Absence of systemic in vivo genotoxicity after dermal exposure to ethyl acrylate and tripropylene glycol diacrylate in Tg.AC (v-Ha-ras) mice

Abstract

Acrylates may be polymerized to stable surface coatings (paints, lacquers, inks, etc.) by alkylation via the Michaelis-type addition reaction. Thus, acrylates have an inherent potential as electrophiles to be genotoxic, limited in their biological activity by their physicochemical properties. To evaluate their systemic genotoxicity, ethyl acrylate (EA), tripropylene glycol diacrylate (TPGDA), or Lacquer A, an ultraviolet radiation curable lacquer containing TPGDA as the active ingredient, were applied dermally to Tg.AC mice (3 times a week for 20 weeks). Peripheral blood leukocytes were evaluated for DNA damage (single-strand breaks, alkali labile sites, DNA crosslinking) at weeks 4, 8, 12, 16, and 20 by using the alkaline (pH: 13) single cell gel (SCG) assay. Peripheral blood polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) were evaluated for the presence of micronuclei at week 20. The extent of DNA migration in leukocytes and the frequency of micronucleated erythrocytes was not significantly altered by treatment with TPGDA when administered alone or in Lacquer A or with EA, at doses that induced cell proliferation in keratinocytes. The absence of genotoxicity in these two cell populations suggests that these acrylates are not genotoxic or that they are not absorbed systemically when applied dermally. However, a significant, dose-dependent increase in the percentage of PCE relative to the vehicle control was present in mice treated with TPGDA, while a dose-dependent, but nonsignificant, increase in the percentage of PCE was observed in mice treated with Lacquer A. This observed increase in the rate of erythropoiesis may reflect bone marrow/blood toxicity, a homeostatic mechanism in response to the treatment-induced tumor burden, and/or a hematopoietic response to epidermal keratinocyte cytokines induced by tissue injury.