Hydrocarbons, C10-C12, isoalkanes, <2% aromatics

Endpoint summary

Description of key information

Oral NOAEL (Rat): >1000 mg/Kg bw/day

Inhalation NOAEC (Rat): ≥ 10400 mg/m³

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1989-11-07 to 1990-12-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to or similar to guideline study OECD 408: no data on GLP.

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

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, Kingston, New York, USA
- Age at study initiation: Approximately 6 to 7 weeks
- Weight at study initiation: Males, 204.3 to 246.7 grams; Females, 151.2 to 191.8 grams
- Fasting period before study: none
- Housing: Individual (except during the first two weeks of acclimation)
- Diet (e.g. ad libitum): Purina Certified Rodent Chow #5002 (mash), ad libitum; Ralston Purina Company, St. Louis, Missouri USA.
- Water (e.g. ad libitum): Automatic watering system, ad libitum
- Acclimation period: 13 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 68-76 degrees F
- Humidity (%): 40-70% relative humidity
- Photoperiod (hrs dark / hrs light): 12 hours light/12 hours dark


IN-LIFE DATES: From: 1989-11-20 To: 1990-04-18

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The test material was diluted in carrier to the appropriate concentration by the Compound Preparation Department. Fresh dosing solutions were prepared at least weekly and maintained under a nitrogen blanket until used.

VEHICLE
- Concentration in vehicle: 0.1, 0.5, or 1.0 g/kg
- Amount of vehicle (if gavage): 2 ml/kg
- Lot/batch no. (if required): Corn oil (Mazola), Best Foods, CPC. The following batch/lot numbers were used: SEPT2690B, OCT2090B, JAN0191A, FEB1591B, JUN0391A, JUN0491A, JUN1191A
- Purity: 100%

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentration analyses were performed every 4 weeks by the testing laboratory, with an exception for the last analysis which was performed at five weeks.

Duration of treatment / exposure:

Seven days per week

Frequency of treatment:

13 weeks

Remarks:

Doses / Concentrations:
0.1, 0.5, and 1.0 g/kg
Basis:
other: gavage dose

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Post-exposure recovery period in satellite groups: 28 days

- Two additional groups of ten males each at the Control and 0.5 g/kg dose levels were added following excessive premature mortality due to gavage accidents. The statistical t-test was performed to compare these added groups with the original male animals at these dose levels to assure they were statistically similar before combining the groups.

Positive control:

None.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Twice daily on Monday through Friday. Once daily on Saturdays, Sundays and holidays.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once daily

BODY WEIGHT: Yes
- Time schedule for examinations: During the week prior to dosing, at dosing initiation (Day 0), and weekly thereafter. Additionally, body weights were recorded at the scheduled sacrifice and at death for animals which succumbed prior to study termination.

FOOD CONSUMPTION
- Time schedule for examinations: Measured weekly during the test period.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Prior to dose initiation and prior to scheduled terminal sacrifice (5 to 8 days). Animals in the satellite group were examined approximately one week prior to both the main study terminal sacrifice and the recovery terminal sacrifice.
- Dose groups that were examined: All

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Pre-dose, day 32, and terminal sacrifice (Days 92 and 93 for the main study animals; Day 120 for the satellite group)
- Anaesthetic used for blood collection: Yes (methoxyflurane)
- Animals fasted: Yes (overnight)
- How many animals: All animals
- Parameters checked: erythrocyte count, hematocrit, hemoglobin, leukocyte count (total and differential), mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelets, reticulocyte count.
- Note: Slides were prepared for reticulocyte count but not evaluated since RBC parameters appeared normal.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Pre-dose, day 32, and terminal sacrifice (Days 92 and 93 for the main study animals; Day 120 for the satellite group)
- Anaesthetic used for blood collection: Yes (methoxyflurane)
- Animals fasted: Yes (overnight)
- How many animals: All animals
- Parameters checked: albumin, blood urea nitrogen, calcium, cholesterol, creatinine, electrolytes (Na+, K+, Cl-), gamma glutamyl transferase, glucose, phosphorus, serum alanine transferase, serum aspartate aminotransferase, total bilirubin, total protein, triglycerides

