Dodecane

Endpoint summary

Description of key information

Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test – NOAEL ≥ 1000 mg/kg for rats (OECD 422)

Repeated Dose Oral 90d - NOAEL ≥ 5000 mg/kg bw/day for rats (OECD 408)

Repeated Dose Inhalation 90d – NOAEC ≥ 10400 mg/m³ for rats (similar to OECD TG 413)

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to or similar to guideline study OECD 422: GLP

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 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

yes

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

Males were treated from day 14 prior to the mating phase until the end of the mating phase and then killed, Females were treated from day 14 prior to mating, through day 4 of lactation and then killed.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Males were treated from day 14 prior to the mating phase until the end of the mating phase and then killed, Females were treated from day 14 prior to mating, through day 4 of lactation and then killed.

Frequency of treatment:

7days/week

Remarks:

Doses / Concentrations:
0, 25, 150, or 1000 mg/kg/day (10 ml/kg dosing volume)
Basis:
other: gavage

No. of animals per sex per dose:

10 male, 10 female per group
Control group: 10 male, 10 female, 0.5% methylcellulose

Control animals:

yes

Observations and examinations performed and frequency:

Effects on general toxicity, neurobehavioral activity, clinical chemistry, and hematology were evaluated. Gross necropsies and histopathologic examination of tissues were conducted with emphasis on the male reproductive tract.

Sacrifice and pathology:

All surviving animals were sacrificed following dosing

Statistics:

Adult body and organ weight, food consumption, clinical chemistry, open field activity and hematologic data (raw or transformed) were compared using either parametric or nonparametric (Kruskal-Wallis) ANOVA depending on whether the data were found to be homogeneous or nonhomogeneous using Bartlett's homogeneity of variance procedure. If ANOVA analysis indicated significant differences, Dunnett's test and Mann Whitney's U test, for parametric and nonparemetric data, respectively, were used to analyze for differences between the various dose groups.

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 specified

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

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 or clinical signs of toxicity or behavioral changes were noted. No significant differences in body weights or feed consumption were observed. Startle reflex, open field test, and forelimb grip reflex performance data also revealed no treatment-related findings.
There were also no treatment-related changes in hematology or blood chemistry parameters, organ weights or gross pathology. An apparent treatment-related, slight to moderate hyperplasia of the non-glandular mucosa of the stomach, associated with degeneration, hyperkeratosis and submucosal subacute inflammation and, in a few cases, with erosion, was seen in animals of all treated groups. This effect was considered an artifact of the dosing method and not directly related to the toxicity of the test material. No other treatment related histological changes were observed.

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

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

Critical effects observed:

not specified

Conclusions:

Based on these data, the no-observable- adverse effect level (NOAEL) for repeated dose toxicty was >= 1000 mg/kg/day, the highest dose tested.

Executive summary:

Groups of 10 male and 10 female Sprague Dawley rats were dosed with decane daily by gavage at exposure levels of 0, 25, 150, or 1000 mg/kg/day. Males were dosed from the 14th day prior to mating, during mating until the end of the mating period. Females were dosed from the 14th day prior to the start of the mating phase to day 4 of lactation.  Oral dosing of decane produced no evidence of any adverse effects on clinical observations, organ weights, gross pathology, neurobehavioral activity, clinical chemistry or hematology endpoints. Evidence of irritation of the nonglandular mucosa of the stomach was observed, but was considered an artifact of the dosing method and not attributed to the inherent toxicity of the test material.  Based on these data, the no-observable- adverse effect level (NOAEL) for repeated dose toxicty was >=1000 mg/kg/day, the highest dose tested. 

Reference 2

Endpoint:

short-term repeated dose toxicity: oral

Type of information:

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

Adequacy of study:

weight of evidence

Study period:

1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to or similar to guideline study OECD 422:GLP.

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 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

Number of Animals: Males, 48; females, 48 (total)
Crj:CD (SD strain) SPF male and female rats 8 weeks old were purchased from Nippon Charles River Co., Ltd., and quarantined for 14 days. The administration was started when the animals were 10 weeks old, and the mean body weight (body weight range) of males at the start of administration was 400.3 g (374-431 g), and that of females was 226.5 g (192-255 g).

The animals were individually placed in metal bracket cages with a metal mesh floor before mating, one male and one female per cage during mating, one mother animal per cage during gestation, and a mother and her newborns after birth.

Animals were maintained in a barrier-isolated room with a temperature of 23 +/- 3°C, humidity of 55 +/- 10%, ventilation changes of 10-15 times per hour, and an illumination of 12 hr/day. After the 17th day of gestation, the metal mesh floor was changed to a stainless steel pan spread with a floor-covering material for experimental animals. Solid feed (CRF-1, manufactured by Oriental Yeast Industry Co., Ltd.), and tap water (tap water of the City of Sapporo) were given freely.

Route of administration:

oral: gavage

Vehicle:

olive oil

Details on oral exposure:

The administration of the test substance was carried out by oral gavage. The volume administered was 5 mL per kg of body weight, and it was calculated based on the results of body weight measured on the day closest to the day of administration. The administration period was 46 days, which included 14 days before mating and during the mating period for males. The administration period for the female rats began 14 days before mating and continued until after the first 3 days of nursing. The administration was started when the animals were 10 weeks old, and the mean body weight (body weight range) of males at the start of administration was 400.3 g (374-431 g), and that of females was 226.5 g (192-255 g).

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

The administration period was 46 days, which including 14 days before mating and during the mating period for males. The administration period for the female rats began 14 days before mating and continued until after the first 3 days of nursing.

Duration of treatment / exposure:

Once per day

Dose / conc.:

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

Remarks:

Vehicle

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

Female: 12; Male: 12 per dose

Control animals:

yes, concurrent no treatment

Observations and examinations performed and frequency:

General conditions, body weight and feed intake:
For all cases, the general conditions were observed once a day throughout the study term. The body weight measurements were carried out on the 1st (before administration), 2nd, 5th, 7th, 10th and 14th day after administration and subsequently, every 7 days (including the last day of administration) as well as 0th, 1st, 3rd, 5th, 7th, 10th, 14th, 17th and 20th day of gestation and the 0th, 1st and 4th day of nursing for females. In addition, the body weight gain and rate were calculated from the 1st day of administration to the 46th day for males and for females, from the 1st day to the 14th day, 0th day to the 20th day of gestation and 0th day to the 4th day of nursing. The amount of feed intake was measured on the same days as those of body weight measurements except mating period and dissection day for males and 0th day of gestation and 0th day of nursing for females. Incidentally, with respect to the number of day of pregnancy, the successful copulation day was set as the 0th day of gestation, and in the case of lactation, the day of delivery completion was set as the 0th day of nursing.

