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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No acute or long term effects to aquatic algae up to the limit of water solubility.

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Additional information

Since no studies investigating the toxicity to aquatic algae of fatty acids, C16-18, 2-hydroxyethyl ester (CAS 97281-23-7) are available, a read across to structurally related substances (CAS 85116-97-8 and 91031-31-1) was conducted, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5.

In the first read across study the green algae Pseudokirchnerella subcapitata was exposed to fatty acids C16-18 esters with diethylene glycol (CAS 85116-97-8) according to OECD guideline 201 and GLP (Vryenhoef, 2015). Since the test substance is poorly soluble in water, Water Accommodated Fractions (WAF) of 10, 20, 40, 80 and 100 mg/L (nominal) were prepared. The nominal loading rates were analytically verified by HPLC/MS analysis and resulted in concentrations 0.00452 - 0.0407 mg/L at study initiation and depleted below the limit of quantification at the end of the study after 72 h. Statistical analysis resulted in significant difference between the control and the treatment of 40 mg/L. Thus, the NOELR (72 h) was set to 20 mg/L based on growth rate. However, the inhibition of growth was < 10% in all treatments resulting in an ErL10 (72 h) > 160 mg/L.

A second read across study investigated the algae toxicity of fatty acidss, C16-18, esters with ethylene glycol (CAS 91031-31-1) according to DIN 38412-9 under GLP conditions (Stelter, 1994). The green algae Scenedesmus subspicatus was exposed to nominal concentrations of 10 and 100 mg/L without a further filtration step. No inhibition of growth up to the limit of water solubility was observed resulting in an 72 h-ErC50 > 100 mg/L (nominal). An 72 h-EC10 of 34 mg/L was determined, since growth stimulation was observed in both concentrations 

Based on the results of the structurally related substances (CAS 91031-31-1 and 85116-97-8), it can be considered that no acute or long term effects will occur by fatty acids, C16-18, 2-hydroxyethyl ester (CAS 97281-23-7) to aquatic algae up to the limit of water solubility.