducted using the test material 2-methylbutane. Male and female rats (24 per treatment group) were treated by oral gavage with 2-methylbutane at 0, 100, 300, and 1000 mg/kg/day. Males were dosed for 10 weeks prior to mating and during mating and females were dosed from 2 weeks before mating to day 21 of lactation.

 

No treatment-related effects of 2-methylbutane were found in relation to the reproductive capacity of parental animals or the pre- and post-natal development of the F1 generation.

 

At 1000 mg/kg/day, a2u-globulin nephropathy observed in male rats. This effect is not relevant to human health. While several organs had altered weights, they changes were within the normal biological range and were considered to be not toxicologically relevant.

Therefore, the reproductive and developmental NOAEL >= 1000 mg/kg/day, the highest dose tested. The systemic NOAEL for male rats the NOAEL = 300 mg/kg/day based on the a2u-globulin nephropathy observed that is not relevant to human health. The systemic NOAEL for female rats was NOAEL >= 1000 mg/kg/day, the highest dose tested.

Reference 2

Endpoint:

two-generation reproductive toxicity

Type of information:

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

Adequacy of study:

key study

Study period:

1989-09-18 to 1990-06-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it followed a protocol comparable to OECD Guideline 416.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

GLP compliance:

yes (incl. QA statement)

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Portage, MI
- Age at study initiation: (P) 28 days; (F1) 29-31 days
- Weight at study initiation: (P) Males: 75-100 g; Females: 65-80 g
- Housing: individually except during mating and lactation in stainless steel wire mesh cages, females were housed in plastic cages from gestational day (GD 20) through weaning; animals were identified by ear notches or toe clips
- Diet (e.g. ad libitum): Certified Ground Rodent Diet RMH 3200, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: two weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 68-73 degree F
- Humidity (%): 40-63
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark


IN-LIFE DATES: From: Sept. 18, 1989 To: June 16, 1990

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

not specified

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 900 l glass and stainless steel chambers.
- Method of holding animals in test chamber: cages
- Source and rate of air: 200 l/min
- Method of conditioning air: Test substance was metered from a piston pump into a heated glass evaporator with a temperature of 36-61 degree C. Conditioned air was passed through the evaporator, where it carried the vapor into the exposure chamber.
- Temperature, humidity: monitored every 30 minutes
- Air flow rate: 200 l/min
- Air change rate: 20 min
- Treatment of exhaust air: filtration


TEST ATMOSPHERE
- Brief description of analytical method used: GC with flame ionization detection
- Samples taken from breathing zone: yes, six times per exposure

Details on mating procedure:

- M/F ratio per cage: 1/1 - If mating failed, females were switched to the male of an unmated pair in the same dose group after 7 days. If mating failed again, they were switched after another 7 days.
- Length of cohabitation: 3 weeks, including during exposure
- Proof of pregnancy: vaginal plug, day 0

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples were taken six times per exposure period and analyzed with GC-FID. Distribution of test substance was evaluated by sampling nine different areas of the exposure chamber.

Duration of treatment / exposure:

10 weeks pre-breeding, 3 weeks during breeding
Females continued to be exposed through GD 19. Exposure was resumed on postnatal day 5, and continued through weaning.
The F1 generation was treated similarly, but pre-breeding exposure was 8 weeks.

Frequency of treatment:

6 hrs/day, 5 days/week

Details on study schedule:

- F1 parental animals not mated until 9 weeks after selected from the F1 litters.
- Selection of parents from F1 generation when pups were 28 days of age.
- Age at mating of the mated animals in the study: 13-16 weeks

Remarks:

Doses / Concentrations:
0, 900, 3000, 9000 ppm
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
892, 2995, 9019 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

25 per sex per dose

Control animals:

yes, sham-exposed

Details on study design:

none provided

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily
- Cage side observations: mortality, toxicity, littering, mating

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION:
- Food consumption: Yes, food consumption of pregnant females was measured in 3-4 day intervals, and through postnatal day 28.

Litter observations:

STANDARDISATION OF LITTERS
Parents of the F2 generation were selected on day 28 postpartum, at least one pup per litter was selected, with a second pup selected only if all litters were already represented. The F2 generation was standardized on day 4 postpartum.


PARAMETERS EXAMINED
The following parameters were examined in F1 and F2 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical abnormalities


GROSS EXAMINATION OF DEAD PUPS:
yes, for external abnormalities

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals after parturition of the first litter
- Maternal animals: All surviving animals day after weaning.


GROSS NECROPSY
- Gross necropsy consisted of external surfaces, orifices, cranial cavity, carcass, brain, spinal cord, thoracic cavity, abdominal cavity, pelvic cavity, cervical tissues and organs

HISTOPATHOLOGY / ORGAN WEIGHTS
Tissues from 25 male and females from the high dose and control groups were examined including testes of males failing to mate.

Postmortem examinations (offspring):

SACRIFICE
- The F1 offspring not selected as parental animals and all F2 offspring were sacrificed at 28 days of age.
- These animals were subjected to postmortem examinations as follows: stillborn and pups dying during lactation, culled pups


GROSS NECROPSY
- Gross necropsy consisted of external examinations.

Statistics:

Quantitative continuous variables were compared by use of Levene's test for equal variance, analysis of variance, and t-tests. Significance for t-tests were corrected by the Bonferroni method. Nonparametric data was evaluated using the Kruskal-Wallis test, followed by the Mann-Whitney test. Indices were compared using Fisher's exact test. 0.05 was used as the criteria for statistical significance.

Reproductive indices:

mating index, fertility index, gestational index, live birth index,

Offspring viability indices:

4-day survival index, 7-day survival index, 14-day survival index, 21-day survival index, lactation index

Clinical signs:

no effects observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Organ weight findings including organ / body weight ratios:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Other effects:

not examined

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

effects observed, treatment-related

F0 GENERATION

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
No treatment related effects observed.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
There were no treatment related effects to food consumption. Males in the 9000 ppm group had reduced body weight during week 13. Body weight gains in this group were reduced during weeks 7, 11-12, and 12-13. Males in the 3000 ppm group had reduced body weight gain in weeks 4-5, and reduced weight in weeks 9-10. Females weight gains were reduced in the 9000 ppm group in weeks 5-6.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Lactational food consumption was significantly reduced during days 7-11, and days 19-21 in the 9000 ppm group. No other reproductive parameters differed significantly from controls.

GROSS PATHOLOGY (PARENTAL ANIMALS)
No treatment related abnormalities were seen.

HISTOPATHOLOGY (PARENTAL ANIMALS)
Hyaline droplet nephropathy and tubular basophilia were seen in the 9000 ppm males.

F1 GENERATION
CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
No treatment related effects were observed. One female in the 900 ppm group died on day 83 due to prolonged delivery.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Body weights of 9000 ppm males were significantly reduced throughout the exposure period. Weight gain was reduced in this group during the weeks 9-10, and 10-11. Females in the 9000 ppm group had reduced body weight during the first 3 weeks of pre-breeding exposure.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
In the 9000 ppm group, food consumption was reduced on gestational days 0-4, and 4-7, and gestational intervals 0-7, and 7-14. This group also had reduced food consumption during lactational days 21-24, 26-27, 21, and 28. In the 3000 ppm group, food consumption was reduced during lactational days 22-23, and in the 900 ppm group during days lactational days 21-22.