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
- Included: physical examination of the external surface, all orifices, the carcass, the cranial, thoracic and abdominal cavities with their associated organs and tissues.
- The following tissues and organs were taken and preserved in 10% neutral buffered formalin for all animals: adrenals, aorta, brain (three levels), epididymides, esophagus, eyes with optic nerve, femoris muscle with sciatic nerve, femur, heart, kidneys, lacrimal gland, large intestine colon and cecum, liver, lungs, mammary glands, mesenteric lymph nodes, ovaries, oviducts, pancreas, pituitary, prostate, rectum, salivary glands, seminal vesicles, skin, small intestine duodenum, jejunum, and ileum, spinal cord cervical mid-thoracic and lumbar, spleen, sternum with marrow, stomach, testes, thymus, thyroids/parathyroids, trachea, urinary bladder, uterus corpus and cervix, and all tissues showing abnormalities.

HISTOPATHOLOGY: Yes
- Preserved tissues from the control and high dose groups, as well as from all animals that succumbed during the study, were processed, sectioned, stained (hematoxylin and eosin) and examined microscopically. Gross lesions, tissue masses, liver, lungs and kidneys from the low and mid dose group were also processed, sectioned, stained and examined microscopically.
-At the completion of the satellite recovery period, tissues from the animals in this group were examined microscopically with particular emphasis on the organs and tissues which displayed toxic effects in the other treatment groups.

Statistics:

The following parameters were statistically analyzed for significant difference:
mean hematology parameters
mean serum chemistry parameters
mean organ weights
mean organ to body weight ratios
mean body weights, by weighing period

Comparisons were limited to within sex analysis. Statistical evaluation of equality of means was done by an appropriate one-way ANOVA and a test for ordered response in the dose groups. First Bartlett's test was performed to determine if the dose group have equal variance. If so, the testing was done using parametric methods; otherwise nonparametric techniques were used.

Parametric methods: one-way ANOVA using the F distribution with Dunnett's post-test; regression analysis for linear response in the dose group; linear lack of fit

Nonparametric methods: Kruskall-Wallis test for equality of means with Dunn's Summed Rank post-test; Jonckheere's test for monotonic trend in the dose response

Bartlett's test was conducted at the 1% level of significance. All other tests were conduced at the 5% and 1% level of significance.

The statistical t-test was used to compare the additional control and 0.5 g/kg group animals to the original animals at these dose levels in order to justify their combination. In addition, the t-test was used to compare the high dose and satellite groups to ensure similar results in order to accurately evaluate the recovery effects.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Details on results:

CLINICAL SIGNS AND MORTALITY
- Minimal clinical in-life observations were noted in the majority of animals and were considered to be incidental and not treatment-related. These observations included a very low incidence of sores, scabs, alopecia, dyspnea, rales, soft stool, nasal discharge, ocular and dental abnormalities, urine staining, unthrifty coat, and signs of general poor health.
- Treatment-related mortality was not apparent at any dose level. All deaths occuring prior to Day 12 were considered to be the result of dosing accidents, as well as deaths on Day 45 and Day 68.

BODY WEIGHT AND WEIGHT GAIN
Overall increases in body weight were noted for all animals surviving to scheduled study termination. There were no statistically significant differences between the control and test animals' body weights nor between the high dose and the satellite animals' mean body weights.

FOOD CONSUMPTION
There were no significant differences in the food consumption values for the treated males when compared to the control animals. Dose related increases were evident in the mean food consumption values for treated females over most of the weighing periods, however, these findings are not considered to be an adverse effect.

OPHTHALMOSCOPIC EXAMINATION
No treatment-related findings noted at the terminal ophthalmological examination.

HAEMATOLOGY
The changes noted in the hematology values were considered to be minimal and not biologically significant. A trend toward anemia in high dose males was suggested by a dose-related decrease in male red blood cells, hematocrit, and hemoglobin observed at both the interim and terminal analysis; however, these changes were within the range of normal biological variation. There were no significant differences noted in any hematology parameter in female animals at either the interim or terminal analysis.

