Hydrocarbon waxes (petroleum), oxidized, Me esters, calcium salts

Toxicity to aquatic algae and cyanobacteria

Description of key information

72 hour EL50 >100 mg/L loading rate WAF, 72 hour NOELR = 100 mg/L loading rate WAF, Desmodesmus subspicatus, OECD 201, Vryenhoef 2012

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

Key Study

The potential for a structurally analogous substance to cause acute toxic effects to aquatic plants was determined in a GLP compliant study (Vryenhoef 2012) performed according to the standardised guidelines OECD 201 and Method C.3 of the Commission Regulation (EC) No. 761/2009. The study was reported in sufficient detail so as to accurately represent the toxicity of the material.

The toxicity of the test material was determined in an Algal Growth Inhibition Test. Due to the low aqueous solubility and complex nature of the test item, for the purposes of the test the test material was prepared as a Water Accommodated Fraction (WAF).

Following a preliminary range-finding test, Desmodesmus subspicatus was exposed to a WAF of the test item at a single nominal loading rate of 100 mg/l (six replicate flasks) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C.

Exposure to the test material gave EL50 values of greater than 100 mg/l loading rate WAF. The No Observed Effect Loading Rate was 100 mg/l loading rate WAF.

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.

The study was performed to a good standard and was assigned a reliability score of 2 using the principles for assessing data quality as set out in Klimisch (1997) as a result of the data being used in a read across capacity. Read across is justified on the basis of similar chemical structures and analogous results from a batch of physico-chemical tests, including water solubility.

 

Supporting Information

The toxicity of the test material to aquatic plants was investigated in the algae Selenastrum capricornutum in accordance with the standardised guideline OECD 201. During the study, algal cells were exposed to Water Accommodated Fractions (WAF) of test material at 0, 156, 313, 625, 1250, 2500, 5000 and 10000 mg/L. Algal cells were exposed for 72 hours under continuous illumination and cells counts determined by light microscopy. Under the conditions of the test, the EL50 for growth rate was determined to be 3860 mg/L while the NOEC was determined to be 1250 mg/L.

The non-GLP study was performed in line with an accepted standardised guideline with a sufficient level of reporting to assess the quality of the relevant results. The study was assigned a reliability score of 2 and considered suitable for assessment as an accurate reflection of the test material. However, it was deemed more appropriate to select the more reliable study conducted on a structural analogue as the key data to be used.

 

The available data are considered to be complete and the result determined, 72 hour EL50 >100 mg/L loading rate WAF, was taken forward for risk assessment.