GROSS PATHOLOGY (PARENTAL ANIMALS)
No treatment related abnormalities were seen.

HISTOPATHOLOGY (PARENTAL ANIMALS)
Hyaline droplet nephropathy and tubular basophilia were seen in the 9000 ppm males.

Key result

Dose descriptor:

NOAEC

Effect level:

3 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: reduced body weight

Remarks on result:

other: Generation: F1, F2

Dose descriptor:

LOAEC

Effect level:

9 000 ppm

Sex:

male/female

Basis for effect level:

other: reduced body weight

Remarks on result:

other: Generation: F1, F2

Key result

Dose descriptor:

NOAEC

Effect level:

9 000 ppm

Sex:

male/female

Basis for effect level:

other: reduced body weight

Remarks on result:

other: Generation: reproductive toxicity

Clinical signs:

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Histopathological findings:

not examined

F1 GENERATION
VIABILITY (OFFSPRING)
The number of dead pups was increased in the 900 ppm exposure group, however, as this was not seen at higher doses, it was not considered treatment related.

BODY WEIGHT (OFFSPRING)
The body weight of pups in the 9000 ppm group were reduced beginning on lactational day 14. Body weight gains in this group were reduced during lactational days 14-21 for females, and lactational days 7-14 for all pups.


GROSS PATHOLOGY (OFFSPRING)
No treatment related effects were noted.

F2 GENERATION
VIABILITY (OFFSPRING)
Viability was unaffected by exposure.

BODY WEIGHT (OFFSPRING)
The body weight of pups in the 9000 ppm group were from lactational day 7-28. Body weight gains in this group were reduced during lactational days 14-21 for females, and lactational days 7-14 for all pups. There were significantly reduced body weight gains in pups in the 9000 ppm group during lactational days 4-7, and 7-14, and slightly reduced weight gains on lactational days 14-21.

GROSS PATHOLOGY (OFFSPRING)
No treatment related effects were noted.

Key result

Dose descriptor:

NOAEC

Generation:

F1

Effect level:

3 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: Reduced Body weight

Dose descriptor:

LOAEC

Generation:

F1

Effect level:

9 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: Reduced body weight

Key result

Reproductive effects observed:

no

Significant Results of Reproductive Toxicity Study on Rats

Concentration (ppm)	0	900	3000	9000
Body weight of F0 adult males - week 13 (g)	463.7 (48.93)	455.2 (34.22)	455.2 (40.25)	436.1 (24.83)
Body weight gain of F0 adult males - week 4-5 (g)	32.6  (8.98)	28.9 (8.56)	24.2 (7.89)	28.9 (3.78)
Body weight gain of F0 adult males - week 6 -7 (g)	25.4 (6.17)	25.4 (6.28)	23.7 (4.94)	21.2 (4.31)
Body weight gain of F0 adult males - week 9-10 (g)	24.2 (6.00)	21.6 (6.07)	18.6 (6.82)	19.9 (6.17)
Body weight gain of F0 adult males - week 11-12 (g)	11.9 (5.40)	10.7 (6.51)	12.7 (4.83)	3.3 (5.70)
Body weight gain of F0 adult males - week 12-13 (g)	11.8 (6.26)	7.4 (6.34)	8.7 (7.28)	6.4 (6.09)
Body weight gain of F0 adult females - week 0-1 (g)	0.3 (3.08)	3.4 (3.25)	1.9 (2.74)	0.8 (3.67)
Body weight gain of F0 adult females - week 5-6 (g)	11.8 (4.01)	11.0 (4.40)	12.3 (3.57)	9.0 (3.20)
Lactational food consumption F0 - day 7-11 (g/animal/day)	44.63 (3.859)	42.93 ()	43.54 (3.796)	41.45 (3.244)
Lactational food consumption F0 - day 19-21 (g/animal/day)	64.41 (5.833)	64.87 (5.439)	62.32 (6.595)	59.81 (8.212)
No. dead F1 pups - lactational day 4	5	26	12	7
F1 pup body weight - lactational day 21 (g)	41.93 (3.950)	42.50 (4.125)	39.97 (3.292)	38.92 (3.996)
F1 female pup body weight - lactational day 21 (g)	41.48 (4.151)	41.75 (4.168)	39.52 (3.430)	38.10 (4.063)
Body weight changes in F1 pups - lactational day 7-14 (g)	11.91 (1.617)	12.11 (1.328)	11.48 (1.381)	10.56 (1.780)
Body weight changes in F1 male  pups - lactational day 7-14 (g)	12.00 (1.628)	12.24 (1.306)	11.41 (1.708)	10.71 (1.847)
Body weight changes in F1 female pups - lactational day 7-14 (g)	11.81 (1.677)	12.00 (1.420)	11.51 (1.536)	10.35 (1.789)
Body weight changes in F1 female pups - lactational day 14-21 (g)	15.86 (1.933)	15.47 (2.162)	14.39 (1.744)	14.24 (2.343)
Food consumption in F1 females - week 0-1 (g/animal/day)	20.9 (1.87)	20.9 (2.00)	20.7 (2.68)	19.0 (1.62)
Food consumption in F1 females - week 1-2 (g/animal/day)	21.5 (1.45)	21.2 (2.29)	21.2 (2.80)	19.1 (1.90)
Food consumption in F1 females - week 3-4 (g/animal/day)	22.0 (2.40)	21.8 (2.74)	21.5 (2.98)	19.6 (1.99)
Food consumption in F1 females - week 5-6 (g/animal/day)	20.8 (2.02)	21.2 (2.60)	20.6 (2.87)	19.1 (2.00)
Food consumption in F1 females - week 7-8 (g/animal/day)	20.3 (1.84)	20.3 (2.24)	20.0 (2.37)	18.4 (1.99)
F1 Gestational food consumption - day 0-4 (g/animal/day)	22.87 (3.172)	21.93 (2.407)	21.93 (3.237)	19.67 (1.703)
F1 Gestational food consumption - day 4-7 (g/animal/day)	24.31 (3.047)	23.63 (3.228)	23.42 (3.077)	21.81 (2.072)
F1 Gestational food consumption - day 0-7 (g/animal/day)	23.48 (2.972)	22.44 (2.503)	22.57 (2.905)	20.56 (1.760)
F1 Gestational food consumption - day 7-14 (g/animal/day)	26.28 (3.268)	25.25 (3.108)	24.52 (3.055)	23.70 (2.565)
F1 lactational food consumption - day 21-22 (g/animal/day)	87.77 (15.326)	79.55 (8.381)	80.31 (8.272)	74.01 (9.711)
F1 lactational food consumption - day 22-23 (g/animal/day)	91.26 (10.218)	87.42 (9.649)	83.36 (8.764)	81.23 (10.532)
F1 lactational food consumption - day 23-24 (g/animal/day)	97.23 (11.339)	94.59 (9.185)	90.30 (6.703)	85.17 (13.188)
F1 lactational food consumption - day 26-27 (g/animal/day)	115.86 (11.445)	114.19 (16.261)	109.85 (11.689)	105.38 (15.023)
F1 lactational food consumption - day 21-28 (g/animal/day)	102.87 (7.787)	100.49 (8.471)	97.47 (6.852)	94.04 (10.541)

Conclusions:

The NOAEC for both male and female rats (adults and offspring) was 3000 ppm (10560 mg/m3). The LOAEC for these groups was 9000 ppm based on reduced body weight. There were no adverse effects to reproduction, therefore the NOAEC for reproduction is 9000 ppm (31680 mg/m3).

