Hydrocarbons, C7, n-alkanes, isoalkanes, cyclics

Endpoint summary

Description of key information

Sub-chronic Repeated Dose Inhalation – NOAEC = 12470 mg/m³for rats

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

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

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific principles, acceptable for assessment. Only one dose employed; statistical methods not identified.

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

Principles of method if other than guideline:

Single concentration repeated dose study for peripheral nerve toxicity.

GLP compliance:

no

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: not specified
- Weight at study initiation: 308 ± 18 g

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: room air

Remarks on MMAD:

MMAD / GSD: not applicable, vapour

Details on inhalation exposure:

TEST ATMOSPHERE
- Brief description of analytical method used: gas chromatography and Kitagawa gas detection

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Animals were actually exposed to 2960 ± 200 ppm of Normal-Heptane.

Duration of treatment / exposure:

16 weeks

Frequency of treatment:

12 hours/day, 7 days/week

Remarks:

Doses / Concentrations:
12.47 mg/L (re-calculated; corresponding to 3000 ppm)
Basis:
nominal conc.

No. of animals per sex per dose:

7 males

Control animals:

yes, sham-exposed

Details on study design:

- Post-exposure recovery period: none

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: no data
- Cage side observations included: behaviour


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: before and after 4, 5, 12, 16 weeks of exposure


BODY WEIGHT: Yes
- Time schedule for examinations: not further specified, very likely weekly


OTHER:
Neurophysiology: motor nerve conductivity velocity (MCV), distal latency (DL), mixed nerve conduction velocity (MNCV)
- Time schedule: before and at 4, 5, 12, 16 weeks of exposure

Sacrifice and pathology:

GROSS PATHOLOGY: No data
HISTOPATHOLOGY: Yes (one rat): gastrocnemeius and soleus muscles, the dorsal trunk of the tail nerve and the tibial nerve were examined by light and electron microscopy

Statistics:

Employed but not identified by test name.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Details on results:

CLINICAL SIGNS AND MORTALITY
No abnormal behavioural changes were observed.

BODY WEIGHT AND WEIGHT GAIN
Body weight gain was statistically significantly depressed (p<0.01) after 8 weeks of exposure compared to controls but gradually increased throughout the experiment, albeit to body weight levels below control values, but not statistically significantly lower.


HISTOPATHOLOGY: NON-NEOPLASTIC
Peripheral nerves, muscles and neuromass junctions, examined microscopically, were normal.

OTHER FINDINGS
Neurophysiology: There were no statistically significant differences in motor nerve conduction velocity, distal latency or mixed nerve conduction velocity in any region of the tail.

Key result

Dose descriptor:

NOAEC

Remarks:

neurotoxicity

Effect level:

12 470 mg/m³ air (nominal)

Sex:

male

Basis for effect level:

other: No adverse effect seen at the highest concentration tested

Key result

Dose descriptor:

NOAEC

Remarks:

systemic

Effect level:

12 470 mg/m³ air (nominal)

Sex:

male

Basis for effect level:

other: no effects except reversible body weight changes

Critical effects observed:

not specified

Normal-Heptane is not a neurotoxicant in this assay system.

Conclusions:

Normal-heptane is not a neurotoxicant in this assay system.

Executive summary:

Normal-heptane is not a neurotoxicant in this assay system.

Reference 2

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Study period:

17 April 1978 - 30 March 1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions. Limited documentation on animal housing, only 2 concentrations tested, exposure duration 84 days, no ophthalmological examination.

