2-aminoethanol

Endpoint summary

Description of key information

Animal data demonstrate that MEA does not have a sensitising potential.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

Guinea pig maximisation test

GLP compliance:

not specified

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Currently no LLNA study is available for assessment. The Guinea Pig Maximization Test (GPMT) has been carried out as an animal test to predict human sensitization for over a decade and is recommended by international test guidelines such as OECD.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

not specified

Details on test animals and environmental conditions:

Albino guinea pigs of the Dunkin-Hartley strain were obtained from SahIins Försöksdjursfarm Malmö, Sweden) and kept in groups of three in plastic cages.

Route:

intradermal and epicutaneous

Vehicle:

water

Concentration / amount:

0.6 % (intradermal) and 10.3 % (epicutaneous)

Route:

epicutaneous, open

Vehicle:

water

Concentration / amount:

0.41, 2.05 and 4.1 %

No. of animals per dose:

15 animals used for the test substance (5 animals per concentration)
12 animals used for controls

Details on study design:

The GPMT protocol with the same experimental design as in a previous study on a similar substance (Boman et al., 1993) was followed. Groups of 15 animals were induced with either the test substance, diethanolamine (DEA) or triethanolamine (TEA) and then challenged after three weeks with the inducing amine and the two others. Prior to the topical induction, pretreatment with 10% sodium dodecyl sulphate was carried out. The concentrations used for induction and challenge were based on previous experience with TEA and the concentrations of the test substance and DEA were equimolar to those of TEA. The challenge reactions were read blindly 48 and 72 h after application or the patches (Finn chambers). Two separate experiments were carried out with the test substance. Control groups of twelve animals were given the same treatment (Freund's Complete Adjuvant, vehicle, occlusion, etc.) except for the inducing amine.

Challenge controls:

no data

Positive control substance(s):

no

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

4.1%

No. with + reactions:

2

Total no. in group:

15

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

2.05%

No. with + reactions:

1

Total no. in group:

15

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.41%

No. with + reactions:

2

Total no. in group:

15

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

4.1 %

No. with + reactions:

3

Total no. in group:

15

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

2.05 %

No. with + reactions:

2

Total no. in group:

15

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

0.41 %

No. with + reactions:

3

Total no. in group:

15

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

negative control

Dose level:

-

No. with + reactions:

0

Total no. in group:

12

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

negative control

Dose level:

-

No. with + reactions:

0

Total no. in group:

12

Key result

Reading:

1st reading

Hours after challenge:

72

Group:

other: vehicle control

Dose level:

-

No. with + reactions:

2

Total no. in group:

15

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

4.1%

No. with + reactions:

1

Total no. in group:

15

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

2.05%

No. with + reactions:

2

Total no. in group:

15

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.41%

No. with + reactions:

1

Total no. in group:

15

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

4.1%

No. with + reactions:

1

Total no. in group:

15

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

2.05%

No. with + reactions:

1

Total no. in group:

15

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

0.41%

No. with + reactions:

0

Total no. in group:

15

Key result

Group:

positive control

Remarks on result:

not measured/tested

After challenge with 4.1 %, 2.05 % and 0.41 % of the test substance, 3/15, 2/15 and 3/15 animals reacted positively after 72 hours. Two out of 15 animals showed a reaction to the vehicle. Of the 12 control animals, none reacted to the test substance or the vehicle. Possible cross reactions to 5 % of triethanolamine and 7 % of diethanolamine occurred in 3 and 2 animals, respectively. In a 2nd test, only 1 or 2 animals showed a reaction to 4.1 % and 2.05 % of the test substance, but none of the animals reacted to 0.41 % of the test substance or the physiological saline solution used as a vehicle in this study. Moreover, reactions to 10 % of triethanolamine and 7 % of diethanolamine were only observed in 1 and 2 animals, respectively. Of the 12 control animals none reacted to one of the ethanolamines, and 1/12 animals reacted to the vehicle after 24 hours.