Executive summary:

The purpose of this study was to determine the effect of commerical hexane on reproduction in rats. Groups of 25 male and 25 female rats were exposed to nominal concentrations of 0, 900, 3000, or 9000 ppm of test substance for 10 weeks pre-breeding, 3 weeks during breeding, and postnatal days 4 -28. After weaning, pups were selected to be parents for the F2 generations, and treated similarly to their parents, except their pre-breeding exposure was 8 weeks. During exposure, animals were monitored for mortality, clinical signs, food consumption, and body weight. Offspring were examined for body weight, survival, and viability. Both parents and offspring were sacrificed and examined for gross abnormalities, and in the case of adults histopathology. Reproductive parameters were similar in exposure groups and control groups. There was reduced body weight in the F1 and F2 generation in both sexes in the 9000 ppm exposure group in both adults and offspring. The NOAEC is therefore 3000 ppm (10560 mg/m3), and the LOAEC is 9000 ppm (31680 mg/m3). Since there were no adverse effects in offspring without adverse maternal effects, the NOAEC for reproduction is 9000 ppm (31680 mg/m3).

Reference 3

Endpoint:

extended one-generation reproductive toxicity - with developmental neurotoxicity (Cohorts 1A, 1B without extension, 2A and 2B)

Data waiving:

other justification

Justification for data waiving:

other:

Justification for type of information:

The ‘justification for the read across’ is provided in the ‘Attached justification’ section below.

Species:

rat

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

One key read across study from a structural analogue available for assessment.

Effect on fertility: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

31 680 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

One key read across study from a structural analogue available for assessment.

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

There is no reproductive toxicity data available for Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich, however; data is available for a structural analogues, 2-methylbutane and commercial hexane and presented in the dossier. This data is read across to Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

Oral

2 -methylbutane

A one-generation reproductive toxicity study using Sprague-Dawley rats was conducted (Yu, 2011) using the test material 2-methylbutane. Male and female rats (24 per treatment group) were treated by oral gavage with 2-methylbutane at 0, 100, 300, and 1000 mg/kg/day. Males were dosed for 10 weeks prior to mating and during mating and females were dosed from 2 weeks before mating to day 21 of lactation. No treatment-related effects of 2-methylbutane were found in relation to the reproductive capacity of parental animals or the pre- and post-natal development of the F1 generation. At 1000 mg/kg/day, a2u-globulin nephropathy observed in male rats. This effect is not relevant to human health. While several organs had altered weights, they changes were within the normal biological range and were considered to be not toxicologically relevant. Therefore, the reproductive and developmental NOAEL >= 1000 mg/kg/day, the highest dose tested. The systemic NOAEL for male rats the NOAEL = 300 mg/kg/day based on the a2u-globulin nephropathy observed that is not relevant to human health. The systemic NOAEL for female rats was NOAEL >= 1000 mg/kg/day, the highest dose tested.

Inhalation

5 -80% n-hexane

A study (Daughtrey, 1994) was conducted to determine the effect of commerical hexane on reproduction in rats. Groups of 25 male and 25 female rats were exposed to nominal concentrations of 0, 900, 3000, or 9000 ppm of test substance for 10 weeks pre-breeding, 3 weeks during breeding, and postnatal days 4 -28. After weaning, pups were selected to be parents for the F2 generations, and treated similarly to their parents, except their pre-breeding exposure was 8 weeks. During exposure, animals were monitored for mortality, clinical signs, food consumption, and body weight. Offspring were examined for body weight, survival, and viability. Both parents and offspring were sacrificed and examined for gross abnormalities, and in the case of adults histopathology. Reproductive parameters were similar in exposure groups and control groups. There was reduced body weight in the F1 and F2 generation in both sexes in the 9000 ppm exposure group in both adults and offspring. The NOAEC is therefore 3000 ppm (10560 mg/m3), and the LOAEC is 9000 ppm (31680 mg/m3). Since there were no adverse effects in offspring without adverse maternal effects, the NOAEC for reproduction is 9000 ppm (31680 mg/m3).

An OECD 443 test is proposed for structural analogue, Hydrocarbons, C7-C9, isoalkanes. This endpoint will be updated subsequent to ECHA's approval of the testing proposal and availability of data upon completion of the study. An OECD Guideline 422 screening reproductive/developmental toxicity study (oral route) in rodents is also planned with Hydrocarbons, C6-C10, n-alkanes, isoalkanes, cyclics, >5% n-hexane (EC# 920-191-2).

Effects on developmental toxicity

Description of key information

There is no data available for Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich. However, data is available for structural analogues, Pentane; Hydrocarbons, C7-C9, isoalkanes; and commercial hexane and presented in the dossier. This data is read across to Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

Pentane

Prenatal Developmental Toxicity Study (OECD TG 414, rats) - Oral Administration - The maternal and developmental NOAELs were 1000 mg/kg bw/day.

Hydrocarbons, C7 -C9, isoalkanes

Prenatal Developmental Toxicity Study (OECD TG 414, rats) - Inhalation Administration - The maternal and developmental NOAECs were 1200 ppm.

Commercial hexane

Prenatal Developmental Toxicity Study (OECD TG 414, rats) - Inhalation Administration - The maternal NOAEC was 3000 ppm (10560mg/m³). The developmental NOAEC was 9000 ppm (31680 mg/m^3).

Prenatal Developmental Toxicity Study (OECD TG 414, mice) - Inhalation Administration - The maternal NOAEC was 900 ppm (3168mg/m³). The developmental NOAEC was 3000 ppm (10560 mg/m³).

Additionally, OECD Guideline 414 (Prenatal Developmental Toxicity) rodent and non-rodent species tests are proposed for structural analogue, Hydrocarbons, C7-C9, isoalkanes. This endpoint will be updated subsequent to ECHA's approval of the testing proposals and availability of data upon completion of the studies.

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Study period:

1996-07-25 to 1997-04-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it is was performed according to GLPs and in compliance with OECD principles 414.

