Reaction product of p-nonylphenol, formaldehyde and diethanolamine, propoxylated

Toxicity to aquatic algae and cyanobacteria

Description of key information

To determine the toxicity of polypropoxylated p-nonylphenol-formaldehyde-diethanolamine, Mannich base to algae, a GLP-compliant algae toxicity test was performed in accordance with OECD guideline 201 (Toxi-Coop Zrt, 2013). Exponentially-growing cultures of Pseudokirchneriella subcapitata (algal concentration of approx. 1.0E+04 cells/mL) were exposed to nominal test item concentrations of 1.0, 2.6, 6.4, 16.0, 40.0 and 100 mg/L and a blank control for 72 hours under static conditions. Nominal concentrations were analytically verified. The corresponding calculated geometric mean test item concentrations were NA, 1.4, 3.9, 11.2, 22.1 and 59.9 mg/L (the lowest concentration was below the analytical quantification limit at the end of the test and therefore excluded from the result evaluation). The algal cell concentration was determined by microscope in each testing flask in 24-hour intervals and mean growth rates and yield calculated. From the observations, the 0-72 h average specific growth rates and yield were calculated to be significantly different from that of the control group in the concentrations of 3.9, 11.2, 22.1 and 59.9 mg/L. Based on the findings, the 72 -h ErC50 (growth rate) and 72 -h EyC50 (yield) are calculated to be 5.6 mg/L and 4.0 mg/L, respectively. The ErC10 and EyC10 values are determined at 3.5 and 1.8 mg/L, respectively. The NOEC is determined at 1.4 mg/L for both endpoints. As the analytically determined concentrations deviated more than ± 20% from nominal over the test period of 72 hours, results are based on the measured concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

5.6 mg/L

EC10 or NOEC for freshwater algae:

3.5 mg/L