title: Phototoxicity and chronic toxicity of methyl paraben and 1,2-hexanediol in Daphnia magna.
abstract: Parabens are used as antimicrobial preservatives in consumer products. Exposure to methylparaben (MP) has been associated with adverse health outcomes, therefore, an alternative compound, 1,2-hexanediol (1,2-H), has been applied for cosmetics. In the present study, the phototoxicity of MP and 1,2-H, as well as the toxic effect caused by chronic exposure, were investigated using Daphnia magna. The 48 h acute toxicity tests with D. magna were conducted under indoor or ultraviolet (UV) light irradiation conditions, i.e., exposure to 4 h/d sunlight. Changes in the transcription of genes related to oxidative stress were determined in D. magna juveniles, to investigate the underlying mechanism of phototoxicity. The 21 d chronic toxicity tests of MP and 1,2-H were performed under indoor light irradiation. Exposure to MP under environmental level of UV light was more detrimental to D. magna. Transcripts of catalase and glutathione-S-transferase genes in D. magna was significantly increased by co-exposure to MP and UV light. After 21 d of chronic exposure to MP and 1,2-H, the reproduction no-observed effect concentrations for D. magna were 1 and >10 mg/L, respectively. The present study showed that exposure to UV could magnify the toxicity of MP on daphnids. Although acute and chronic toxicities of 1,2-H were generally lower than those of MP, its effects on other aquatic organisms should not be ignored. Further studies are needed to identify other mechanisms of MP phototoxicity.
authors.affiliation: Department of Environmental Health, Graduate School of Yongin University, Yongin, 17092, Republic of Korea.
authors.forename: Jiyun
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Health, Environment and Safety, Eulji University, Seongnam, 13135, Republic of Korea.
authors.forename: Nayeon
authors.initials: N
authors.lastname: Park
authors.affiliation: Department of Health, Environment and Safety, Eulji University, Seongnam, 13135, Republic of Korea.
authors.forename: Younglim
authors.initials: Y
authors.lastname: Kho
authors.affiliation: Graduate School of Public Health, Seoul National University, Seoul, 08826, Republic of Korea.
authors.forename: Kiyoung
authors.initials: K
authors.lastname: Lee
authors.affiliation: Department of Environmental Health, Graduate School of Yongin University, Yongin, 17092, Republic of Korea. kyungheeji@yongin.ac.kr.
authors.forename: Kyunghee
authors.identifier: http://orcid.org/0000-0001-8123-7445
authors.initials: K
authors.lastname: Ji
mesh_terms: D000818:Animals; D003358:Cosmetics; D003621:Daphnia / Q000187:drug effects*; D006018:Glycols; D006586:Hexanes; D018384:Oxidative Stress; D010226:Parabens / Q000633:toxicity*; D036401:Toxicity Tests, Chronic; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D003358:Cosmetics; D006018:Glycols; D006586:Hexanes; D010226:Parabens; D014874:Water Pollutants, Chemical; C015358:methylparaben; C119102:1,2-hexanediol
keywords: 1,2-hexanediol; Daphnia magna; Methyl paraben; Phototoxicity; Ultraviolet light