Justification for type of information:

The justification for read across is provided as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.31 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:CD BR VAF/Plus

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Portage, Michigan
- Age at study initiation: 14 to 16 weeks (females)
- Weight at study initiation: 243 to 316 grams (females)
- Fasting period before study: no
- Housing: individually-housed except during mating in suspended stainless-steel, wire mesh cages
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 20 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 24
- Humidity (%): 40 to 70
- Air changes (per hr): not reported
- Photoperiod (hrs dark / hrs light): 12 hours light and 12 hours dark

- IN-LIFE DATES: From: 1996-10-07 To: 1996-11-08

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Test material formulations were prepared weekly by mixing appropriate amounts of test material with vehicle; test-material formulations were divided into individual samples for each day and stored in a refrigerator until needed.

VEHICLE
- Justification for use and choice of vehicle (if other than water): test material was soluble in carrier
- Concentration in vehicle: not reported
- Amount of vehicle (if gavage): not reported
- Lot/batch no. (if required): not reported
- Purity: not reported

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Test material formulations were evaluated for stability, homogeneity, and achieved concentration. Stability and homogeneity were evaluated prior to the start of the study as part of the dose-range finding study (Study no. 157533; achieved concentration was evaluated on the first and third dosing mixture preparations. Results from the dose-range finding study indicate that the test material formulations were stable for at least 7 days at 2% and 20% w/v and homogenous (with the relative standard deviation being 1% for both sample sets). Test material formulations were found to be within 16% of the nominal concentration.

Details on mating procedure:

- Impregnation procedure: [artificial insemination / purchased timed pregnant / cohoused]: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: not reported
- Females were placed in cage with male. After confirmation of mating, each female was returned to its own cage. New females were then placed in the males' cages until the required number of mated females was obtained by continuous cohabitation in consideration of lab scheduling.
- Further matings after two unsuccessful attempts: not reported
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: vaginal plug and/or sperm in vaginal rinse referred to as day 0 of pregnancy

Duration of treatment / exposure:

gestation day (gd) 6 though 15

Frequency of treatment:

daily

Duration of test:

IN-LIFE DATES: From: 1996-10-07 To: 1996-11-08

Remarks:

Doses / Concentrations:
0, 100, 500, or 1000 mg/kg/day
Basis:
nominal conc.
Dosing volumes were 5 mL/kg and based on the most recent individual body weights

No. of animals per sex per dose:

25 dams per group

Control animals:

yes

Details on study design:

- Dose selection rationale: A dose-range finding study (Study no. 157533), in which rats were dosed with n-pentane via gavage at levels of 0, 250, 500, 750, and 1000 mg/kg. Maternal signs of toxicity were observed at 1000 mg/kg and included decreased body weight gain and food consumption over the treatment period and overall gestation interval; no other signs of toxicity were observed in dams or fetuses.
- Rationale for animal assignment (if not random): Mated females were assigned to dose groups in the order of mating.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: At least twice daily during treatment and at least once daily at other times during the study

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily during gestation

BODY WEIGHT: Yes
- Time schedule for examinations: gd 0, 6, 9, 12, 15, 18, and 21

FOOD CONSUMPTION: Yes
- Time schedule for examinations: gd 0, 6, 9, 12, 15, 18, and 21

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: Ovaries

OTHER: Surviving dams and those that delivered prior to scheduled necropsy were scarified by carbon dioxide asphyxiation and exsanguination. Dams that delivered prior to scheduled necropsy were examined for gross lesions, and the number of implantation sites or concepti in each horn was counted. Surviving dams were necropsied, and uterine weight with ovaries attached was recorded. Uteri of all non-pregnant females were stained with ammonium sulfide to confirm pregnancy status.

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: location of implantations

Fetal examinations:

- External examinations: yes: all per litter (number of live and dead fetuses was counted; fetuses were weighed, sexed, and examined for gross malformations)
- Soft tissue examinations: yes: half per litter
- Skeletal examinations: yes: half per litter
- Head examinations: yes: half per litter

Statistics:

Statistical methods used are presented in the table below. Statistical evaluation of equality of means was conducted by a one-way analysis of variance and a test for ordered response in dose groups. Equal variances were evaluated by Bartlett's test. Equal variances were then tested using parametric methods, otherwise nonparametric techniques were used. Percentages, where appropriate, were calculated and transformed by Cochran's transformation, followed by the arc sine transformation. Both raw and transformed percentages were tested for statistical significance. The Bartlett's test was conducted at the 1% level of significance; all other tests were conducted at the 5% and 1% level of significance.

Indices:

preimplantation loss
postimplantation loss

Historical control data:

not provided

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
There were no treatment-related changes in mean body weight, body weight gain, uterine weight, corrected body weight, food consumption, or uterine implantation data. There were no treatment-related mortalities or clinical signs of toxicity.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There were no treatment-related changes in growth or increased fetal death. There were no changes in total malformations or variations.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Basis for effect level:

other: There were no signs of developmental toxicity observed during this study.

Abnormalities:

not specified

Key result

Developmental effects observed:

no

^a Data obtained from pages 28 -29 in the study report.

Cesarean section observations^a
Observation	Dose (mg/kg bw/day)
	0	100	500	1000
No. Animals assigned (mated)	25	25	25	25
No. Animals pregnant	24	25	23	25
Pregnancy rate (%)	96	100	92	100
No. Nonpregnant	1	0	2	0
Maternal wastage
No. died	0	0	0	0
No. Died pregnant	0	0	0	0
No. Died nonpregnant	0	0	0	0
No. Aborted	0	0	0	0
No. Premature delivery	1	1	0	0
Corpora lutea/Dam	15.26±1.63	15.88±1.68	15.43±1.78	15.68±2.21
Implantations/Dam	14.52±1.70	14.88±2.33	14.83±1.83	15.16±2.32
Total No. litters	23	24	23	25
Total number of live fetuses Live fetuses/Dam	310 13.48±1.78	346 14.42±2.26	318 13.83±2.19	359 14.36±2.29
Total number of dead fetuses Dead fetuses/Dam	0 0.0±0.0	0 0.0±0.0	0 0.0±0.0	0 0.0±0.0
Total No. resorptions	24	11	23	19
Early	22	11	23	18
Late	2	0	0	1
Resorptions/Dam	1.04±0.98	0.46±0.59	1.00±0.95	0.76±0.83
Early	0.96±0.98	0.46±0.59	1.00±0.95	0.72±0.84
Late	0.09±0.29	0.0±0.0	0.0±0.0	0.04±0.20
Litters with total resorptions	0	0	0	0
Mean fetal weight (g)	0	0	0	0
Males	5.34±0.38	5.45±5.40	5.40±0.44	5.42±0.46
Females	5.13±0.40	5.12±0.37	5.21±0.37	5.14±0.55
Sex ratio (% male)	49	49	47	50
Preimplantation loss (%)	4.6±7.8	6.3±12.5	4.0±5.3	3.5±4.7
Postimplantation loss (%)	7.1±6.5	3.0±3.7	7.0±7.0	5.3±5.6

^a Data obtained from pages 32 -34 and 73 -167 in the study report.

