coconut oil, reaction products with glycerol esters of 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzenepropanoic acid

Bioaccumulation: aquatic / sediment

Description of key information

Significant accumulation in organisms is not to be expected. 

Additional information

For two components of the uvcb substance experimental data on the potential to bioaccumulate are available. Furthermore, data on metilox as possible stable degradant are available (BASF SE 1998). The test was performed with two exposure levels (1 mg/L and 0.1 mg/L). According to these data, the three test items had BCF values clearly below 2000.

-         Component 1 (glycerol di-metilox ester): BCF ≤ 52

-         Component 2 (glycerol tri-metilox ester): BCF ≤ 16

-         Metilox: BCF ≤ 532

 

Due to the uvcb character of the substance, additional QSAR calculations with OASES Catalogic v5.11.5, US EPA T.E.S.T. v4.0.1 and US EPA EPISuite v4.10 have been performed on the single components (A – F and metilox).

 

Overview of the calculated BCF values.

	A	B	C	D	E	F	metilox
Catalogic	4.26	12.32	7.01	6.9	7.43	7.43	13.73
T.E.S.T.	60.43	542.56	63.19	26.59	4.36	10.56	66.76
EPISuite	29.06	608.3	626.9	123.4	3.16	3.16	3.16
DiamMax-average [Å]	14.56	12.96	21.96	25.18	23.53	24.90	12.46

 

According to these results none of the single components can be regarded as bioaccumulative. Furthermore, according to ECHAs guidance on information requirements and chemical safety assessment Chapter R.11: PBT Assessment an average maximum diameter of greater than 1.7 nm (17 Å) plus a molecular weight of greater than 1100 can be used in a weight of evidence approach to show that the substance is not bioaccumulative. Four of the components (including the main components) have a DiamMax-average of clearly above 1.7 nm (17 Å) which is a sign of reduced bioavailability due to hindered passage into the cell membranes. However, the additional criterion of a molecular weight of greater than 1100 is not met by any of the components. Nevertheless, it can be assumed that due to the DiamMax-average decreased passage of cell membranes occur.

According to ECHAs guidance on information requirements and chemical safety assessment Chapter R.11: PBT Assessment the log Kow can be used as a screening criterion due to the fact that the uptake of an organic substance is driven by its hydrophobicity. For organic substances with a log Kow value below 4.5 it is assumed that the affinity for the lipids of an organism is insufficient to exceed the B criterion (i.e. a BCF < 2000). At log Kow values between 4 and 5, log BCF increases linearly with log Kow. However, at very high log Kow (> 6), a decreasing relationship between the two parameters is observed. If the calculated log Kow is higher than 10, the aquatic BCF of a substance is probably lower than 2000 L/kg.

For the present uvcb compound representative log Kow calculations have been performed:

Glycerol mono-metilox ester:           3.59

Glycerol di-metilox ester:                  9.4

Glycerol tri-metilox ester:                15.2

Glycerol di-metilox fatty ester:        15.6

Metilox:                                                 5.11

Only two components (glycerol mono-metilox ester and metilox) are in the range of 4 to 5. All other components are either clearly above 6 or even above 10.

It can reasonably be assumed that due to the log Kow values only the glycerol mono-metilox ester and metilox itself have a potential for bioaccumulation. All other components are considered to be not bioaccumulative.

 

Furthermore, the PBT Expert Working Group of the Technical Committee of New and Existing Chemicals has agreed that at this stage of knowledge metilox itself (CAS 6386-38-5) should be deleted from the list of potential PBT / vPvB substances.

 

In conclusion, considering all available information in a weight of evidence approach none of the components of the uvcb substance are assumed to be bioaccumulative.