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Toxicological information

Dermal absorption

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Administrative data

Endpoint:
dermal absorption
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented report, which has partly been reported in Betts et al., 2006

Data source

Referenceopen allclose all

Title:
Unnamed
Year:
1993
Title:
Unnamed
Year:
2006

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The absorption of neat methyl methacrylate through human epidermis in vitro was examined under occluded and unoccluded conditions.
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Radiolabelling:
yes

Test animals

Species:
human
Strain:
other: not applicable
Sex:
not specified
Details on test animals and environmental conditions:
Human abdominal whole skin (dermis plus epidermis) was obtained post-mortem from subjects of various ages.

Administration / exposure

Type of coverage:
other: occlusive or open
Vehicle:
unchanged (no vehicle)
Duration of exposure:
10 h
Doses:
9430 mg/cm2
No. of animals per group:
3 samples per treatment
Control animals:
no

Results and discussion

Percutaneous absorption
Dose:
9430 mg neat MMA/cm2
Parameter:
percentage
Absorption:
2.4 %
Remarks on result:
other: 1 h
Remarks:
occlusive conditions; unocclussive conditions: 0.48%

Any other information on results incl. tables

Significant levels of MMA were detected in the receptor fluid within 10 min of treatment in the presence or absence of occlusion. Under both conditions, maximal rates of absorption were recorded within the first hour of exposure, with higher values recorded following application under occlusion compared with open exposure (274 compared with 107 mg/cm2/hr). The absorption rate for open application of MMA decreased very rapidly and profoundly thereafter, with an average rate of 3.5 mg/cm2/hr recorded over the 10-hr period. A less marked decrease in absorption rate was recorded over the same time period for occluded epidermis (152 mg/cm2/hr). The differences in absorption rate were paralleled by differences in the mean percentage dose of MMA absorbed. Within 1 hr of treatment, considerably more MMA had been absorbed from occluded, compared with unoccluded, tissue (2.41% and 0.48%, respectively). Given that the rate of absorption from unoccluded epidermis decreased very markedly 1 hr after application, it is not surprising that the total percentage of the dose absorbed after 10 hr had risen to only 0.56%. In contrast, after 10 hr of occlusion, 15% of the total applied dose of MMA was detected in the receptor fluid. Given the volatility of this material, the marked reduction in absorption of MMA under unoccluded conditions is likely to be a result of the loss, by evaporation, of MMA from the epidermal surface.

Applicant's summary and conclusion

Conclusions:
MMA absorption rate through occluded human epidermis was 152 mg/cm²/hr.The absorption rate though unoccluded (open) application decreased very rapidly after 10 minutes to an average rate of 3.5 mg/cm²/hr . The differences in absorption rate were paralleled by differences in the mean percentage dose of MMA absorbed and most likely reflected evaporation.