 

External examinations^a
Observations^b	Dose (mg/kg bw/day)
	0	100	500	1000
No. Fetuses (litters) examined	309 (23)	346 (24)	318 (23)	359 (25)
No. Fetuses (litters) affected with variations	0 (0)	0 (0)	0 (0)	0 (0)
No. Fetuses (litters) affected with malformations	0 (0)	0 (0)	1 (1)	1 (1)

^a Data obtained from pages 35 in the study report.

^b Some observations may be grouped together.

^c Fetal (litter) incidence

 

Visceral examinations^a
Observations^b	Dose (mg/kg bw/day)
	0	100	500	1000
No. Fetuses (litters) examined	156 (23)	172 (24)	161 (23)	178 (25)
No. Fetuses (litters) affected with variations	0 (0)	3 (2)	2 (2)	1 (1)
No. Fetuses (litters) affected with malformations	4 (3)	7 (4)	2 (2)	9 (6)

^a Data obtained from page 35 in the study report.

^b Some observations may be grouped together.

^c Fetal (litter) incidence

 

Skeletal examinations^a
Observations^b	Dose (mg/kg bw/day)
	0	100	500	1000
No. Fetuses (litters) examined	154 (23)	174 (24)	157 (23)	181 (25)
No. Fetuses (litters) affected with variations	27 (14)	31 (13)	25 (13)	44 (17)
No. Fetuses (litters) affected with malformations	0 (0)	0 (0)	1 (1)	0 (0)

^aData obtained from page 35 in the study report.

^bSome observations may be grouped together.

^cFetal (litter) incidence

 

 

Conclusions:

There were no signs of maternal toxicity at any dose level. There were no treatment-related changes in mean body weight, body weight gain, uterine weight, corrected body weight, food consumption, or uterine implantation data. There were no treatment-related mortalities or clinical signs of toxicity. The maternal NOAEL is 1000 mg/kg/day.

There were no signs of developmental toxicity at any dose level. There were no treatment-related changes in growth or increased fetal death. There were no changes in total malformations or variations. The developmental NOAEL is 1000 mg/kg/day.

Executive summary:

In a developmental toxicity study, n-pentane was orally administered via gavage to 25 Crl:CD BR VAF rats per dose at dose levels of 0, 100, 500, or 1000 mg/kg bw/day from days 6 through 15 of gestation.  There were no signs of maternal toxicity at any dose level.  There were no treatment-related changes in mean body weight, body weight gain, uterine weight, corrected body weight, food consumption, or uterine implantation data.  There were no treatment-related mortalities or clinical signs of toxicity.  A maternotoxic dose was not used.  However, the highest dose tested was 1000 mg/kg/day, and no adverse effects were observed.  In general, the highest dose tested does not need to exceed 1000 mg/kg/day unless potential human exposure data indicate the need for higher doses.  Therefore, the study reported a maternal NOAEL of 1000 mg/kg/day.  

 

There were no signs of developmental toxicity at any dose level. There were no treatment-related changes in growth or increased fetal death. There were no changes in total malformations or variations. The developmental NOAEL is 1000 mg/kg/day.

 

This study received a Klimisch score of 1 and is classified as reliable without restriction because it was performed according to GLPs and in compliance with OECD principles 414.

Reference 2

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Study period:

1989-03-27 to 1989-04-20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it followed a protocol comparable to OECD Guideline 414.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes (incl. QA statement)

Species:

mouse

Strain:

CD-1

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kingston, NY
- Age at study initiation: 42 days at arrival
- Weight at study initiation: 30 g male, 24 g females
- Housing: individually in stainless steel wire mesh cages, identified with toe clips and ear notches
- Diet (e.g. ad libitum): Prolab Certified Rodent Food, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 66-72 degree F
- Humidity (%): 50-71
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark


IN-LIFE DATES: From: April 5, 1989 To: April 18, 1989

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 4320 l glass and stainless steel chambers.
- Method of holding animals in test chamber: cages
- Source and rate of air: 1000 l/min
- Method of conditioning air: Test substance was metered from a piston pump into one or two heated glass evaporator with a temperature of 27-70 degree C. Conditioned air was passed through the evaporator, where it carried the vapor into the exposure chamber.
- Temperature, humidity: monitored every 30 minutes
- Air flow rate: 1000 l/min
- Air change rate: 20 min, 14 air changes per hour
- Treatment of exhaust air: filtration


TEST ATMOSPHERE
- Brief description of analytical method used: GC with flame ionization detection
- Samples taken from breathing zone: yes, 7 times per exposure

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples were taken seven times per exposure period and analyzed with GC-FID. Distribution of test substance was evaluated by sampling five different areas of the exposure chamber.

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: March 27, 1989-April 2, 1989
- Proof of pregnancy: vaginal plug referred to as day 0

Duration of treatment / exposure:

gestation day (GD) 6-15

Frequency of treatment:

6 hrs/day

Duration of test:

GD 18

No. of animals per sex per dose:

30 pregnant females per exposure group

Control animals:

yes

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations: mortality, clinical signs



BODY WEIGHT: Yes
- Time schedule for examinations: GD 0, 6, 9, 12, 15


FOOD CONSUMPTION: Yes

WATER CONSUMPTION: Yes


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 18
- Organs examined: gravid uterus, ovaries, cervix, vagina, abdominal cavities, thoracic cavities, liver, kidneys

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Number of corpora lutea: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: live and dead fetuses

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter were examined for thoracic and abdominal visceral abnormalities
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: [all per litter / half per litter / #? per litter ] / No / No data

Statistics:

Quantitative continuous variables were compared by use of Levene's test for equal variance, analysis of variance, and t-tests with Bonferroni probabilities. Nonparametric data was evaluated using the Kruskal-Wallis test, followed by the Mann-Whitney U test. Indices were compared using Fisher's exact test. 0.05 was used as the criteria for statistical significance.

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
There were no significant treatment related effects to body weight, clinical signs, food consumption, weight changes, or organ weights. There was increased water consumption on GD 6-9, 9-12, 6-15, and 15-18 in the 3000 ppm group. There was also increased water consumption in the 900 ppm group on GD 3-6 and 6-9. There was a statistically significant increase in lung color changes in the 9000 ppm group. Four dams also had brown foci. Two dams in the 3000 ppm group had lung color changes as well, and three had dark brown foci.

Dose descriptor:

NOAEC

Effect level:

900 ppm

Basis for effect level:

other: maternal toxicity

Dose descriptor:

LOAEC

Effect level:

3 000 ppm

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEC

Effect level:

3 000 ppm

Basis for effect level:

other: developmental toxicity

Dose descriptor:

LOAEC

Effect level:

9 000 ppm

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
Gestational parameters were similar between exposure and control groups. There was a statistically significant increase in two skeletal malformations in the 9000 ppm group, bilateral bone island at the first lumbar arch, all intermediate phalanges of the hindlimb unossified. No other dose related abnormalities were noted.

