Sodium 2,4-dichlorophenoxyacetate

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

No data was available on the sensitizing potential of the test substance. Therefore, data of a structural analogous substance, dimethylammonium 2,4-dichlorophenoxyacetate (CAS 2008-39-1), was used for read-across.

The assessment of systemic effects of salts of 2,4-D is based on data generated with 2,4-D acid. This read across is justified because 2,4-D acid and its salts are toxicologically equivalent once they have entered the system. This is due to the only diffusion-limited rate of reaching the acid-base equilibrium between the protonated acid and its deprotonated salt form in an aqueous environment like the human body. Thus, salts of 2,4-D will exert the same systemic effects as the corresponding acid.

The skin sensitisation potential of dimethylammonium 2,4-dichlorophenoxyacetate (CAS 2008-39-1) was evaluated in guinea pigs according to OECD Guideline 406 (Skin Sensitisation) following the protocol of the Guinea Pig Maximization Test ( Magnusson & Kligman) (RA-S, CAS 2008-39-1, Key, Kita, 1998, Aminopielik 600, skin sensitisation, RL2). 8 Male and 4 female animals in the treated group and 5 males and 1 female in the control group were induced by intradermal injection and epicutaneous application of the test substance. For intradermal induction, a series of three intradermal injections were conducted with either a 1:1 mixture (v/v) of Freund's complete adjuvant (FCA) and water, a 1:1 mixture (v/v) of 1% water solution of the test substance and FCA in water (1:1 v/v) or a 1:1 mixture (v/v) of 1% water solution of the test substance and FCA in water (1:1 v/v). Control animals received water instead of the test substance. These injections were conducted on day 0 of the experiment. 24 before topical induction on day 7, 0.5 ml of 10% sodium lauryl sulfate in vaseline was applied to the test area of the animals in order to create a local irritation. The induction by topical application was conducted with a 50% solution of the test substance which was applied to the test area of the animals for 48 h under occlusive conditions. The challenge was conducted 14 days after last induction application by applying a 40% solution of the substance for 24 h to the left flank of the animal under occlusive conditions. Animals were evaluated for skin reactions 24, 48 and 72 h after challenge.

5 test animals (42%) showed a discrete erythema at the left flank whereas the control animals did not react to the challenge exposure. These effects observed were not reversible within the time of observation (72 h).

 

On the basis of this study,sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9)is classified as sensitising to the skin under the conditions tested.

Migrated from Short description of key information:
RA-S, CAS 2008-39-1, Key, Kita, 1998, Aminopielik 600, skin sensitisation, RL2 - sensitising

Respiratory sensitisation

Endpoint conclusion

Additional information:

Migrated from Short description of key information:
No data on respiratory sensitisation was available.

Justification for classification or non-classification

According to the DSD (67/548/EEC) and CLP (EC No. 1272/2008) criteria for classification and labelling of dangerous substances sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9)is classified as sensitising to the skin.