CLINICAL CHEMISTRY
Many small differences were noted in in treated groups compared to controls, but the majority were considered to be within normal biological variation and thus not biologically significant. Effects that were considered to be biologically significant included a dose-related decrease in triglyceride values in male animals at both the interim and study termination analyses (mid- and high-dose groups statistically different from controls). After the recovery period, mean male triglyceride values increased nearly two-fold such that they were equivalent to the terminal value of control animals. In female animals, a dose-related decrease in aspartate animotransferase occured at study termination, reaching statistical significance in the mid- and high-dose groups. No recovery effect was noted in the satellite animals. While these findings indicate a persistent effect, there were no corresponding histopathologic changes to indicate organ damage.

ORGAN WEIGHTS
Mean liver weights and mean relative liver weights for the 500 mg/kg (15 and 21% respectively for males; 32 and 36% respectively for females) and the 1000 mg/kg (22 and 28%, respectively for males; 31 and 25% respectively for females) dose group animals were significantly greater than the control group values. Histopathologic examination of these tissues revealed slight differences in the comparison of liver cell size between all dose groups and the controls. However, these differences were not sufficient to account for the observed increases in the mean and relative liver weights for the mid- and high-dose groups. Comparison of the liver weight parameters in the satellite group and the high dose group following the 28 day recovery period indicates that these changes were reversible following cessation of dosing. Other effects not considered related to treatment included an increase in female mean kidney weight and an increase in the mid dose male relative kidney and testes weights.

GROSS PATHOLOGY
No observable effects in the majority of animals. There were single or low incidences of kidney, lymphoid, spleen, uterus, ocular, dental, adrenal, skin/fur and lung abnormalities noted intermittently among all groups. One mid-dose female was noted with a subcutaneous mass incorporating the vagina and rectum and one satellite female with a kidney and oviduct mass.

HISTOPATHOLOGY: NON-NEOPLASTIC
No microscopic changes related to treatment were observed in any animal in any dose group. All animals who died prior to study termination (except one control female) had lesions in the thoracic cavity consistent with intubation accidents. There were no significant findings in the control female that could clearly be associated with a cause of death.

Key result

Dose descriptor:

NOAEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: No treatment-related mortality or significant adverse clinical effects occurred.

Key result

Critical effects observed:

not specified

Conclusions:

The NOAEL for rats orally exposed to Isopar M (MRD-89-526) is greater than 1000 mg/kg body weight, based on the lack of treatment-related mortality and adverse clinical effects.

Executive summary:

A 90 -day subchronic study was conducted in rats to assess the toxicity of Isopar M (MRD-89 -256). The test mixture was administered by oral gavage at a dose of 0, 100, 500, or 1000 mg/kg, 7 days per week for a period of 13 weeks. The control animals received a carrier (corn oil) dose and a satellite group was dosed at 1000 mg/kg, 7 days/week for 13 weeks and was then observed for reversibility, persistence or delayed occurrence of toxic effects for 28 days post-treatment. Observations were made as to the nature, onset, severity, and duration of toxicological signs. No treatment-related mortalities or clinical effects were observed. Animals in all dose group exhibited an overall mean weight gain. Minimal changes were noted in the hematology and serum chemistry values, however, all were considered to be either within normal biological variation or not adverse effects. The mean absolute and relative liver weights for both the 500 and 1000 mg/kg dose groups (both sexes) were significantly greater than the corresponding control values; however, these changes were found to be reversible following the 28 day recovery period. Slight increases in mean kidney weights were also noted in the 500 and 1000 mg/kg female dose groups, however, these changes were not considered to be adverse effects. All histopathological findings were minimal and no treatment related adverse effects were noted. Based on the data recorded in this study, the NOAEL for Isopar M is greater than 1000 mg/kg.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Only study available.

