Cumene

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to guideline standards in context of the National Toxicology Program with detailed decription

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

2009

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

yes

Remarks:

; Additional investigations, see examinations; 5 concentrations tested; Original GLP-Report not publicly available

GLP compliance:

yes

Remarks:

Batelle Toxicology Northwest (Richland, WA)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Cumene

EC Number:

202-704-5

EC Name:

Cumene

Cas Number:

98-82-8

Molecular formula:

C9H12

IUPAC Name:

isopropylbenzene

Details on test material:

- Name of test material (as cited in study report): Cumene

- Substance type:
- Physical state: colorless liquid with a sharp, penetrating, aromatic odour
- Analytical purity: 99.9% peak area
- Impurities (identity and concentrations): No impurities >0.05% peak area detected
- Purity test date: Not specified
- Lot/batch No.: Lot 200556852
- Expiration date of the lot/batch: No data
- Stability under test conditions: stable over the test period, no degradation of bulk chemical was detected

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Taconic Laboratory Animals and Services (Germantown, NY)
- Age at study initiation: approx. 6 weeks old on first day of study
- Weight at study initiation: 81+/- 1 to 81 +/- 3 g
- Fasting period before study:
- Housing: individually
- Diet (e.g. ad libitum): NTP-2000 irradiated pelleted diet (Zeigler Brothers, Inc, Gardeners, PA); changed weekly
- Water (e.g. ad libitum): Tap water (Richland, WA, muncipal supply) via automatic watering system (Edstrom Industries, Waterford, WI)
- Acclimation period: 11 d (females) or 12 d (males)


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 +/- 2 (75 +/- 2° F)
- Humidity (%): 55 +/- 15
- Air changes (per hr): 15 +/- 2
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: inhalation exposure chamber (Harford Systems Division of Lab Products, Inc., Aberdeen, MD),
- Method of holding animals in test chamber: individually
- Source and rate of air: No data
- Method of conditioning air: No data
- System of generating particulates/aerosols: Vapour was generated by evaporating the substance in glass column with glass beads
- Temperature, humidity, pressure in air chamber:
- Air flow rate: Not specified
- Air change rate: 15 per hour
- Method of particle size determination: Condensation particle counter (Model 3022A, TSI, Inc., St. Paul, MN). No particle counts greater than 200 particles/cm³ were detected.
- Treatment of exhaust air: No data


TEST ATMOSPHERE
- Brief description of analytical method used: GC FID
- Samples taken from breathing zone: no

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentrations in the exposure chambers were monitored by online-gas chromatography every 20 min.

Duration of treatment / exposure:

6 h plus T90 (=12 min)

Frequency of treatment:

5 days per week (excluding holidays) for 14 weeks

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
62.5, 125, 250, 500, and 1000 ppm
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
62.9 +/- 1, 125 +/- 3, 251 +/- 5, 504 +/- 10, and 1009 +/- 16 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

10 male and 10 female (core study); 10 male and 10 female (haematology and clinical chemistry study)

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Based on results of 14 d study

Positive control:

No

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: on day 3, day 23 and week 14 (see below )
-Blood was collected from the retroorbital sinus of clinical pathology rats on days 3 and 23 and from core study rats at the end of the study for hematology and clinical chemistry.

BODY WEIGHT: Yes
- Time schedule for examinations: initially, weekly and at the end of the study (core study anaimals)


FOOD CONSUMPTION: No data


FOOD EFFICIENCY: No data


WATER CONSUMPTION: No data


OPHTHALMOSCOPIC EXAMINATION: No


HAEMATOLOGY:
- Endpoints: hematocrit; packed red cell volume; hemoglobin; erythrocyte, reticulocyte, and platelet counts; mean cell volume; mean cell hemoglobin; mean cell hemoglobin concentration; and leukocyte counts and differentials.
- Blood was collected from the retroorbital sinus of haematology and clinical chemistry rats on days 3 and 23 and from core study rats at the end of the study for hematology and clinical chemistry.


CLINICAL CHEMISTRY:
- Endpoints: urea nitrogen, creatinine, total protein, albumin, alanine aminotransferase, alkaline phosphatase, creatine kinase, sorbitol dehydrogenase, and bile acids


URINALYSIS: No


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes, on core study animals


ORGAN WEIGHTS: Yes, heart, right kidney, liver, lung, right testis, and thymus


HISTOPATHOLOGY: Yes, complete histopathology was performed on 0 and 1,000 ppm core study rats. In addition to gross lesions and tissue masses, the following tissues were examined: adrenal gland, bone with marrow, brain, clitoral gland, esophagus, eyes, harderian gland, heart and aorta, large intestine (cecum, colon, rectum), small intestine (duodenum, jejunum, ileum), kidney, larynx, liver, lung (with mainstem bronchus), lymph nodes (mandibular, mesenteric, bronchial, mediastinal), mammary gland, nose, ovary, pancreas, parathyroid gland, pituitary gland, preputial gland, prostate gland, salivary gland, skin, spleen, stomach (forestomach and glandular), testis (with epididymis and semina vesicle), thymus, thyroid gland, trachea, urinary bladder, and uterus. In addition, the kidney of male rats in the remaining groups were examined.

Other examinations:

Spermatology and Vaginal Cytology:
spermatid heads per testis, spermatid heads per gram testis, spermatid counts, epididymal spermatozoal motility and concentration.

Reproductive tissue evaluation:
Weight of left cauda, left epididymis, and left testis
Vaginal cytology for determmination of estrous cycle stage.

Renal Toxicity Study:
Determination of alpha2u-globulin, soluble protein, hyaline droplets, cell proliferation indices, and histopathology.