Key result

Dose descriptor:

NOAEC

Effect level:

900 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: Color changes in lung

Dose descriptor:

LOAEC

Effect level:

3 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: Color changes in lung

Key result

Dose descriptor:

NOAEC

Effect level:

3 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

skeletal malformations

Dose descriptor:

LOAEC

Effect level:

9 000 ppm (nominal)

Sex:

male/female

Basis for effect level:

skeletal malformations

Abnormalities:

not specified

Developmental effects observed:

not specified

Results of Developmental Toxicity Study on Mice

	0.0 ppm	900.0 ppm	3000.0 ppm	9000.0 ppm
No. of dams with lung color change	0	0	2	12
All inter. Phalanges (hindlimb) unossified (litters, %)	76.9	72.0	84.0	100.0
Bone island - first lumbar arch - bilateral  (litters, %)	0.0	0.0	8.0	23.1

Conclusions:

In mice, the maternal NOAEC was 900 ppm, and the maternal LOAEC was 3000 ppm (10560 mg/m3) based on color changes in the lungs. The developmental NOAEC was 3000 ppm and the LOAEC was 9000 ppm(31680 mg/m3) in mice.

Executive summary:

The purpose of this study was to examine the developmental toxicity of commercial hexane in mice. Groups of 30 pregnant female mice were exposed to concentrations of 0, 900, 3000, or 9000 ppm for 6 hrs/day during gestational days 6 -15. The animals were then sacrificed on GD 18. During the study, the animals were examined for clinical signs, mortality, food and water consumption, and body weights taken. After sacrifice, the internal organs were examined, and the uterus was examined for viable fetuses, number of resorptions, and number of corpora lutea. Fetuses were examined for malformations. Necropsy revealed color changes in the lungs of females in the 3000 and 9000 ppm groups. Fetuses in from dams in the 9000 ppm group had a statistically significant increase in some skeletal abnormalities. The maternal NOAEC in mice was 900 ppm (3168 mg/m3), and the LOAEC 3000 ppm based on lung color changes. The developmental NOAEC in mice was 3000 ppm (10560 mg/m3) and the LOAEC 9000 ppm (31680 mg/m3) based on skeletal abnormalities.

Reference 3

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Study period:

1989-03-24 to 1989-04-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study is classified as reliable without restriction because it followed a protocol comparable to OECD Guideline 414.

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes (incl. QA statement)

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kingston, NY
- Age at study initiation: 63 days males, 56 days females at arrival
- Weight at study initiation: 250-300 g male, 175-200 g females
- Housing: individually in stainless steel wire mesh cages, identified with ear tags
- Diet (e.g. ad libitum): Prolab Certified Rodent Food, ad libitum
- Water (e.g. ad libitum): tap water, ad libitum
- Acclimation period: 2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 63-74 degree F
- Humidity (%): 40-71
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark


IN-LIFE DATES: From: April 9, 1989 To: April 21, 1989

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 4320 l glass and stainless steel chambers.
- Method of holding animals in test chamber: cages
- Source and rate of air: 1000 l/min
- Method of conditioning air: Test substance was metered from a piston pump into one or two heated glass evaporators with a temperature of 27-70 degree C. Conditioned air was passed through the evaporators, where it carried the vapor into the exposure chamber.
- Temperature, humidity: monitored every 30 minutes
- Air flow rate: 1000 l/min
- Air change rate: 20 min, 14 air changes per hour
- Treatment of exhaust air: filtration


TEST ATMOSPHERE
- Brief description of analytical method used: GC with flame ionization detection
- Samples taken from breathing zone: yes, 7 times per exposure

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples were taken seven times per exposure period and analyzed with GC-FID. Distribution of test substance was evaluated by sampling five different areas of the exposure chamber.

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: April 2, 1989-April 6, 1989
- Proof of pregnancy: vaginal plug referred to as day 0

Duration of treatment / exposure:

gestation day (GD) 6-15

Frequency of treatment:

6 hrs/day

Duration of test:

GD 21

No. of animals per sex per dose:

25 pregnant females per exposure group

Control animals:

yes

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations: mortality, clinical signs

BODY WEIGHT: Yes
- Time schedule for examinations: GD 0, 6, 9, 12, 15, 18, 21

FOOD CONSUMPTION: Yes

WATER CONSUMPTION: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: gravid uterus, ovaries, cervix, vagina, abdominal cavities, thoracic cavities, liver, kidneys

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Number of corpora lutea: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: live and dead fetuses

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter were examined for thoracic and abdominal visceral abnormalities
- Skeletal examinations: Yes: half per litter

Statistics:

Quantitative continuous variables were compared by use of Levene's test for equal variance, analysis of variance, and t-tests with Bonferroni probabilities. Nonparametric data was evaluated using the Kruskal-Wallis test, followed by the Mann-Whitney U test. Indices were compared using Fisher's exact test. 0.05 was used as the criteria for statistical significance.

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
There were no treatment related effects to mortality or pregnancy rates. In the 9000 ppm exposure group, there was a significant reduction in weight gain on GD 6-9, and GD 6-15, and slightly reduced on GD 9-12. In the 3000 ppm group, there was a significant reduction in weight gain on GD 9-12, but significantly increased on GD 18-21. Food consumption was significantly reduced in the 9000 ppm group on days 6-9, 9-12, 12-15, and 6-15. There were color changes in the lungs of females in the 9000 ppm group. These changes were also seen in one female each in the 0, 900 and 3000 ppm groups. The color changes in the 900 and 3000 ppm groups were not considered treatment related. There were no treatment related effects to gestational parameters.

Dose descriptor:

NOAEC

Effect level:

3 000 ppm

Basis for effect level:

other: maternal toxicity

Dose descriptor:

LOAEC

Effect level:

9 000 ppm

Basis for effect level:

other: maternal toxicity

Key result

Dose descriptor:

NOAEC

Effect level:

9 000 ppm

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
There were no treatment related effects to the development of fetuses.

Key result

Dose descriptor:

NOAEC

Effect level:

3 000 ppm

Sex:

male/female

Basis for effect level:

other: Color changes in lung, Body weight reduces, Food consumption reduce

Dose descriptor:

LOAEC

Effect level:

9 000 ppm

Sex:

male/female

Basis for effect level:

other: Color changes in lung, Body weight reduces, Food consumption reduce

Abnormalities:

not specified

Developmental effects observed:

not specified

Gestational Body Weight Changes (g)

	0.0 ppm	900.0 ppm	3000.0 ppm	9000.0 ppm
Day 0-6	28.21 (11.819)	31.55 (6.463)	31.19 (9.344)	29.36 (8.245)
Day 6-9	11.55 (8.103)	9.12 (6.009)	11.18 (4.539)	4.34 (6.029)
Day 9-12	16.02 (5.296)	16.31 (5.531)	11.33 (8.446)	12.65 (4.974)
Day 12-15	17.03 (6.807)	19.04 (4.473)	21.84 (9.577)	19.03 (6.453)
Day 15-18	43.52 (9.483)	41.27 (5.755)	37.83 (16.192)	44.11 (9.902)
Day 18-21	51.61 (15.190)	57.79 (8.681)	63.34 (11.295)	57.30 (12.247)
Day 6-15	44.59 (12.727)	44.47 (9.565)	44.35 (9.870)	36.02 (7.850)

Conclusions:

In rats, the maternal NOAEC was 3000 ppm (10560 mg/m3), and the maternal LOAEC was 9000 ppm (31680 mg/m3) based on color changes in the lungs, reduced body weight gain, and reduced food consumption. The developmental NOAEC 9000 ppm (31680 mg/m3) in rats.

