Ethylhexyl methoxycinnamate (EHMC) is a widely used UV filter present in a large number of personal care products (PCPs). Under normal conditions, EHMC occurs in a mixture of two isomers: trans-EHMC a ...

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Ethylhexyl methoxycinnamate (EHMC) is a widely used UV filter present in a large number of personal care products (PCPs). Under normal conditions, EHMC occurs in a mixture of two isomers: trans-EHMC and cis-EHMC in a ratio of 99:1. When exposed to sunlight, the trans isomer is transformed to the less stable cis isomer and the efficiency of the UV filter is reduced. To date, the toxicological effects of the cis-EHMC isomer remain largely unknown. We developed a completely new method for preparing cis-EHMC. An EHMC technical mixture was irradiated using a UV lamp and 98% pure cis-EHMC was isolated from the irradiated solution using column chromatography. The genotoxic effects of the isolated cis-EHMC isomer and the nonirradiated trans-EHMC were subsequently measured using two bioassays (SOS chromotest and UmuC test). In the case of trans-EHMC, significant genotoxicity was observed using both bioassays at the highest concentrations (0.5 - 4 mg mL-1 ). In the case of cis-EHMC, significant genotoxicity was only detected using the UmuC test at concentrations of 0.25 - 1 mg mL-1 . Based on these results, the NOEC was calculated for both cis- and trans-EHMC, 0.038 and 0.064 mg mL-1 , respectively. Risk assessment of dermal, oral and inhalation exposure to PCPs containing EHMC was carried out for a female population using probabilistic simulation and by using Quantitative in vitro to in vivo extrapolation (QIVIVE). The risk of cis-EHMC was found to be ∼1.7 times greater than trans-EHMC. In the case of cis-EHMC, a hazard index of 1 was exceeded in the 92nd percentile. Based on the observed differences between the isomers, EHMC application in PCPs requires detailed reassessment. Further exploration of the toxicological effects and properties of cis-EHMC is needed in order to correctly predict risks posed to humans and the environment (1)

Ultraviolet (UV) filters are widely used in the formulation of personal care products (PCPs) to prevent damage to the skin, lips, and hair caused by excessive UV radiation. Therefore, large amounts of these substances are released daily into the aquatic environment through either recreational activities or the release of domestic sewage. The concern regarding the presence of such substances in the environment and the exposure of aquatic organisms is based on their potential for bioaccumulation and their potential as endocrine disruptors. Although there are several reports regarding the occurrence and fate of UV filters in the aquatic environment, these compounds are still overlooked in tropical areas. In this study, we investigated the occurrence of the organic UV filters benzophenone-3 (BP-3), ethylhexyl salicylate (ES), ethylhexyl methoxycinnamate (EHMC), and octocrylene (OC) in six water treatment plants in various cities in Southeast Brazil over a period of 6 months to 1 year. All of the UV filters studied were detected at some time during the sampling period; however, only EHMC and BP-3 were found in quantifiable concentrations, ranging from 55 to 101 and 18 to 115 ng L(-1), respectively. Seasonal variation of BP-3 was most clearly noticed in the water treatment plant in Araraquara, São Paulo, where sampling was performed for 12 months. BP-3 was not quantifiable in winter but was quantifiable in summer. The levels of BP-3 were in the same range in raw, treated and chlorinated water, indicating that the compound was not removed by the water treatment process (2).

Regarding safety, this component did not show alarm thresholds (3).

Other studies

Fate of UV filter Ethylhexyl methoxycinnamate in rat model and human urine: Metabolism, exposure and demographic associations.
Huang Y, Law JC, Zhao Y, Shi H, Zhang Y, Leung KS.
Sci Total Environ. 2019 Jun 4;686:729-736. doi: 10.1016/j.scitotenv.2019.05.440.

Estimation of physicochemical properties of 2-ethylhexyl-4-methoxycinnamate (EHMC) degradation products and their toxicological evaluation.
Gackowska A, Studziński W, Kudlek E, Dudziak M, Gaca J.
Environ Sci Pollut Res Int. 2018 Jun;25(16):16037-16049. doi: 10.1007/s11356-018-1796-6.

References_______________________________________________________

(1) New probabilistic risk assessment of ethylhexyl methoxycinnamate: Comparing the genotoxic effects of trans- and cis-EHMC.
Nečasová A, Bányiová K, Literák J, Čupr P.
Environ Toxicol. 2017 Feb;32(2):569-580. doi: 10.1002/tox.22260.

(2) The occurrence of UV filters in natural and drinking water in São Paulo State (Brazil).
da Silva CP, Emídio ES, de Marchi MR.
Environ Sci Pollut Res Int. 2015 Dec;22(24):19706-15. doi: 10.1007/s11356-015-5174-3.

(3) Skin absorption and human exposure estimation of three widely discussed UV filters in sunscreens--In vitro study mimicking real-life consumer habits.
Klimová Z, Hojerová J, Beránková M.
Food Chem Toxicol. 2015 Sep;83:237-50. doi: 10.1016/j.fct.2015.06.025.

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