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1980

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented study report equivalent or similar to OECD guideline 413.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

GLP compliance:

not specified

Species:

rat

Strain:

other: albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Shell Toxicology Laboratory Breding Unit
- Age at study initiation: 10-13 weeks
- Housing: three of one sex per cage
- Diet (e.g. ad libitum): ad libitum except during exposure
- Water (e.g. ad libitum): ad libitum

During the period of the test the laboratory temperature varied between 19.4°C and 26.1°C and the relative humidity between 37% and 74%.
Barometric pressure was within the range 753 to 768 mm Hg

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: no data

Details on inhalation exposure:

The atmospheres were generated by completely evaporating the solvent into the streams of ventilating air entering the chambers using micrometering pumps and vaporizers. The vaporizers consisted of electrically heated quartz tubes whose surface temperatures were adjusted during preliminary experiments to the minimal for complete evaporation of the solvent.

Each chamber was constructed of aluminum, with a volume of 1 m3 and was ventilated by air drawn from the laboratory through dust filters. The exhaust ducts from each chamber entered a common exhaust duct through which the air was drawn by a fan situated on the roof of the laboratory.

The total air flow rate through the main duct exhausting all four chambers was recorded continuously throughout the test by means of an electro—anemometer mounted in the duct. Slight adjustments were made as required to compensate for the effects of wind at the efflux point. The total flow rate was maintained at 2.0 + 0.03 m3 ∙min- 1. The individual flow rates through each chamber were balanced before the exposures began but were not checked further throughout the test since any significant changes would have been detected by the resulting changes in toxicant concentration. The flow rates were adjusted to 0.50 m3 ∙min- 1.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The test atmospheres were analyzed sequentially by means of a total hydrocarbon analyzer fitted with a flame-ionisation detector (Beckman 109A). The analyzer was calibrated during the test by means of known concentrations of SHELLSOL TD, prepared in a Teflon FEP gas sampling bag.

The recorder traces from the analyser were examined daily and a ‘daily mean concentration’ value was estimated by visual inspection. The daily mean concentrations for each of the test atmospheres were then ‘pooled’ to give weekly mean concentrations. The overall means of the weekly mean concentrations are given below:
Nominal concentration Observed concentration
(mg/m3) (mg/m3) (ppm)
10400* 10186 SD 327 1444
5200 5200 SD 207 737
2600 2529 SD 116 359
*83% saturated.

The desired concentrations of solvent in the test atmospheres were reached within 10 mm of the start of each exposure period. They then stayed remarkably constant throughout the 6 h exposure period.

Duration of treatment / exposure:

Six hours/day

Frequency of treatment:

five days/week for 13 weeks

Remarks:

Doses / Concentrations:
0, 2600, 5200, 10400 mg/m3
Basis:
nominal conc.

No. of animals per sex per dose:

6 animals/sex/dose (total of 12 animals/dose)

Control animals:

yes, sham-exposed

Details on study design:

The start and finish of the experiment was staggered in order that the optimum number of animals could be examined histopathologically after exposure. On each of four consecutive days, four male and four female rats per chamber were started on the experiment. The remaining two males and two females were started the next day. Thirteen weeks later, four male and four female rats per chamber were removed from the experiment for pathological examination on each of four consecutive days. The remaining two males and two females were removed the next day.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule for examinations: daily

DETAILED CLINICAL OBSERVATIONS: Yes


BODY WEIGHT: Yes
- Time schedule for examinations: weekly


FOOD CONSUMPTION:
- Food consumption for each animal determined weekly: Yes


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data


WATER CONSUMPTION: Yes
- Time schedule for examinations: weekly


OPHTHALMOSCOPIC EXAMINATION: No



HAEMATOLOGY: Yes
- Time schedule for collection of blood: 18h after the last 13 week exposure
- How many animals: all


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: 18h after the last 13 week exposure
- How many animals: all



URINALYSIS: Yes / No / No data
- Time schedule for collection of urine:
- Metabolism cages used for collection of urine: Yes / No / No data
- Animals fasted: Yes / No / No data
- Parameters checked in table [No.?] were examined.


NEUROBEHAVIOURAL EXAMINATION: No



OTHER:

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes for all animals exposed to the high and medium concentrations, plus the control animals. Kidneys of low concentration males were also examined.

