O,O'-dioctadecylpentaerythritol bis(phosphite)

Endpoint summary

Description of key information

In the absence of any quantitative data, 50% absorption following oral administration is assumed for risk assessment purposes.
As the log Pow of Weston 618 is > 4 and the molecular weight is > 500, a default dermal absorption of 10% will be used for risk assessment purposes.
Exposure to Weston 618 via inhalation is unlikely to occur, however 100% will be used for inhalation absorption for risk assessment purposes. 

Key value for chemical safety assessment

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

100

Additional information

Information describing the potential behaviour of the test material within the body during the early phase of biotransformation was presented in Schreitmüler (2003) in an in vitro, non pre-validated, test performed in simulated gastric juices and simulated intestinal fluid. The study measured the presence of two hypothesised hydrolysis products 1-octadecanol and perntaerythritol. The study was performed and reported to a high standard and as such was assigned a reliability score of 2 in accordance with the criteria as outlined in Klimisch (1997) for assessing the quality of data. The hydrolysis determination of the by product (the oxidised form of the test material (parent)) in gastric juice simulant and intestinal fluid simulant, showed the stability of the oxidised parent substance during incubation. It was found that 1-octadecanol is contained in the test material to a considerable extent (prior to incubation) and pentaerythritol was not found to be a hydrolysis product. Under the conditions of the test, a complete hydrolysis of test material (parent) and its oxidised by-product in gastric juice and intestinal fluid simulant into 1-octadecanol, pentaerythritol and phosphoric acid, could not be shown.

A toxicokinetic profile for Weston 618 has been determined on the basis of the physical-chemical properties of Weston 618, and on in vitro studies and acute and repeat dose toxicity studies. Based on the physical-chemical properties of Weston 618, no significant absorption by the oral, dermal or inhalation routes is expected. Weston 618 is hydrolytically unstable and is expected to hydrolyse in the gastrointestinal tract. Weston 618 was shown to be unstablein simulated gastric juicein anin vitrostudy, althoughcomplete hydrolysis to 1-octadecanol, pentaerythritol and phosphoric acid was not demonstrated.

No clear evidence of systemic exposure was seen in the oral, dermal and inhalation studies,and no conclusions could be drawn regarding the distribution of any absorbed material.  

It is not possible to determine from the oral toxicity studies whether Weston 618 is poorly absorbed or whether it is of low toxicity, therefore for risk assessment purposes, 50% absorption following oral administration is assumed for risk assessment purposes.

Exposure to Weston 618 via inhalation is unlikely to occur, however 100% will be used for inhalation absorption for risk assessment purposes.

Although no evidence of dermal absorption was seen in the acute dermal toxicity or skin corrosivity studies, based on estimation of mammalian dermal absorption in accordance with principles adopted within the EFSA guidance on estimating dermal absorption of pesticide active substances(EFSA, 2012), a dermal absorption value of 10% will be used for risk assessment purposes.