Results and discussion

Results of examinations

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 specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

no effects observed

Details on results:

HAEMATOLOGY
>= 500 ppm m: Leukocytes and and lymphocytes significantly increased on day 23 and week 14.
1000 ppm m+ f: platelets were significantly increased at week 14


CLINICAL CHEMISTRY
>= 62.5 ppm f: bile acids were singificantly increased on day 3 and day 23
>= 250 ppm m+ f: alanine transferase and alkaline phosphatase was significantly reduced on day 23 and week 14 (f: alkaline phosphatase only at 500 ppm and greater). See table below.
>= 500 ppm m: albumine was increased on week 14.
>= 500 ppm m: bile acids were significantly increased at all three periods
1000 ppm f: albumine was increased on week 14.


ORGAN WEIGHTS
>= 125 ppm m: relative and absolute kidney weights were significantly increased (relative at 62.5 ppm). See table below.
>= 250 ppm m: relative and absolute liver weights were significantly increased at 250 ppm or greater (relative at 62.5 ppm).
>= 500 ppm f: relative kidney weights were significantly increased
1000 ppm m: lung weights (absolute and relative) were significantly increased
1000 ppm f: absolute weights changes only observed in liver (Relative weights of liver increased significantly at 125 ppm or greater)


HISTOPATHOLOGY: NON-NEOPLASTIC
>= 125 ppm, m: severity of hyaline droplet accumulation in the renal cortical tubules increased. See table below.
>= 250 ppm m: significantly increased incidences of medullary granular casts

OTHER FINDINGS
>= 125 ppm: significat increase in alpha2uGlobulin, both related to g kidney as well as µg soluble protein. See table below.
>= 250 ppm: soluble protein increased significantly

Estrous cycle:
>= 250 ppm f: Exposed females differed significantly from the chamber control females in the relative length of time spent in estrus (+) and proestrus (-).

Effect levels

1

Dose descriptor:

NOAEC

Effect level:

125 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: haematology; clinical chemistry; organ weights

2

Dose descriptor:

LOEC

Effect level:

250 ppm (nominal)

Sex:

male/female

Basis for effect level:

other: haematology; clinical chemistry; organ weights

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

	Chamber Control	62.5 ppm	125 ppm	250 ppm	500 ppm	1,000 ppm
Male
Alanine aminotransferase (IU/L)
Day 3	64 ± 2	61 ± 1	61 ± 1	64 ± 2	60 ± 2	56 ± 1**
Day 23	44 ± 1	39 ± 1*	39 ± 1**	38 ± 1**	35 ± 1**	35 ± 0**
Week 14	113 ± 6	113 ± 11	110 ± 12	70 ± 4**	61 ± 3**	50 ± 2**
R. Kidney weight
Absolute	0.923 ± 0.024	0.980 ± 0.025	1.010 ± 0.031*	1.059 ± 0.021**	1.070 ± 0.017**	1.152 ± 0.023**
Relative	2.962 ± 0.032	3.128 ± 0.051**	3.131 ± 0.056**	3.194 ± 0.036**	3.411 ± 0.045**	3.561 ± 0.029**
Renal toxicity
Soluble protein (mg/mL)	21.22 ± 1.27	23.43 ± 0.51	23.93 ± 0.93	25.36 ± 0.69*	25.51 ± 0.73**	26.16 ± 1.09**
alpha2u-Globulin (nmol/g kidney)	172.2 ± 22.3	328.1 ± 69.6	383.4 ± 46.3**	420.7 ± 50.1**	363.2 ± 41.4**	575.2 ± 74.8**
alpha2u-Globulin (ng/μg sol. protein)	76.46 ± 9.24	130.98 ± 27.27	150.90 ± 19.23*	154.35 ± 16.98**	133.01 ± 14.25**	209.79 ± 31.34**
Nonneoplastic Lesions in the Kidney
Cortex Renal Tubule, Accumulation, Hyaline Droplet [a]	10 (1.1) [b]	10 (1.4)	10 (1.9)	10 (2.4)	10 (3.0)	10 (2.9)
Cortex Renal Tubule, Regeneration	8 (1.0)	6 (1.2)	8 (1.5)	10 (1.8)	10 (2.1)	10 (2.1)
Medulla, Casts Granular	0	0	2 (1.0)	8** (1.5)	10** (2.5)	9** (2.2)

*: p = 0.05, **: p =0.01, [a] Number of animals with lesion, [b] Average severity grade of lesions in affected animals: 1=minimal, 2=mild, 3=moderate, 4=marked

Applicant's summary and conclusion

Conclusions:

Based on the effects on effects observed in haematology, clinical chemistry and organ weights the NOAEC was 125 ppm (LOEC 250 ppm).

Executive summary:

Groups of 10 male and 10 female rats were exposed to cumene vapor at concentrations of 0, 62.5, 125, 250, 500, or 1,000 ppm, 6 hours plus T90 (12 minutes) per day, 5 days per week for 14 weeks. Additional clinical pathology groups of 10 male and 10 female rats were exposed to the same concentrations for 23 days. All rats survived to the end of the study, and mean body weights of all exposed groups were similar to those of the chamber controls. Kidney and liver weights of 250 ppm or greater males and liver weights of 1,000 ppm females were significantly greater than those of the chamber controls. There were significant differences between exposed and chamber control females in the relative length of time spent in the estrous stages. The amount of alpha2u-globulin in the right kidneys was significantly increased in male rats exposed to 125 ppm or greater. The incidences of medullary granular casts in males exposed to 250 ppm or greater were significantly increased. The severities of renal tubule cortex hyaline droplet accumulation and regeneration increased with increasing exposure concentration in male rats.