Sunscreens (UV filters) can be found in cosmetics and in other personal care products, but also in food packaging materials, pharmaceuticals, plastics, textiles, and vehicle maintenance products to prevent the photodegradation of polymers and pigments. Organic UV filters are often used together with inorganic filters to increase the overall efficacy. 1,2 HMS (3,3,5-trimethylcyclohexylsalicylate; Figure 1) is an organic UV filter that absorbs UVB radiation at wavelengths from 290 to 320 nm, that can be found in many cosmetics. 3 The presence of alkyl-substituted cyclohexane ring in UV filters can considerably alter the lipophilicity of the whole molecule which might possibly have a significant effect on metabolism. 4 Studies have shown that HMS passes by systemic circulation after topical application of a gel formulation in rats. 3 Hence, HMS has been shown to cause hormonal dysfunction when absorbed in in vivo and in vitro studies. 5-7 HMS accumulates in aquatic biota and humans through the food chain 1,8 ; therefore, it is important to consider the effects on health and know its mechanisms of action.

Pyrethroid pesticides are frequently used for household insect control of insects and in agriculture and livestock. Flumethrin is a pyrethroid that is used against ectoparasites in many animals. The goal of this study was to evaluate the cytotoxic, apoptotic, genotoxic, and estrogenic effects of flumethrin on the mammalian breast cancer cell line (MCF-7). Compared with control groups, a dose-dependent decrease was observed in cell viability at concentrations of 100 µM and higher. The cytotoxic and apoptotic effects detected by LDH assay and AO/EtBr staining increased significantly at a concentration of 1000 µM. The expression of BCL2, which is an anti-apoptotic gene, significantly decreased, whereas BAX, TP53, and P21 expression significantly increased. The results of a comet assay indicated that flumethrin significantly changed tail length, tail % DNA, tail moment, and Olive tail moment in concentrations above 1 and 10 µM. In addition, a 0.1 µM concentration of flumethrin affected ERα receptor mediated cell proliferation and increased transcription of estrogen-responsive pS2 (TFF1) and progesterone receptor (PGR) genes. As a result, flumethrin-induced apoptosis and cytotoxicity at a high concentration, while induced genotoxicity even at lower concentrations. Flumethrin is an endocrine disrupting insecticide with estrogenic effects at very low concentrations.