Other examinations:

Organ weights
After post-mortem examinations the following organs were weighed:
Brain
Liver
Heart
Spleen
Kidneys
Testes

Histopatholgy. Tissues taken for histological examination were:

Mammary gland (posterior site with skin)
Mesenteric lymph node
Pancreas
Stomach
Intestine at 5 levels
Caecum
Spleen
Liver (middle, left and triangular lobes)
Adrenals
Kidneys
Ovaries or testes
Uterus or prostate
Seminal vesicles
Urinary bladder
Thyroid (with oesophagus and trachea)
Trachea (mid course and bifurcation)
Heart
Lungs
Nasal cavity
Thymus
Eye and lacrimal glands
Salivary gland (submaxillary)
Brain
Spinal cord (thoracic)
Pituitary
Tongue
Sciatic nerves
Muscle (femoral)
Knee joint and femur
Plus any other macroscopic lesion in any tissues.
The samples marked were held in 4% neutral formalin and only processed for histological examination if indicated by clinical or other pathological findings.

Statistics:

Body and organ weights were analysed by covariance analysis using initial body weight as the covariate. Reported means were adjusted for initial body weight if a significant covariance relationship existed: where no significant covariance relationship was found, unadjusted means were reported.

Organ weights were further examined by covariance analysis using the terminal body weight as the covariate. The organ weight means are reported as adjusted for terminal body weight if a significant covariance relationship existed. Although not a true covariance analysis (because the terminal body weights are dependent upon treatment), the analysis does provide an aid to the interpretation of organ weights when there are differences in terminal body weights. The analysis attempts to predict what the organ weights would have been, had all the animals had the same terminal body weight.
Clinical, chemical and haematological parameters were examined using analysis of variance.

The analysis allowed for the fact that animals were multihoused. Differences in response can be affected by cage environment as well as by treatment but this effect is minimal in a study of this duration.
The significance of any difference between treated and control group means was tested using the Williams t test (1971, 1972). However, if a monotonic dose response could not be assumed Dunnett’s test (1964) was used.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

No deaths were recorded and clinical signs of toxicity were absent in the low and medium exposure groups; the high exposure groups were slightly lethargic when examined up to one hour after cessation of exposure. Body weight gain was slightly reduced in all female groups and in high exposure males. Water intake was increased in the high exposure males only.

Female aspartate amino transferase and alanine amino transferase were decreased in all female groups exposed to SHELLSOL-TD. No pathological changes were detected which could explain the observed decreases in these enzymes. In view of this lack of supporting evidence and the fact that the control values for these two parameters were high when compared with historical controls in the laboratory, these changes were not considered toxicologically significant.

Male alkaline phosphatase, potassium, chloride and albumin were increased at the high exposure level. These were considered to represent biological variation in the rat and were not considered treatment-related.

Male kidney weights were increased at all exposure levels. Hyaline intracytoplasmic inclusions and an increased incidence of tubular degeneration and/or dilatation were seen in the cortical tubules of all exposed males. These are a common effect observed in repeated-dose animal studies with hydrocarbon solvents. These kidney changes have been identified to result from an alpha2u-globulin-mediated process that because of its sex and species specificity, is not regarded as relevant to humans.

A low grade anemia was evident in all males exposed to SHELLSOL TD, characterized by slight reductions in haemoglobin, packed cell volume and total erythrocyte counts. Splenic weight was increased in the high concentration males. These changes were not seen in females and were not considered dose-related and therefore considered not toxicologically relevant.

Male and female liver weights were increased at the high and medium exposures, and male liver weights at the low exposures also. No lesions were identified histologically in the livers of treated animals that could account for the increased weight. This change was considered a physiological response to exposure rather than a toxic response and as such is not of toxicological significance.

Key result

Dose descriptor:

NOAEC

Effect level:

> 10 400 mg/m³ air (nominal)

Sex:

male/female

Basis for effect level:

other: No treatment-related mortality or significant adverse clinical effects occurred.

Key result

Critical effects observed:

not specified

Conclusions:

The NOAEC for SHELLSOL TD is 10186 mg/m3 (actual) (1444 ppm) under the test conditions of this study.

