Reaction mass of Pentaerythritol bis (2-ethylhexanoate) bis (3,5,5-trimethylhexanoate) and Pentaerythritol tris (2-ethylhexanoate) 3,5,5-trimethylhexanoate and Pentaerythritol 2-ethylhexanoate tris (3,5,5-trimethylhexanoate) and Pentaeryhthritol tetrakis(2-ethylhexanoate) and Pentaerythritol tetrakis (3,5,5-trimethylhexanoate)

Endpoint summary

Description of key information

A toxicokinetic assessment was performed based on the available data of the substance. Based on the physical/chemical properties of the substance, absorption factors for this

substance are derived to be 50% (oral), 50% (inhalation) and 10% (dermal) for risk assessment purposes. The substance is expected to accumulate in adipose tissue.

Key value for chemical safety assessment

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

50

Additional information

A chemical can enter the body via the gastrointestinal tract, the lungs and the skin.

In general, a substance needs to be dissolved before it can be taken up from the gastrointestinal tract after oral administration.

Reaction mass of Pentaerythritol bis (2-ethylhexanoate) bis (3,5,5-trimethylhexanoate) and Pentaerythritol tris (2-ethylhexanoate) 3,5,5-trimethylhexanoate and Pentaerythritol 2-ethylhexanoate tris (3,5,5-trimethylhexanoate) and Pentaeryhthritol (RB68) consists of several constituents with molecular weights varying between 640.9 - 697 g/mol.

The substance is experimentally determined to have a water solubility below 0.53 mg/L, however the actual water solubility is estimated to be around 0.65 ng/L for each individual constituent of the substance. Both the high molecular weight and very low water solubility do not favor passive uptake in the gastro-intestinal (GI) tract. The partition coefficient (log Pow) of the substance is experimentally determined to be higher than 6.2 and the actual value is estimated to be between 12.34 and 13.86. The high log Pow indicates that the substance is highly lipophilic and can therefore be expected to form micelles assisted by bile salts and as such be solubilized and absorbed from the GI tract into the lymphatic system or epithelial cells. As signs of systemic toxicity were observed in the oral toxicity studies absorption of the substance can take place from the GI tract. Based on the considerations mentioned above, for risk assessment purposes, oral absorption of the substance is set at 50%.

The substance has a low vapor pressure (1.0 x 10-5 Pa) and therefore it is not likely that the substance can reach the respiratory tract via inhalation as vapor. The substance is a slight viscous liquid which can form fine droplets (aerosols) that can enter the nasopharyncheal region and subsequently the trachea/bronchial/pulmonary regions of lungs. In case the substance would reach these different regions it will not diffuse or dissolve into the mucus lining of the respiratory tract due to its very low water solubility. Macrophages which are present on the surface and in the mucus lining of the respiratory tract will remove a part of the undissolved substance by phagocytosis. In this process the cells can transport the substance into the lymphatic system. The remaining part of the undissolved substance can be cleared from the respiratory tract by mucocilliary mechanisms which transport it towards the pharynx where it is swallowed. As the substance is not directly available for uptake in the respiratory tract but can be partly transported by macrophages into the lymphatic system, for risk assessment purposes, the inhalation absorption of the substance is set at 50%.

According to the criteria given in the REACH Guidance, a default value of 100% dermal absorption should be used unless MW >500 and log Pow <-1 or >4, in which case a value of 10% skin absorption should be chosen. The constituents of the substance have a molecular weight above 500 and an estimated log Pow between 12.34 and 13.86 therefore the criteria for 10% absorption are met. The available in vivo data do not indicate that deviation from this value is needed as the substance does not irritate or affect the skin which could increase the dermal uptake. Therefore, for risk assessment purposes, the dermal absorption of substance is set at 10%.

Once absorbed, wide distribution of the substance throughout the body is not expected due to its high molecular weight and as the water solubility of the substance is limited. After oral absorption the substance may be metabolized in the gastrointestinal tract by the microbiome or in the liver after systemic uptake. Lipophilic substances such as RB68 tend to accumulate in adipose tissue under normal repeated intermittent exposure, therefore the bioaccumulation potential is considered high. The major routes of excretion for substances from systemic circulation are the urine and/or the feces. Due to its low water solubility and lipophilic character the substance can be excreted in the bile and subsequent the feces if no enterohepatic recycling occurs.