Methyl palmitate

Short-term toxicity to aquatic invertebrates

Description of key information

In the SCAE-Me category a trend for the toxicity of aquatic invertebrates can be observed. The highest toxicity was determined for methyl laurate (CAS 111-82-0, fatty acid chain length C12). The toxicity decreases with shorter and longer chain length of the fatty acids.
Of the substances to be registered, the following SCAE-Me show toxicity to aquatic invertebrates and algae leading to a classification R50 according to 67/548/EWG and Aquatic Acute 1 according to Regulation (EC) No 1272/2008:  
¿ Methyl laurate (CAS 111-82-0) 
¿ Fatty acids, C12-18 and C18 -unsatd., methyl esters (CAS 1234694 -02 -0) 
¿ Fatty acids, C8-18 and C18-unsatd., Me esters (CAS 67762-37-2) 
¿ Fatty acids, C12-14 (even numbered), methyl esters (CAS 308065-15-8) 
This SCAE-Me show also toxicity to aquatic invertebrates, but do not lead to a classification:
¿ Methyl octanoate (CAS 111-11-5) 
¿ Methyl decanoate (CAS 110-42-9) 
¿ Fatty acids, C8-10, Me esters (CAS 85566-26-3) 
All other SCAE-Me of this category are not toxic to aquatic organisms. This are: 
¿ Methyl myristate (CAS 124-10-7) 
¿ Methyl palmitate (CAS 112-39-0) 
¿ Methyl stearate (CAS 112-61-8) 
¿ Fatty acids, C16-18, Me esters (CAS 85586-21-6)

Additional information

Four studies, investigating the short-term toxicity to aquatic invertebrates of SCAE-Me, are available for the SCAE-Me category. In addition, two QSAR-calculations for one SCAE-Me were performed.

Table1: Experimental results, QSAR-calculations and Read across of the key studies, which were used for the single substances of the SCAE-Me.

CAS-No.	111-11-5	110-42-9	111-82-0	124-10-7	112-39-0	112-61-8
Daphnia acute toxicity	QSAR, LC50 (48h) = 5.6 mg/L	Experimental result,D. magna, EC50 (48h) = 1.1 mg/L(meas. arithm. mean)	Experimental result,D. magna, EC50 (48h) = 0.255 mg/L (meas. arithm. mean)	Experimental result,D. magna, EC50 (48h) > 0.02 mg/L (meas. initial), EC50 (48h) > 100 mg/L (nominal)	RA from 124-10-7: Experimental result,D. magna, EC50 (48h) > 0.02 mg/L (meas. initial), EC50 (48h) > 100 mg/L (nominal)	RA from 67762-26-9: Experimental result,D. magna, EC50 (48h) > 100 mg/L (nominal)

 

Table2: Read across, this was used for the UVCB substances of the SCAE-Me.

CAS-No.	85566-26-3	1234694-02-0	67762-37-2	308065-15-8	85586-21-6
Daphnia acute toxicity	RA from 110-42-9:Experimental result,D. magna, EC50 (48h) = 1.1 mg/L(meas. arithm. mean)	RA from 111-82-0: Experimental result,D. magna, EC50 (48h) = 0.255 mg/L (meas. arithm. mean)	RA from 111-82-0: Experimental result,D. magna, EC50 (48h) = 0.255 mg/L (meas. arithm. mean)	RA from 111-82-0: Experimental result,D. magna, EC50 (48h) = 0.255 mg/L (meas. arithm. mean)	RA from 67762-26-9: Experimental result,D. magna, EC50 (48h) > 100 mg/L (nominal)

 