Executive summary:

SHELLSOL TC was administered by inhalation to albino rats for 6 hours/day, 5 days/week for 13 weeks at nominal vapor concentrations of 10400 mg/m³, 5200 mg/m³, and 2600 mg/m³ to assess inhalation toxicity.  No mortality or treatment-related effects in any of the hematology and serum chemistry values were observed.  Liver and kidney weights were increased in male rats at all exposure levels, male heart weights were increased at the highest exposure level and liver and kidney weights were increased in female rats at 10400 mg/m3.  In addition, the male rats exposed to SHELLSOL TC at all concentrations showed tubular degeneration and hyaline inclusion-droplets in the epithelium.  There was also scattered degeneration of the proximal renal tubules which showed cytoplasmic pallor and shrinkage. Occasionally the degenerate tubules were surrounded by a lymphocyte infiltrate. Many tubules also showed dilatation of the cortico-medullary junction, the dilated tubule being filled with a flocculent eosinophilic material. The kidney effects observed in male rats are indicative of alpha-2u-globulin nephropathy.  Alpha-2u-globulin nephropathy, also known as hyaline droplet nephropathy, results from the formation of complexes with a naturally occurring protein (alpha-2u-globulin) in the kidneys of male rats.  These complexes can accumulate in the proximal renal tubule and may produce species-specific histopathological changes.  These kidney effects are specific to male rats and are not considered to be of biological relevance to humans.  Histopathological examination did not reveal any abnormalities that were considered treatment related.  As there were no pathologic changes, changes in organ weights mentioned above were judged to have been compensatory rather than toxic effects.  Based on these results, the No Observed Adverse Effect Concentration (NOAEC) was greater than or equal to 10400 mg/m³.

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:

The justification for read across is provided 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

Key result

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 alpha-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 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. Renal effects were strictly limited to males, therefore the authors concluded an alpha-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

10 400 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

Two key read across studies availablle from structural analogues.

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There is data available for Hydrocarbons, C10-C12, isoalkanes, <2% aromatics. Additionally, data is also available for structural analogue, Hydrocarbons, C7-C9, isoalkanes. This data is read across to 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

Hydrocarbons, C10-C12, isoalkanes, <2% aromatics

A key 90-day subchronic toxicity study was conducted in rats to assess the toxicity of Hydrocarbons, C10-C12, isoalkanes, <2% aromatics (ExxonMobil Corp., 1990). The test mixture was administered by oral gavage at a dose of 0, 100, 500, or 1000 mg/Kg, 7 days per week for a period of 13 weeks. The control animals received a carrier (corn oil) dose and a satellite group was dosed at 1000 mg/Kg, 7 days/week for 13 weeks and was then observed for reversibility, persistence or delayed occurrence of toxic effects for 28 days post-treatment. Observations were made as to the nature, onset, severity, and duration of toxicological signs. No treatment-related mortalities or clinical effects were observed. Animals in all dose group exhibited an overall mean weight gain. Minimal changes were noted in the haematology and serum chemistry values, however, all were considered to be either within normal biological variation or not adverse effects. The mean absolute and relative liver weights for both the 500 and 1000 mg/kg dose groups (both sexes) were significantly greater than the corresponding control values; however, these changes were found to be reversible following the 28 day recovery period. Slight increases in mean kidney weights were also noted in the 500 and 1000 mg/kg female dose groups, however, these changes were not considered to be adverse effects. All histopathological findings were minimal and no treatment related adverse effects were noted. Based on the data recorded in this study, the NOAEL was determined to be greater than 1000 mg/Kg.

Additionally, in order to comply with standard information requirements for Annex X substances, OECD Guideline 90-day sub-chronic (OECD 408) toxicity tests are proposed for structural analogues Hydrocarbons, C7-C9, isoalkanes, <2% aromatics (EC# 921-728-3) and Isohexadecane (2,2,4,4,6,8,8-heptamethylnonane (EC# 224-506-8)). The testing proposals for the same have been presented in the lead registrant dossiers for these substances already submitted to ECHA. These studies will be conducted subsequent to ECHA's approval and this endpoint will be updated upon completion of the above studies.