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 413 (Subchronic Inhalation Toxicity: 90-Day Study)

GLP compliance:

no

Limit test:

no

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, Wilmington, Mass. 01887
- Age at study initiation: males 6 wks, females 7 wks
- Weight at study initiation: males 185 g mean (range 165-217 g); females 162 g mean (range 138-189)
- Fasting period before study: no
- Housing: paired in chamber, individual out of chamber
- Diet (e.g. ad libitum): Standard laboratory pellet diet (Purina Laboratory Chow) ad libitum (out of chamber only)
- Water (e.g. ad libitum): ad libitum (out of chamber only)
- Acclimation period: 13 days

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Remarks on MMAD:

MMAD / GSD: not applicable, vapour

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: stainless steel and glass chambers with 1 cubic meter total volume (760 L effective volume)
- Source and rate of air:
- Method of conditioning air:
- System of generating particulates/aerosols:
- Temperature, humidity, pressure in air chamber:
- Air flow rate: 134 L/min
- Air change rate: 8 per hour
- Method of particle size determination: not applicable, vapour


TEST ATMOSPHERE
- Brief description of analytical method used: Atmospheric sampling was performed using a Wilks Scientific Corp., Miran 1A Ambient Air Analyzer (long pathlength infrared). A calibration curve relating the absorption to the airborne concentration of the test material was prepared. On each exposure day, three samples were drawn from each exposure chamber (at about 1, 3, and 5 hours) and the exposure concentration calculated by comparing the absorption of this sample to the standard curve.
In addition, the composition of the test atmosphere was analyzed for homogeneity by gas chromatographic analysis of several charcoal-trapped vapour samples collected from each chamber during the 12-wk exposure period

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The test atmosphere was analysed for concentration and homogeneity by measurement of the infrared spectrum and by gas chromatographic analysis, respectively. Based on the infrared analysis the animals were exposed to cumulative mean concentrations of 385 and 1200 ppm, respectively. Gas chromatographic analysis of the chamber atmosphere demonstrated that the test material composition was representative of the initial sample.

Duration of treatment / exposure:

12 weeks

Frequency of treatment:

6 hours/day, 5 days/week

Remarks:

Doses / Concentrations:
400, 1200 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

35

Control animals:

yes, sham-exposed

Details on study design:

- Rationale for animal assignment (if not random): assigned to group by weight

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations included: incidence of abnormal signs


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly (full recorded physical assessment)


BODY WEIGHT: Yes
- Time schedule for examinations: weekly, from 5 days prior to exposure through termination


WATER CONSUMPTION: No


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY: Yes (retro-orbital sinus)
- Time schedule for collection of blood: 4, 8, 12 weeks
- Anaesthetic used for blood collection: Yes (exsanguination under ether anesthesia)
- Animals fasted: Yes (fasted overnight prior to bleeding)
- How many animals: 10/sex/group (4 and 8 weeks), 15/sex/group (12 weeks, all survivors)
- Parameters examined: hemoblobin, hematocrit, erythrocyte count, clotting time, total and differential leukocytes


CLINICAL CHEMISTRY: Yes (retro-orbital sinus)
- Time schedule for collection of blood: 4, 8, 12 weeks
- Animals fasted: Yes (exsanguination under ether anesthesia)
- How many animals: 10/sex/group (4 and 8 weeks), 15/sex/group (12 weeks, all survivors)
- Parameters examined: blood urea nitrogen, serum glutamic pyruvic transaminase (SGPT), glucose, alkaline phosphatase


OTHER:
Organ weights and organ/body weight ratios determined in animals sacrificed at 4, 8 and 12 weeks (adrenals, brain (sans pituitary), gonads, kidneys, liver, lungs)

Sacrifice and pathology:

GROSS PATHOLOGY: Yes: adrenals, brain (without pituitary), gonads, kidneys, liver, lungs
HISTOPATHOLOGY: Yes (control and 1200 ppm group): adrenals (2), bone marrow (sternal), brain (2 sections), eye, gonad, heart (with coronary vessels) intestine, colon, duodenum, ileum, kidneys (2), liver (2 sections), lung (2 sections), lymph node (mesenteric), mammary gland, pancreas, pituitary, salivary gland, skeletal muscle, skin, spinal cord (cervical), spleen, stomach, thyroid, trachea, urinary bladder, uterus/prostate, gross lesions, tissue masses

Statistics:

Body weight, hematology and clinical chemistry parameters, organ weights and organ/body weight ratios were statistically evaluated. Mean values for all treatment groups were compared to the control group at each time interval (4, 8, and 12 weeks). Hematology and clinical chemistry parameters were compared by the F-test and Student's t-test. When variances differed significantly (F-test), Student's t-test was appropriately modified using Cochran's approximation (t'). Body weight, organ weight and organ/body weight ratios were compared to control according to Dunnett.

