2-propylheptyl methacrylate

Endpoint summary

Description of key information

Short description of key information on bioaccumulation potential result: 
As indicated in a dermal absorption study, The esters of adjacent molecular size to Propylheptyl methacrylate, Ethylhexyl methacrylate and Dodecyl methacrylate are  metabolised during penetration of the skin and are not expected to enter the circulation as the parent ester.
Gastro intestinal-, respiratory- and dermal absorption to a major extent are not expected due to physico chemical properties and in vitro dermal absorption studies,  where methacrylate esters of molecular weight equal to or greater than butyl methacrylate were not detected in the receptor fluid and are not expected to enter the circulation as the parent ester.
Short description of key information on absorption rate: 
Extrapolated from Ethylhexyl methacrylate and Dodecyl methacrylate data, Propylheptyll methacrylate appears to be absorbed through rat skin and epidermis to a low extent, 0.26 – 0.6 % in 24 hrs. It is fully metabolized to methacrylic acid during the passage (first-pass effect). As indicated by a PB-PK model used in this study, human skin is 14 times less permeable to  methacrylate esters than rat skin.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - dermal (%):

0.6

Additional information

Experiments on the C8 ester Ethylhexyl methacrylate and the C12 ester Dodecyl methacrylate (Lauryl methacrylate) with rat skin and human epidermis demonstrate that the methacrylate esters of a molecular size adjacently to the C10 ester in principle can be dermally absorbed (0.26 – 0.6 % over 24 hrs).

 

As a tendency confirmed with experiments on esters up to a chain length of C8, absorption decreases with increasing ester chain length. Due to the slow diffusion and the metabolic competency of the skin, the ester undergoes complete hydrolysis to methacrylic acid and the long-chain alkyl alcohol. In the organism, the acid is further metabolised via the valine pathway of the citric acid cycle the alcohol may be further metabolised by the two standard metabolic pathways for fatty alcohols.

Absortion by inhalation can be almost excluded due to the low vapour pressure of the esters.

GI absorption is not a favoured route of absorption as well. Only few amounts of the esters may be absorbed by micellular solubilisation.

Discussion on bioaccumulation potential result:

In principle, GI-, respiratory- and dermal absorption to a major extent is not expected due to physico chemical properties ( low water solubility:, molecular weight: 226 g/mol)

Metabolism of will start with hydrolysation resulting in methacrylic acid and propylheptanol. While the acid is further metabolised via the valine pathway of the citric acid cycle the alcohol may be further metabolised by the two standard metabolic pathways for fatty alcohols. Alkyl esters of methacrylic acid up to C8 (2-ethylhexyl methacrylate) showed rapid metabolism with half lives in rat blood of less than 30 min.

Experimental studies of the toxicokinetics of Ethylhexyl methacrylate and Dodecyl methacrylate are only available for dermal absorption. In this in vitro studies, the esters were not detected in the receptor fluid, only the metabolite methacrylic acid. Therefore, in analogy 2 -Propylheptyl methacrylate it is not expected to enter the circulation as the parent ester.

Discussion on absorption rate:

Extrapolated from Ethylhexyl methacrylate and Dodecyl methacrylate data, Isodecyl methacrylate appears to be absorbed through rat skin and epidermis to a low extent, 0.26 – 0.6 % in 24 hrs. It is fully metabolized to methacrylic acid during the passage (first-pass effect). As indicated by a PB-PK model used in this study, human skin is 14 times less permeable to methacrylate esters than rat skin.