Sodium 2,4-dichlorophenoxyacetate

Endpoint summary

Description of key information

Oral Toxicity
Key, NZPO "Organika-Rokita, Kita, 1991, acute oral, RL2 – LD50 = 552 mg/kg bw
Inhalative Toxicity
RA-S, CAS 2008-39-1, Key, Rydzynski and Swiercz, 1998, Aminopielik 600, rat, acute inhal., RL2 – LC50 >3080 mg/m³ air (females) and 3258 mg/m³ air (males) (based on an active ingredient content of 60.6% and doses of 5083 mg/m³ air (females) and 5377 mg/m³ air (males) used in the respective study)
Dermal toxicity
Key, NZPO "Organika-Rokita", Kita, 1991, Acute dermal, rat, RL1- LD50 > 5000 mg/kg bw

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

552 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

5 000 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

3 080 mg/kg bw

Additional information

Studies conducted to examine the acute toxicity of sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9) were conducted according to OECD-guidelines No. 401 (Acute oral toxicity) and 402 (Acute dermal toxicity). Data of a study conducted with a structural analogue substance (dimethylammonium 2,4-dichlorophenoxyacetate (CAS 2008-39-1) according to OECD 403 (Acute inhalation toxicity) 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 test substance was applied orally (gavage) in doses of 364, 473, 615 and 800 mg/kg bw to 5 male and 5 female Wistar rats and the animals were observed for 14 consecutive days. Signs of intoxication (dejection and less activity) were observed in rats of the highest dose groups. In the lower dose groups no toxic signs were observed except for animals shortly before death which were less mobile and had bristled hair. Reduced body weight was noted in all dose groups. All animals of the highest dose group died within the first two days after application. In the other dose groups, 4 (615 mg/kg bw), 3 (473mg/kg bw), and 0 (364 mg/kg bw) animals died, respectively. The oral LD50 value calculated was 552 mg/kg bw (Key, NZPO "Organika-Rokita, Kita, 1991, acute oral, RL2).

  

The acute inhalative toxicity of the test formulation containing dimethylammonium 2,4-dichlorophenoxyacetate(CAS 2008-39-1), a structural analogue substance of sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9) was used for read across. 5 Wistar rats of both sexes were exposed (whole body) to test atmospheres of 5377 mg/m³ air ± 1352 (females) and 5083 mg/m³ air ± 1422 (males), respectively. During the exposure and upon removal from the chamber, signs of laboured or irregular breathing and body convulsions were observed. 3 Male and 4 female animals survived the exposure to the test substance. The deaths of one male and one female animal were recorded on day 1 after exposure, another male animal died on day 2. The LC value was calculated to be above 5000mg/m³ air (RA-S, CAS 2008-39-1, Key, Rydzynski and Swiercz, 1998, Aminopielik 600, rat, acute inhal., RL2).

 

A dermal study was conducted according to OECD 402. 5000 mg/kg bw of sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9) were applied to the dorsal area of the trunk of 5 female Wistar rats for 24 h under semiocclusive conditions.No signs of systemic toxicity, no signs of dermal irritation and no deaths occurred. Body weight gain was normal except for one female animal, which showed a body weight loss in the first week but recovered during the second week. The dermal LD50 value is therefore > 5000 mg/kg bw under the conditions tested (Key, NZPO "Organika-Rokita", Kita, 1991, Acute dermal, rat, RL1).

 

Taken together, the available data on acute inhalative and dermal toxicity confirmed that sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9) is not acute toxic if applied via dermal or inhalative routes. A LD 50 value of 552 mg/kg bw resulting from oral application indicates a moderate acute toxicity under the conditions tested.

Justification for classification or non-classification

According to the DSD (67/548/EEC) criteria for classification and labelling of dangerous substances sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9)is classified harmful after acute oral application.

According to CLP (EC No. 1272/2008) criteria for classification and labelling of dangerous substances sodium 2,4-dichlorophenoxyacetate (CAS 2702-72-9)is classified to Category 4 after acute oral application.