ε-Caprolactone, oligomeric reaction products with 2,2'-oxydiethanol

Endpoint summary

Description of key information

No specific toxicokinetic data are available; a theoretical assessment of the toxicokinetic properties of ε-Caprolactone, oligomer reaction products with 2,2’-oxydiethanol is presented.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

50

Absorption rate - inhalation (%):

100

Additional information

ε-Caprolactone, oligomer reaction products with 2,2’-oxydiethanol is a UVCB substance and has a number of structurally similar components of variable molecular weight. The major component of ε-Caprolactone, oligomer reaction products with 2,2’-oxydiethanol is the oligomer of diethylene glycol (DEG) with two molecules of ε-caprolactone (ECL); i.e. DEG-2ECL. The other components are oligomers in the range DEG-1ECL to DEG-10ECL.

Absorption

ε-Caprolactone, oligomer reaction products with 2,2’-oxydiethanol is partly soluble in water and has a Log Pow (experimental) of 1.8. Molecular weights of the oligomers range from 218 (DEG-1ECL) to 1246 (DEG-10ECL); molecular weights of the DEG-1ECL, DEG-2ECL and DEG-3ECL oligomers are below 500, whereas molecular weights of the DEG-4ECL and higher oligomers are above 500. The physicochemical properties of the substance therefore indicate that oral absorption may be limited. An absence of clinical signs at the limit dose of 2000 mg/kg bw in the acute oral toxicity study does not provide any evidence for oral absorption. OECD Toolbox indicates the potential for hydrolysis of the substance under the pH conditions encountered in the gastrointestinal tract; therefore systemic exposure to the hydrolysis products may occur.

The molecular weight and Log Pow values of the substance indicate that dermal absorption is likely to be limited.

There are no data relating to inhalation absorption; however the potential for inhalation exposure is very limited. In the absence of any data, default assumptions are made regarding the relative extent of oral, dermal and inhalation exposure.

Distribution

There is no evidence of systemic distribution from the acute oral toxicity study and the physicochemical properties of the substance indicate that oral bioavailability may be limited.

Metabolism

OECD QSAR Toolbox predicts extensive hepatic metabolism of the oligomers via hydrolysis of the ester bond and oxidation of the hydroxyl groups. Dermal metabolism is also predicted, but is likely to occur to a smaller extent. 

Excretion

The extent of oral bioavailability is unknown, but may be low. Based on the predicted metabolism of the substance, the metabolites are predicted to be excreted rapidly in the urine.

Bioaccumulation

Based on the likely low bioavailability and predicted rapid metabolism, the potential for bioaccumulation is predicted to be low.