Inhalation

Hydrocarbons C7-C9, isoalkanes, <2% aromatics

Systemic toxicity of hydrocarbons, C7-C9, iso-alkanes was assessed in a 12-week inhalation toxicity study in rats (ExxonMobil Chemical,1979). In this study, repeated exposure to 400 or 1200 ppm of the test substance for 6 hours/day, 5 days/week, for 12 weeks resulted in male rat kidney effects consistent with the alpha-2µ-globulin-induced nephropathy in male rats. There was no treatment-related mortality and clinical findings were unremarkable. Under the test conditions, the NOAEC (excluding male rat nephropathy) was determined to be >1200ppm.

The fact, that alpha-2µ-globulin-induced nephropathy was 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-2µ -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 are not relevant for risk assessment in humans. Therefore, additional experimental data were used to evaluate repeated dose toxicity via inhalation.

Hydrocarbons, C10-C12, isoalkanes, <2% aromatics

In a key sub-chronic toxicity study (Shell, 1980), the test material (Hydrocarbons, C10-C12, isoalkanes, <2% aromatics) was administered by inhalation to albino rats for 6 hours/day, 5 days/week for 13 weeks at nominal vapor concentrations of 10400 mg/m³, 5200 mg/m³, and 2600 mg/m³ to assess inhalation toxicity.  No mortality or treatment-related effects in any of the hematology and serum chemistry values were observed.  Liver and kidney weights were increased in male rats at all exposure levels, male heart weights were increased at the highest exposure level and liver and kidney weights were increased in female rats at 10400 mg/m³.  In addition, the male rats exposed to the test material at all concentrations showed tubular degeneration and hyaline inclusion-droplets in the epithelium.  There was also scattered degeneration of the proximal renal tubules which showed cytoplasmic pallor and shrinkage. Occasionally the degenerate tubules were surrounded by a lymphocyte infiltrate. Many tubules also showed dilatation of the cortico-medullary junction, the dilated tubule being filled with a flocculent eosinophilic material. The kidney effects observed in male rats are indicative of alpha-2u-globulin nephropathy.  Alpha-2u-globulin nephropathy, also known as hyaline droplet nephropathy, results from the formation of complexes with a naturally occurring protein (alpha-2u-globulin) in the kidneys of male rats.  These complexes can accumulate in the proximal renal tubule and may produce species-specific histopathological changes.  These kidney effects are specific to male rats and are not considered to be of biological relevance to humans.  Histopathological examination did not reveal any abnormalities that were considered treatment related.  As there were no pathologic changes, changes in organ weights mentioned above were judged to have been compensatory rather than toxic effects.  Based on these results, the No Observed Adverse Effect Concentration (NOAEC) was determined to be greater than or equal to 10400 mg/m³.

In a supporting sub-chronic toxicity study (ExxonMobil Corp., 1978), the test material (Hydrocarbons, C10-C12, isoalkanes, <2% aromatics) was administered by inhalation to rats at vapor concentrations of 300 or 900 ppm for 6 hours/day, 5 days/week for 12 weeks.  No treatment-related effects on mortality were observed and there were no significant alterations in hematology or clinical chemistry parameters.  Body weights were decreased and kidney weights were elevated in male rats at 300 and 900 ppm.  Relative mean liver weights were elevated in males at 900 ppm, but no changes were noted in histopathology.  Under the conditions of this study, the No Observed Adverse Effect Concentration (NOAEC) was determined to be greater than 900 ppm (> 5220 mg/m³).

In a supporting short-term toxicity study (Chevron Phillips, 1969), four rhesus monkeys were exposed to 4.2 mg/L of the test material (Hydrocarbons, C10-C12, isoalkanes, <2% aromatics) for 6 hours/day, for 3 days a week for 4 weeks. A total of 13 treatments were completed. There were no noted changes in behavior, clinical chemistry, hematological, or histopathological parameters. The NOAEC in primates was determined to be > 4.2 mg/L (> 4200 mg/m³).

Justification for classification or non-classification

Based on available data, Hydrocarbons, C10-C12, isoalkanes, <2% aromatics do not meet the criteria for classification for repeated dose toxicity (STOT-RE) under the new Regulation (EC) 1272/2008 on classification, labeling and packaging of substances and mixtures (CLP).