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EC number: 203-966-3 | CAS number: 112-39-0
Sediment toxicity
Administrative data
Link to relevant study record(s)
Description of key information
The results of the chemical safety assessment do not indicate the need to investigate further the toxicity to sediment organisms
Key value for chemical safety assessment
Additional information
No experimental data evaluating the toxicity to sediment organisms is available for methyl palmitate (CAS No. 112-39-0). According to Regulation (EC) No. 1907/2006, Annex X, Column 2, 9.5.1, long-term toxicity testing shall be proposed by the registrant if the results of the chemical safety assessment indicate the need to investigate further the effects of the substance on sediment organisms. Since the substance is readily biodegradable, chronic exposure of sediment organisms is unlikely. Furthermore, the substance is not expected to be toxic to aquatic organisms up to the limit of water solubility. In addition, available data indicate that methyl palmitate is not bioaccumulative. Based on the available information, toxicity to sediment organisms is not expected to be of concern.
Intrinsic properties and fate
Methyl palmitate is readily biodegradable (75% biodegradation in 28 days). 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, 2008). 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 exhibits a log Koc values > 4 and is insoluble in water (< 0.004 mg/L). The Guidance on information requirements and chemical safety assessment, Chapter R7.b (ECHA, 2008) 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, 2008)) 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 one can assume that the availability of methyl palmitate in the sediment environment is generally very low, which reduces the probability of chronic exposure of sediment organisms in general.
Aquatic ecotoxicity data
Acute and chronic aquatic toxicity tests performed on fish, invertebrates, algae and microorganisms showed no adverse effects occurred in the range of the water solubility of the substance(< 0.004 mg/L). The obtained results indicate that methyl palmitate is likely to show no toxicity to sediment organisms as well.
Metabolism/Bioaccumulation
After absorption, methyl palmitate is expected to be enzymatically hydrolyzed by carboxylesterases yielding the corresponding alcoholand fatty acids. QSAR estimations using BCFBAF v3.01 support the expected rapid biotransformation of this substance with BCF/BAF valuesof 95.6 and 238.5 L/kg,respectively (well below the trigger value of 2000 for substances fulfilling the B criterion, as mentioned in Annex XIII, 1.1.2 of Regulation (EC) No. 1907/2006).
The metabolism of the hydrolysis products: alcohol (i.e. methanol) and fatty acids is well established and not of concern in terms of bioaccumulation (for further information seechapter 5.3 of the technical dossier).
In conclusion, no potential for bioaccumulation is to be expected for methyl palmitate.
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, methyl palmitate will be bioavailable to sediment organisms mainly via feed and contact with suspended organic particles. After uptake by sediment species, extensive and fast biotransformation of the substance by carboxylesterases into fatty acids and methanol is expected. The supporting BCF/BAF values estimated with the BCFBAFv3.01 program, Arnot-Gobas model including biotransformation, also indicate that this substance will not be bioaccumulative. Furthermore, aquatic toxicity data show that no effects are expected up to the limit of water solubility of the substance (0.004 mg/L). Therefore, methyl palmitate is unlikely to pose a risk for sediment organisms in general and testing is thus omitted.
A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within CSR.
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