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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
2011-11-18 - 2012-01-26
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The GLP study was conducted according to an internationally accepted guideline. All study parameters are given in detail. Nevertheless, according to the ECHA's practical guide 6: "How to report read-across and categories" the maximum for read-cross is 2.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
standard acute method
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
other: liquid
Details on test material:
Molecular formula C15H16
Molecular weight 196.29
CAS Number 40766-30-1
Description Clear colourless liquid (determined at NOTOX)
Batch PTE-01
Purity ≥ 95%
Test substance storage At room temperature in the dark under nitrogen
Stability under storage conditions Stable

Test animals

Species:
rat
Strain:
other: Crl:WI(Han)
Sex:
male/female
Details on test animals and environmental conditions:
Conditions
Animals were housed in a controlled environment, in which optimal conditions were considered to be approximately 15 air changes per hour, a temperature of 21.0 ± 3.0°C (actual range: 19.6 - 21.9°C), a relative humidity of 40-70% (actual range: 40 - 56%) and 12 hours artificial fluorescent light and 12 hours darkness per day.

Accommodation
Before exposure
Group housing of five animals per sex per cage in labelled Makrolon cages (type IV; height 18 cm) containing sterilised sawdust as bedding material (Litalabo, S.P.P.S., Argenteuil, France) and paper as cage-enrichment (Enviro-dri, Wm. Lillico & Son (Wonham Mill Ltd), Surrey, United Kingdom).
Acclimatisation period was at least 5 days before start of treatment under laboratory conditions.

After exposure
Group housing as described above, except that a paper sheet was introduced into the cage covering the bedding and cage enrichment to prevent suffocation in case of bad health condition. At the end of the Day of exposure the paper sheet was removed.

Diet
Free access to pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany) except during exposure to the test substance.

Water
Free access to tap water except during exposure to the test substance.

Animal husbandry on the Day of exposure
The animals were moved to the inhalation area to in order to perform the exposure. During the exposure, there was no access to food and water. After exposure, the animals were returned their cages which were placed in a fume cupboard for a short time period to allow test substance remnants to evaporate. A sheet of filter paper was used to cover the bedding material to prevent suffocation in case of bad health condition and in order to recover and to aid the clinical observations. The sheet was removed and before the end of the exposure day, the animals were returned to the animal room.

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
air
Details on inhalation exposure:
The design of the exposure chamber is based on the flow past nose-only inhalation chamber (Am. Ind. Hyg Assoc. J. 44(12): 923-928, 1983). The chamber consisted of three animal sections with eight animal ports each. Each animal port had its own atmosphere inlet and exhaust outlet. The animals were placed in restraining tubes and connected to the animal ports. The number of animal sections and number of open inlets were adapted to the air flow in such a way that at each animal port the theoretical air flow was at least 1 L/min, which ensures an adequate oxygen supply to the animals. The main inlet of the test atmosphere was located at the top section and the main outlet was located at the bottom section. The direction of the flow of the test atmosphere guaranteed a freshly generated atmosphere for each individual animal.
All components of the exposure chamber in contact with the test material were made of stainless steel, glass, rubber or plastic. To avoid exposure of the personnel and contamination of the laboratory the exposure chamber was placed in a fume hood, which maintained at a slight negative pressure.
Fifteen minutes after the last animal was placed the generation of the test atmosphere was started. The exposure time was 4 hours.

Test atmosphere generation
The test substance was transferred to a nebulizer (LC SPRINT Baby rood, Pari, Starnberg, Germany) by means of a rotating pump (type VL500 digit, VERDER Lab Tec GmbH & Co. KG, Haan, Germany) and nebulized with pressurized air. The primary aerosol was diluted with humidified pressurized air and passed through the exposure chamber. The mean total airflow was 19 L/min for the 5 mg/L exposure group and 34 L/min for the 1 mg/L exposure group.
From the exposure chamber the test atmosphere was passed through a filter before it was released to the exhaust of the fume hood.
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
Target concentrations were based on the cut off concentration values specified in the UN and EC classification guidelines. Five animals of each sex were initially exposed in a limit test for 4 hours to a target concentration of the test substance of 5 mg/L. Based on the mortality observed, five animals of each sex were exposed to the next lower target concentration of 1 mg/L.
No. of animals per sex per dose:
5 male and 5 females per dose group.
Control animals:
no

