Report Date: October 1994
The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program. The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by NTP in March 2009. The findings and conclusions for this study should not be construed to represent the views of the NTP or the U.S. Government.
Introduction: Acrylate esters have a widespread use in the manufacturing of numerous industrial and consumer products. They are most commonly used to produce polymers and resins used in such products as latex paint, fabric finishes, floor polishes, specialty plastics and dirt release agents. Ethyl Acrylate was selected for evaluation as a sensitizing agent for contact hypersensitivity in mice.
Design: Ethyl Acrylate was obtained from Aldrich Chemical Company as a clear liquid (99%, Lot #14707D2). Dilutions were made in acetone which served as the vehicle. Three assays were used in this assesment, a primary irritancy study, to screen for toxicity and determine the Minimal Irritating Concentration and the Maximal Non-Irritating Concentration and two assays, the Mouse Ear Swelling Test and the local lymph node assay, to test the dermal sensitizing potential of EAC.
For irritancy studies, nine mice were used to test four concentrations of test article in vehicle plus vehicle and untreated controls. Each mouse received a different treatment on each of its ears, one on the right ear and one on the left ear. The treatment combinations may be two different concentrations of test material, one concentration of test material and the vehicle, one concentration of the test material and no treatment, or the vehicle and no treatment. Each concentration of test material and the vehicle was tested three times. Animals were dosed on 4 consecutive days and checked daily for signs of morbidity. The lowest concentration of test article to demonstrate significant irritation when compared to the vehicle controls, as determined by calculating the percent ear swelling at 24 hours post last treatment, was considered the Minimal Irritating Concentration. The highest concentration not to demonstrate a significant irritation over the vehicle controls was considered the Maximal Non-Irritating Concentration. Doses chosen for the hypersensitivity assays were based on the MIC and MNC.
Animals were dosed on the back for 3 consecutive days, rested for 4 days and then challenged on the right ear. Pre, 24 and 48 hours post treatment ear measurements were taken and used to calculate the percent ear swelling. Measurements from animals dosed with varying concentrations of test article were compared to the EAC background control group for significance.
After 3 consecutive days of dosing, animals were rested for 1 day and then injected with 3H-thymidine; I5 hours later animals were sacrificed, lymph nodes dissected out and lymph node counts made on a Beta counter. Test groups were compared to vehicle controls for significance.
Results: There were no treatment-related effects on survival or body weights. Studies using increasing concentrations from 0.3% to 30% EAC did not reveal a biologically significant irritancy response. No statistically significant allergic contact hypersensitivity response was demonstrated by the MEST in mice sensitized with 10%, 20%, or 30% EAC either 24 or 48 hours following challenge I. The positive control group, sensitizing concentration of 0.25% DNFB and challenge concentration of 0.5% DNFB, produced a statistically significant contact hypersensitivity response as compared to the 0.5% DNFB challenge only group. The 0.5% DNFB challenge only group showed a significant response when compared to the vehicle-treated group. None of the concentrations of EAC tested, 10%, 20%, or 30%, caused a significant response as compared to the vehicle-treated group in the LLNA. The positive control for the LLNA, 0.25% DNFB, did show a significant increase as compared to the vehicle control.
Conclusion: A significant allergic contact hypersensitivity response was not demonstrated in female B6C3FI mice to ethyl acrylate.