Urinary tests:
In the final week (43rd-44th day of administration) during the administration term, 6 male cases of each group were placed in metabolism-measurement cages, and their urine samples were collected under non-starvation conditions. For urine samples, collected in about 3 hr, pH, protein, glucose, ketone, urobilinogen, bilirubin, occult blood reaction, and sedimentation (microscopic observation) were tested, and for urine samples collected for 21 hr, volume, and specific gravity were measured. In addition, the amount of drinking water (weight) in urine samples was also measured.

Hematological tests:
Before dissection, all male animals were starved for about 16 hr, blood samples were collected from the femoral vein under ether anesthesia, and EDTA•2K-treated blood samples were used to measure the erythrocyte count, mean erythrocyte volume, platelet count, leucocyte count, hemoglobin content (cyanmethemoglobin method), hematocrit (calculated from erythrocyte count and mean erythrocyte volume), mean erythrocyte hemoglobin content (calculated from erythrocyte count and hemoglobin content), mean erythrocyte hemoglobin concentration (calculated from hematocrit and hemoglobin content), reticulocyte proportion (Brecher method) and leucocyte fraction (microscopic observation). In addition, untreated blood samples were used to measure coagulation time (fluid viscosity change air pressure measurement, Gryner Microcogulometer). Furthermore, plasma samples, which were prepared by collecting blood samples from the abdominal aorta, treating with sodium citrate and subsequently carrying out centrifugation at 3,000 rpm for 10 min, were used to measure prothrombin time (thromboplastin method) and activated partial thromboplastin time (ellagic acid method).

Hematobiochemical test:
After the hematological tests, serum samples of all male cases, which were prepared by collecting from the abdominal aorta, were used to measure GOT, GPT (IFCC method), GPT (glutamyl-p-nitroanilide substrate clathrate method), choline esterase (butyrylthiocholine iodide substrate method), blood glucose (hexokinase method), total cholesterol and phospholipids (enzymatic method), triglyceride (free glycerol deduction method), total bilirubin (azobilirubin method), urea nitrogen (urease-indophenol method), creatinine (Yaffe method), calcium (OCPC method), inorganic phosphorus (Fiske-Subbarow method), total protein (Biuret method) and albumin (BCG method) (Hitachi automated analyzer, Model 7150); sodium and potassium (flame photometry: Corning flame photometer, Model 480); chlorine (coulometric titration method: Hiranuma chloride counter, Model CL-6M); A/G ratio (calculated from total protein and albumin); and protein fraction (cellulose acetate electrophoresis).

Sacrifice and pathology:

Dissection and organ weight measurement:
After the 46th day of administration, all males were sacrified ex sanguine under ether anesthesia after blood sampling and dissected. Any newborns that died were dissected immediately after discovery. Females that successfully copulated were sacrificed on the 4th day of nursing. Female rats who did not successfully copulate on the 25th day of gestation (infertile cases) on the 26th day of gestation were sacrified. The implantation sites in the uterus and corpus luteum of pregnancy in the ovaries were counted. In addition, the weight measurements were carried out for the liver, kidney, thymus gland, adrenal gland, testes, epididymis and ovary, and the ratio to body weight was calculated.

Histopathological observation:
The following tissues were embedded in paraffin and stained with hematoxylin-eosin or with oil red O staining/ luxol fast blue-Bodian double stain to conduct a histopathological examination: the liver, kidney, spleen, heart, lung, brain (cerebrum and cerebellum), hypophysis, thymus gland, adrenal gland, thyroid gland, stomach (anterior stomach and glandular stomach), duodenum, jejunum, ileum, cecum, colon, rectum, testes, epididymis, prostate gland, ovary and abnormal sites.

Statistics:

Fisher’s accuracy probability test was carried out to compare the control and undecane-administered groups for the sexual cycle, copulation index, fertility index, gestation index and nursing index. Other test parameters were analyzed by using Bartlett’s homogeneity of variance and subsequently single dimensional configuration variance analysis or Kruskal-Walls method. If the results were found to be significant, the Dunnett ‘s method or Mann-Whitney U-test method was used to compare the undecane-administered groups from the control group. However, those qualitative items in urinary tests were analyzed by using the Kruskal-Walls method and Mann-Whitney U-test method. The viability of newborns on the 4th day and body weight were analyzed using the litter as a unit and the results were compared with the control group. A significance level of less than 5% was considered to be statistically significant.

Clinical signs:

no effects observed

Mortality:

not examined

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:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

In males given 1000 mg/kg a decrease in hemoglobin concentration and an increase in white blood cell count was observed; however, no corresponding findings in females, autopsy, or histopathology were observed.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

In males given 1000 mg/kg a decrease in albumin, and increases in a2-globulin, GPT, cholinesterase and total cholesterol were observed; however, no corresponding findings in females, autopsy, or histopathology were observed.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Details on results:

In the repeat dose toxicity test, salivation was observed in males and females given 300 and 1000 mg/kg. Body weight gain was suppressed in males given 1000 mg/kg, and body weights were increased in females given 1000 mg/kg during the lactation period. Food consumption was decreased in males given 300 and 1000 mg/kg in the first half of the administration period, increased in males given 1000 mg/kg in the second half of the administration period, and increased in females given 1000 mg/kg in the second half of pregnancy and during the lactation period. Hematological and blood chemical examinations revealed a decrease in hemoglobin concentration, an increase in the white blood cell count, a decrease in albumin, and increases in a2-globulin, GPT, cholinesterase and total cholesterol in males given 1000 mg/kg. Relative liver weights and absolute and relative thymus weights were increased in males given 1000 mg/kg, and absolute and relative liver weights were elevated in females given 1000 mg/kg. No effects were detected in the autopsy or histopathology findings. Due to the lack of effects in both sexes and the lack of corresponding histopathology, these effects are determined not to be toxicologically relevant. The NOAEL for repeat dose toxicity is considered to be 1000 mg/kg/day for both sexes.