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 1 - < 5 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Mortality:
At 5 mg/L, on the day following exposure (Day 2) three males and two females were found dead and the remaining animals were sacrificed for ethical reasons.
At 1 mg/L, one female was sacrificed for ethical reasons on Day 2. No further mortality occurred.
Clinical signs:
At 5 mg/L, the animals showed gasping and laboured respiration during exposure. After exposure, hunched posture, lethargy, flat posture, laboured respiration, piloerection, ptosis and/or moribund status were shown by the animals.
At 1 mg/L, no clinical signs were noted during exposure. After exposure, the animals showed lethargy, hunched posture, piloerection and/or ptosis between Days 1 and 4. In addition, the female sacrificed on Day 2 showed uncoordinated movements, chromodacryorrhoea, hypothermia, shallow respiration and a lean appearance.
Body weight:
At 5 mg/L, body weights loss was noted in the animals found dead or sacrificed on Day 2. At 1 mg/L, overall body weight gain and body weight loss in males and females was within the range expected for rats of this strain and age used in this type of study.
Gross pathology:
At 5 mg/L, macroscopic post mortem examination of the animals that were found dead or sacrificed for ethical reasons during the study revealed abnormalities of the lungs (many dark red foci), stomach (black foci in the glandular mucosa), liver (pale discoloration) and mandibular lymph nodes (dark red discoloration). At 1 mg/L, no abnormalities were found at macroscopic post mortem examination of the animals.
Incidental findings included advanced autolysis which is not toxicologically relevant and pelvic dilation of the kidneys which is occasionally seen among rats of this age and strain and therefore considered not related to treatment.

Any other information on results incl. tables

The Mass Median Aerodynamic Diameter (MMAD) and geometric standard deviation (gsd) were determined twice. For the 5 mg/L exposure group, the MMAD was 2.9 μm (gsd 1.9) and 2.6 μm (gsd 2.1). For the 1 mg/L exposure group, the MMAD was 2.8 μm (gsd 2.1) and 2.9 μm (gsd 1.9).

Applicant's summary and conclusion

Interpretation of results:
Toxicity Category IV
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The inhalatory LC50, 4h value of Phenyl-tolyl-ethane in Wistar rats was established to be within the range of 1 – 5 mg/L.
Executive summary:

Phenyl-tolyl-ethane was administered as an aerosol by inhalation for 4 hours to two groups of five male and five female Wistar rats each group. Animals were subjected to daily observations and determination of body weights on Days 1, 2, 8 and 15. Macroscopic examination was performed on the day of death or after terminal sacrifice (Day 15).

At 5 mg/L, on the day following exposure (Day 2) three males and two females were found dead and the remaining animals were sacrificed for ethical reasons. At 1 mg/L, one female was sacrificed for ethical reasons on Day 2. No further mortality occurred. At 5 mg/L, the animals showed gasping and laboured respiration during exposure. After exposure, hunched posture, lethargy, flat posture, laboured respiration, piloerection, ptosis and/or moribund status were shown by the animals. At 1 mg/L, no clinical signs were noted during exposure. After exposure, the animals showed lethargy, hunched posture, piloerection and/or ptosis between Days 1 and 4. In addition, the female sacrificed on Day 2 showed uncoordinated movements, chromodacryorrhoea, hypothermia, shallow respiration and a lean appearance. At 5 mg/L, body weights loss was noted in the animals found dead or sacrificed on Day 2. At 1 mg/L, overall body weight gain and body weight loss in males and females was within the range expected for rats of this strain and age used in this type of study. At 5 mg/L, macroscopic post mortem examination of the animals that were found dead or sacrificed for ethical reasons during the study revealed abnormalities of the lungs (many dark red foci), stomach (black foci in the glandular mucosa), liver (pale discoloration) and mandibular lymph nodes (dark red discoloration). At 1 mg/L, no abnormalities were found at macroscopic post mortem examination of the animals. The inhalatory LC50, 4h value of Phenyl-tolyl-ethane in Wistar rats was established to be within the range of 1 – 5 mg/L.