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
No treatment-related mortality occured (1 male of the 1200 ppm group was accidentally killed).
Several animals in all groups exhibited dry rales and red and mucoid nasal discharge (more numerous in the treated groups, but not clearly treatment-related), moist rales, excessive lacrimation, hair loss and chromodacryorrhea were found in a limited number of animals in all groups (not treatment-related)
1200 ppm: singular occurrences of excessive salivation, laboured, irregular breathing; yellow staining of the anogenital fur in 6 males and 35 females from wk 3 through 12
400 ppm: yellow staining of the anogenital fur in 2 females
Control: singular occurrences of excessive salivation and bleeding inside the ear; a limited number of animals with brown staining of the ano-genital region and soft stool; three observations (in one animal) of an abnormally dark red or red and yellow eye

BODY WEIGHT AND WEIGHT GAIN
1200 ppm: mean body weights in males significantly higher at wk 2 and significantly lower (p?0.05) from wk 8 through 11 than in controls
400 ppm: mean body weight and weight gains in males similar to control throughout the study, except wk 2 (significantly higher, p?0.01), in females mean body weights significantly depressed (p?0.01 and p?0.05) at wk 5 through 8.

HAEMATOLOGY
Several statistically significant (p < 0.05 and p < 0.01) decreases in mean hematocrit values of males and females of both treated groups at wk 4 and 8, statistically significant decreases (p?0.05) in mean hemoglobin values at wk 8 in the males of both treated groups and the females of the 400 ppm group at wk 4. Mean red blood cell values were significantly decreased in 1200 ppm males at wk 8 and 400 ppm females at wk 12. Since all values were within normal biological limits, these findings were not considered to be treatment-related.

CLINICAL CHEMISTRY
Mean SGPT levels were significantly (p?0.01) depressed in 1200 ppm males at wk 4, 400 and 1200 ppm males at wk 8, and in 1200 ppm females at wk 12. Mean blood urea nitrogen levels were significantly increased in the males of both treated groups at wk 8. Mean glucose levels were significantly (p?0.01 or p?0.05) increased in 400 ppm males at wk 8, decreased in 1200 ppm males at wk 12, and decreased in 1200 ppm females at wk 4 and 12. The observed effects were not considered to be treatment-related.

ORGAN WEIGHTS
Mean kidney weights and kidney/body weight ratios were significantly (p?0.05) higher in the 1200 ppm males at wk 8. In the 400 ppm males these values were also elevated, but not statistically significant. At wk 12, mean kidney weights and kidney/body weight ratios for 400 and 1200 ppm males were significantly (p?0.01) elevated, indicating a treatment-related response. The only other statistically significant (p?0.05) findings were elevated mean adrenal/body weight ratios for the 1200 ppm males at wk 4 and the 400 ppm females at wk 12.

GROSS PATHOLOGY
Microscopic evaluation of organs and tissues from the control and high level exposure groups revealed a mild tubular injury in the kidneys of some exposed male rats sacrificed after exposure for 8 and 12 wk. Other changes were unrelated to group or sex and were considered to be spontaneous.

HISTOPATHOLOGY: NON-NEOPLASTIC
See Gross Pathology

Key result

Dose descriptor:

NOAEC

Effect level:

1 200 ppm (nominal)

Sex:

male

Basis for effect level:

other: overall effects

Critical effects observed:

not specified

Significantly increased mean kidney weights and kidney/body weight ratios were observed in males at 400 ppm, which were considered to be treatment-related by the authors of the study.

The kidney was confirmed as potential target organ for the test material-induced toxicity by the observation of mild tubular injury found in the histopathological examination of high dose males.

