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Repeated dose toxicity: inhalation

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Administrative data

Endpoint:
chronic toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1978/08/29-1980/01/25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well-conducted study comparable to standard studies.

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1981
Report Date:
1981
Reference Type:
publication
Title:
Inhalation toxicity of high flash aromatic naphtha.
Author:
Clark DG, Butterworth ST, Martin JG, Roderick HR, Bird MG
Year:
1989
Bibliographic source:
Toxicol Ind Health. 1989 May;5(3):415-28.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 452 (Chronic Toxicity Studies)
GLP compliance:
no
Remarks:
prior to GLP
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Shell Toxicology Laboratory Breeding Unit
- Age at study initiation: 8-9 weeks
- Weight at study initiation: 150-300 g
- Housing: Hanging aluminum cages with stainless steel mesh bases. Paper lined catch trays were beneath each layer of cages and cleaned daily. Animals were identified using an ear punch/notch system.
- Diet (e.g. ad libitum): PRD Labsure food was available ad libitum
- Water (e.g. ad libitum): tap water ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): appox. 20
- Humidity (%): 50%
- Air changes (per hr): continuous airflow of 3-6 m³/min
- Photoperiod (hrs dark / hrs light): 12 hrs light/ 12 hrs dark

IN-LIFE DATES: 1978/08/29-1980/01/25

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: 8 m³stainless steel chamber.
- Method of holding animals in test chamber: cages
- Source and rate of air: air drawn from laboratory at 3-6m³/min
- Method of conditioning air: filters
- System of generating particulates/aerosols: Vapors were generated using quartz tubes with their surface temperature adjusted to 148°C, (high concentration), 130°C (medium concentration), 225°C (low concentration). The vapor entered the experiment chamber via micrometering pumps.
- Temperature, humidity, pressure in air chamber: 14-29.5°C, 35.5-73.5% humidity
- Air flow rate: 3-6m³/min
- Air change rate: continuous

TEST ATMOSPHERE
- Brief description of analytical method used: Test atmospheres were analyzed by a total hydrocarbon analyser for 10 min at intervals of 40 min during exposures. Test atmospheres were also analyzed continuously for 2 hrs during each exposure using gas chromatographs with a flame iionization detector.
- Samples taken from breathing zone: yes
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Control: Nominal 0 mg/m^3, measured 0 mg/m³
Low: Nominal 450 mg/m^3, measured 470 +/- 29 mg/m³
Medium: Nominal 900 mg/m^3, measured 970 +/- 70 mg/m³
High: Nominal 1800 mg/m^3, measured 1830 +/- 130 mg/m³
Duration of treatment / exposure:
12 months
Frequency of treatment:
6 hrs per day, 5 days per week except for 8 public holidays, 2 snowdays, and exposure limited on 2 other days for unknown reasons
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 470 mg/m³, 970 mg/m³, 1830 mg/m³
Basis:
analytical conc.
No. of animals per sex per dose:
50
Control animals:
yes, concurrent no treatment
Details on study design:
- Rationale for animal assignment (if not random): Randomized block design with each control and experimental group in one block from the same litter.
- Post-exposure recovery period in satellite groups: 4 months
Positive control:
None

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: before start of experiment, weekly for first 4 weeks, monthly thereafter

HAEMATOLOGY: Yes
- Time schedule for collection of blood: 10 animals of each sex from the high exposure and control groups had blood drawn at weeks 1, 2, 3, 4, 6, 8, 12, 16, 20, 24, 28, and 32 of exposure. Blood was also taken from 10 animals of each sex from each exposure level at the 26 and 52 week sacrfice, and from the 4 month recovery group.
- How many animals: 10 of each sex
- Parameters checked: Repeated sampling - erythrocyte count, mean cell volume, hemoglobin concentration, leucocyte count, mean corpuscular hemoglobin concentration, and hematocrit
Terminal sampling - erythrocyte count, mean cell volume, hemoglobin, leucocyte count, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, hematocrit, prothrombin time, kaolin-cephalin coagulation time, erythrocyte osmotic fragility. Reticulocytes were only counted in the high exposure and control groups at the 12 month sacrifice.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Blood taken from 10 animals of each sex from each exposure level at the 26 and 52 week sacrfice, and from the 4 month recovery group.
- Animals fasted: overnight
- How many animals: 10 of each sex
- Parameters checked: 12 month sacrifice - total protein, urea nitrogen, alkaline phosphatase, chloride ion, total bilirubin, total calcium, inorganic phosphate, uric acid, sodium, potassium, alanine amino transferase, aspartate amino transferase, glucose concentration, protein eleectrophoresis,
26 week sacrifice - protein, urea, alkaline phosphatase, alanine amino transferase, aspartate amino transferase, chloride, sodium, potassium, portein electrophoresis

