Reaction mass of chlorodifluoroacetic acid and trifluoroacetic acid

Toxicity to aquatic algae and cyanobacteria

Description of key information

Based on experimental data on each constituent, the reaction mass is considered as toxic to algae. 

Key value for chemical safety assessment

EC50 for freshwater algae:

7.7 mg/L

EC10 or NOEC for freshwater algae:

0.32 mg/L

Additional information

No data on toxicity to aquatic plants is available on the reaction mass of chlorodifluoroacetic acid (CDFA) and trifluoroacetic acid (TFA).

The following data are available on each constituent:

For CDFA, in a 72 hour toxicity study (2012), the cultures of Pseudokirchneriella subcapitata were exposed to nominal concentrations of 0.32, 1, 3.2, 10, 32, 100, 316 mg CDFA/L under static conditions in accordance with the OECD Testing Guideline 201 and under GLP conditions. The correct dosing of the test item was performed by using ion chromatography with conductivity detection (IC-CD). During the test the algae were exposed to a mean of 110 % of nominal. Therefore, all reported results refer to nominal concentrations. The results on growth rate were: 72-hour ErC50 = 7.71 mg/L, 72-hour ErC10 = 0.122 mg/L and NOErC = 0.32 mg/L.

 

For TFA, the GLP compliant OECD 201 study performed by Ineris in 2017 was identified as key study. Green algae (Pseudokirchneriella subcapitata) were exposed during 72h to the test item in static conditions.The initial nominal concentrations were 0.9, 2.5, 7.0, 19.5, 54.7, 153.1, 428.6 and 1200 mg/L (corresponding to the following geometric mean of measured concentration at T0h and at T72h: 0.9, 2.7, 7.2, 20.2, 55.6, 157.6, 438.0 and 1207 mg/L). The test concentrations were analytically monitored by ion-exchange chromatography with gradient elution and conductimetric detection. The test item has been satisfactorily maintained within ± 20 % of the nominal concentration in all test conditions. The endpoint was inhibition of growth, expressed as logarithmic increase of biomass (average specific growth rate) during the exposure period. All validity criteria were fulfilled.In conclusion, the following toxicity values have been determined for the test item trifluoroacetic acid based on nominal concentrations: 72 -hour ErC50 = 237.07 mg/L, 72 -hour ErC10 = 5.59 mg/L and NOErC (72h) = 2.5 mg/L.

Considering that the reaction mass of chlorodifluoroacetic acid (CDFA) and trifluoroacetic acid (TFA) is mainly composed of CDFA which is the more toxic of the two constituents, the reaction mass is considered as toxic to algae.