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Ecotoxicological information

Endpoint summary

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Description of key information

Additional information

Fish

There is one key and one supporting acute toxicity study on fish.

The key study was performed to assess the acute toxicity of the test item to rainbow trout (Oncorhynchus mykiss). The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No 203 and Method C.1 of Commission Regulation (EC) No. 440/2008.

Following preliminary range-finding tests, fish were exposed, in groups of seven, to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading rates of 1.0, 1.8, 3.2, 5.6 and 10 mg/l for a period of 96 hours at a temperature of approximately 14°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 2 and 6 hours after the start of exposure and then daily throughout the test until termination after 96 hours.

Chemical analysis of the 1.8, 3.2, 5.6 and 10 mg/l loading rate WAFs showed measured concentrations to range from 0.0250 to 8.67 mg/l at 0 hours (fresh media) and 0.00972 to 8.09 mg/l at 24 hours (old media). Analysis of the 1.8 mg/l loading rate WAF at 72 (fresh media) and 96 hours (old media) showed measured concentrations of 0.0808 and 0.0543 mg/l respectively.

The dissolved test item may have been one or several components of the test item. Given that 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 acute toxicity of the test item to the freshwater fish rainbow trout (Oncorhynchus mykiss) has been investigated and gave a 96-Hour LL*50value of 2.4 mg/l loading rate WAF with 95% confidence limits of 1.8 – 3.2 mg/l loading rate WAF. The No Observed Effect Loading rate was 1.8 mg/l loading rate WAF.

 

In a supporting study the acute toxicity of the substance to Atlantic cod (Gadus morhua L.) was reported in the publication: Environmental Toxicology and Chemistry, Vol. 17, No. 4 pp. 740 -746, 1998. Title: Acute Toxicity and Toxicokinetics of 4 -Heptylphenol in Juvenile Atlantic Cod (Gadus Morhua L.) Authors: Tollefsen KE, Ingerbrigtsen K, Olsen AJ, Zachariassen, KE & Johnsen S.

The study was performed under flow through conditions. Fish were exposed to the test substance for 168 h at nominal concentrations of 0.5, 1, 2.1, 4.2 umol/L. and a loading of 5.7 g fish/L.

The 168 h LC50 was 2.7 umol/L (or 0.52 mg/L) . The 96 h LC50 was estimated by interpolation to be 2.9 umol/L (or 0.56 mg/L). Control groups, exposed to methanol alone showed no mortality.

Daphnia

In a key study performed to OECD 202 and EC Method C2 the 48–hr-acute toxicity of test substance to Daphnia magna was studied under static conditions. Daphnids were exposed to control, and test chemical at the mean measured test concentrations of 0.041, 0.059, 0.10, 0.19, 0.30, 0.61, 1.1, 2.0 and 3.2 mg/L. Immobilisation was observed at 24 and 48 hrs.

The 48-hour EC50 based on the mean measured concentrations was 0.38 mg/L (95% CL = 0.32 - 0.46 mg/L). The NOEC based on immobilisation was 0.19 mg/L.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Algae

In a key study performed to OECD Guideline No 201 and EC Method C3, following a preliminary range-finding test, Scenedesmus subspicatus was exposed to solutions of the test material at nominal concentrations of 0.048, 0.095, 0.19, 0.38, 0.75 and 1.5 mg/L (three replicate flasks per concentration) for 72 hours, under constant illumination and shaking at a temperature of 24±1°C. The test material solutions were prepared by shaking an excess (100 mg/L) of test material in culture medium at 300 rpm at a temperature of 30°C for 24 hours prior to removal of any undissolved test material by filtration (0.2µm) through a preconditioned filter to produce a saturated solution with a nominal test concentration of 30 mg/L. This "saturated" solution was then further diluted, as necessary, to provide the remaining test groups. The nominal test concentrations were based on the results of chemical analysis of a saturated solution prepared during the range-finding test where the measured concentration of the saturated solution was 31.7 mg/L.

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

Exposure of Scenedesmus subspicatus to the test material, based on nominal test concentrations, gave an EbC50 (72h) value of 0.25 mg/L; 95% confidence limits 0.21 - 3.0 mg/L and an ErC50 (0 -72h) value of 1.2 mg/L (It was not possible to calculate 95% confidence limits for the ErC50 value as the data generated did not fit the models available for calculation of confidence limits.) The NOEC (72h) was 0.048 mg/L.

Analysis of the test preparations at 0 hours showed measured test concentrations to range from 83% to 101% of nominal. At 72 hours analysis of the test preparations showed a decline in measured test concentrations in the range of 40% to 67% of nominal. Given that the stability analysis indicated that the test material was stable over a 72-hour period it was considered that the decline in measured test concentrations was due to adsorption to algal cells. A greater decline in measured test concentrations was observed at the lower test concentrations due to there being a greater number of algal cells present.

Microorganisms

A study was performed to assess the effect of the test item on the respiration of activated sewage sludge. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2010) No 209 "Activated Sludge, Respiration Inhibition Test".

 Following a preliminary range-finding test activated sewage sludge was exposed to an aqueous dispersion of the test item at concentrations of10,32,100,320 and 1000mg/l (3 replicates) for a period of 3 hours at a temperature of 20±2°C with the addition of a synthetic sewage as a respiratory substrate.

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 EC50value of 58mg/l, 95% confidence limits 42-81mg/l. 

The reference item gave a 3-Hour EC50value of 12mg/l, 95% confidence limits 10-15 mg/l.