Dose descriptor:

NOAEL

Effect level:

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

Sex:

male/female

Basis for effect level:

other: No effects noted at highest dose tested.

Critical effects observed:

no

Conclusions:

The NOAEL for repeat dose toxicity is considered to be >=1000 mg/kg/day for both sexes. The NOAELs for reproductive performance is considered to be >=1000 mg/kg/day.

Executive summary:

In the repeat dose toxicity test, male and female rats were given 0, 100, 300 and 1000 mg/kg orally by gavage. Male rats were dosed from the 14^thday prior to mating and during the mating period. Female rats were dosed from the 14^thday prior to mating until after the 3^rdday of nursing. Salivation was observed in males and females given 300 and 1000 mg/kg. Body weight gain was suppressed in males given 1000 mg/kg, and body weights were increased in females given 1000 mg/kg during the lactation period. Food consumption was decreased in males given 300 and 1000 mg/kg in the first half of the administration period, increased in males given 1000 mg/kg in the second half of the administration period, and increased in females given 1000 mg/kg in the second half of pregnancy and during the lactation period. Hematological and blood chemical examinations revealed a decrease in hemoglobin concentration, an increase in the white blood cell count, a decrease in albumin, and increases in a2-globulin, GPT, cholinesterase and total cholesterol in males given 1000 mg/kg. Relative liver weights and absolute and relative thymus weights were increased in males given 1000 mg/kg, and absolute and relative liver weights were elevated in females given 1000 mg/kg. No effects were detected in the autopsy or histopathology findings. Due to the lack of effects in both sexes and the lack of corresponding histopathology, these effects are determined not to be toxicologically relevant. The NOAEL for repeat dose toxicity is considered to be 1000 mg/kg/day for both sexes.

Reference 3

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

key study

Study period:

1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented study report equivalent or similar to OECD guideline 408: GLP

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

Principles of method if other than guideline:

According to EPA guideline 82-1

GLP compliance:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague Dawley Inc.
- Age at study initiation: ca. 8 weeks
- Weight at study initiation: 238-295g (males); 180-236g (females)
- Housing: individual
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 16 days


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


IN-LIFE DATES: From: 1990-12-17 To:1991-07-13

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Test material was mixed with corn oil to ensure a 10ml/kg dose volume at all dose levels.

Test material mixtures were administered by oral gavage at a dose volume of 10ml/kg. The control animals received carrier at a dose of 10ml/kg. The satellite group was dosed at the high dose level for the same duration as main test and allowed to recover for 28 days post-treatment.

VEHICLE
- Amount of vehicle (if gavage): 10ml/kg

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

7 days/week

Remarks:

Doses / Concentrations:
5000 mg/kg
Basis:
actual ingested

Remarks:

Doses / Concentrations:
2500 mg/kg
Basis:
actual ingested

Remarks:

Doses / Concentrations:
500 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

10 animals/sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

Test material mixtures were administered by oral gavage at three different doses at a dose volume of 10ml/kg. The control animals received carrier at a dose of 10ml/kg. The satellite group was dosed at the high dose level for the same duration as the main test and allowed to recover for 28 days post-treatment.

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

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily monday-friday and once daily on weekends and holidays

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: prior to dosing, the day of dose initiation, and weekly thereafter

OPHTHALMOSCOPIC EXAMINATION: Yes
at study initiation and during the final week of the main study

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at main study termination and on satellite animals on the day of recovery sacrifice
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals:all

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at main study termination and on satellite animals on the day of recovery sacrifice
- Animals fasted: Yes
- How many animals: all

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

The following parameters were statistically analyzed for significant differences: mean hematology parameters, serum chemistry parameters, organ weights, organ to body weight ratios, body weights, mean food consumption. Comparisons were limited to within sex analysis. Statistical evaluation of equality of means was done by an appropriate one way analysis of variance and a test of ordered response in the dose groups. First, Bartlett’s test was performed to determine if the dose groups have equal variance. If the variances were equal, the testing was done using parametric methods, otherwise nonparametric techniques were used.

For the parametric procedures, a standard one way ANOVA using the F distribution to assess significance was used. If significant differences among the means were indicated, Dunnett’s test was used to determine which treatment groups differ significantly from control. In addition to ANOVA, a standard regression analysis for liner response in the dose groups and linear lack of fit were preformed.

For the nonparametric procedure the test of equality of means was performed using the Kruskal-Wallis test. If significant differences among the means was indicated, Dunn’s Summed Rank test was used to determine which treatment group differ significantly from control. In addition, Jonckheere’s test for monotonic trend in the dose response was performed.

The statistical t-test was used to compare the satellite group’s main study termination and recovery termination hematology and clinical chemistry values. In addition, the t-test was used to compare the satellite group's and the control group's relative organ weights. The t-test was also 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:

no effects observed

Details on results:

CLINICAL SIGNS AND MORTALITY
One male and 1 female died in the control group, 2 females died in the 2500 mg/kg dose group, 4 females died in the 5000 mg/kg dose group, 2 males and 3 females died in the satellite group. With the exception of one 2500 mg/kg female, all of the other 13 listed spontaneous deaths appear to be a result of dosing trauma and/or aspiration of test material (due to physical characteristics of test material and the high dosage volume).

The majority of animals in the control, low and mid dose groups displayed no observable abnormal clinical signs. Observations included but are not limited to scabs, maloccluded incisors, alopecia and staining of fur, dry/wet rales, dyspnea, nasal discharge. The type and incidence of abnormal clinical signs were similar between the high dose and satellite groups with a dramatic increase in incidence when compared to mid dose group. Clinical signs most frequently noted included swollen anus, ano-genital staining, emaciation, and alopecia. During the satellite recovery period, the incidence of abnormal signs decreased over time with an increase in the number of animals exhibiting no observable abnormalities.

BODY WEIGHT AND WEIGHT GAIN
Statistically significant decreases from controls at the p<=0.05 level of significance were noted for mid dose males on days 77, 84, 91 and termination and for the high dose males on Day 42. A statistically significant decrease (p<=0.01) was noted for the high dose group males on Day 49 and continued through the end of the treatment period. Statistically significant decreases were noted for mid dose females (p<=0.05) on day 91 and for high dose females on days 77 and 91. At termination both mid and high dose females displayed a statistically significant decrease in body weight.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Statistically significant increases in food consumption which were linearly related to dose were noted for males on Days 28 through 56 and Day 70 through termination. Significance levels were noted for both the mid and high dose males during these periods. These trends were also evident in the females where statistically significant increases in food consumption were noted on Days 21, 42, 49, and 63 through 95.

