2-[7-(diethylamino)-2-oxo-2H-1-benzopyran-3-yl]benzoxazole-5-sulphonamide

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

December 2016 to March 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)

Version / remarks:

2009

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: Guidance document on acute inhalation toxicity testing; number 39, ENV/JM/MONO

Version / remarks:

2009

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: REACH: Guidance on information requirements and chemical safety assessment Chapter R.7a: Endpoint specific guidance.

Deviations:

no

Principles of method if other than guideline:

Trial generations were performed in order to develop a method for a suitable test atmosphere.

GLP compliance:

no

Remarks:

The trial generations have non-GLP status but were carried out in the quality assure environment of the testing facility.

Test material

Test material information

Constituent 1

Reference substance name:

2-[7-(diethylamino)-2-oxo-2H-1-benzopyran-3-yl]benzoxazole-5-sulphonamide

EC Number:

270-393-3

EC Name:

2-[7-(diethylamino)-2-oxo-2H-1-benzopyran-3-yl]benzoxazole-5-sulphonamide

Cas Number:

68427-35-0

Molecular formula:

C20H19N3O5S

IUPAC Name:

2-[7-(diethylamino)-2-oxo-2H-chromen-3-yl]-1,3-benzoxazole-5-sulfonamide

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: Yellowish orange powder
- Storage conditions of test material: At room temperature
- Stable under storage conditions until: 30 November 2020 (expiry date)

Administration / exposure

Details on inhalation exposure:

EXPOSURE CHAMBER
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 consists of animal sections with eight animal ports each. Each animal port has its own test atmosphere inlet and exhaust outlet. The number of animal sections and number of open inlets will be adapted to the air flow in such a way that at each animal port the theoretical air flow is at least 1 L/min. The main inlet of the test atmosphere is located at the top section and the main outlet is located at the bottom section. The direction of the flow of the test atmosphere guarantees a freshly generated atmosphere for each individual animal. All components of the exposure chamber in contact with the test material are made of stainless steel, glass, rubber or plastic. To avoid exposure of the personnel and contamination of the laboratory the exposure chamber is placed in a fume hood which is maintained at a slight negative pressure.

DETERMINATION OF THE NOMINAL CONCENTRATION
The nominal concentration was calculated by dividing the amount of test material used by the volume of pressurised air (average air flow times exposure time) entering the exposure chamber used for exposure of the animals. Due to the small volume of the exposure chamber the equilibrium time was negligible.

DETERMINATION OF THE ACTUAL CONCENTRATION
Samples of the test atmosphere were drawn through glass fibre filters. The amount of test material collected was measured gravimetrically. The actual concentration in each sample was calculated from the amount of test material collected and the volume of the sample.

TEST ATMOSPHERE GENERATION; METHODS AND RESULTS
METHOD 1
- Rationale: The test material appears as a coarse sticky powder that easily forms larger agglomerates. Reducing the size of the powder would reduce the particle size and improve the efficiency of the generation.
- Method: The test material was ground with an automatic grinder (Retsch PM100 Planetary Ball Mill, Retsch gmbh, Haan, Germany).
- Result: The test material became a hard solid layer on the bottom of the mill-cup.
- Conclusion: A single grinding session is not successful.

METHOD 2
- Rationale: Adjustment of the grinding procedure may be successful.
- Method: The test material was removed from the bottom of the mill cup after the first grinding session with an automatic grinder (Retsch PM100 Planetary Ball Mill, Retsch gmbh, Haan, Germany). This session was repeated twice.
- Result: The test material could be scraped from the mill cup and was passed through a sieve (250 μm).
- Conclusion: A fine powder, but still easily forming larger agglomerates.

METHOD 3
- Rationale: Generate a dust with the ground and sieved test material.
- Method: The test material was administered to a stream of pressurised air using a combination of a spiral feeder (Randcastle Extrusion Systems, Cedar Grove, NJ, USA) and an air mover (FOX-093, Foxvalve).
- Result: The test material remained behind in the spiral feeder and was not fed to the system.
- Conclusion: Not a suitable set up.

METHOD 4
- Rationale: Improve the feed to the exposure system.
- Method: A vibrator was attached to the dust feeder in order to stimulate the movement of the test material.
- Result: The feed was still not sufficiently high and the resulting dust concentration was close to zero mg/L.
- Conclusion: Not a suitable set up.

METHOD 5
- Rationale: Use another feeder in order to feed the powder to the system.
- Method: The test material was administered to a stream of pressurised air using a brush feeder. The brush feeder avoids compression of the powder.
- Result: The test material was not fed to the system by the brush feeder.
- Conclusion: Not a suitable set-up.