The fact, that these effects were strictly limited to male rats and that the test substance belongs to a category of substances which are known for their ability to induce nephropathy in male rats due to their exclusive expression of alpha-2u-globulin, the protein known to play the crucial role in the onset of this disease, the observed effects in the kidney have to be regarded as species-specific and therefore not relevant for risk assessment in humans. Therefore, these effects were not considered for the determination of the NOAEC.

Conclusions:

In a 12 -week inhalation study with rats the test substance hydrocarbons, C7 -C9, isoalkanes was tested. Significantly increased mean kidney weights and kidney/body weight ratios were observed in males at 400 ppm, which were considered to be treatment-related by the authors of the study.

The kidney was confirmed as potential target organ for the test material-induced toxicity by the observation of mild tubular injury found in the histopathological examination of high dose males.

The fact, that these effects were strictly limited to male rats and that the test substance belongs to a category of substances which are known for their ability to induce nephropathy in male rats due to their exclusive expression of ?2u-globulin, the protein known to play the crucial role in the onset of this disease, the observed effects in the kidney have to be regarded as species-specific and therefore not relevant for risk assessment in humans. Therefore, these effects were not considered for the determination of the NOAEC.

Renal effects were strictly limited to males, therefore the authors concluded an ?2u-globulin-related mechanism for the observed nephropathy. The observation was not considered for determination of the NOAEC.

Executive summary:

In a 12 -week inhalation study with rats the test substance hydrocarbons, C7 -C9, isoalkanes was tested. Significantly increased mean kidney weights and kidney/body weight ratios were observed in males at 400 ppm, which were considered to be treatment-related by the authors of the study. The kidney was confirmed as potential target organ for the test material-induced toxicity by the observation of mild tubular injury found in the histopathological examination of high dose males. The fact, that these effects were strictly limited to male rats and that the test substance belongs to a category of substances which are known for their ability to induce nephropathy in male rats due to their exclusive expression of ?2u-globulin, the protein known to play the crucial role in the onset of this disease, the observed effects in the kidney have to be regarded as species-specific and therefore not relevant for risk assessment in humans. Therefore, these effects were not considered for the determination of the NOAEC. Renal effects were strictly limited to males, therefore the authors concluded an ?2u-globulin-related mechanism for the observed nephropathy. The observation was not considered for determination of the NOAEC.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

12 470 mg/m³

Study duration:

subchronic

Experimental exposure time per week (hours/week):

84

Species:

rat

Quality of whole database:

1 short-term study, 3 key sub-chronic studies from structural analogues and 1 substance specific chronic study available for assessment.

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

a short-term toxicity study does not need to be conducted because a reliable sub-chronic (90 days) or chronic toxicity study is available, conducted with an appropriate species, dosage, solvent and route of administration

Critical effects observed:

not specified

Reference 2

Endpoint:

sub-chronic toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There is no short-term repeated dose toxicity data is available for Hydrocarbons, C7, n-alkanes, isoalkanes, cyclics. Sub-chronic data is available for structural analogues Heptane and Hydrocarbons, C7 -C9, isoalkanes. Chronic data is available for Hydrocarbons, C7, n-alkanes, isoalkanes, cyclics. The data is read across to Hydrocarbons, C7, n-alkanes, isoalkanes, cyclics 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:

 

An OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents) 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.

 

Inhalation:

 

