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Description of key information

Short description of key information on bioaccumulation potential result: 
No ADME studies are available for propylene glycol n-propyl ether (PnP) as such. Therefore, the toxicokinetics assessment is based on the available data from repeated dose toxicity studies and on data for the structurally related propylene glycol n-butyl ether (PnB).

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
100
Absorption rate - dermal (%):
30
Absorption rate - inhalation (%):
100

Additional information

Both oral and inhalation absorption rates for PnP were set at 100%. For detailed information, refer to read-across justification document for P-series glycol ethers. Dermal absorption rate was based on PM and set at 30%.

No ADME studies are available for propylene glycol n-propyl ether (PnP) as such. The assessment is based on available data from repeated dose toxicity studies and on structurally related propylene glycol ethers. PnP is expected to be metabolised predominantly in the liver to propylene glycol and the propyl alcohol. These metabolites may be further metabolised to CO2 and water, with the latter ultimately being excreted in expired air. Alternatively, PnP (or the intermediate metabolite) may be conjugated in the liver with glucuronide, sulfate, or glutathione for excretion, predominantly in the urine.

Discussion on bioaccumulation potential result:

Metabolism of PnP takes place predominantly in the liver where mixed function oxidase cleaves the ether linkage, yielding propylene glycol and the alcohol. These two products may be further metabolised to CO2 and water, with the latter ultimately being excreted in expired air, or the parent or the metabolites can be conjugated in the liver with glucuronide, sulfate, or glutathione. Excretion takes place predominantly in the urine.

PnP is rapidly absorbed and distributed throughout the body when introduced by inhalation or oral exposure. Dermal absorption is somewhat slower but subsequent distribution also is rapid.

Overall, no bioaccumulation potential is expected for PnP and other glycol ethers.

As a class, the propylene glycol ethers are rapidly absorbed and distributed throughout the body when introduced by inhalation or oral exposure. Metabolism studies (by oral exposure) conducted with several PGEs support this conclusion. While not tested directly, absorption by inhalation exposure also would be expected to be rapid for PGEs aerosols that are in the respirable range. Rapid absorption, distribution, and elimination occurred within 48 hours for several PGEs. Most excretion for PGEs is via the urine and expired air. A small portion is excreted in the feces.

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