Executive summary:

The purpose of this study was to examine the developmental toxicity of commercial hexane in rats. Groups of 25 pregnant female rats were exposed to concentrations of 0, 900, 3000, or 9000 ppm for 6 hrs/day during gestational days 6 -15. The animals were then sacrificed on GD 21. During the study, the animals were examined for clinical signs, mortality, food and water consumption, and body weights taken. After sacrifice, the internal organs were examined, and the uterus was examined for viable fetuses, number of resorptions, and number of corpora lutea. Fetuses were examined for malformations. Necropsy revealed color changes in the lungs of females in the 9000 ppm groups along with reduced body weight gain, and reduced food consumption. No treatment related abnormalities was seen in the fetuses. The maternal NOAEC in rats was 3000 ppm (10560 mg/m3), and the LOAEC 9000 ppm based on lung color changes, reduced body weight gain, and reduced food consumption. The developmental NOAEC in rats was 9000 ppm (31680 mg/m3).

Reference 4

Endpoint:

developmental toxicity

Type of information:

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

Adequacy of study:

key study

Study period:

September 1978 - Dezember 1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles, acceptable for assessment, limited documentation.

Justification for type of information:

The justification for read across is provided as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

other: Food and Drug Administration 1966 "Guidelines for Reproduction Studies for Safety Evaluation of Drugs for Human Use", Segment II (Teratology Study).

Deviations:

yes

Remarks:

Administration via inhalation route

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

other: CD (SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Labs, Inc., Wilmington, Mass. 01887
- Age at study initiation: 9 wks
- Fasting period before study: no
- Housing: individually (except during mating)
- Diet (e.g. ad libitum): Standard Laboratory diet (Purina Lab Chow), fresh food presented as needed, except during each 6-hour exposure.
- Water (e.g. ad libitum): Automated water system (Elizabethtown Water Company), except during each 6-hour exposure.
- Acclimation period: 18 days


ENVIRONMENTAL CONDITIONS
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

not specified

Vehicle:

unchanged (no vehicle)

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 1 cubic meter exposure chamber
- Method of holding animals in test chamber: no data
- Method of conditioning air:
- Temperature, humidity, pressure in air chamber: room temprature, dried air
- Method of particle size determination: not applicable

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

No details given.

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/1
- Length of cohabitation: overnight
- Verification of same strain and source of both sexes: no, males from in-house colony
- Proof of pregnancy: vaginal plug and/or sperm in vaginal smear referred to as day 0 of pregnancy

Duration of treatment / exposure:

GD6 - 15

Frequency of treatment:

6 hours/day

Duration of test:

until GD21 (all surviving dams), until day 21 postmating (all surviving non-pregnant females)

No. of animals per sex per dose:

20 females

Control animals:

yes, sham-exposed

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily
- Cage side observations included: mortality, gross signs of toxicologic or pharmacologic effects


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: GD 0, 6-15, and 21


BODY WEIGHT: Yes (including calculation of Body Weight Change)
- Time schedule for examinations: GD 0, 6-15, and 21


POST-MORTEM EXAMINATIONS: Yes, all females
- Sacrifice on gestation day # 21
- Organs examined: appendix containing the data was missing

OTHER:
Dams showing signs of abortion or premature delivery were sacrificed and fetuses obtained 19 days or later were processed and examined for skeletal anomalies. Only grossly abnormal fetuses obtained earlier than GD19 weresaved for possible future examination.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes (evidence of implantation, but no recognizable fetus)
- Number of late resorptions: Yes (recognizable dead fetus undergoing degeneration)
- Dead fetuses: Yes (dead fetus with no visible degeneration)
- Live fetuses

Fetal examinations:

- External examinations: Yes: all fetuses (weight, crown-rump distance from the parietal-interparietal suture to the base of the tail, malformations, sex based upon anogenital distance)
- Soft tissue examinations: Yes: two-thirds of fetuses (gross dissection and examination of viscera including internal sex determination)
- Skeletal examinations: Yes: two-thirds of fetuses (malformations and ossification variations)
- Head examinations: No data

Statistics:

Comparisons between negative and positive control and between negative control and each test substance-treated group were made where applicable (incidence data) by the chi-square method or by the F-test and Student's t-test (absolute data). When variances differed significantly, Student's t-test was appropriately modified using Cochran's approximation (t'). Mean number of live fetuses, resorptions, implantations and corpora lutea were compared to control by the one-tailed t-test.

Details on maternal toxic effects:

Maternal toxic effects:no effects

Key result

Dose descriptor:

NOAEC

Effect level:

1 200 ppm (nominal)

Basis for effect level:

other: maternal toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Key result

Dose descriptor:

NOAEC

Effect level:

1 200 ppm (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: teratogenicity

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

no

A) Maternal data:

Pregnancy rates were comparable between the negative control and the treated groups. No mortality occurred in the negative control and the treated groups. Mean body weight gain during the pre-dosing and the dosing intervals were comparable between negative control and treated groups, during the post-dosing interval mean weight gain was statistical significant higher in the treated groups.

Physical observations:

No indication of a treatment effect. Likewise, the data were generally comparable between the negative and the positive control groups.

Reproduction data:

Mean number of corpora lutea, implantation sites, live fetuses, resorption sites, and the incidence of dams with one or more resorption sites were comparable between the negative control and the treated groups.

Implantation efficiency values were slightly higher in the treated groups than in the negative control, in some instances differences were statistically significant, however, this was not considered indicative of an adverse effect.

In contrast, in the positive control group the mean number of live fetuses was significantly decreased and the mean number of resorption sites significantly increased compared to the negative control. Likewise, the incidence of dams with two or more resorptions was also significantly higher than in the negative control group. The mean number of corpora lutea, implantations, and the implantation efficiency value were comparable between the positive and negative control groups.

Gross postmortem examinations:

Few gross lesions were observed at necropsy of treated females (not further specified), no treatment-related effect was indicated.

B) Fetal data:

Mean fetal weights and mean crown-rump distances of both sexes were comparable for negative control and treated groups, while in the positive control group they were significantly lower. Mean numbers of male and female fetuses were comparable between negative control and treated groups. Likewise, sex ratio data was comparable for these groups. In contrast, the mean numbers of male and female fetuses in the positive control group were significantly lower compared to the negative control, due to lower numbers of fetuses in this group.

Variations in degree of ossification:

These variations may represent delays in the ossification process or slight ossification irregularities. The incidences of fetuses with ossification variations was comparable between negative control and the 400 ppm-treated group. In the 1200 ppm-treated group the incidence of fetuses with at least one ossification variation was significantly higher compared to the negative control. The incidence of litters containing fetuses with ossification variations was comparable between negative and treated groups. Likewise, the types and incidences of ossification variations were generally similar between the negative control and the treated groups.

