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Toxicity to aquatic algae and cyanobacteria

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Description of key information

No toxic affects to aquatic algae up to the limit of water solubility.

Key value for chemical safety assessment

Additional information

In accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to three structurally related category members, fatty acids, C8-10 mixed esters with dipentaerythritol, isooctanoic acid, pentaerythritol and tripentaerythritol (CAS 189200-42-8), fatty acids, C8-10 (even numbered), di-and triesters with propylidynetrimethanol (CAS 11138-60-6) and fatty acids, C16-18 (even numbered), esters with pentaerythritol (CAS 85116-93-4) was conducted. This read-across is justified in detail in the overall summary (IUCLID chapter 6.1) and within the category justification in IUCLID Section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substances were used for the assessment. The fatty acid chain length of C8 – C10 of the first two read-across substances are similar to those of the target substance. In addition, the first read-across substance fatty acids, C8-10 mixed esters with dipentaerythritol, isooctanoic acid, pentaerythritol and tripentaerythritol contains the same alcohol component, i.e. pentaerythritol, and is a tetra-ester. The final read across substance is a mono-tetraester containing a fatty acid chain length of C16 –C18, nevertheless it is significant as it pins the longer chain length end of the polyol esters category and shows that at this chain length no toxicity to algae is expected up to the limit of water solubility.

The first study with the read-across substance fatty acids, C8-10 mixed esters with dipentaerythritol, isooctanoic acid, pentaerythritol and tripentaerythritol (CAS 189200-42-8) was performed according to OECD 201 under GLP conditions (Febbo, 1995). The green algae Scenedesmus capricornutum was exposed to nominal concentrations of 62.5 mg/L, 125 mg/L, 250 mg/L, 500 mg/L and 1000 mg/L. The test solution was prepared by adding the appropriate amount of test substance with subsequent stirring and sampling of the aqueous portions (WAFs) through the outlet at the bottom of the vessels. No inhibition of growth of Scenedesmus capricornutum up to the limit of water solubility was observed resulting in an EL50 > 1000 mg/L (nominal). A NOELR of ≥ 1000 mg/L was determined based on effects on growth rate.

For the second read across substance fatty acids, C8-10 (even numbered), di-and triesters with propylidynetrimethanol (CAS 11138-60-6) a study conducted according to OECD 201 and GLP (Häner. 2007) as limit test is available. The green algae Desmodesmus subspicatus was exposed to a limit concentration of 100 mg/L (nominal). A water accommodated fraction (WAF) was prepared by stirring the test substance in algal medium for 24 h and removing undissolved materials by filtration. No inhibition of growth rate and effects on biomass were observed resulting in an EL50 > 100 mg/L.

The third read across study investigated the toxicity of fatty acids, C16-18 (even numbered), esters with pentaerythritol (CAS-No. 85116-93-4) to algae. This static algal growth inhibition test with Pseudokirchneriella subcapitata was conducted according to GLP, and EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) determined an ErL50 and ErL10 (72 h) of > 100 mg/L (WAF loading rate). It can be concluded that no toxicological effects on algae are expected up to the water solubility for this read-across substance.

Based on these results from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar ecotoxicological profile, it can be concluded that reaction mass of Heptanoic acid 3-pentanoyloxy-2,2-bis-pentanoyloxymethyl-propyl ester, Heptanoic acid 2-heptanoyloxymethyl-3-pentanoyloxy-2-pentanoyloxymethyl-propyl ester and Heptanoic acid 3-heptanoyloxy-2-heptanoyloxymethyl-2-pentanoyloxymethyl-propyl ester (former CAS 68441-94-1) will not exhibit effects to aquatic algae up to the limit of water solubility. As it can be seen in the data matrix of the category justification in section 13 and the overall endpoint summary IUCLID 6.1, all reliable data in the polyol esters category support this hazard assessment by showing a consistent pattern of results, i.e. no toxic effects were observed to aquatic algae or other aquatic organisms up to the limit of water solubility.