Heptane

In a 4 -week inhalation study (Simonsen and Lund, 1995) with rats the substance heptane was tested. There were no differences in mean body weight gain until after cessation of exposure. From the termination of exposure over the remaining 8 weeks of the study, the body weight gain in n-heptane exposed rats was lower than in controls, statistically significant at 4000ppm. For the ABR, measured wave forms recorded with implanted and needle electrodes were similar but amplitudes were largest with implanted electrodes. The overall ratio between amplitudes was 1.4 for peak Ia and 2.5 for peak IV of the ABR. Exposure to 4000ppm reduced the amplitudes of components Ia and IV, most consistently for IV and most pronounced at higher frequencies (16, 32 kHz) and intensities (65-95 dB). The reduction in ABR corresponds to an increase in auditory threshold of approximately 10dB at all frequencies. Neither latency nor interpeak latencies of components Ia or IV were changed. Under the conditions of this test, n-heptane induced a loss of auditory sensitivity equal to 10dB in male rats exposed to 4000ppm for 28 days and tested by measurement of auditory brain stem response 2 months after cessation of exposure. No clinical signs of neuropathy were observed. Under the test conditions, Normal-Heptane induced a loss of auditory sensitivity equal to 10dB in male rats (NOAEC: 3.3 mg/L air (analytical)).

 

In a 16 -week inhalation study (Takeuchi et al. 1980, 1981, Ono et al. 1979) with rats the substance heptane was tested. Body weight gain was statistically significantly depressed (p<0.01) after 8 weeks of exposure compared to controls but gradually increased throughout the experiment, albeit to body weight levels below control values, but not statistically significantly lower. There were no statistically significant differences in motor nerve conduction velocity, distal latency or mixed nerve conduction velocity in any region of the tail. Under the test conditions, it was conducted that normal-heptane is not a neurotoxicant in this assay system.

 

In a 26 -week inhalation study (Shell, 1980) with rats the substance heptane was tested. The only treatment-related observations were labored breathing or rapid breathing and slight prostration during the first week of study during exposure only, and anogenital fur and dry rales during weekly observations. The in chamber signs were generally more numerous and severe in the higher dose group and appeared to abate by the second week of the study. Serum alkaline phosphatase was slightly elevated in high dose females and slightly elevated in low dose females. All other clinical chemistry values appeared normal with the exception of one high dose male with markedly elevated serum glutamic pyruvic transaminase and serum alkaline phosphatase levels compared to all other male rats on test. Under the conditions of this study, the LOAEL determined for the test substance, Normal-Heptane, for acute CNS depression and the NOAEL for systemic toxicity is 12.35 mg/L (re-calculated from 2,970 ppm).

 

Hydrocarbons, C7 -C9, isoalkanes

In a 12 -week inhalation study (Exxon, 1979) with rats the test substance hydrocarbons, C7 -C9, isoalkanes was tested. Significantly increased mean kidney weights and kidney/body weight ratios were observed in males at 400 ppm, which were considered to be treatment-related by the authors of the study. The kidney was confirmed as potential target organ for the test material-induced toxicity by the observation of mild tubular injury found in the histopathological examination of high dose males. The fact, that these effects were strictly limited to male rats and that the test substance belongs to a category of substances which are known for their ability to induce nephropathy in male rats due to their exclusive expression of ?2u-globulin, the protein known to play the crucial role in the onset of this disease, the observed effects in the kidney have to be regarded as species-specific and therefore not relevant for risk assessment in humans. Therefore, these effects were not considered for the determination of the NOAEC. Renal effects were strictly limited to males, therefore the authors concluded an ?2u-globulin-related mechanism for the observed nephropathy. The observation was not considered for determination of the NOAEC.

 

Hydrocarbons, C7, n-alkanes, isoalkanes, cyclics

In a chronic supporting study, the only significant toxic effect of chronic exposure to inhaled MCH found was renal change in male rats. The exposure related renal injury was not seen in female rats and in other species (mice, hamsters and dogs). Only male rats exposed to 2000 ppm MCH had significantly greater incidence of renal tubular dilation at exposure termination, and progression of renal pathology to papillary hyperplasia and medullary mineralization occured only in the group exposed to the higher level.

In this study, 400 ppm MCH had no pathologic effects on male rat kidney that could be distinguished from controls. Under the conditions of this inhalation study, exposure to 2000 ppm MCH produced no tumors. The test substance is not classified according to EU GHS.

Justification for classification or non-classification

Based on available substance specific and read across data, Hydrocarbons, C7, n-alkanes, isoalkanes, cyclics does not meet the classification for repeated dose toxicity (STOT-RE) under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP).