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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
23 August 2019 - 20 September 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020
Report date:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 433 draft (Acute Inhalation Toxicity: Fixed Concentration Procedure) (not officially approved)
Version / remarks:
2018
Deviations:
not specified
GLP compliance:
yes (incl. QA statement)
Test type:
fixed concentration procedure
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Tar, wood
EC Number:
294-436-0
EC Name:
Tar, wood
Cas Number:
91722-33-7
Molecular formula:
not applicable
IUPAC Name:
Tar, wood
Test material form:
liquid: viscous
Remarks:
dark brown

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Laboratories, Raleigh, North Carolina 27610
- Age at study initiation: Approximately 9 weeks
- Weight at study initiation: 249.7 g to 265.2 g
- Fasting period before study: not specified
- Housing: Teklad 7070C Certified Diamond Dry Cellulose Bedding, Envigo, Madison, Wisconsin; 2-3 animals per cage; entichment provided
- Diet ad libitum: Teklad Global 16% Protein Rodent Diet (Certified), 2016C, Envigo, Madison, Wisconsin
- Water ad libitum: pot water
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 26 °C
- Humidity (%): 30 to 70%.
- Air changes (per hr): not specified
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: To:
AM Morning observation
PM Afternoon observation
RTC Observations upon return to their home cage after exposure
1HrPD Observations 1 hour after exposure
2HrPD Observations 2 hours after exposure
NDD Observations on non-exposure days

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Remarks:
liquid aerosol
Vehicle:
air
Mass median aerodynamic diameter (MMAD):
ca. 2.2 µm
Geometric standard deviation (GSD):
>= 1.78 - <= 1.81
Remark on MMAD/GSD:
MMAAD Gravimetr.: 2.3 (std: 1.77 - 1.82)
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus:
- Exposure chamber volume:
- Method of holding animals in test chamber:
- Source and rate of air:
- Method of conditioning air:
- System of generating particulates/aerosols:
- Method of particle size determination:
- Treatment of exhaust air:
- Temperature, humidity, pressure in air chamber: 20°C, 56% rel hum.

TEST ATMOSPHERE
- Brief description of analytical method used: HPLC/UV
- Samples taken from breathing zone: yes

VEHICLE
- Composition of vehicle (if applicable): not applicble
- Concentration of test material in vehicle (if applicable): not applicble
- Justification of choice of vehicle: not applicble
- Lot/batch no. (if required): not applicble
- Purity: not applicble

TEST ATMOSPHERE (if not tabulated)


CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: Wood Tar has been evaluated for acute oral toxicity in rats and was found to be non-lethal at 2000 mg/kg. Also, an in vitro evaluation of dermal toxicity was done using human skin and the test item was found to be irritating but not corrosive. On the basis of these results which indicate that the test might have low toxicity, the initial exposure level for this study was selected to be 1.0 mg/L as per the OECD Guidelines (OECD 433, 2018).
Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
target: 1,0 mg/L
analytical: 1,6 mg/L
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: daily
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Results and discussion

Effect levelsopen allclose all
Key result
Sex:
male
Dose descriptor:
LC0
Effect level:
1.6 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Key result
Sex:
male
Dose descriptor:
LC50
Effect level:
> 1.6 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Remarks on result:
not determinable because of methodological limitations
Mortality:
Not occured
Clinical signs:
other: not occured
Body weight:
unchanged
Gross pathology:
No macropathology findings, in one animal testes small bilateral, soft bilateral. Not considered to be an effect of treatment.

Applicant's summary and conclusion

Interpretation of results:
study cannot be used for classification
Conclusions:
The presented GLP-inhalation study followed international guidance and no deviations from guideline were reported.
The single reported effect concentration is the starting concentration of a planned series of concentrations, and represents the only achievable concentration of the test item. Therefore it is concluded the reported value represents the NOEC and the LOEC and LOEC and the LC50 must be >1.6 mg/L.
Executive summary:

Sprague-Dawley CD® rats (5 males) were exposed once to Wood Tar by nose-only inhalation of liquid aerosol at 1.0 mg/L of air for 4 hours. After a 14-day observation period the animals were euthanized and necropsied. Parameters evaluated during the study were: viability, clinical observations, body weights and macroscopic observations.

Wood Tar was exposed to rats for 4 hours at 1.6 mg/L based on analytical results. This exposure level was well tolerated and a higher exposure level of 5.0 mg/L was thus planned. However, additional aerosol trials demonstrated that the exposure at the target of 1.0 mg/L was essentially a maximum attainable exposure level. Therefore, the 5.0 mg/L exposure was not conducted and the study was considered completed.

Thus, the LC50 would be estimated to be >1.6 mg/L.