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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The toxicity of Naphthalenesulfonic acid, methyl, butyl, sodium salt to algae is read across from the structurally related substance naphthalenesulfonic acid, bis(1-methylethyl)-, methyl derivatives, sodium salts.

In addition algae rangefinding tests have been performed with two batches of Aromatic Hydrocarbons, C10-13, Reaction Products With Branched Nonene Sulphonated, sodium salt to evaluate which of two relatively similar alkylnaphthalene sulphonates is the more toxic substance. The results obtained indicate that there is a slightly higher toxicity observed for the batch containing a higher fraction of long alkyl chain derivative when compared to the batch with a lower content of long alkyl chain derivative.

The lowest ErC50 is observed in the algae test with naphthalenesulfonic acid, bis(1-methylethyl)-, methyl derivatives, sodium salts. This result (ErC50>100 mg/L and the ErC10 =14.8 mg/L) will be used as a worst-case for read across for those alkylnaphthalenesulphonates for which the algae data are missing.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
14.8 mg/L

Additional information

The toxicity of Naphthalenesulfonic acid,bis(1-methylethyl)-, methyl dervis., sodium salt to Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and EC no C.3. 

The study was conducted under static conditions with the nominal test item concentrations 6.25 - 12.5 – 25.0 – 50.0 - 100 mg/L (factor 2). For each concentration level an appropriate amount of the test item was weighed out. The test item was applied onto a glass slide. The glass slide with the test item was inserted in a brown glass flask with an appropriate amount of dilution water. The dispersions were shaken for at least 24 hours with 20 rpm at room temperature. After a separation phase of 1 hour, the loading concentrations were removed by siphoning (from the approximate centre of the glass flask).

Since the test item is labeled as UVCB but water solubility is above the limit loading concentration, WAF approach is used for media preparation but test media is considered to be a true solution of the test item.

Three replicates were tested for each test item loading and six replicates for the control. The environmental conditions were within the acceptable limits.

 

The test media were clear throughout the test period. The concentrations of the test item Naphthalenesulfonicacid,bis(1-methylethyl)-, methyl dervis., sodium salt in all test concentration levels with algae and the control were analytically verified by UPLC-DAD at the start and at the end of exposure.

The measured concentrations of Naphthalenesulfonic acid,bis(1-methylethyl)-, methyl dervis., sodium saltin the fresh media (0 h) were between 103 and 120% of the nominal values. The measured concentrations in the media after 72 hours were between 99 and 119% of the nominal values.The measured test item concentrations were all within ± 20% of the nominal concentrations. This indicates that the test item concentrations were successfully maintained for the duration of the test.

 

Therefore, all effect values given are based on the nominal test item concentrations of Naphthalenesulfonicacid,bis(1-methylethyl)-, methyl dervis., sodium salt.

The observed ErC50 and ErC10 are >100 and 14.8 mg/L respectively.