OPHTHALMOSCOPIC EXAMINATION
No treatment-related findings.

HAEMATOLOGY
A statistically significant increase in platelets which was linearly related to dose in both the males and females was observed. In addition the male animals displayed a linear dose related increase in white blood cells. The mid dose male values were noted to differ significantly from those of controls for hematocrit and hemoglobin at the p<=0.01 level of significance and mean corpuscular volume and mean corpuscular hemoglobin at the p<=0.05 level of significance.

CLINICAL CHEMISTRY
Statistically significant increases in males (p<=0.01) for urea nitrogen and gamma glutamyl transpeptidase for the high dose males and also the mid dose males for urea nitrogen. An increase for cholesterol was noted for the mid and high dose groups of both sexes (p<=0.01). An increase in alanine aminotransferase was also noted for the mid and high dose males (p<=0.01). Glucose levels were significantly lower than the control values (p<=0.01) for both sexes in the mid and high dose and for the male low dose (P<=0.05). A statistically significant increase in bilirubin in the high dose of both sexes was observed. Other parameters showing statistically significant differences from controls included creatinine, chloride, tryglycerides.

ORGAN WEIGHTS
Liver weights were elevated in male and female rats at 2500 and 5000 mg/kg/day. Adrenal weights were significantly increased in male and female rats at 5000 mg/kg and in female rats at 2500 and 5000 mg/kg. Testes weights were elevated in male rats at 5000 mg/kg. Both the male and female relative kidney weights for all treated groups were significantly different from the control value (p<=0.01).

GROSS PATHOLOGY
Most frequently observed abnormalities include small and large intestine distension (mid and high dose groups); swollen anus (high dose groups), staining of the fur (mid and high dose groups).

Dose descriptor:

NOAEL

Effect level:

>= 5 000 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

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

Critical effects observed:

not specified

Conclusions:

The No Observed Adverse Effect Level (NOAEL) following oral exposure to MRD-89-582 for 90-days is greater than or equal to 5000 mg/kg/day.

Executive summary:

MRD-89-582 was administered by oral gavage to rats at concentrations of 500, 2500 and 5000 mg/kg, 7 days a week for 13 weeks to assess the subchronic toxicity.  An additional group of animals, dosed at 5000 mg/kg/day, was held for 4 weeks to assess reversibility.  No treatment-related mortality was observed; however, male body weights were decreased while food consumption increased in the 2500 and 5000 mg/kg dose groups.  Liver weights were elevated in male and female rats at 2500 and 5000 mg/kg/day.  Adrenal weights were significantly increased in male and female rats at 5000 mg/kg and in female rats at 2500 and 5000 mg/kg.  Testes weights were elevated in male rats at 5000 mg/kg.  Kidney effects occurred in males at all dose levels, and 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.

Dose-related changes in hematology or serum chemistry parameters were observed and were consistent with the changes seen in the liver.  Histological findings of hepatocellular hypertrophy (liver cell enlargement) were seen in livers of both sexes in all dose groups.  These findings are believed to have been a compensatory response and not an indication of toxicity.  Additionally, these liver effects were reversible and occurred only at high doses that are not typical of hydrocarbon exposures for humans.  Other treatment-related effects were mucosal thickening and other signs of irritation of the stomach and anus which appear to be the direct result of high dose intubation of a the locally irritating test substance.  These effects are believed to have been a compensatory response to local irritation and not an indication of toxicity.  All treatment-related effects were reversible within the 4-week recovery period.  Based on the results, the No Observed Adverse Effect Level (NOAEL) for the 90-day study was greater than 5000 mg/kg/day.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

5 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

2 short-term studies (1 key and 1 weight of evidence) and 1 key sub-chronic study available from structural analogues

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

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.

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:

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.

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.

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:

experimental study

Adequacy of study:

supporting study

Study period:

1981

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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

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:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Central Institute for the breeding of laboratory animals TNO, Zeist Netherlands
- Weight at study initiation: 35-50g
- Housing: individually
- Diet (e.g. ad libitum): ad libitum, removed during exposure
- Water (e.g. ad libitum): ad libitum, removed during exposure
- Acclimation period:1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.0-20
- Humidity (%): 40-60

IN-LIFE DATES: From: 13 January 1982 To: 16 April 1982

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

The test atmospheres are obtained as follows: filtered and dried air from the compressed—air line was passed through a glass evaporator, filled with isododecane. To obtain the desired isododecane concentration in the test atmosphere the airflow laden with isododecane was mixed in the proper ratio with the main airflow passed through the exposure chambers.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The analysis of test atmospheres to monitor the isododecane concentration was carried out by gas chromatography. Samples were taken automatically at regular intervals by means of a timer controlled 7-port gas-sampling valve. The sample loop was calibrated by comparing the area of the isododecane peak obtained from a loop sample with the area of the isododecane peak obtained from a sample taken simultaneously with a gas— tight syringe. The detector response to isododecane was calibrated by injecting known amounts of a standard solution of isododecane in diethylether.

The actual overall mean concentrations of isododecane in the various test atmospheres were 12.5, 50.2, 99.9 and 201.1 ppm.

Duration of treatment / exposure:

6h/day

Frequency of treatment:

5 days/week for 13 weeks

Remarks:

Doses / Concentrations:
0, 200.3, 599.3, or 1799 ppm
Basis:
analytical conc.

Remarks:

Doses / Concentrations:
0, 200, 600, or 1800 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

20 males and 20 females/dose group

Control animals:

yes

Details on study design:

A subchronic inhalation toxicity study with isododecane was carried out by exposing groups of twenty male and twenty female rats to atmospheres containing 0, 200, 600, or 1800 ppm isododecane 6 hours a day, 5 days a week, for a period of 13 weeks.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations:just before the start of the first exposure and once every week thereafter

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: weeks 6 and 12
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 10 animals/sex/dose

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: weeks 6 and 12.
- Animals fasted: Yes
- How many animals:10 rats/sex/group

URINALYSIS: Yes
- Time schedule for collection of urine: weeks 6 and 12
- Animals fasted: Yes

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

The following organs were weighed:
adrenals, lungs with trachea and larynx, brain, pituitary, heart, spleen, kidneys, testes/ovaries, liver, thymus, thyroid (with parathyroid)

Samples of the organs weighed and of the following tissues and organs were preserved in a neutral aqueous phosphate-buffered 4% formaldehyde solution.

