Octanoic acid, mixed tetraesters with 2-ethylhexanoic acid, heptanoic acid and pentaerythritol

Endpoint summary

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

100

Absorption rate - inhalation (%):

100

Additional information

No published data could be identified on the toxicokinetics of the substance. However, as per REACH guidance document R7. C (June 2017), information on absorption, distribution, metabolism and excretion may be deduced from the physico-chemical properties including:

-       Water solubility

-       Partition coefficient

-       Vapour pressure

-       Molecular weight

The substance is a UVCB, with the majority of the constituents having a molecular weight >500. It is a liquid with a tested water solubility of 0.69 μg/L. Volatility was determined to be very low (1.6E-8 Pa at 20°C) and the estimated partition coefficient of the substance is 12.04.

Taking into account the log Kow (12.04) and the water solubility (0.69 μg/L), bioaccumulation of the substance is likely to be low. According to ECHA Guidance for PBT assessment R.11, the aquatic BCF of a substance is probably lower than 2000 if the calculated log Kow is higher than 10. This is supported by the indication of poor bioavailability following oral absorption (as can be seen below) and therefore, less tendency to bioaccumulate.

Oral and gastrointestinal (GI) absorption: Given the very low water solubility and high partition coefficient of the substance, it is unlikely to be soluble in the GI fluid. However, due to the high log Kow some extent of micellar solubilisation might occur. Therefore, the substance may be considered to be partially absorbed through the GI system leading to low oral bioavailability. This is supported by the absence of any sign of systemic toxicity in acute or repeated dose studies. However, in the absence of actual data, the default value of 50% has been considered for oral absorption.

Dermal absorption:

Similarly, for dermal route, the high molecular weight along with very low water solubility indicates poor absorption. Also, due to the high log Kow the rate of transfer between the stratum corneum and the epidermis is likely to be low. However, in absence of actual data, a default 100% absorption is assumed.

Inhalation absorption: The high log Kow of the substance along with poor water solubility indicates that some extent of micellar solubilisation might occur upon inhalation exposure. Therefore, similar to oral absorption, a low bioavailability of the substance might be assumed through inhalation route. In the absence of actual data,a default value of 100% has been considered for inhalation absorption.

Metabolism: QSAR profiling of the constituents present at greater than 5% revealed aliphatic hydroxylation or ester hydrolysis as the initial metabolic step.