2-ethoxyphenol

Endpoint summary

Additional information

Invertebrates:

Two studies were available. One was selected as key study (Harlan 2010) because it was with reliability 1 according to Klimisch scale, and the other one (Palla & Dion, 1983) as supporting study because it was quoted reliability 3 due to the lack of details of the study, but the result was near to those of the key study.

The summary of the key study is the following:

The acute toxicity of the test item GUETOL to Daphnia magna was determined in a 48‑hour static test (Harlan, 2010), according to the EU C.2, and the OECD 202.

The nominal test item concentrations tested were 1.0, 3.2, 10, 32, and 100 mg/L. Additionally, a control group (test water without test item) was tested in parallel. The test was performed using glass tubes completely filled with test medium that were tightly sealed with glass stoppers to avoid losses of test item (closed system).

At the start and at the end of the test, the analytically determined concentrations of the test item in the test media were between 96 and 103% of the nominal values. Thus, the correct dosing of the test item GUETOL was confirmed. Furthermore, it has been demonstrated that the test item was stable during the test period of 48 hours under the conditions of the test, and the reported biological results are based on the nominal concentrations of the test item.

 

The biological test result was as follows:

– 48-hour EC50:

16 mg/L (95%CL: 14 and 20 mg/L)

Based on the results of this study, guetol would be considered as harmful for aquatic invertebrates.

Aquatic algae:

Two studies were available. One (Harlan, 2010) was selected as key study (reliability 1, GLP and OECD 201 and EE C3 compliant). The summary of this study is the following:

The influence of the test item GUETOL on the growth of the freshwater green algal species Pseudokirchneriella subcapitata was investigated in a 72‑hour static test (Harlan, 2010), according to OECD Guideline 201 (2006), the EU Commission Directive 92/69/EEC, C.3 (1992) and the Commission Regulation (EC) No 761/2009, C.3.

 

The nominal concentrations of the test item of 1.0, 3.2, 10, 32 and 100 mg/L were tested in parallel with a control.

 

The test was performed using Erlenmeyer flasks completely filled with test medium and tightly sealed with glass stoppers to avoid losses of test item (closed system).

 

The measured concentrations of the test item in the test media of the nominal test concentrations of 1.0 to 100 mg/L were between 98 and 102% of the nominal values at the start of the test. Thus, the correct dosing of the test item GUETOL was confirmed. During the test period of 72 hours, a decrease of test item concentration in the test media of the two lowest test item concentrations occurred. At the end of the test, 29 to 97% of the nominal values were found.

 

The biological results were related to the mean measured test item concentrations (calculated as the geometric means of the concentrations measured at the start and at the end of the test).

 

The test item had a statistically significant inhibitory effect on the growth of the algae (average growth rate and yield) at the test item concentrations of 2.7 and 32 mg/L based on mean measured concentrations (results of Dunnett’s tests, one-sided smaller, a =0.05,Table 1 andTable 2) after the test period of 72 hours. For the yield of the algae, a statistically significant inhibitory effect was also determined at the highest mean measured concentration of 96 mg/L.

 

However, the inhibition of the growth rate and yield was not estimated as a biologically relevant toxic effect, since the inhibition followed no dose-response-relationship and was <10% at the three highest test concentrations. Furthermore, in accordance with the test guidelines an effect within a range of 10 to 20% appears to be appropriate to represent the NOEC.

The 72 hour NOEC was, therefore, determined to be higher than or equal to 96 mg/L (mean measured test concentration).

Based on nominal concentrations the NOEC is higher than or equal to 100 mg/L.

 

The EC₁₀, EC₂₀, and EC₅₀ could not be calculated. The EC₂₀ and EC₅₀ were determined from the raw data to be >96 mg/L based on mean measured concentrations, and to be >100 mg/L based on nominal concentrations.

Based on the results of this study, guetol would not be considered as harmful for algae.

The other study (Kramer et al., 1986) was not taken into account for the assessment, because the publication was poorly described, duration of the study was too short (6 hours), and the temperature of the test too high.