URINALYSIS: Yes
- Time schedule for collection of urine: male and females from each exposure group at 0, 3, 6, 9, and 12 months exposure, and 3 months after exposure.
- Parameters checked: Glucose, protein, ketones, bilirubin, blood pigments, pH, nitrite, urobilinogen
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
Animals were sacrificed by injection of sodium pentobarbitone. All external surfaces, orifices, and the throacic and abdominal cavities were then examined. The following organs were then weighed: liver, kidneys, spleen, brain, heart, testes

HISTOPATHOLOGY: Yes
Histopathology was done on the following organs: salivary gland, stomach, heart, brain, spinal cord, pituitary gland, sciatic and posterier tibial nerves, lungs, prostate, seminal vesicles, testes, ovaries, uterus, skeletal muscle, adrenal glands, thyroids with esophagus and trachea, caecum, spleen, thymus, lymph node, mammary gland, small intestine, large intestine, pancreas, liver, kidneys, urinary bladder, eye and lachrymal glands, nasal cavity, spinal cord, tongue, knee joint and femur, any lesions
Statistics:
Body and organ weights were analyzed by covariance analysis. Hematological and clinical parameters were examined using analysis of variance. Significance of any difference between treated and control goup means was tested using the Williams t test. If a monotonic dose response could not be assumed, Dunnett's test was used instead.

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 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:
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
No clinical signs attributable to exposure were observed. Five animals died during the study. 2 males and 1 female in the control group died during the exposure phase of the experiment, and 2 males in the medium exposure group died during the recovery phase. These deaths were not considered attributable to exposure to the test substance. 37 animals were removed from the study during both the exposure and recovery phase for various health reasons, most commonly sore hocks. The number of removals was similar for all exposure levels, including the control group and was not attributable to exposure to the test substance.


BODY WEIGHT AND WEIGHT GAIN
Body weight gain was decreased the first 4 weeks in high exposure males, and medium exposure females. High exposure females had decreased body weight gains for the first 12 weeks of exposure, but recovered after exposure was terminated.

HAEMATOLOGY
Though some statistically significant changes were observed, particularly in males, no biologically significant changes were observed.

CLINICAL CHEMISTRY
Minor clinical chemical changes were observed at both the 26 and 12 month sacrifice, but were within normal ranges.

URINALYSIS
No differences between exposure and control groups were observed.

ORGAN WEIGHTS
Liver and kidney weights in the high dose males were significantly increased, but there were no histopathological lesions, so this was considered a functional hypertrophy of the organs.

HISTOPATHOLOGY: NON-NEOPLASTIC
No histopathological changes that could be attributable to exposure to the test substance were detected.

Effect levels

open allclose all
Dose descriptor:
NOAEC
Effect level:
1 800 mg/m³ air (nominal)
Sex:
male
Dose descriptor:
NOAEC
Effect level:
900 mg/m³ air (nominal)
Sex:
female
Basis for effect level:
other: body weight reduction

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
The NOAEC for male rats was determined to be 1800 mg/m3, the highest concentration tested. The NOAEC for female rats was determined to be 900 mg/m3, due to the reduced body weight noted.
Executive summary:

This study examined the effects of 12 months of inhalation exposure of rats to a commercial mixture of Hydrocarbons, C9 Aromatics. Male and female rats were exposed to concentrations of 450, 900, or 1800 mg/m³ 6 hrs/day, 5 days/week, for up to 12 months. Some of the rats were sacrificed at 26 weeks, others at 12 months, and others after a 4 month recovery period after the end of the 12 month exposure. Animals were examined for clinical signs and behaviour twice daily, and weighed weekly for the first 4 weeks, and monthly thereafter. After sacrifice, the animals were examined for clinical chemistry, hematology, urine analysis, gross pathology, histopathology, and organ weights. No deaths attributable to exposure to the test substance occurred. There was depressed weight during the first few months of the experiment in medium (900 mg/m³) and high dose males (1800 mg/m³). However, the animals quickly recovered and this effect is not considered biologically significant. High dose females (1800 mg/m³) had depressed weight gain for the first 3 months of exposure, but recovered in subsequent months and in the satellite recovery group. No other adverse effects attributable to exposure to the test substance were seen. Based on the reversibility of the reduced weight gain and the lack of any noted pathology, the NOAEC for male rats was 1800 mg/m³ and the NOAEC for female rats was 900 mg/m3.