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Acute Toxicity: inhalation

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acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01JAN1980 - 06MAR1980
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
The study is well-documented, sufficient concentrations were tested and the test substance concentration was verified. The study was conducted equivalant to OECD guideline, but not following GLP principles.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 403 (Acute Inhalation Toxicity)
GLP compliance:
Test type:
acute toxic class method
Limit test:

Test material

Test material form:
other: liquid
Details on test material:
- Name of test material (as cited in study report): TAKENATE 600
- Chemical name: 1,3-Bis(isocyanatomethyl)cyclohexane (H6XDI)
- Substance type: Organic
- Physical state: colourless mobile liquid
- Storage condition of test material: in 1 litre metal container (purged with dry nitrogen), stored in fume cupboard at room temperature

Test animals

Details on test animals or test system and environmental conditions:
- Source: Charles River UK, Manston Road, Margate, Kent
- Age at study initiation: 6-8 weeks
- Weight at study initiation: 155 - 202g
- Fasting period before study: no
- Housing: 5 male or 5 female rats/ cage, polypropylene cages with detachable wire mesh tops and floors, suspended on a movable rack (except during 4 hour exposure and 48 hour post exposure when rats were hold in a ventilated cabinet)
- Diet: Spratt's Laboratory Diet I, measured amount
- Water: tap water, ad libitum
- Acclimation period: 5 days

- Temperature (°C): 18.4 - 24.3
- Humidity (%): 31.1 - 42.9

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
whole body
Details on inhalation exposure:
- Exposure apparatus: whole body exposure chambers
- Exposure chamber volume: 0.13m3
- Source and rate of air: clean, dry air (compressed and oil-free)
- System of generating aerosols: an aerosol generator mixed clean dry air at a rate of 30 litres/ minute with the test substance at a flow rate between 0.15 and 0.021 mL per minute
- Method of particle size determination: samples were drawn by a May multistage liquid impinger with 0.04M dibenzylamine solution
- Temperature in chambers(°C): 20.3 - 25.4

- Samples taken from breathing zone: yes (5 samples/ exposure from the exposure chamber to determine test substance concentration and 2 samples to determine particle size distribution)
- Brief description of analytical method used: HPLC (samples were drawn through a gas absorption trap (jet impinger type) with 0.04M dibenzylamine in 1,2 dichloroethane)

The mean concentration and standard deviation of the mean concentration of each group was as follows:
72.7 mg/m3 (10.50)
114.7 mg/m3 (26.59)
147.1 mg/m3 (31.47)
239.1 mg/m3 (21.00)
531.6 mg/m3 (75.37)

The mean percentage by weight of respirable particles (aerodynamic diameter <5.5μm was 88.1% (3.94%).
Analytical verification of test atmosphere concentrations:
Duration of exposure:
4 h
72.7, 114.7, 147.1, 239.1 and 531.6 mg/m3
No. of animals per sex per dose:
Control animals:
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: continuously during exposure and at least twice daily during the observation period
- Frequency of weighing: daily
- Necropsy of survivors performed: yes, gross macroscopy, lung weight was determined (lungs, livers and kidneys collected for possible microscopic examination)
- Other examinations performed: amount of food and water consumed by cage was measured daily
LD50 calculated by log probit method (Miller and Tainter, Proc. Soc. Exp. Biol. Med. 57 (2), 1944, pp 261 - 264).
The standard error was calculated from the formula: S.E. of LC50 = 2s/√(2N)
2s = estimated increment in concentration of the test substance between probits 4.0 and 6.0 corresponding to 16% and 84% mortality and N is the total number of rats in groups with mortality between 6.7% and 93.3%.

Results and discussion

Effect levelsopen allclose all
Dose descriptor:
Effect level:
> 147.1 - < 239.1 mg/m³ air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
other: calculated LD 50 = 189.9 mg/m3 (standard error = 34.9 mg/m3)
Dose descriptor:
Effect level:
> 0.147 - < 0.239 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
No mortality was seen in the control group. At 72.7 mg/m3 one male died 48 hours after exposure, and one female died 8 days after exposure. At 114.7 mg/m3, one male died at 5 hours after exposure. All rats survived exposure to 147.1 mg/m3. At 239.1 mg/m3, 9/10 rats died (2 rats during exposure, 2 rats died within 1 hour after exposure, the other 3 between 36 and 48 hours after exposure, one male rat surrvived) and at the highest concentration all rats died (during or immediately after exposure).
Clinical signs:
other: No clinical signs were seen in the control group during or after exposure. During exposure, rats exposed to 72.7 mg/m3 showed salivation and hunched posture. At higher concentrations salivation, lacrimation, hunched or prone posture, peripheral vasodilat
Body weight:
At 72.7 and 114.7 mg/m3 marked decrease in group mean bodyweight was noted in the first 3 days after exposure, subsequent body weight gain was comparable to that of the control rats. Surviving rats at 147.1 mg/m3 also showed decrease in body weight gain during first three days after exposure, after this body weight gain was lower than that of the control rats for a further 3 days. The surviving male at 239.1 mg/m3 showed decreased body weight gain during first 5 days after exposure.
Gross pathology:
Gross pathology of rats that died as a result of exposure revealed haemorrhage, oedema and areas of hepatisation in the lung and distended gas filled stomachs at 72.7 and 114.7 mg/m3. At 147.1 mg/m3, scattered dark red foci or small area's of consolidation in the lungs of 4 rats were seen. Areas of hepatisation were also seen in the lungs of 2 rats exposed at 72.7 mg/m3 killed at the end of the observation period. A 7 mm diameter hemispherical lesion was observed on the liver of one male. At 239.1 mg/m3, oedema. Hepatisation affecting large areas of the lung and distended gas filled stomachs were seen in rats that died as a result of exposure. Findings for the rat that survived were small areas of hepatisation and a few scattered dark red foci in the lung. the adrenals of this rat were pale and enlarged. At the highest dose, oedema and hepatisation affecting large areas of the lung were seen in all rats.
Other findings:
Food and water consumption:
At 72.7, 114.7 and 147.1 mg/m3 food and water consumption was reduced to 25-30% of normal for 3 days following exposure. Normal food and water consumption resumed over the next 2-3 days.
The surviving male at 239.1 mg/m3 consumed little or no food during 5 days after exposure. Water consumption was 10-15% of normal consumption.

Lung weight to body weight ratio:
Within normal limits for surviving rats; high values for early decedents.

Applicant's summary and conclusion

Interpretation of results:
Category 2 based on GHS criteria
In an acute inhalation toxicity, conducted equivalent to OECD 403, the LD50 of 1,3-H6XDI was found to be > 0.147 mg/L and < 0.239 mg/L.
Executive summary:

An acute inhalation toxicity was performed equivalent to OECD 403 with 1,3H6XDI. Five male and female rats were exposed to aerosols for 4 hours (whole body exposure) and followed for 14 days. Mortality was 0, 2, 1, 0, 9 and 10 rats at 0, 72.7, 114.7, 147.1, 239.1 and 531.6 mg/m3. The time of death correlated with exposure consentration. During exposure, rats showed salivation, lacrimation, hunched or prone posture, peripheral vasodilation and laboured breathing (gasping at two highest doses). The rapidity of onset of these reactions was related to the exposure level. During observation period, laboured breathing and rales were observed in all exposed animals. Brown staining (or dark red discharge) around snouts and peripheral vasodilation was observed in all rats 3 days post exposure. Persistence of the observations was dependent on exposure concentration. Dose-dependent decrease in body weight gain was noted during first 3 to 5 days after exposure. Subsequent body weight gain was comparable to that of the control rats for rats dosed at 72.7 and 114.7 mg/m3, but for rats dosed higher body weight gain remained lower, or further decreased (at 239.1 mg/m3). Gross macroscopy revealed substance related effects in the lungs (oedema and hepatisation, dose-dependent severity).

As the LD50 of 1,3-H6XDI was found to be > 147.1 mg/m3 and < 239 mg/m3, which correlates to > 0.147 mg/L and < 0.239 mg/L, 1,3H6XDI is classified as category 2 for inhalation toxicity according to Regulation EC 1272/2008.

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