Reaction mass of 2-[2-(benzoyloxy)ethoxy]ethyl benzoate, 1-[2-(benzoyloxy)propoxy]propan-2-yl benzoate, and 2-[2-[2-(benzoyloxy)ethoxy]ethoxy]ethyl benzoate

Toxicity to aquatic algae and cyanobacteria

Description of key information

Toxicity data for the reaction mass is provided from available studies of the three individual components of the reaction mass.  The key values identified for the chemical safety assessment are the most sensitive endpoints from the individual tests of the components, therefore providing a conservative assessment of the hazard for the reaction mass.  

 

DPGDB:

Toxicity to aquatic algae and cyanobacteria:

- Key study, reliability 1, OECD 201, Pseudokirchneriella subcapitata - The EbC50 (biomass, 72 h) was 0.7 mg/L and the ErC50 (Growth rat,e 0 - 72 h) was 3.2 mg/L. The EbC50 (biomass, 96 h) was 0.62 mg/L and the ErC50 (Growth rate, 0 - 96 h) was 2.5 mg/L. The corresponding 72 hour and 96 hour "no-observed effect concentration" (NOEC) for biomass were 0.16 mg/L and <0.07 mg/L, respectively. The corresponding 72 hour and 96 hour "no-observed effect concentration" (NOEC) for Growth Rate were 0.68 mg/L and 0.27 mg/L, respectively.

 

DEGDB:

Toxicity to aquatic algae and cyanobacteria:

-Key study, reliability 1, OECD 201, Raphidocelis subcapitata.  The ErC10, ErC20, and ErC50 (growth rate 0-72 hours) were 1.6, 2.1, and 3.7 mg/L respectively.  The EyC10, EyC20, and EyC50 (yield 72 hours) were 0.48, 0.70, and 1.4 mg/L respectively.

- Disregarded study, reliability 3, OECD 201, Pseudokirchneriella subcapitata - The 72h EL50 (Area under the curve, biomass) was 5.2 mg/L and the 72h EL50 (Growth rate) was 11 mg/L. The corresponding "No-observed effect loading rate" (NOELR) were 2.2 mg/L and 1.0 mg/L, respectively. The 96h EL50 (Area under the curve, biomass) was 5.9 mg/L and the 96h EL50 (Growth rate) was 15 mg/L. The corresponding NOELR for both were 2.2 mg/L. Study endpoints were based upon nominal loading rates. Analytical measurement of the exposure solutions were made, however the final measurements were all at non-detect levels resulting in the geometric mean measured concentrations being unreliable. Because of the unreliability this study was repeated and the results are presented above as the key study for this component.

 

TEGDB

Toxicity to aquatic algae and cyanobacteria:

-Key study, reliability 1, OECD 201, Raphidocelis subcapitata.  The ErC10, ErC20, and ErC50 (growth rate 0-72 hours) were 1.5, 2.5, and 6.2 mg/L respectively.  The EyC10, EyC20, and EyC50 (yield 72 hours) were 0.36, 0.57, and 1.4 mg/L respectively.

- Disregarded study, reliability 3, OECD 201, Pseudokirchneriella subcapitata - The EL50 (Area under the curve 72h and 96h) for TEGDB was 33 mg/L and the EL50 (Growth rate 0 - 72h and 0 - 96h) was >100 mg/L. The "No-observed effect loading rate" (NOELR) was 10 mg/L. Study endpoints were based upon nominal loading rates. Analytical measurement of the exposure solutions were made, however the final measurements were all at non-detect levels resulting in the geometric mean measured concentrations being unreliable. Because of the unreliability this study was repeated and the results are presented above as the key study for this component.

Key value for chemical safety assessment

EC50 for freshwater algae:

3.2 mg/L

EC50 for marine water algae:

3.2 mg/L

EC10 or NOEC for freshwater algae:

0.68 mg/L

EC10 or NOEC for marine water algae:

0.68 mg/L

Additional information

This substance is a reaction mass of dipropylene glycol dibenzoate (DPGDB), diethylene glycol dibenzoate (DEGDB) and triethylene glycol dibenzoate (TEGDB). No testing has been performed on the reaction mass itself, but data are available for DPGDB, DEGDB and TEGDB individually. All the studies were performed according to international test guidelines and in compliance with GLP.  The algal growth inhibition studies were performed on Raphidocelis subcapitata (formally known as Selenastrum capricornutum or Pseudokirchnerella subcapitata). In the initial studies the substance was introduced using a water accommodated fraction (WAF) and the endpoints were reported using nominal loading rates. The exposure solutions in these studies were analytically measured at the beginning and end of the exposures. The studies were re-evaluated based upon the measured concentrations documented in the study reports. The studies of DEGDB and TEGDB both had final analytical measurements of the exposure solutions that were at non-detect levels and therefore the geometric means of the measured concentrations are belived to be unreliable. Algal tests were reconducted for these two components of the reaction mass. The algal test of DPGDB provided analytical measurements of the exposure solutions that are believed to be reliable and the endpoints were recalculated based upon the geometric mean measured concentrations. All existing data suggest that the components of the reaction mass have quantitatively similar properties and the hazard assessment (PNEC derivation) for the reaction mass will be based upon a worst-case evaluation of data from the individual components. 

 

The key values are:

Short-term toxicity to aquatic algae and cynaobacteria: EC50 = 3.2 mg/L (DPGDB 72 hour ErC50)

Long-term toxicity to aquatic algae and cynaobacteria: NOEC = 0.68 mg/L(DPGDB 72 hour NOEC growth rate)