In the category, there can be observed a trend for the toxicity of aquatic invertebrates. This is related to the toxicity mode of action (narcosis). Thus, a linear dependence on log Kow is expected. The highest toxicity was determined for methyl laurate (CAS 111-82-0, fatty acid chain length C12). In the GLP-study (Ministry of the Environment of Japan, 2006) according to OECD 202 the EC50 (48h) was determined as 0.255 mg/L for Daphnia magna. The toxicity decreases with shorter and longer chain length of the fatty acids. For methyl decanoate (CAS 110-42-9, fatty acid chain length C10), a lower toxicity for Daphnia magna was estimated. In one GLP-study (Bouwman, 2010) according to OECD 202 an EC50 of 1.1 mg/L was determined for methyl decanoate. Two QSAR-calculations for methyl octanoate (CAS 111-11-5, fatty acid chain length C8) yielded LC50 of 5.6 mg/L (ECOSAR, 2010) and LC50 = 11.6 mg/L (von der Ohe, 2005). The more conservative of the two values was accepted as the key value, what is additionally confirmed by a good performance of ECOSAR model for C10 and C12. Thus, the model estimation can be considered as validated. The toxicity of aquatic invertebrates for methyl octanoate is as expected lower than the toxicity for methyl decanoate. One study (Hudson, 2000) for methyl octanoate (CAS 111-11-5) was conducted with the marine copepod Acartia tonsa and conducted an EC50 (48h) > 10000 mg/L. Methyl myristate (CAS 124-10-7, fatty acid chain length C14) showed no toxicity to Daphnia magna. One GLP-study (Migchielsen, 2010) according to OECD 202 generated an EC50 (48h) > 0.02 mg/L (meas. initial) respectively EC50 (48h) > 100 mg/L (nominal). Due to the very low solubility of the test substance in water, concentration levels that might be toxic for daphnia could not be reached. Therefore, no toxicity in the range of water solubility could be observed. Thus and due to the low water solubility of methyl palmitate (CAS 112-39-0) and methyl stearate (CAS 112-61-8), which have a chain length of C16 respectively C18, no toxicity for aquatic invertebrates can be expected in the range of water solubility for methyl palmitate (0.004003 mg/L) and methyl stearate (0.0003 mg/L). In addition for methyl stearate (CAS 112-61-8), a study (Küch, 1996) with Daphnia magna according to EU Method C.2 showed no toxicity in the range of water solubility (EC50 > 100 mg/L) for the analogue substance Fatty acids, C14-18 and C16-18-unsatd., Me esters (CAS 67762-26-9), a substance with a high percentage of C18 Fatty acid.

The UVCB substances could be derived from the single substances. The substances with the highest percentage in the UVCB are decisive. Therefore, methyl decanoate (CAS 110-42-9) and methyl octanoate (CAS 111-11-5) were used as read across for Fatty acids, C8-10, Me esters (CAS 85566-26-3), as these both substances are the main components of Fatty acids, C8-10, Me esters. Due to the more sensitive result for D. magna for methyl decanoate (CAS 110-42-9), this study was used as key study. Further, as Fatty acids, C12-18 and C18 -unsatd., methyl esters (CAS 1234694 -02 -0), Fatty acids, C8-18 and C18-unsatd., Me esters (CAS 67762-37-2) and Fatty acids, C12-14 (even numbered), methyl esters (CAS 308065-15-8) have a great percentage of C12 Fatty acid (> 30%), methyl laurate (CAS 111-82-0) was used as read across for these UVCB substances. The UVCB Fatty acids, C16-18, Me esters (CAS 85586-21-6) with a great percentage of C16 and C18 Fatty acids could be deviated from methyl palmitate (CAS 112-39-0) and methyl stearate (CAS 112-61-8), which were extrapolated from methyl myristate (CAS 124-10-7). In addition, the result from the study (Küch, 1996) with Fatty acids, C14-18 and C16-18-unsatd., Me esters (CAS 67762-26-9) according to EU Method C.2 could be considered, which determined an EC50 > 100 mg/L for Daphnia magna.

Of the substances to be registered, the following SCAE-Me show toxicity to aquatic invertebrates leading to a classification R50 according to 67/548/EWG and Aquatic Acute 1 according to Regulation (EC) No 1272/2008: 

·       Methyl laurate (CAS 111-82-0)

·       Fatty acids, C12-18 and C18 -unsatd., methyl esters (CAS 1234694 -02 -0)

·       Fatty acids, C8-18 and C18-unsatd., Me esters (CAS 67762-37-2)

·       Fatty acids, C12-14 (even numbered), methyl esters (CAS 308065-15-8)

 

This SCAE-Me show also toxicity to aquatic invertebrates, but do not lead to a classification:

·       Methyl octanoate (CAS 111-11-5)

·       Methyl decanoate (CAS 110-42-9)

·       Fatty acids, C8-10, Me esters (CAS 85566-26-3)

 

All other SCAE-Me of this category are not toxic to aquatic organisms. This are:

·       Methyl myristate (CAS 124-10-7)

·       Methyl palmitate (CAS 112-39-0)

·       Methyl stearate (CAS 112-61-8)

·       Fatty acids, C16-18, Me esters (CAS 85586-21-6)