Succinic anhydride, alkylation products with C12-rich branched olefins from propene oligomerisation, hydrolyzed, esterification products with propylene oxide

Endpoint summary

Additional information

Acute toxicity

Fish

A study was performed to assess the acute toxicity of the test item to rainbow trout (Oncorynchus mykiss). The method followed was designed to be compatible with OECD TG 203 referenced as Method C.1 of Commission Regulation (EC) No. 440/2008.

Due to the low aqueous solubility and complex nature of the test item, for the purposes of the test, the test medium was prepared as a Water Accommodated Fraction (WAF).

In accordance with the recommendations of REACH, the test was conducted according to the threshold approach recommended by ECHA. Using this approach the lowest EL50 from either the acute algal or daphnia study is set as the threshold loading rate and a limit test conducted at this threshold loading rate. As the EL50 in both the algal and daphnia studies was > 100 mg/L loading rate WAF, the test was conducted at a single loding rate of 100 mg/L loading rate WAF to ensure that toxicity was not observed at this loading rate.

Seven fish were exposed to a WAF of the test item, at a single nominal loading rate of 100 mg/L for a period of 96 hours at a temperature of approximately 15 deg C under semi-static test conditions. The number of mortalities and any sub-lethal effects of exposure in each test and control vessel were determined 3 and 6 hours after the start of exposure and then daily throughout the test until termination after 96 hours.

Chemical analysis of the fresh test preparations at 0 and 72 hours showed measured test concentrations of 40 and 77 mg/L, and from the old test preparations at 24 and 96 hours showed measured test concentrations of 43 and 69 mg/L.

Given that the toxicity cannot be attributed to a single component or a mixture of components, but to the test item as a whole, the results were based on nominal loading rates only.

Exposure of rainbow trout to the test item gave a 96 -h LL50 value > 100 mg/L loading rate WAF. The NOELR was 100 mg/L loading rate WAF. It was considered unnecessary and unrealistic to test at loading rates in excess of 100 mg/L loading rate WAF.

Daphnia magna

A study was performed to assess the acute toxicity of the test item to Daphnia magna. The method followed was designed to be compatible with OECD TG 202, referenced as Method C.2 of Commission Regulation (EC) No. 440/2008.

Due to the low aqueous solubility and complex nature of the test item, for the purposes of the test, the test medium was prepared as a Water Accommodated Fraction (WAF).

Following a preliminary range-finding test, twenty daphnids (4 replicates of 5 animals) were exposed to a Water Accommodated Fraction (WAF) of the test item at a single nominal loading rate of 100 mg/L for 48 hours at a temperature of approximately 20 deg C under static test conditions.

The number of immobilized Daphnia and any adverse reactions to exposure were recorded after 24 and 48 hours.

Chemical analysis of the test preparations at 0 and 48 hours showed measured test concentrations of 77 and 81 mg/L respectively. Given that the toxicity cannot be attributed to a single component or a mixture of components, but to the test item as a whole, the results were based on nominal loading rates only. Exposure of Daphnia magna to the test item gave a 48-h EL50 value of > 100 mg/L loading rate WAF. The NOELR was 100 mg/L loading rate WAF.

Algae

A study was performed to assess the effect of the test item on the growth of the green alga Pseudokirchneriella subcapitata. The method followed was designed to be compatible with OECD TG 201, referenced as Method C.3 of Commission Regulation (EC) 761/2009.

Due to the low aqueous solubility and complex nature of the test item for the purposes of the test the test item was prepared as a Water Accommodated Fraction (WAF).

Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to WAFs of the test item over a range of nominal loading rates of 6.25, 12.5, 25, 50 and 100 mg/L (three replicate flasks per concentration) for 72 hours under constant illumination and shaking at a temperature of 24 +/-1 deg C.

Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group using a Coulter Multisizer Particle Counter.

Analysis of the test preparations at 0 and 72 hours showed measured test concentrations to range from 0.044 to 94 mg/L.

Given that the toxicity cannot be attributed to a single component or mixture of components but to the test item as a whole, the results were based on nominal loading rates only.

The ErL50 (0 -72h) was > 100 mg/L loading rate WAF and the NOErLR was 50 mg/L loading rate WAF. The EyL50 (0 -72h) was 67 mg/L loading rate WAF and the NOEyLR was 50 mg/L loading rate WAF.

Inhibition of sewage sludge micro-organisms

A study was performed to assess the effect of the test item on respiration of activated sewage sludge. The method followed was designed to be compatible with OECD TG 209.

Following a preliminary range-finding test, activated sewage sludge was exposed to an aqueous dispersion of the test item at concentrations of 250, 500, 750 and 1000 mg/L (5 replicates) for a period of 3 hours at temperatures between 20 and 22 deg C with the addition of a synthetic sewage as a respiratory substrate. One extra concentration was added in order to determine the NOEC.

The rate of respiration was determined after 3 hours contact time and compared to data for the control and a reference item, 3,5 -dichlorophenol.

The effect of the test item on the respiration of activated sewage sludge gave a 3 -hour EC50 value of > 1000 mg/L. During the definitive test a NOEC was not achieved, however during the second range-finding test a NOEC value of 100 mg/L was observed. The reference item gave a 3 -hour EC50 value of 6.5 mg/L, 95% confidence limits 5.0 -8.5 mg/L.

Discussion

The substance is known to be a surfactant and, in conjunction with the determined lack of ready biodegradation (17 % in 28 days), the critical micelle concentration (CMC) is expected to be low. Algae, like sewage sludge micro-organisms, are anionic and it is likely that in the WAF, the surfactant molecules surround the relatively small number of algae that are in the solution, reducing their capacity to take up minerals and potentially even blocking active sites. Considering the results of the algal study, it appears that the critical concentration is somewhere > 50 mg/L loading rate WAF.

In the environment it is unlikely that this situation would occur as the substance would be totally adsorbed to suspended solids, sediment and organic matter before it could reach a concentration effecting algal cells. Although there would be a similar effect in the ASRI, with sewage sludge micro-organisms, the impact is mitigated due to hydrophobicity and therefore the effect is minor in comparison to that observed in the algal study. As the 50 mg/L loading rate is much higher than the experimentally derived water solubility of the substance (less than 7.55 x 10E-2 g/L of solution at 20.0 ± 0.5 °C) the result of the algal study should not be used for PNEC derivation, risk assessment or for the purpose of classification and labelling.