METHOD 6
- Rationale: Make adjustment to the brush feeder.
- Method: A softer brush was placed into the brush feeder.
- Result: The test material was fed to the system by the brush feeder and a concentration of 3.6 mg/L was obtained. However, this concentration could not be maintained since test material deposits blocked the inlet of the fox air mover.
- Conclusion: Not a suitable set-up to maintain the concentration sufficiently long.

METHOD 7
- Rationale: Improve the inlet to the air mover.
- Method: A tube with a larger diameter was placed between the brush feeder and air mover.
- Result: No test material was fed to the air mover.
- Conclusion: Not a suitable set-up.

METHOD 8
- Rationale: Avoid the air mover to be blocked by test material deposits.
- Method: The FOX-090 air mover was replaced with an air mover with a larger inner diameter (AIR-VAC, Milford, CT, USA). The set-up from method 5 was used.
- Result: The concentration obtained was 1.0 mg/L but after a few minutes the concentration dropped to 0 mg/L.
- Conclusion: Concentration obtained was too low.

METHOD 9
- Rationale: Improve the feed to the air mover.
- Method: Tubing with a larger diameter was placed between the feeder and air mover.
- Result: The concentration obtained was between 0.49 and 0.80 mg/L but after a few minutes the concentration dropped to 0 mg/L.
- Conclusion: Concentration obtained was too low.

METHOD 10
- Rationale: Improve the feed to the exposure system.
- Method: Tubing with a larger diameter was placed between the air mover and first cyclone.
- Result: The concentration obtained was 3.1 mg/L. The MMAD was 5.3 μm (gsd 1.63).
- Conclusion: The MMAD exceeded the recommended range of 1 to 4 μm as defined in the OECD guidelines and the concentration was below the target concentration of 5 mg/L.

METHOD 11
- Rationale: Increase the concentration.
- Method: One of the two cyclones was removed from the system.
- Result: The concentration obtained was 2.3 mg/L. The MMAD was 4.8 μm (gsd 1.66).
- Conclusion: The MMAD was reduced but still exceeded the recommended range of 1 to 4 μm as defined in the OECD guidelines. The concentration was lower but might be increased with some flow adjustments.

METHOD 12
- Rationale: Reduce the MMAD further.
- Method: The last cyclone was removed from the system.
- Result: The concentration obtained was between 1.3 - 2.2 mg/L. The MMAD was 3.6 μm (gsd 1.83). However, the feed to the Air-VAC was very high and the system was blocked very rapidly by test material deposits before and after the AIR-VAC.
- Conclusion: The concentration was relatively low and could not be maintained.

METHOD 13
- Rationale: Avoid deposits before and after then AIR-VAC air mover.
- Method: The set-up from method 11 was used with one cyclone and the feeder was tilted to improve the feed to the AIR-VAC and the tubing between the AIR-VAC and cyclone was kept as short as possible.
- Result: The concentration obtained was between 2.3 - 2.8 mg/L. The MMAD was 5.3 μm (gsd 1.77).
- Conclusion: The concentration was relatively low and the MMAD still exceeded the recommended range of 1 to 4 μm as defined in the OECD guidelines.

Overall Conclusion:
It was concluded that it was not possible to generate a suitable dust due to test material deposits as a result of formation of agglomerates and the high feed to the system.

METHOD 14
- Rationale: The powder may be aerosolised with the use of a carrier.
- Method: The test material was mixed with water, in order to nebulise the substance as a solution/suspension.
- Result: The test material did not mix with water.
- Conclusion: The use of water as a carrier is technically not possible.

Results and discussion

Preliminary study:

It was concluded that it was not possible to generate a suitable dust due to test material deposits as a result of formation of agglomerates and the high feed to the system. The use of water as a carrier is technically not possible.

Applicant's summary and conclusion

Conclusions:

It was concluded that it was not possible to generate a suitable dust due to test material deposits as a result of formation of agglomerates and the high feed to the system. The use of water as a carrier is technically not possible.

Executive summary:

Trial generations were performed in order to develop a method for a suitable test atmosphere in order to carry out acute inhalation toxicity testing in accordance with the standardised guidelines OECD 436, Guidance document on acute inhalation toxicity testing; number 39, ENV/JM/MONO and REACH: Guidance on information requirements and chemical safety assessment Chapter R.7a: Endpoint specific guidance.

It was concluded that it was not possible to generate a suitable dust due to test material deposits as a result of formation of agglomerates and the high feed to the system. The use of water as a carrier is technically not possible.