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The sensitising potential of MEA, as well as di- and triethanolamine, was studied using the guinea pig maximisation test (Wahlberg and Boman, 1996). Groups of 15 animals were induced with either MEA, DEA or TEA and then challenged after three weeks with the inducing amine and the two others. Prior to the topical induction, pretreatment with 10% sodium dodecyl sulphate was carried out. The challenge reactions were read blindly 48 and 72 h after application of the patches. Control groups of twelve animals were given the same treatment (FCA, vehicle, occlusion, etc.) except for the inducing amine. No statistically significant difference between actively induced animals and control animals was observed and there was no indication of cross reactivity.

Additionally an local lymph node assay with hydrochloride salt of the substance, which is a close analogue of the substance, is available. In this study, according to OECD Guideline 429, female CBA/Ca mice were exposed to concentrations up to 70% of the hydrochloride salt. No signs of systemic toxicity were noticed. The statistically significant increases in cellularity, caused by the 70% concentration and in 3H-thymidine incorporation into the lymph node cells, caused by the 70% and 30% preparations, failed to reach the stimulation index criterion of 1.5 or 3, respectively, and thus lie below the threshold of immunologic relevance. Lymph node weights were not statistically significantly increased.

 

Respiratory sensitisation

Link to relevant study records

Reference

Endpoint:

respiratory sensitisation, other

Remarks:

In vivo / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Measurement of bronchoconstriction (Pao) and analysis of Histamine in Bronchoalveolar Lavage Fluid (BALF) in the guinea pig in vivo. Measurement of contraction of the guinea pig trachea ex vivo, following exposure to the test substance and the test substance in combination with other agents known to affect respiratory function.

GLP compliance:

no

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: SLC, Hamamatsu, Japan
- Weight at study initiation: 350–450 g

No. of animals per dose:

4

Details on study design:

Animal Preparation:
Animals were anesthetized with pentobarbital sodium (50 mg/kg, i.p.) and placed on a heated blanket to maintain body temperature at approximately 37 °C. The trachea was cannulated, and the lungs were ventilated artificially with room air at 70 strokes/min with a tidal volume of 10 mL/kg body weight. Airway opening pressure (Pao) was monitored using a pressure transducer positioned on a side arm of the tracheal cannula to provide an index of the change in tracheobronchial resistance to airflow. Aerosols of solutions were inhaled through the tracheal cannula after nebulization while drugs were injected intravenously through a catheter inserted into the jugular vein. The Pao was recorded with a polygraph. Body temperature was monitored with a probe inserted into the rectum.

Determination of the Pao Increase Induced by Aerosols of MEA Solution or Potassium Hydroxide Solution:
Pao increase was determined after inhalation of an aerosol of 0.1 mL/kg of 3.3% test substance solution (pH 12.0) via the tracheal cannula. The Pao increase was calculated as the difference between the baseline value and the maximum-response value after treatment of the group with the test substance (n = 4). As control, an aerosol of potassium hydroxide (KOH) solution at the same pH was inhaled. In the same manner as for the test substance group, control group (n = 4) underwent measurement of the Pao increase after inhalation of an aerosol of 0.1 mlL/kg of 0.056% KOH solution (pH 12.0) via tracheal cannula.

Furthermore:
- Pao Increase induced by inhaled MEA after administration of Atropine Sulfate, Diphenhydramine Hydrochloride, FK-3657, or Pranlukast was determined. Acetylcholine, histamine, bradykinin and cysteinyl leukotriene are well-known mediators inducing bronchoconstriction. To investigate involvement of these mediators in MEA-induced bronchoconstriction, an aerosol of MEA solution was inhaled after administration of agents that suppress actions of these mediators.
- For further investigation of involvement of acetylcholine in MEA induced bronchoconstriction, a group of guinea pigs (n = 4) inhaled an aerosol of MEA solution after administration of a carbamate, acetylcholinesterase inhibitor, which would enhance the action of acetylcholine.
- To assess the role of histamine in MEA-induced bronchoconstriction, histamine in bronchoalveolar lavage fluid (BALF) was measured in another group of guinea pigs (n = 4) during MEA-induced bronchoconstriction.
- To investigate participation of the agonistic effect of MEA at histamine-H1 receptors or muscarinic receptors in MEA-induced bronchoconstriction, contraction of epithelially denuded trachea was measured in vitro during superfusion with MEA after previous exposure to a histamine-H1 receptor antagonist or a muscarinic receptor antagonist.

