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Administrative data

Link to relevant study record(s)

Description of key information

No specific study was performed on absorption, distribution, metabolism and/or excretion (ADME) of WS406663. Its systemic availability after topical or oral administration is expected to be very limited based on its relatively high molecular weight, low water solubility and high lipohilicity restricting the bioavailability of the substance. Availability of WS406663 under a vapour state is unlikely, because of its low vapour pressure. 
Based on the available data the bioacumulation potential cannot be judged. However, based on the very low dermal, oral and inhalative bioavailability of the substance and absence of adverse effects in all toxicological tests performed with the read-across source substance a low bioaccumulation potential (if any) is expected.

Key value for chemical safety assessment

Additional information

No specific study was performed on absorption, distribution, metabolism and/or excretion (ADME) of WS406663. Predictions on the toxicokinetic behaviour were made based on physical-chemical properties and information from toxicological studies. These data were obtained by read-across from the read-across source substance WS405777.As outlined in the „Validity Assessment Report“ for the read-across approach (see IUCLID Section 13) read-across from testing data obtained with the UVCB substance WS405777 is considered appropriate for the safety evaluation as well as classification and labelling of the mono-constituent substance WS406663 based on the close chemical similarity between the two substances.

WS406663 is a mono-constituent substance with one impurity that may be contained up to 15%. The molecular formula of the main constituent is C40H80N2O4, that of the impurity is C58H114N2O6. In principle these two substances are saturated C40and C58compounds. The substances contain two amide bonds (plus one ester bond in the impurity) and two (three in the impurity) non-terminal and non-vicinal hydroxyl groups as the only functional groups. The following data on physical chemical properties of WS406663 are the basis for this toxicokinetics assessment.

- Molecular weight: 653 Da (main constituent), 935 Da (impurity)
- Water solubility: < 1 mg/l (determined with the r-a source substance WS405777); 2.3 x 10-9mg/l (calculated by US EPA WSKOWWIN)
- Melting point: 136°-141°C; substance decomposes before boiling (>250°C)
- Octanol/water partition coefficient: log Pow> 6 (determined with the r-a source substance WS405777); log Pow= 12.3 (calculated by US EPA KOWWIN)
- Vapour pressure: 2 x 10-6Pa (determined with the r-a source substance WS405777)

In all toxicological tests performed according to Annexes VII and VIII of the REACH Regulation with the read-across source substance WS405777 no adverse effects were observed up to the highest doses required to be tested according to the relevant guidelines.

The ECHA “Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance, 2014” document provides guidance, which physico-chemical properties commonly determine dermal, oral, and inhalatory absorption of substances.

Bioavailability of WS406663 in general is expected to be very limited, because of the relatively high molecular weight, very low water solubility and high lipohilicity of the substance. Accordingly, systemic availability of WS406663 after topical administration is expected to be very limited. Also systemic availability of WS406663 after oral administration is expected to be very limited. In toxicity studies with single or repeated oral exposure to the read-across source substance WS405777 no effects were observed. Availability of WS406663 under a vapour state is unlikely, because of its low vapour pressure.

Based on the available data on WS406663 and the read-across source substance WS405777 the bioacumulation potential of WS406663 cannot be judged. However, based on the physical-chemical properties systemic bioavailability of WS406663 via dermal, oral and inhalation exposure is expected to be very low. Also the bioaccumulation potential is expected to be very low based on the relatively high molecular weight and the very high octanol/water partition coefficient of the main constituent and the impurity.

Conclusion

While toxicokinetic data is not available on WS406663, based on the properties of the substance and based on the favourable toxicological testing results obtained with the read-across source substance WS405777 the target substance WS406663 is expected to be hardly bioavailable. Bioaccumulation is not expected. Further information on distribution, metabolism or excretion is not available.