Reaction products of 2,2'-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane with maleic anhydride and methacrylic acid

Endpoint summary

Description of key information

The dermal absorption of Modified Small Vinyl Ester was calculated using results for constituents from QSAR estimations with US-EPA Dermwin v2.01.  The constituents bisGMA, monomaleic-bisGMA, oligomeric reaction products, epoxy-monoGMA, and dihydroxy-monoGMA all are calculated to have low to negligible individual dermal absorption rates - below 0.2%. The highest value is  for dihydroxy-bisGMA, being 0.19% . 
The residual methacrylic acid (<0.5%) is rapidly absorbed through the skin. The relative dermally absorbed doses are calculated to 18, 95 and 100%, respectively at contact times of 1-hour, 8-hours and 24-hours. The calculated systemic dose at 24-hours contact to both hands and forearms (1980 cm2) is 45 mg/kg bw, which approximately 12 times lower than the lowest NOAEL found in mice in repeated exposure toxicity studies (ca. 550 mg/kg bw/d).
Epoxy-monoGMA, dihydroxy-monoGMA and the residual methacrylic acid account for only a maximum of 5%, 5% and 1% of the composition, respectively. Their contribution to the overall dermal absorption is evaluated to be insignificant due their low concentrations. Thus, the overall dermal absorptions for Modified Small Vinyl Ester based on constituents bisGMA, monomaleic-bisGMA, and the oligomeric part, accounting for approximately 98% of Modified Small Vinyl Ester, are less than 3*10-5%, 8*10-5%, and 1.4*10-4%, for 1-hour, 8-hour, and 24-hour dermal contact times, respectively. The oligomeric part is evaluated not to be absorbed through the skin. Thus, the overall relative dermal absorption for Modified Small Vinyl Ester is less the 0.00014%.
It is evaluated that dermal absorption of Modified Small Vinyl Ester is negligible and consequently that Modified Small Vinyl Ester is not systemically bioavailable by skin contact

Key value for chemical safety assessment

Absorption rate - dermal (%):

0

Additional information

The dermal absorption of Modified Small Vinyl Ester was calculated using results for the main compounds from QSAR estimations with US-EPA Dermwin v2.01. The relative absorption rates for Modified Small Vinyl Ester were calculated for three exposure times (1 h, 8 h and 24 h). For the constituents bisGMA, monomaleic-bisGMA, epoxy-monoGMA, and dihydroxy-monoGMA, the individual relative dermal absorption rates for calculated on the basis of QSAR estimations to be lower than 0.2% at 24 h contact time for dihydroxy-monoGMA and even lower for bisGMA and epoxy-monoGMA, and for the shorter contact times. The oligomeric part is evaluated not to be absorbed through the skin.

Only for the residual methacrylic acid (<0.5%) the relative absorption rate is not negligible; which was calculated to 18, 95 and 100%, respectively for the three exposure times. However, it should be noted that for contact with both hands and forearms (11% of the body surface of a human weighing 70 kg bw) the dermally absorbed doses of methacrylic acid using the US-EPA model are estimated to 3, 16 and 45 mg/kg bw, respectively for the contact periods of 1-hour, 8-hours and 24-hours. The latter dose is approximately 12 times lower than the lowest NOAEL for methacrylic acid found in mice in repeated exposure toxicity studies (ca. 550 mg/kg bw/d).

Epoxy-monoGMA, dihydroxy-monoGMA and the residual methacrylic acid account for only a maximum of 5%, 5% and 1% of the composition, respectively. Their contribution to the overall dermal absorption is evaluated to be insignificant due their low concentrations. Thus, the overall dermal absorptions for Modified Small Vinyl Ester based on constituents bisGMA, monomaleic-bisGMA and the oligomeric part, accounting for approximately 98% of the substance, are less than 3*10-5%, 8*10-5%, and 1.4*10-4%, for 1-hour, 8-hour, and 24-hour dermal contact times, respectively. The oligomeric part is evaluated not to be absorbed through the skin. Thus, the overall relative dermal absorption for Modified Small Vinyl Ester is less the 0.00014%.

It is evaluated that dermal absorption of Modified Small Vinyl Ester is negligible and consequently that Modified Small Vinyl Ester is not systemically bioavailable by skin contact.