Radia 7838

Endpoint summary

Description of key information

Short description of key information on bioaccumulation potential result: 
Toxicokinetic Assessment report according to Guidance for the implementation of REACH. Guidance on information requirements and chemical safety assessment. Chapter R.7c: Endpoint specific guidance. European Chemical Agency, May 2008.

Additional information

This substance is a polyester. The toxicokinetic assessment is based on the physical/chemical properties as determined for Radia 7838 and it is anticipated that these properties are representative for all constituents in this substance. The different components in Radia 7838 however are considered to have different lipophilicity. This is represented by the octanol/water partition coefficient which is given as a range (< 0.3 - > 6.5).

The water solubility of Radia 7838 is very low (<1 mg/L). Since in general a substance needs to be dissolved before it can be taken up from the gastro-intestinal tract, it is unlikely that Radia 7838 will show a high systemic exposure after oral administration. As ionized substances do not easily pass the GI wall, the presence of free hydroxyl groups in the molecule will further impair the absorption. It is not to be expected that the not clearly defined molecular weight (approx. 400) will further lower the passage through biological membranes. As its lipophilic character (logPow< 0.3 - > 6.5) is not clearly defined, no conclusions can be drawn based on this parameter and hence on how this might influence passive diffusion and on the relevance of micellular solubilization. For risk assessment purposes the oral absorption of Radia 7838 is set at 50%. The results of the toxicity studies do not provide reasons to deviate from this proposed oral absorption factor.

No significant cleavage of the ester bond(s) is to be expected in the gastro-intestinal tract, due to the limited water solubility of Radia 7838. In the case absorption of Radia 7838 occurs, cleavage of the ester bonds and conjugation is to be expected. Radia 7838, the resulting metabolites and conjugation products will be excreted via feces (high molecular substances) or via urine (low molecular substances).

The low vapour pressure of Radia 7838 (<1.47x10^-3Pa) indicates that the availability of the substance for inhalation will be limited. However, once present in the respiratory tract, the low water solubility of Radia 7838 (<1 mg/L) indicates a potential for accumulation, while based on its undefined lipophilic character (logPow< 0.3 - > 6.5) the potential for absorption directly across the respiratory tract epithelium cannot be assessed. For risk assessment purposes the inhalation absorption of Radia 7838 is set at 100% as a worst case assumption.

The low water solubility of Radia 7838 (<1 mg/L) does not facilitate dermal absorption. As its lipophilic character is not clearly defined (logPow< 0.3 - > 6.5), but approx. 80% of the substance shows a logPow of >4 and the molecular weight is approx. 400, the criterion for 100% dermal absorption as given in the REACH guidance (MW < 500 and/or -1 < log Po/w < 4) is partially met. It is generally accepted however that dermal absorption is not higher compared to oral absorption. Therefore, for risk assessment purposes the dermal absorption is considered to be 50%.

Based on the present available data, no additional conclusions can be drawn on the metabolism and excretion of Radia 7838 after dermal and inhalatory absorption.

Discussion on bioaccumulation potential result:

For risk assessment purposes an oral and dermal absorption of 50%, and an inhalation absorption of 100% is derived.