Reaction mass of 2,6-bis(1-phenylethyl)phenol and 2,4,6-tris(1-phenylethyl)phenol

Long-term toxicity to aquatic invertebrates

Description of key information

TSP: 21d NOEC >= 35 µg/L for reproduction and parental immobilisation.
DSP: 21d NOEC = 115 µg/L for reproduction and parental immobilisation.

Additional information

No study are available on the reaction mass of 2,4,6 -tris(1 -phenylethyl)phenol and Bis(1 -phenylethyl)phenol for this endpoint. However, two reliable studies are available for its two main components (i.e. Tristyrenated phenol and Distyrenated phenol). Therefore, they were selected as key studies. In both studies a Daphnia magna Reproduction Test on 21 days in semi-static conditions was conducted according to the OECD TG 211 (1998) and GLP.

In the first study (NOACK, 2008), the test item was tristyrenated phenol, which was applied at saturated concentration. A column elution system as generator system was applied for the preparation of the saturated solution.

Ten test organisms, individually held, were used for the limit concentration and control. The test solutions were renewed 3 times per week. The saturated solution of the test item and the control were analytically verified by HPLC-MS/MS of samples on days 0, 5, 7, 12, 14, 19 (fresh media, 0 h) and on days 2, 7, 9, 14, 16, 21 (old media, 48h). The measured concentrations of the saturated solution were between 15.1 and 55 µg/L with a mean of 35 µg/L.

No immobilisation of parent animals occurred in the control or in the test group.

After 21 days, the average number of juveniles per parent was 105 in the control group and 107 in the test group.The reproductive output was not statistically significant reduced when compared to the control at the mean measured concentration 35 µg/L (One Way Analysis of Variance, p = 0.05).

No stillborn juveniles and aborted eggs were produced by the control group. Related to the total number of produced juveniles (dead + alive), the percentage of dead juveniles was < 1% at the mean measured concentration 35 µg/L.

The first appearance of living juveniles was on day 8 for all 10 parents in the test group, and for 9 parents in the control group. One parent in the control group had a first appearance of living juvenile the day 9.

Water quality parameters as pH-value, dissolved oxygen, water hardness and temperature were determined to be within the acceptable limit. The OECD validity criteria were fulfilled.

Due to the compliance to the OECD Test Guideline and the GLP, this study is considered as reliable without restriction.

In the second study (NOACK, 2006), the test item was distyrenated phenol. A slow energy stirring method was used for the preparation of the test solutions.

The saturated solution was diluted to the corresponding nominal test concentrations selected after a preliminary acute immobilisation test (72h, static) and a preliminary reproduction test (16 days, semi static) as follows: 18.75, 37.5, 75, 150 and 300 µg/L. Samples of all concentrations and control were analytically verified by HPLC on days 0, 5, 12, 19 (fresh media) and on days 2, 7, 14, 21 (old media). The mean recovery rates were between 76 and 107%. All effect values are given based on the mean measured test item concentrations: 20.1, 35.7, 56.9, 115 and 249 µg/L.

Ten test organisms, individually held, were used per concentration and control. The test solutions were renewed 3 times per week.

The test item did not induce significant mortality (>= 20%) of parent animals at any of the test item concentrations =< 115 µg/L. The EC50 for immobilisation of parental after 21 days with confidence interval (CI) was calculated by probit analysis to be 204 (186 - 225) µg/L.

After 21 days, the mean number of offspring alive produced per parent animal surviving at the end of the test was 94.7 juveniles in the control group. At the concentration of 249 µg/L the reduction of reproduction came to 73% compared to the control. This reduction is statistically significant. In the other concentrations no statistically significant reduction compared to the control was determined (ANOVA, One Way Analysis of Variance, p < 0.05).

No stillborn juveniles and aborted eggs were produced by the control group. Related to the total number of produced juveniles (dead + alive), the percentage of dead juveniles was 10% at 249 µg/L and =< 5% at all other concentration levels.

The first day of appearance of living juveniles at all test item concentrations and control groups producing juveniles was between day 8 and day 9.

At the end of the test the total length and the dry weight of all living animals at each concentration and control were determined. Because only one parent animal survived at the tested concentration of 249 µg/L, statistical evaluation was only possible for the concentration levels 20.1 to 115 µg/L. The body length of the surviving daphnids of these treatment groups were compared to the control by ANOVA One Way Analysis of Variance, p< 0.05. There was no statistically significant difference.

Water quality parameters as pH-value, dissolved oxygen, water hardness and temperature were determined to be within the acceptable limit. The OECD validity criteria were fulfilled.

Based on these results, it can be concluded that the 21d NOEC of Distyrenated phenol is 115 µg/L for both reproduction and parental immobilisation.

Due to the compliance to the OECD Test Guideline and the GLP, this study is considered as reliable without restriction.