2,2-bis[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate

Sediment toxicity

Additional information

Experimental data evaluating the toxicity to sediment organisms is not available for 2,2-bis[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate (CAS 25811-35-2). Since the substance is readily biodegradable, exposure of sediment organisms is unlikely. Furthermore, the substance is not toxic to aquatic organisms up to the limit of water solubility (WS < 0.05 mg/L). In addition, available data indicate, that the substance is not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.

Intrinsic properties and fate

2,2-bis[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate (CAS 25811-35-2) is readily biodegradable (96% biodegradation in 28 days; Häner, 2006). According to the Guidance on information requirements and chemical safety assessment, Chapter R.7b, readily biodegradable substances can be expected to undergo rapid and ultimate degradation in most environments, including biological Sewage Treatment Plants (STPs) (ECHA, 2012). Therefore, after passing through conventional STPs, only low concentrations of these substances are likely to be (if at all) released into the environment.
Furthermore, the substance is insoluble in water (WS < 0.05 mg/L) and as a high log Koc (>5). The Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2012) states that once insoluble chemicals enter a standard STP, they will be extensively removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms. Nevertheless, once this contact takes place, these substances are expected to be removed from the water column to a significant degree by adsorption to sewage sludge (Guidance on information requirements and chemical safety assessment, Chapter R.7a, (ECHA, 2012)) and the rest will be extensively biodegraded (due to ready biodegradability). Thus, discharged concentrations of these substances into the aqueous/sediment compartment are likely to be negligible.
Considering this information the availability 2,2-bis[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate (CAS 25811-35-2) in the sediment environment can be expected to be generally very low, which reduces the probability of exposure of sediment organisms in general.

Aquatic ecotoxicity data

Acute and chronic values obtained in tests conducted on fish, invertebrates, algae and microorganisms showed no adverse effects in the range of the water solubility of the substance (WS< 0.05 mg/L).
Therefore, toxic effects of 2,2-bis[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate (CAS 25811-35-2) on sediment organisms are unlikely.

Metabolisms/Bioaccumulation

The substance 2,2-bis[[(1-oxoheptyl)oxy]methyl]propane-1,3-diyl bisheptanoate (CAS 25811-35-2) has a log Kow > 5 (KOWWIN v1.67) indicating a potential for bioaccumulation. But due to the low water solubility, rapid environmental biodegradation and metabolisation via enzymatic hydrolysis, a relevant uptake and bioaccumulation in aquatic organisms is not expected. After absorption, the substance is expected to be enzymatically hydrolyzed by carboxylesterases yielding free fatty acid and the free alcohol (e. g. pentaerythritol). From literature it is well known, that these hydrolysis products will be metabolized and excreted in fish effectively (Heymann, 1980; Lech & Bend, 1980; Lech & Melancon, 1980; Murphy & Lutenske, 1990). This is supported by low calculated BCF and BAF values of 0.895 L/kg ww respectively (BCFBAF v3.01, Arnot-Gobas, including biotransformation, upper trophic). Please refer to IUCLID Section 5.3 for a detailed overview on bioaccumulation of the substance. Thus, taking all information into account, the bioaccumulation of this category member is assumed to be low.

Conclusion

Due to its readily biodegradable nature, extensive degradation of this substance in conventional STPs will take place and only low concentrations are expected to be released (if at all) into the environment. Once present in the aquatic compartment, further biodegradation will occur and, due to the high log Kow, low water solubility and high adsorption potential, sediment organisms might be mainly exposed via feed and contact with suspended organic particles. After uptake by sediment species, extensive and fast biotransformation of the substance by carboxylesterases into the free fatty acid and the corresponding alcohol is expected. The supporting BCF/BAF values estimated with the BCFBAF v3.01 program, Arnot-Gobas model including biotransformation, also indicate that this substance will not be bioaccumulative. Furthermore, aquatic toxicity data show that no effects occur up to the limit of water solubility. Therefore, the substance does not pose a risk for sediment organisms in general and testing is thus omitted, hence toxicity to sediment organisms is not expected to be of concern and thus there is no need to investigate further the effects on sediment organisms.

In conclusion, due to a) the observed absence of toxicological effects on aquatic organisms, b) the lack of chronic exposure and c) the, acknowledged metabolisation of fatty acid esters, toxic effects on sediment dwelling invertebrates can be excluded.