Aorta, pancreas, axillary lymph nodes, parotid salivary glands, caecum, prostate coagulating glands, sciatic nerve, colon, seminal vesicles, duodenum, skeletal muscle (thigh), epididymides, skin (flank), spinal cord, eyes, sternum (with bone marrow), ileum, stomach, jejunum, submaxillary salivary glands, mesenteric lymph nodes, sublingual salivary glands, nose (sections at 4 levels), urinary bladder, oesophagus, uterus (with cervix), all gross lesions

The lungs were fixed (after weighing) by intratracheal infusion of the fixative under 10 cm water pressure.
The kidneys of all rats were embedded in paraffin wax, sectioned, stained with haematoxylin and eosin, and examined by light microscopy.

Statistics:

Statistical analyses of body weights and organ to-body weight ratios were carried out using analysis of co-variance followed by the Dunnetts Test, whereas the haematological and biochemical data were evaluated by means of the Mann/Whitney U-test. For statistical analysis of the histopathological data, chi-square analysis was used according to the limitations outlined by Siegel (1956).

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:

no effects observed

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

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:

- Growth retardation was observed in females of the 1800 ppm group.
- In week 5 red blood cell counts were lower in males and females of the 1800 ppm group than in controls. At the end of the 13 week exposure period the red blood cell values of this test group were similar to the control values.
- The plasma alkaline phosphatase activity was increased in females of the 1800 ppm group.
- Males and females of the 1800 ppm group and the males of the 600 ppm group produced relatively large amounts of urine of low density at the end of the experimental period. This was also observed in week 5 in females of the 200 and 1800 ppm groups. Furthermore, sperm cells were more frequently absent in urine samples of the males of the 600 and 1800 ppm groups than in those of the control and 200 ppm groups, both in week 5 and 13.
- Degree and incidence of inflammatory reactions in the respiratory tract appeared to be lower in males at the 1800 ppm and in females at the 600 and 1800 ppm level than in controls.
- The relative weights of the gonads and kidneys of the males and females of the 1800 ppm group as well as the relative kidney weights of the males of the 600 ppm group were increased. Upon gross examination at autopsy the incidence of greenish kidneys appeared to be increased in males at the 1800 ppm level. A dose related increase in the incidence of histopathological changes was found in the kidneys of males at each of the exposure levels tested. These changes were consistent of tubular nephrosis. 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.

Dose descriptor:

NOAEL

Effect level:

>= 1 800 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: NOAEL >= 10440 mg/m^3, No treatment-related mortality or significant adverse clinical effects occurred.

Critical effects observed:

not specified

Conclusions:

The NOAEL for isododecane is greater than or equal to 1800 ppm (>=10440 mg/m3; nominal, vapor) under the test conditions of this study.

Executive summary:

A subchronic inhalation toxicity study with isododecane was carried out by exposing groups of twenty male and twenty female rats to atmospheres containing 0, 200, 600, or 1800 ppm isododecane 6 hours a day, 5 days a week, for a period of 13 weeks. No treatment-related effects on mortality were observed and there were no significant alterations in hematological, blood chemical or urinary values, or in organ weights, that were toxicologically relevant. An increased incidence of tubular nephrosis was found in the kidneys of males at all levels of exposure. These lesions were characterized by a loss of cytoplasmic eosinophilia and striation, a loss of brush border, and an increases cellular and nuclear size of epithelium of mainly the proximal tubules. 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.  Based on these results, the No Observed Adverse Effect Level (NOAEL) was greater than or equal to 1800 ppm (10440 mg/m³).

Reference 3

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1978

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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

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

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Chrales River
- Age at study initiation: 6-7 weeks
- Weight at study initiation: 154-180g
- Housing: individually
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Test material was transferred from a reservoir using a metering pump into a heated flask and flash evaporated. A stream of clean air was also passed through the flask and the vapor laden air transferred to a port in the chamber air inlet, where it was diluted with normal chamber intake air to give the desired concentration. Adjustments to the exposure air concentration were made by changing the rate of flow of test material through the metering pump.
- Exposure apparatus: stainless steel and glass chambers
- Temperature, humidity, pressure in air chamber:
- Air flow rate: 135 liters/minutes
- Air change rate: every 5.6 minutes



TEST ATMOSPHERE
- Brief description of analytical method used: Wilks Scientific Corp. Miran IA Ambient Air Analyzer (long pathlength infrared)
- Samples taken from breathing zone: no

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Atmospheric sampling was performed using a Wilks Scientific Corp., Miran IA Ambient Air Analyzer (long path length infrared). The infrared spectrum of the test material was measured and a strong band associated with the test material was observed at 3.4 microns. A calibration curve relating the absorption at the wavelength to the airborne concentration of the test material was prepared. On each exposure day, three samples were drawn from each exposure chamber and the exposure concentration calculated by comparing the absorption of this sample to the standard curve.

Duration of treatment / exposure:

6 hours/day, 5 days/week for 12 weeks

Frequency of treatment:

6 hours/day, 5 days/week for 12 weeks

Remarks:

Doses / Concentrations:
300 ppm
Basis:
nominal conc.

Remarks:

Doses / Concentrations:
900 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

35 animals/sex/dose (total of 70 animals/group, 20 were necropsied after 4 weeks of exposure; 20 necropsied after 8 weeks; 30 necropsied after 12 weeks of exposure)

Control animals:

yes

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly


BODY WEIGHT: Yes
- Time schedule for examinations: weekly from 10 days prior to exposure through termination

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No

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: No

WATER CONSUMPTION: No
- Time schedule for examinations:

OPHTHALMOSCOPIC EXAMINATION: No
- Time schedule for examinations:
- Dose groups that were examined:

HAEMATOLOGY: Yes
- Time schedule for collection of blood: pretest, day 0, weeks 4, 8, and 12
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes
- How many animals: 10/sex/group at each timepoint except for 12 week timepoint 15/sex/group

CLINICAL CHEMISTRY: Yes / No / No data
- Time schedule for collection of blood: pretest, day 0, weeks 4, 8, and 12
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes
- How many animals: 10/sex/group at each timepoint except for 12 week timepoint 15/sex/group

URINALYSIS: No data

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Statistics:

Body weight, hematology and clinical chemistry parameters, organ weights, and organ/body weight ratios were analyzed. Mean values for all dose groups were compared to their respective control groups at each time interval.

