Reaction mass of disodium 2-[[2-hydroxy-3-[[methyl-(2-oxido-2-oxoethyl)amino]methyl]-5-nonylphenyl]methyl-methylamino and sodium 2-[(2-hydroxy-5-nonylphenyl)methyl-methylamino]acetate

Endpoint summary

Description of key information

Toxicity to aquatic algae and cyanobacteria

The effect of the test item, Reaction mass of disodium N,N'-[(2-hydroxy-5-nonylphen-1,3-ylene)bis(methylene)]bis[N-methylaminoacetate] and sodium N-[(2-hydroxy-5-nonylphenyl)methyl]-N-methylaminoacetate, on the growth of the green alga Pseudokirchneriella subcapitata was assessed at a GLP accredited laboratory according to the OECD Guideline 201, “Freshwater Alga and Cyanobacteria, Growth Inhibition Test”. All validity criteria were fulfilled. 

 

Following a preliminary range-finding test, P. subcapitata was exposed to nominal test concentrations of 0.10, 0.32, 1.0, 3.2 and 10 mg/L for 72-hours, under constant illumination and shaking at a temperature of 24 ±1°C. Algal population samples were removed from each control and treatment group daily and cell concentrations determined using a Coulter® Multisizer Particle Counter. Chemical analysis of test samples showed a decline in measured test concentrations throughout the tests, therefore as per regulatory guidance it was considered justifiable to base study results on geometric mean measured test concentrations to give a “worst-case” analysis of the data. The geometric mean measured test concentrations were determined to be 0.060, 0.15, 0.41, 2.1 and 8.0 mg/L (between 41% and 80% of the nominal test concentrations).

 

Exposure of P. subcapitata to the test item over a 72-hour period resulted in ErC₅₀ and EyC₅₀ values of 2.0 and 0.33 mg/L respectively, based on geometric mean measured test concentrations. The 72-hour NOEC and LOEC values based on both growth rate and yield were 0.15 and 0.41 mg/L, respectively. Positive control (potassium dichromate) test results were within the normal ranges, thus demonstrating satisfactory conditions of the test.

Short-term toxicity to aquatic invertebrates

The acute toxicity of the test item, Reaction mass of disodium N,N'-[(2-hydroxy-5-nonylphen-1,3-ylene)bis(methylene)]bis[N-methylaminoacetate] and sodium N-[(2-hydroxy-5-nonylphenyl)methyl]-N-methylaminoacetate, to the aquatic invertebrate Daphnia magna was assessed at a GLP accredited laboratory according to the OECD Guideline 202 ("Daphnia sp. Acute Immobilisation Test").

Exposure of test organisms to the test item over a 48-hour period resulted in an EC₅₀ value of 3.7 mg/L based on immobilisation.

Short-term toxicity to fish

The acute toxicity of the test item, Reaction mass of disodium N,N'-[(2-hydroxy-5-nonylphen-1,3-ylene)bis(methylene)]bis[N-methylaminoacetate] and sodium N-[(2-hydroxy-5-nonylphenyl)methyl]-N-methylaminoacetate, to fish was assessed at a GLP accredited laboratory according to the OECD Guideline 203 ("Fish, Acute Toxicity Test").

No mortality or sub-lethal effects of exposure were observed in fish exposed to either the control or nominal limit concentration of 3.2 mg/L over the 96-hour exposure period, thus the 96-hour LC₅₀ value is >3.2 mg/L.

Toxicity to microorganisms

The effect of the test item, Reaction mass of disodium N,N'-[(2-hydroxy-5-nonylphen-1,3-ylene)bis(methylene)]bis[N-methylaminoacetate] and sodium N-[(2-hydroxy-5-nonylphenyl)methyl]-N-methylaminoacetate, on the respiration of activated sewage sludge microorganisms was assessed at a GLP accredited laboratory according to the OECD Guideline 209, “Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation)” (Best, 2019).

Activated sewage sludge was exposed to aqueous dispersions of the test item at nominal concentrations of 7.6, 76 and 760 mg/L for a period of 3 hours at measured temperatures of 20 to 21°C with the addition of synthetic sewage as a respiratory substrate. Respiration rate was determined after 3 hours contact time and compared to data from an untreated control. Similar measurements were also made with the reference substance, 3,5-dichlorophenol, as a positive control.

The reference substance gave a 3‑hour EC₅₀ value of 6.8 mg/L, with 95% confidence limits of 5.3 to 8.8 mg/L, thus confirming the acceptability of the inoculum used in the test system.

The test item showed no statistically or biologically (≥10%) significant inhibition of respiration of activated sewage sludge microorganisms at concentrations up to and including 76 mg/L, the highest tested concentration at which the test item appeared to be completely dissolved within the test medium. Inhibition >50% occurred at a nominal concentration of 760 mg/L that exceeded the apparent solubility limit of the test item under the conditions of the test. It is concluded that the 3‑hour NOEC and EC₁₀ are ≥76 and >76 mg/L, respectively. The EC₅₀ could not reliably be determined, but it also exceeds 76 mg/L.