Results:

An aerosol of 3.3% MEA solution (0.1 mL kg−1) delivered via the trachea significantly induced bronchoconstriction. More potently than did an aerosol of KOH solution (0.1 mL/kg) at the same pH.
MEA-induced bronchoconstriction was significantly suppressed by premedication with an intravenous injection of atropine sulfate or diphenhydramine, but was not suppressed by premedication with intravenous administration of FK-3657 or enteral administration of pranlukast.
MEA-induced bronchoconstriction was not enhanced by premedication with an intravenous injection of neostigmine.
In BALF obtained during MEA-induced bronchoconstriction, the histamine concentration was not significantly higher than in BALF obtained during KOH-induced bronchoconstriction or in BALF after inhalation of physiologic saline.
Contraction of epithelially denuded trachea during superfusion with MEA (10 mM) was suppressed by pretreatment with superfusion of pyrilamine maleate (10 and 100 μM), a histamine-H1 receptor antagonist, in a dose dependent manner. Contraction of the epithelially denuded trachea during superfusion with MEA (10 mM) was suppressed by pretreatment with superfusion of atropine sulfate (10 and 100 μM), a muscarinic receptor antagonist, in a dose dependent manner.

Interpretation of results:

study cannot be used for classification

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Kamije et al (2009) evaluated the respiratory sensitisation in the guinea pig in vivo using measurementsof bronchoconstriction (Pao) and analysis of Histamine in Bronchoalveolar Lavage Fluid (BALF) following exposure to the test substance. In addition, measurements were made of contraction of the guinea pig trachea ex vivo, following exposure to the test substance and the test substance in combination with other agents known to affect respiratory function. Exposure to the test substance caused a significant increase in bronchoconstriction over control, which was decreased by co administration of atropine and diphenhydramine hydrochloride. The test substance did not cause an increase in histamine in BALF. The observed effects are likely of mechanistic origin. A possible mechanism of action is via direct agonistic effects at histamine H1 and muscarinic receptors. Therefore, this study provides no evidence for respiratory sensitization or occupational asthma.

Three case studies were published related to either occupational asthma or accidental exposure to products containing ethanolamines. The first case study of 20 patients diagnosed with occupational asthma confirmed one case to be caused by triethanolamine via a skin prick test with pure triethanolamine. Skin prick tests with products containing ethanolamines did not result in positive reactions (Mäkelä, 2011). A second case study describes a patient that ingested an alkaline detergent containing 3.3% of the test substance. The patient was found to have acute respiratory stress syndrome and there were areas in his lungs with severely damaged alveoli. The patient died on the 4th hospital day (Kamijo, 2004). The third case study describes three workers with occupational asthma that all reacted positively to respiratory challenges with products containing triethanolamine. One of the workers also reacted positive on a standard skin prick test. None of them was able to continue their work, due to their asthma (Savonius, 1994). These studies suggest that ethanolamines (more specifically: triethanolamine) can lead to respiratory sensitisation. However, they do not provide conclusive information on the possible respiratory sensitisation to the test substance.

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for the purpose of classification under Regulation (EC) No 1272/2008. Based on these information the test item is not considered to be classified for skin or respiratory sensitisation under Regulation (EC) No 1272/2008, as amended for the tenth time in Regulation (EU) No 2017/776.