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):

not examined

Food efficiency:

not examined

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

not examined

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:

CLINICAL SIGNS AND MORTALITY
Two control females died spontaneously in the control group. all other animals survived the duration of the study. Several animals in all groups were observed with slight dry rales. These observations were typically more numerous in the test animals than the controls, however a dose response pattern was not established. Ano-genital staining of the fur was observed in the male and female rats of the low dose group and high dose group, however more staining was observed in the low dose group than the high dose group indicating an absence of a dose response. All other observations were unremarkable.

BODY WEIGHT AND WEIGHT GAIN
Mean body weights for all treated female rats were similar to the respective controls. Mean body weights for the treated low dose male rats were similar to controls. Mean body weights for the treated high dose group were significantly lower than the corresponding controls from the fifth week of treatment through termination, with the single exception of the seventh week.


HAEMATOLOGY
All hematologic parameters for treated and control groups were considered to be within normal ranges. The only significant differences observed were in hemoglobin (p<=0.01) and red blood cell counts (p<=0.05) for the low dose animals when compared to their control group. In the males, both hemoglobin and red blood cell count were lower. In the females the red blood cell count (p<=0.01) was higher. In view of the absence of an observed effect in the high dose group, the arbitrary nature of the effect in the low dose group, and the fact that all values were considered normal, this does not appear to be treatment related.

CLINICAL CHEMISTRY
All values were considered to be within normal ranges and no treatment-related effects were observed.


ORGAN WEIGHTS
The kidney/body weight ratios for males were significantly higher (p<=0.01) for the high dose group at all timepoints (4, 8, and 12 weeks). The kidney organ weights were also higher. The ratios for females were not significantly different. The liver/body weight ratios were higher for males and females at the high dose group at all timepoints. The liver organ weights were not significantly higher at this dose for males but were significantly higher in females.

GROSS PATHOLOGY
nothing significant observed

HISTOPATHOLOGY: NON-NEOPLASTIC
nothing significant observed

HISTOPATHOLOGY: NEOPLASTIC (if applicable)
nothing significant observed

Dose descriptor:

NOAEL

Effect level:

>= 900 ppm

Sex:

male/female

Basis for effect level:

other: NOAEL >= 5220 mg/m3, No treatment-related mortality or significant adverse clinical effects occurred.

Critical effects observed:

not specified

Conclusions:

The NOAEL for MRD-77-44 is greater than or equal to 900 ppm (>= 5220 mg/m3) under the test conditions of this study.

Executive summary:

Test material MRD-77-44 was administered by inhalation to Sprague-Dawley rats for 6 hours/day, 5 days/week for 12 weeks at nominal vapor concentrations of 300 ppm and 900 ppm to assess subchronic inhalation toxicity.  Ten animals per sex per group were examined at 4 weeks, 8 weeks and all survivors were sacrificed and examined at 12 weeks. Male body weight gain was significantly decreased at 900 ppm.  There were no treatment-related effects in any of the hematology and serum chemistry values.  Liver and kidney weights were increased in male rats at 900 ppm, and adrenal weights were increased in female rats at 900 ppm.  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 weight to body weight ratios were judged to have been compensatory rather than toxic effects.  Based on these results, the No Observed Adverse Effect Level (NOAEL) was greater than or equal to 900 ppm (>=5220 mg/m³).

Reference 4

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1978

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented study report equivalent or similar to OECD guideline 412.

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:

not specified

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS

- Housing: individual out of chamber
- Diet (e.g. ad libitum): ad libitum when not being exposed
- Water (e.g. ad libitum): ad libitum when not being exposed

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

Compound Administration
Appropriate amounts of the test material were transferred from a reservoir using a metering pump into a heated flask and flash evaporated. A stream of clean air was also passed through the flask and the vapor laden air transferred to a port in the chamber air inlet, where it was diluted with normal chamber intake air to give the desired concentration. Adjustments in the exposure air concentration were made by changing the rate of flow of test material through the metering pump.

Chamber Operation:
The stainless steel and glass chambers in which the animals were exposed had an effective exposure volume of 760 liters. They were operated dynamically at a flow rate of approximately 135 liters per minute. This provided one air change every 5.6 minutes and a 99% equilibrium time of 26 minutes.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Atmospheric sampling was performed using a Wilks Scientific Corp., Miran IA Ambient Air Analyzer (long pathlength infrared). The infrared spectrum of the test material was measured and a strong band associated with the test material was observed at 3.4 microns. A calibration curve relating the absorption at this wave length to the airborne concentration of the test material was prepared. On each exposure day three samples were drawn from each exposure chamber (at about one, three and five 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 hexane scrubber samples collected from each chamber during the 12 week exposure period.

Based on the infrared analysis the animals in Group II received exposure to a mean concentration of 314 ppm of MRD-77-43 and the animals in Group III received exposure to a mean concentration of 922 ppm of MRD-77-43.

Duration of treatment / exposure:

6hr/day

Frequency of treatment:

5days/week for 12 weeks

Remarks:

Doses / Concentrations:
0, 300, 900ppm
Basis:
nominal conc.

