Registration Dossier

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: GLP guideline study (OECD 413)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Dimethyldicykan (Laromin C 260)
- Physical state: liquid
- Analytical purity: > 99.5 %
- Storage condition of test material: refrigerator

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Dr. KarL Thomae GmbH, Germany
- Age at study initiation: 8 weeks
- Weight at study initiation: males: 247 (226 - 266) g, females: 171 (159 - 181) g
- Housing: single
- Diet: SSNIFF R 10 mm Pellets, ad libitum
- Water: water ad libitum
- Acclimation period: 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 °C
- Humidity (%): 30-70 %
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure:
nose/head only
Vehicle:
other: unchanged (no vehicle)
Remarks on MMAD:
MMAD / GSD: 3.5, 1.5, and 2.8 µm, respectively.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
gas chromatography
Duration of treatment / exposure:
3 months
Frequency of treatment:
6 hours each working day (5 days/week)
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0.002, 0.012, 0.048 mg/l (2, 12, 48 mg/m3)
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
2.1±0.58 µg/l, 12.4±12.63 µg/l, 48.2±10.48 µg/l
Basis:
analytical conc.
No. of animals per sex per dose:
10
Control animals:
yes
Details on study design:
- Dose selection rationale: pre study

Examinations

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

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

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

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 data

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: before and at the end of the study
- Dose groups that were examined: control and high dose group

HAEMATOLOGY: Yes
- Time schedule for collection of blood: before first exposure and at day 87.
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: all
- Parameters examined: Erythrocyte count, hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), leucocyte count, thrombocyte count.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: before first exposure and at day 87.
- Animals fasted: No data
- How many animals: all
- Parameters examined: aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, sodium, potassium, chloride, inorganic phosphorus, calcium, bilirubin total, creatinine, glucose, urea, total protein, albumin, cholesterol, triglycerides.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes

HISTOPATHOLOGY: Yes, adrenal gland, bone with marrow, brain, esophagus, eyes, heart, large intestine (cecum, colon, rectum), small intestine (duodenum, jejunum, ileum), kidney, larynx, liver, lungs, ovary, pancreas, pituitary gland, salivary gland, skin, spleen, stomach testis, thymus, thyroid gland, urinary bladder, and uterus, aorta, sternum, skeletal muscles, lacrimal gland, accessorius sex glands, mesenteric lymph nodes, all macroscopic alterations.

Results and discussion

Results of examinations

Details on results:
CLINICAL SIGNS AND MORTALITY
There were no mortalities in the control and high dose groups. One female at 2 µg/l and one male at 12 µg/l died intercurrently after 37 and 48 exposures, respectively. Deaths were judged to be of spontaneous nature.

Scattered occurrence of observations throughout all test groups without relation to dose were noted. No specific substance-related effect noted.

BODY WEIGHT AND WEIGHT GAIN
Compared to control animals statistically reduced mean body weight gain (p<0.01) and reduced body weight from day 50 onwards (p<0.01) was seen in high dose male rats. Body weight was reduced by approx 14% compared to controls on day 85. In high dose females body weight change was significantly reduced (p<0.05) from day 71 onwards. Terminal body weight in females was reduced by 8% and statistically different from controls animals. No other statistically significant effect on body weight parameters were noted.

OPHTHALMOSCOPIC EXAMINATION
no changes in any of the dose groups noted.

HAEMATOLOGY
Significant (p<0.05) reductions in hemoglobin, hemoglobin per erythrocyte, and in mean corpuscular hemoglobin concentration (MCHC) were noted in the male high dose rats only. Polychromatosis was noted.
Clotting test: statistically significant clotting time increase was only seen in females but not in males. This effect was not considered to be treatment related.

CLINICAL CHEMISTRY
Animals at 12 µg/l: statistically significant, but marginal increase of alkaline phosphatase (5.658 µkat/l vs. 4.949 µkat/l in controls) and GPT (glutamate pyruvate transaminase; 1.043 µkat/l vs. 0.845 µkat/l in controls) in male rats. GOT (glutamate oxalo-acetate transaminase) was not changed in male rats. Increase of alkaline phosphatase was only seen in this test group. No other change was noted in male or female animals.

Animals at 48 µg/l: statistically significant increase of GOT and GPT (but not alkaline phosphatase) compared with controls in male rats, but not in females rats. Activity of GPT in serum was 1.081 µkat/l vs. 0.845 µkat/l in control animals (p<0.01). A significant (p<0.01) decrease of serum triglycerides in high dose males was considered to result from a decreased food consumption which was assumed because of the reduced body weight development in this group. This finding was therefore regarded to be a secondary effect.

ORGAN WEIGHTS
Relative organ weight of liver, lung, and kidney was significantly increased in high dose male and female animals on the 1% or 5% level of significance. Relative weight of adrenals (p<0.05) and testes (p<0.01), and absolute lung weight (1.41 g vs. 1.18 g in controls) were significantly increased only in high dose male rats.

HISTOPATHOLOGY: NON-NEOPLASTIC
No effects in low and medium dose animal groups.
Effects in high dose animals included: Local irritative effects on the skin and slight hyperkeratosis in 7/10 male rats. Minimal to slight vacuolization of the craniodorsal olfactory epithelium in both male (2/10) and female (1/10 animals) rats. Significantly increased incidence of slight tubulonephrosis was noted in male rats only (6/10 vs. 1/10 in male controls; 9/10 females vs. 7/10 controls), and extramedulary haematopoesis in spleen was noted only in female rats (9/10). Hemosiderin was noted in spleen of all high dose animals.

Effect levels

Dose descriptor:
NOAEC
Remarks:
systemic toxicity
Effect level:
12 mg/m³ air
Sex:
male/female
Basis for effect level:
other: see 'Remark'

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion