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EC number: 201-204-4
CAS number: 79-41-4
The fastest rate
of absorption of MAA through rat epidermal membrane was recorded as
and this occurred between 0.5 and 4 hrs following application of the
chemical. After 24 h, 93 % of the applied dose appeared in the receptor
chamber indicating a practically complete absorption through rat
epidermis within 24 h.
are only available for methyl-, n-butyl- and 2-ethylhexyl methacrylate.
With the model developed with these experimental data the peak rate of
absorption of methacrylic acid through human skin was estimated being
812 μg*cm-2*hr-1. The rates of absorption through human epidermis are
considerably slower than those measured for MAA through rat epidermis.
Whole rat skin
methacrylates whose rate of absorption through whole rat skin was
investigated, methacrylic acid is the most rapidly absorbed chemical -
faster than all esters, triggered by the small molecular volume. The
peak rate of appearance of MAA occurred between 5 and 8 hrs and was
calculated as 4584 μg cm-2 hr-1. While the esters are partly or
completely hydrolysed by carboxylesterases present in the viable tissue,
MAA passes the tissue almost quantitatively. Of the original dose
applied to the whole skin, 70% appeared in the receptor chamber within
The results of the whole-skin penetration studies and the model predictions for
other methacrylates are presented in the table.
Summary of the peak
rates of absorption of MAA & alkyl-methacrylate esters through whole rat
and human skin
Rat whole rat
Human whole skin
Peak rate of appearance (µg*cm-2*h-1)+- SEM
% age of
over x hours
The values in normal
type were obtained experimentally, whilst those in italics are predicted
** Values are
predicted rates of appearance of total chemical including parent ester
The in vivo and in vitro investigations as well as the PBPK models
developed from the data showed that methacrylic acid and the lower
alkyl-methacrylate esters are rapidly absorbed and the esters are
hydrolyzed at exceptionally high rates to methacrylic acid by high
capacity, ubiquitous carboxylesterases. Further, the removal of the
hydrolysis product, methacrylic acid, also is very rapid (minutes).
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