No. of animals per sex per dose:

70 animals/dose (# of animals equally divided by sex)

Control animals:

yes, concurrent no treatment

Details on study design:

70 animals were used per dose group. For each group, lab tests and necropsy were performed on 20 animals (# of animals equally divided by sex) at 4 weeks and 8 weeks and for 30 animals at 12 weeks.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily


BODY WEIGHT: Yes
- Time schedule for examinations:weekly


HAEMATOLOGY: Yes
- Time schedule for collection of blood: day 0, 4 weeks, 8 weeks, 12 weeks
- Animals fasted: Yes
- How many animals: 10/sex for control and low dose groups, 15/sex for high dose group


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: day 0, 4 weeks, 8 weeks, 12 weeks
- Animals fasted: Yes
- How many animals:10/sex for control and low dose groups, 15/sex for high dose group

70 animals were treated/dose group. Animals were sacrificed at the following observation periods and clinical chem and necropsy performed;
Pretest 10/sex from unsorted group including extras
Day 0 10/sex from extras after sorting
4 weeks 10/sex/group
8 weeks 10/sex/group
12 weeks 15/sex/group (all survivors)

Blood Collection: From retro-orbital sinus
Parameter Evaluated:
Hematology- hemoglobin, hematocrit, erythrocyte count, clotting time, mean corpuscular volume, total and differential leukocytes;
Clinical Chemistry - blood urea nitrogen, serum glutamic pyruvic transalinase, glucose alkaline phosphatase,

Organs Weighed:
kidney
liver
lungs
adrenals
brain (sans pituitary) gonads
Tissues Fixed: (all animals)
adrenals
bone marrow (sternal)
brain (2 sections)
eye (2)
gonads (2)
heart (with coronary vessels)
intestine
colon
duodenum
ileum
kidneys
liver (2 sections)
lung (2 sections)
lymph node (mesenteric)
mammary gland pancreas pituitary salivary gland skeletal muscle skin
spinal cord (cervical) spleen
stomach
thyroid
urinary bladder uterus/prostate gross lesions tissue masses
eyes and testes

All tissues listed above were examined histopathologically for control and 900ppm group

Statistics:

Body weight, hematology and clinical chemistry parameters, organ weights and organ/body weight ratios were analyzed. Mean values for all dose groups were compared to control groups at each time interval.

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:

no effects observed

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

no effects observed

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

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:

CLINICAL SIGNS AND MORTALITY
One control female died spontaneously during the eighth week of the study. All other animals survived the duration of the experiment.
During the experiment several animals in all groups were observed with slight dry rales and/or a slight nasal discharge. These observations were typically more numerous in the test animals compared to the controls; however, a dose response pattern could not be clearly established. Weekly observations revealed from 40% to 75% of the female rats in the high dose group with staining of the anogenital fur during weeks 5 through 12. This compared to less than 10% in the low dose group and none in the control, and is most probably treatment related

BODY WEIGHT AND WEIGHT GAIN
Mean body weights for all treated female rats were similar to controls throughout the experiment. Mean body weights of the treated low dose male rats were significantly (p<0.05) lower from the sixth week of treatment through termination. Mean body weights for the treated high dose males were substantially lower than controls from the sixth week of treatment. These differences were statistically significant (p<0.05) only during weeks 6, 8, 9, and 10. In all cases from week two till termination the high dose group had a higher weight gain than the low dose group. Thus, a dose response effect was not clearly defined and these differences, which were never more than 10% of the total body weight, may not be test material related.

HAEMATOLOGY
All hematologic parameters for treated and control groups were considered to be within normal ranges. A statistically significant difference (p<0.01) was observed in the comparison of the red blood cell counts taken in the twelfth week for treated and control male rats. However the actual values for all groups were considered to be within normal limits. Furthermore, the hemoglobin and hematocrit were similar for all groups.

CLINICAL CHEMISTRY
All clinical chemistry parameters for treated and control groups were considered to be within normal ranges. A statistically significant difference (p<0.05) was observed in the comparison of the serum glutamic — pyruvic transaminase levels in the twelfth week for treated and untreated female rats. However, the observation was of lower enzyme levels in the treated animals and all values were considered to be within normal limits.


ORGAN WEIGHTS
The organ/body weight ratios for the kidney showed a dose response relationship for the male rats. In the low dose group the ratios were significantly higher (p<=0.05) when compared to controls at all three sacrifice intervals. In the high dose group the ratios
were significantly higher at the first interim sacrifice (p<=0.05) and became greater (p<=0.01) at the second interim sacrifice and terminal sacrifice. In the high dose group the organ weights themselves were also significantly higher (p<=0.05) at the second interim and terminal sacrifice. A similar relationship was also observed in the female rats the kidney weight and kidney/body weight ratios were only significant (p<=0.05) for the high dose group at the second interim sacrifice, At no time was a significant difference observed when comparing the low dose female rats to the controls.
The liver weight and liver/body weight ratios also appeared to exhibit a dose response relationship, in that they appeared to increase with increasing dose. In the male rats the ratio differences were significant for the high dose group at the first interim sacrifice
p<=0.01) and terminal sacrifice (p<=0.05). The organ weights were also different (p<=0.05) when the high dose group was compared to controls at the first interim sacrifice. Similar findings were observed in the female rats. The ratios were significantly different for the high dose group at the first interim sacrifice (p<=0.01) and at the second interim sacrifice (p<=0.05). Also, at the first interim sacrifice the organ weights for the high dose group were significantly higher (p<=0.05) than the controls.
At the terminal sacrifice no significant differences of the liver weights were observed.
The testes weights in the high dose rats were significantly higher (p<=0.05) at the second interim sacrifice. Although a similar trend was observed at the terminal sacrifice no significant differences were observed.


GROSS PATHOLOGY
None of the gross or microscopic changes observed were considered attributable to treatment with MRD-77-43. The changes that were observed were of the type that are frequently encountered as spontaneous or incidental lesions in young laboratory rats.

Dose descriptor:

NOAEC

Effect level:

> 900 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: NOAEC > 5220 mg/m^3, No treatment-related mortality or significant adverse clinical effects occurred.

Critical effects observed:

not specified

Conclusions:

The NOAEL for MRD-77-43 is greater than 900ppm (> 5220 mg/m^3; nominal, vapor) under the test conditions of this study.

Executive summary:

MRD-77 -43 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 Level (NOAEL) is greater than 900 ppm (> 5220 mg/m³).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

10 400 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

1 key and 3 supporting read across studies available from structural analogues.

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 repeated dose toxicity data for Dodecane. However, short-term studies are available for structural analogues Decane and Undecane. Sub-chronic data is available for structural analogues Hydrocarbons, C9 -C11, isoalkanes, cyclics, <2% aromatics, Hydrocarbons, C10 -C12, isoalkanes, Hydrocarbons, C10 -C13, n-alkanes, isoalkanes, cyclics, <2% aromatics, and Isododecane. Additionally, OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents) tests are proposed for structural analogues, Hydrocarbons, C9-C11, isoalkanes, cyclics, <2% aromatics and Hydrocarbons, C14-C19, isoalkanes, cyclics, <2% aromatics. 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.

