(2-hydroxy-1,1-dimethylethyl)ammonium toluene-4-sulphonate

Endpoint summary

Description of key information

Propan-1-ol, 2-amino-2-methyl-, 4-methylbenzenesulphonate was considered to be a non-sensitizer under the conditions of the local lymph node assay in the mouse (Pooled Method) test (Envigo, 2017).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

Female CBA/Ca (CBA/CaOlaHsd) strain mice were supplied by Envigo RMS B.V., Inc., Horst, The Netherlands. On receipt the animals were randomly allocated to cages. The animals were nulliparous and non pregnant. After an acclimatization period of at least 5 days the animals were selected at random and given a number unique within the study by indelible ink marking on the tail and a number written on a cage card. At the start of the study the animals were in the weight range of 15 to 23 g, and were 8 to 12 weeks old.

Vehicle:

dimethylformamide

Concentration:

Test item at concentrations of 50%, 25% or 10% w/w in dimethyl formamide was applied.

No. of animals per dose:

4

Details on study design:

The mice were treated by daily application of 25 µL of the appropriate concentration of the test item to the dorsal surface of each ear for three consecutive days (Days 1, 2, 3). The test item formulation was administered using an automatic micropipette and spread over the dorsal surface of the ear using the tip of the pipette.
A further group of four mice received the vehicle alone in the same manner.

Five days following the first topical application of the test item or vehicle (Day 6) all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 3H methyl thymidine (3HTdR: 80 µCi/mL, specific activity 2.0 Ci/mmoL, ARC UK Ltd) giving a total of 20 µCi to each mouse.

Clinical Observations: All animals were observed twice daily on Days 1, 2 and 3 and on a daily basis on Days 4, 5 and 6. Any signs of toxicity or signs of ill health during the test were recorded.
Body Weights: The body weight of each mouse was recorded on Day 1 (prior to dosing) and Day 6 (prior to termination).

Termination: Five hours following the administration of 3HTdR all mice were killed by carbon dioxide asphyxiation followed by cervical separation. The draining auricular lymph nodes from the four mice were excised and pooled for each experimental group. For each group 1 mL of PBS was added to the pooled lymph nodes.
Preparation of Single Cell Suspension: A single cell suspension of pooled lymph node cells was prepared by gentle mechanical disaggregation through a 200 mesh stainless steel gauze. The lymph node cells were rinsed through the gauze with 4 mL of PBS into a petri dish labeled with the study number and dose concentration. The lymph node cell suspension was transferred to a centrifuge tube. The petri dish was washed with an additional 5 mL of PBS to remove all remaining lymph node cells and these were added to the centrifuge tube. The pooled lymph node cells were pelleted at 1400 rpm (approximately 190 g) for 10 minutes. The pellet was re suspended in 10 mL of PBS and re pelleted. To precipitate out the radioactive material, the pellet was re suspended in 3 mL of 5% Trichloroacetic acid (TCA).
Determination of 3HTdR Incorporation: After approximately 18 hours incubation at approximately 4 C, the precipitates were recovered by centrifugation at 2100 rpm (approximately 450 g) for 10 minutes, re suspended in 1 mL of TCA and transferred to 10 mL of scintillation fluid. 3HTdR incorporation was measured by  scintillation counting. The "Poly Q™" vials containing the samples and scintillation fluid were placed in the sample changer of the scintillator and left to stand in darkness for approximately 20 minutes. The purpose of this period of time in darkness was to reduce the risk of luminescence, which has been shown to affect the reliability of the results. After approximately 20 minutes, the vials were shaken vigorously. The number of radioactive disintegrations per minute was then

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

The proliferation response of lymph node cells was expressed as the number of radioactive disintegrations per minute per lymph node (disintegrations per minute/node) and as the ratio of 3HTdR incorporation into lymph node cells of test nodes relative to that recorded for the control nodes (Stimulation Index).
The test item will be regarded as a sensitizer if at least one concentration of the test item results in a threefold or greater increase in 3HTdR incorporation compared to control values. Any test item failing to produce a threefold or greater increase in 3HTdR incorporation will be classified as a "non sensitizer".
The computerized system used in the studywas Delta Controls – ORCAview .

Positive control results:

The Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group was 6.08 for 25% solution of α Hexylcinnamaldehyde, (tech., 85%) in dimethyl formamide.

Parameter:

SI

Value:

0.99

Test group / Remarks:

Group treated with 10% solution of test substance in dimethyl formamide

Parameter:

SI

Value:

1.46

Test group / Remarks:

Group treated with 25% solution of test substance in dimethyl formamide

Parameter:

SI

Value:

1.5

Test group / Remarks:

Group treated with 50% solution of test substance in dimethyl formamide

Cellular proliferation data / Observations:

There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test.
Body weight change of the test animals between Day 1 and Day 6 was comparable to that observed in the corresponding control group animals over the same period.

Interpretation of results:

GHS criteria not met

Conclusions:

Propan-1-ol, 2-amino-2-methyl-, 4-methylbenzenesulphonate was considered to be a non-sensitizer under the conditions of the local lymph node assay in the mouse (Pooled Method) test.

Executive summary:

Local lymph node assay in the mouse (Pooled Method) was used to determine sensitization potetial of Propan-1-ol, 2-amino-2-methyl-, 4-methylbenzenesulphonate. Three groups, each of four animals, were treated with 50 µL (25 µL per ear) of the test item as a solution in dimethyl formamideat concentrations of 50%,25% or10% w/w. A further group offour animals was treated with dimethyl formamide alone.

Test item was considered to be a non-sensitizer under the conditions of the test.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Justification for classification or non-classification

Propan-1-ol, 2-amino-2-methyl-, 4-methylbenzenesulphonate was considered to be a non-sensitizer according to the criteria of EC Regulation 1272/2008.