Sodium 2,4-dichlorophenoxyacetate

Endpoint summary

Description of key information

Skin irritation
Key, NZPO "Organika-Rokita", Kita, 1991, dermal irrit., rabbit, RL1 – not irritating
Eye Irritation
NZPO "Organika-Rokita", Kita, 1991, eye irrit., RL3
RA-S, CAS 2008-39-1, Key, Kita, 1997, Aminopielik 720, eye irritation, RL2 – irritating
RA-S, CAS 2008-39-1, Kita, 1991, Aminopielik 600, eye irritation, RL2 – irritating

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

The irritating potential of sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) was tested in studies conducted according to OECD Guideline 404 (skin irritation/corrosion) and OECD Guideline 405 (eye irritation). In addition, two further eye irritation studies conducted with Dimethylammonium 2,4-dichlorophenoxyacetate (CAS No. 2008-39-1), a structural analogous substance, were used for read across.

 

Skin Irritation

Sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) was tested for skin irritation potential according to OECD Guideline 404 (Key, NZPO "Organika-Rokita", Kita, 1991, dermal irrit., rabbit, RL1): Thedorsal area of the trunk of three New Zealand White rabbits was exposed to 0.5 mL test material for 4 hours under occlusive conditions. Thereafter, the rabbits were observed for 72 h and skin reactions were assessed periodically after removal of the patch using the Draize scheme. No signs of erythema and oedema were observed during the study period.

 

Eye Irritation

Two studies were conducted with dimethylammonium 2,4-dichlorophenoxyacetate (CAS No. 2008-39-1) according to OECD Guideline 405 were used for read across.

In the first study, 0.1 mL of the test material was instilled into the conjunctival sac of one eye of one New Zealand White rabbit. Due to the expected corrosiveness of the test substance, only one animal was used. The animal was observed for 7 days and irritation was scored 24 h, 48 h and 7 days after instillation according to the method of Draize. In deviation from the guideline, the 72 h time point was not evaluated and the animal was observed for only 7 days after application. The test substance caused irritant effects in cornea, iris and conjunctivae at all time points of examination. Opacity covered nearly the whole area of the cornea. The iris was not discernible; it was congested and did not react to light. In the conjunctivae, diffuse beefy red hyperemia was observed and the lids were swollen about half closed. After 48 h necrosis of the mucosa and after 7 days leukoma were observed. The mean scores were: cornea score: 3, iris score 2, conjunctivae score: 3 and chemosis score: 3. These effects were not reversed until the end of the observation period. In addition to that, three animals were exposed to a 1% dilution of the test substance without any adverse effects (RA-S, CAS2008-39-1, Key, Kita, 1997, Aminopielik 720, eye irritation, RL2).

A second study, again conducted according to OECD Guideline 405, resulted in analogous results. 0.1 mL of the test material was instilled into the conjunctival sac of one eye of three New Zealand White rabbits. The animals were observed for 7 days and irritation was scored 24 h, 48 h and 7 days after instillation according to the method of Draize. In deviation from the guideline, the 72 h time point was not evaluated and the animal was observed for only 7 days after application. The test substance caused irritant effects on cornea, iris and conjunctivae. In the cornea a diffuse area of opacity to a discernible translucent area of one quarter was observed. In the conjunctivae hyperemia of the blood vessels and an obvious swelling were noted. The mean scores were: cornea score: 0.83, iris score 0.83, conjunctivae score: 1.5 and chemosis score: 1.5. Although the intensity of these lesions diminished with the passage of time, the effects were not fully reversible until the end of the observation period. Again, the study conducted in parallel with a 1% solution of the test substance caused no irritation of the eyes (RA-S, CAS 2008-39-1, Kita, 1991, Aminopielik 600, eye irritation, RL2).

An acute eye irritation study conducted with the test substance sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) was considered not reliable and therefore not used for risk assessment due to the fact that the actual identity and concentration of the test substance could not be reconstructed and is therefore unclear.

Effects on the eye were observed in all studies summarized above. Whereas the effects observed with the test substance are only of minor degree and are not considered reliable due to unclear dosing and test substance identity, the read-across studies clearly indicate the strong irritating potential. Sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) is classified as eye irritant and therefore the read across to ammonium 2,4-dichlorophenoxyacetate (CAS No. 2008 -39 -1) is justified even so it has a higher pH value.

Taken together, these data indicate that sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) is not irritant or corrosive to the skin but is strongly irritating to the eye.

Effects on eye irritation: highly irritating

Justification for classification or non-classification

According to the DSD and CLP criteria for classification and labelling of dangerous substances sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) is not classified as skin irritant.

According to the DSD (67/548/EEC) criteria for classification and labelling of dangerous substances sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) is classified as severe eye irritant.

According to CLP (EC No. 1272/2008) criteria for classification and labelling of dangerous substances sodium 2,4-dichlorophenoxyacetate (CAS No. 2702-72-9) is classified to Category 1 (irreversible effects on the eye).