In contrast, in the positive control group the incidence of fetuses with at least one variation was significantly higher, ossification was retarded.

Teratology data:

No treatment-related external, gross evisceration, soft tissue and skeletal malformations were observed in the fetuses of the treated and the negative control group. One late resorption from one female of the 400 ppm group showed extreme edema, however, no other unusual observations were noted in the other late resorptions of treated and negative control groups. In contrast, in the positive control group, external malformations were noted in 14.4 % of the fetuses, the most common symptom was craniorachischisis with protruding tongue and clubbed forelimbs. The incidences of soft tissue malformations were comparable between the negative control and the treated groups, no treatment-related effect was indicated. In the positive control group, these incidences were significantly higher than in the negative control.

Conclusions:

Under the design of the study the test substance, hydrocarbons, C7-C9, isoalkanes, produced no negative effects.

Executive summary:

Under the design of the study the test substance, hydrocarbons, C7-C9, isoalkanes, produced no negative effects.

Reference 5

Endpoint:

developmental toxicity

Data waiving:

other justification

Justification for data waiving:

other:

Justification for type of information:

The ‘justification for the read across’ is provided in the ‘Attached justification’ section below.

Species:

rat

Reference 6

Endpoint:

developmental toxicity

Data waiving:

other justification

Justification for data waiving:

other:

Justification for type of information:

The ‘justification for the read across’ is provided in the ‘Attached justification’ section below.

Species:

rabbit

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

One key read across study from a structural analogue available for assessment.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

10 560 mg/m³

Study duration:

subchronic

Species:

mouse

Quality of whole database:

Three key read across studies from structural analogues available for assessment.

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

There is no data available for Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich. However, data is available for structural analogues Pentane; Hydrocarbons, C7-C9, isoalkanes; and commercial hexane. This data is read across to Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich based on analogue read across and a discussion and report on the read across strategy is provided as an attachment in IUCLID Section 13.

 

Inhalation

 

Pentane

In a developmental toxicity study (Exxon, 1997), n-pentane was orally administered via gavage to 25 Crl:CD BR VAF rats per dose at dose levels of 0, 100, 500, or 1000 mg/kg bw/day from days 6 through 15 of gestation.  There were no signs of maternal toxicity at any dose level.  There were no treatment-related changes in mean body weight, body weight gain, uterine weight, corrected body weight, food consumption, or uterine implantation data.  There were no treatment-related mortalities or clinical signs of toxicity.  A maternotoxic dose was not used.  However, the highest dose tested was 1000 mg/kg/day, and no adverse effects were observed.  In general, the highest dose tested does not need to exceed 1000 mg/kg/day unless potential human exposure data indicate the need for higher doses.  Therefore, the study reported a maternal NOAEL of 1000 mg/kg/day. There were no signs of developmental toxicity at any dose level. There were no treatment-related changes in growth or increased fetal death. There were no changes in total malformations or variations. The developmental NOAEL is 1000 mg/kg/day.

 

Commercial hexane

In a key study (API, 1989 rat) the developmental toxicity of commercial hexane in rats was examined. Groups of 25 pregnant female rats were exposed to concentrations of 0, 900, 3000, or 9000 ppm for 6 hrs/day during gestational days 6 -15. The animals were then sacrificed on GD 21. During the study, the animals were examined for clinical signs, mortality, food and water consumption, and body weights taken. After sacrifice, the internal organs were examined, and the uterus was examined for viable fetuses, number of resorptions, and number of corpora lutea. Fetuses were examined for malformations. Necropsy revealed color changes in the lungs of females in the 9000 ppm groups along with reduced body weight gain, and reduced food consumption. No treatment related abnormalities was seen in the fetuses. The maternal NOAEC in rats was 3000 ppm (10560 mg/m3), and the LOAEC 9000 ppm based on lung color changes, reduced body weight gain, and reduced food consumption. The developmental NOAEC in rats was 9000 ppm (31680 mg/m3).

 

In another key study (API, 1989 mouse), groups of 30 pregnant female mice were exposed to concentrations of 0, 900, 3000, or 9000 ppm for 6 hrs/day during gestational days 6 -15. The animals were then sacrificed on GD 18. During the study, the animals were examined for clinical signs, mortality, food and water consumption, and body weights taken. After sacrifice, the internal organs were examined, and the uterus was examined for viable fetuses, number of resorptions, and number of corpora lutea. Fetuses were examined for malformations. Necropsy revealed color changes in the lungs of females in the 3000 and 9000 ppm groups. Fetuses in from dams in the 9000 ppm group had a statistically significant increase in some skeletal abnormalities. The maternal NOAEC in mice was 900 ppm (3168 mg/m3), and the LOAEC 3000 ppm based on lung color changes. The developmental NOAEC in mice was 3000 ppm (10560 mg/m3) and the LOAEC 9000 ppm (31680 mg/m3) based on skeletal abnormalities.

 

Hydrocarbons, C7-C9, isoalkanes

Developmental toxicity of Hydrocarbons, C7 -C9, isoalkanes in rats was examined (Exxon, 1979). Groups of 20 pregnant females were exposed to the test material for 6 hrs/day. Results of physical observations, reproduction data, gross postmortem examinations, foetal weights and mean crown-rump distances were recorded and no treatment-related effect was indicated. No treatment-related external, gross evisceration, soft tissue and skeletal malformations were observed in the fetuses of the treated and the negative control group. One late resorption from one female of the 400 ppm group showed extreme edema, however, no other unusual observations were noted in the other late resorptions of treated and negative control groups. In contrast, in the positive control group, external malformations were noted in 14.4 % of the fetuses, the most common symptom was craniorachischisis with protruding tongue and clubbed forelimbs. The incidences of soft tissue malformations were comparable between the negative control and the treated groups, no treatment-related effect was indicated. In the positive control group, these incidences were significantly higher than in the negative control. Under the design of the study the test substance, Hydrocarbons, C7 -C9, isoalkanes, produced no negative effects.

 

Additionally, OECD Guideline 414 (Prenatal Developmental Toxicity) rodent and non-rodent species tests are proposed for structural analogue, Hydrocarbons, C7-C9, isoalkanes. This endpoint will be updated subsequent to ECHA's approval of the testing proposals and availability of data upon completion of the studies.

Justification for classification or non-classification

Based on the available read across data from structural analogues, Hydrocarbons, C5-C7, n-alkanes, isoalkanes, n-hexane rich is not considered a reproductive toxicant under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP). However, the substance is self classified as a reproductive toxicant (Repr. 2; H361; suspected of damaging fertility or the unborn child) under EU CLP based on the n-hexane content.

Additional tests (OECD 443, OECD 422 and OECD 414 (rodent and 2nd species)) are proposed and will be conducted on a structural analogue subsequent to ECHA's approval of the same. This endpoint will be updated upon completion of the above studies subject to ECHA's approval.