2-phosphonobutane-1,2,4-tricarboxylic acid

Endpoint summary

Description of key information

All aquatic toxicity tests were carried out with analytical monitoring using ion chromatography. Although the aqueous solution was used as test substance, the results refers to the measured concentrations of 2-phophonobutane-1,2,4-tricarboxylic acid and the effect concentrations obtained in these tests can therefore be used for the hazard assessment of the substance (except for the microorganisms, please see further explanations in this section).

 

Fish

A LC50(96h) of >1042 mg/L was concluded from and a NOEC of =1042 mg/L

was found in a prolonged toxicity study in fish (OECD Guideline 204; species: zebra danio) over 14 days (Caspers; Müller, 1994).

Thus, the LC50(96h) is higher than the concentration of the limit test at 100 mg/L.

In respect of classification and labelling no further testing is required and 2-phophonobutane-1,2,4-tricarboxylic acid regarded as not acute toxic to fish.

Daphnia

A prolonged toxicity study in Daphnia magna (covering to OECD guidelines 202 and 211) was performed over 21 days and the effect on mobility was determined:

EC 50 (immobilisation, 21d): >1071 mg/L.

Based on this result, an EC (24h) and a EC50 (48h) value was concluded of >1071 mg/L each (Caspers; Müller, 1994).

Thus, these EC50 values are higher than the concentration of the limit test at 100 mg/L.

In respect of classification and labelling no further testing is required and 2-phophonobutane-1,2,4-tricarboxylic acid is regarded as not acute toxic to aquatic invertebrates (daphnia).

Other study results refer to effects on reproduction:

EC 50 (reproduction, 21d): >329 to < 1071 mg/L

NOEC (reproduction, 21d): 104 mg/L

LOEC (reproduction, 21d): 329 mg/L

Algae

The results found in the growth inhibition test of 2-phophonobutane-1,2,4-tricarboxylic acid in algae are

EC50 (biomass) >140 mg/L and EC50 (growth rate) >1081 mg/L (Caspers; Müller, 1994).

As this values are higher than 100 mg/L, no acute ecotoxicological hazard is indicated for algae (respective aquatic environment) even it is the most sensitive species (compared to daphnia and fish).

The EC10 (growth rate) is fount to be >33.3 mg/L and <65.5 mg/L.

Microoganisms

To assess the toxicity of 2-phophonobutane-1,2,4-tricarboxylic acid to microorganisms, a study was conducted in accordance with Council Regulation (EC) No 440/2008, Method C.11 "Activated sludge respiration inhibition" (2008) - equivalent to OECD Guideline 209 (1984). The activated sludge was exposed to a 50.4 % water solution of 2-phophonobutane-1,2,4-tricarboxylic acid at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 hours.

The test item showed 4.3 % respiration inhibition of activated sludge at a test item concentration of 1000 mg/L.

The effect value related to nominal concentration of the aqueous solution, since no analytical monitoring was performed (Neuhahn, 2008). As a worst case the effect concentration might be converted based upon the water content of the test item, resulting in an EC10 and EC50 of 504 mg/L for the anhydrous substance.

2-phophonobutane-1,2,4-tricarboxylic acid is regarded of low toxicity towards microorganisms.

Additional information

A conditional testing proposal according to REACH Annex IX, 9.1.6. ‘Long-term toxicity testing on fish, (unless already provided as part of Annex VIII requirements)’ is included in the dossier based on BoA decisions A-010-2018 and A-011-2018. The Fish Early Life Stage (FELS) toxicity test (OECD TG 210) is regarded as the most suitable test guideline for addressing the information requirements.

 

As the BoA decision A-010-2018 is currently being challenged before the General Court (T-656/20), we respectfully request ECHA to suspend any decision on the testing proposal and to first await the decision of the General Court in the aforementioned case. Vertebrate studies should always be the last resort to generate information.