 

This endpoint will be updated subsequent to ECHA's approval of the testing proposals and availability of data upon completion of the studies.

Oral: 

 

Decane

In a key study (Sasol, 1995) groups of 10 male and 10 female Sprague Dawley rats were dosed with decane daily by gavage at exposure levels of 0, 25, 150, or 1000 mg/kg/day. Males were dosed from the 14th day prior to mating, during mating until the end of the mating period. Females were dosed from the 14th day prior to the start of the mating phase to day 4 of lactation.  Oral dosing of decane produced no evidence of any adverse effects on clinical observations, organ weights, gross pathology, neurobehavioral activity, clinical chemistry or hematology endpoints. Evidence of irritation of the nonglandular mucosa of the stomach was observed, but was considered an artifact of the dosing method and not attributed to the inherent toxicity of the test material.  Based on these data, the no-observable- adverse effect level (NOAEL) for repeated dose toxicty was >=1000 mg/kg/day, the highest dose tested. 

 

Undecane

In an OECD Guideline 422 study (MHW, 1996), male and female rats were given 0, 100, 300 and 1000 mg/kg orally by gavage. Male rats were dosed from the 14^thday prior to mating and during the mating period. Female rats were dosed from the 14^thday prior to mating until after the 3^rdday of nursing. Salivation was observed in males and females given 300 and 1000 mg/kg. Body weight gain was suppressed in males given 1000 mg/kg, and body weights were increased in females given 1000 mg/kg during the lactation period. Food consumption was decreased in males given 300 and 1000 mg/kg in the first half of the administration period, increased in males given 1000 mg/kg in the second half of the administration period, and increased in females given 1000 mg/kg in the second half of pregnancy and during the lactation period. Hematological and blood chemical examinations revealed a decrease in hemoglobin concentration, an increase in the white blood cell count, a decrease in albumin, and increases in a2-globulin, GPT, cholinesterase and total cholesterol in males given 1000 mg/kg. Relative liver weights and absolute and relative thymus weights were increased in males given 1000 mg/kg, and absolute and relative liver weights were elevated in females given 1000 mg/kg. No effects were detected in the autopsy or histopathology findings. Due to the lack of effects in both sexes and the lack of corresponding histopathology, these effects are determined not to be toxicologically relevant. The NOAEL for repeat dose toxicity is considered to be 1000 mg/kg/day for both sexes.

Hydrocarbons, C10-C13, n-alkanes, isoalkanes, cyclics, <2% aromatics

In a key study (Exxon, 1991), the test material (Hydrocarbons, C10-C13, n-alkanes, isoalkanes, cyclics, <2% aromatics) was administered by oral gavage to rats at concentrations of 500, 2500 and 5000 mg/kg, 7 days a week for 13 weeks to assess the subchronic toxicity.  An additional group of animals, dosed at 5000 mg/kg/day, was held for 4 weeks to assess reversibility.  No treatment-related mortality was observed; however, male body weights were decreased while food consumption increased in the 2500 and 5000 mg/kg dose groups.  Liver weights were elevated in male and female rats at 2500 and 5000 mg/kg/day.  Adrenal weights were significantly increased in male and female rats at 5000 mg/kg and in female rats at 2500 and 5000 mg/kg.  Testes weights were elevated in male rats at 5000 mg/kg.  Kidney effects occurred in males at all dose levels, and 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.

Dose-related changes in hematology or serum chemistry parameters were observed and were consistent with the changes seen in the liver.  Histological findings of hepatocellular hypertrophy (liver cell enlargement) were seen in livers of both sexes in all dose groups.  These findings are believed to have been a compensatory response and not an indication of toxicity.  Additionally, these liver effects were reversible and occurred only at high doses that are not typical of hydrocarbon exposures for humans.  Other treatment-related effects were mucosal thickening and other signs of irritation of the stomach and anus which appear to be the direct result of high dose intubation of a the locally irritating test substance.  These effects are believed to have been a compensatory response to local irritation and not an indication of toxicity.  All treatment-related effects were reversible within the 4-week recovery period.  Based on the results, the No Observed Adverse Effect Level (NOAEL) for the 90-day study was greater than 5000 mg/kg/day.

Inhalation:

 

Hydrocarbons, C9-C11, isoalkanes, cyclics, <2% aromatics

In a supporting study (ExxonMobil, 1978), the test material (Hydrocarbons, C9-C11, isoalkanes, cyclics, <2% aromatics) was administered by inhalation to Sprague-Dawley rats for 6 hours/day, 5 days/week for 12 weeks at nominal vapor concentrations of 300 ppm and 900 ppm to assess subchronic inhalation toxicity.  Ten animals per sex per group were examined at 4 weeks, 8 weeks and all survivors were sacrificed and examined at 12 weeks. Male body weight gain was significantly decreased at 900 ppm.  There were no treatment-related effects in any of the hematology and serum chemistry values.  Liver and kidney weights were increased in male rats at 900 ppm, and adrenal weights were increased in female rats at 900 ppm.  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 weight to body weight ratios were judged to have been compensatory rather than toxic effects.  Based on these results, the No Observed Adverse Effect Level (NOAEL) was greater than or equal to 900 ppm (>=5220 mg/m³).

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

In a key 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/m³to 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 greater than or equal to 10400 mg/m³.

 

In a supporting study (Exxon, 1978), the test material (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 Level (NOAEL) is greater than 900 ppm (> 5220 mg/m³).

 

Isododecane

A supporting subchronic inhalation toxicity study (Bayer, 1981) with isododecane was carried out by exposing groups of twenty male and twenty female rats to atmospheres containing 0, 200, 600, or 1800 ppm isododecane 6 hours a day, 5 days a week, for a period of 13 weeks. No treatment-related effects on mortality were observed and there were no significant alterations in hematological, blood chemical or urinary values, or in organ weights, that were toxicologically relevant. An increased incidence of tubular nephrosis was found in the kidneys of males at all levels of exposure. These lesions were characterized by a loss of cytoplasmic eosinophilia and striation, a loss of brush border, and an increases cellular and nuclear size of epithelium of mainly the proximal tubules. 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.  Based on these results, the No Observed Adverse Effect Level (NOAEL) was greater than or equal to 1800 ppm (10440 mg/m³).

Justification for classification or non-classification

Based on available data, Dodecane does 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).