title: Associations of urinary 5-methyl-2'-deoxycytidine and 5-hydroxymethyl-2'-deoxycytidine with phthalate exposure and semen quality in 562 Chinese adult men.
abstract: 5-methyl-2'-deoxycytidine (5mdC) and 5-hydroxymethyl-2'-deoxycytidine (5hmdC), products of DNA methylation and hydroxymethylation processes, have been detected previously in human urine, but their associations with environmental chemicals or healthy outcomes are unclear. The present investigation explored the associations between urinary 5mdC and 5hmdC with phthalate exposure and semen quality. We assessed semen parameters including sperm concentration, motility, and morphology, before measuring urinary 5mdC, 5hmdC and 13 phthalate metabolites among 562 subfertile men from Nanjing, China. Urinary 5mdC and 5hmdC were positively associated with the levels of low molecular weight phthalate metabolites (Low-MWP), high molecular weight phthalate metabolites (High-MWP), and the sum of all phthalate metabolites (ΣPAEs), respectively. Urinary 5mdC was associated with below-reference sperm concentration (odds ratios for increasing quartiles=1.0, 2.2, 3.0, 2.0; p for trend =0.02), sperm motility (1.0, 1.1, 1.9, 1.3; p for trend =0.05), and sperm morphology (1.0, 1.4, 2.3, 1.5; p for trend =0.05). Sperm concentration was associated with the highest quartile of urinary 5hmdC [odds ratio=1.9 (95% CI: 1.1, 3.6)]. Our findings showed significant associations between urinary 5mdC and 5hmdC with phthalate metabolites and semen parameters, which suggested urinary 5mdC and 5hmdC may be promising biomarkers in future epidemiological studies.
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China.
authors.forename: Yitao
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Reproductive Medical Center, Nanjing Jinling Hospital, Nanjing University, School of Medicine, Nanjing 210002, Jiangsu, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Jing
authors.affiliation: Man-Technology-Environment Research Centre (MTM), School of Science and Technology, Örebro University, SE-70182 Örebro, Sweden.
authors.forename: Leo W Y
authors.initials: LWY
authors.lastname: Yeung
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China.
authors.forename: Nan
authors.initials: N
authors.lastname: Sheng
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Reproductive Medical Center, Nanjing Jinling Hospital, Nanjing University, School of Medicine, Nanjing 210002, Jiangsu, PR China. Electronic address: yaobing@nju.edu.cn.
authors.forename: Bing
authors.initials: B
authors.lastname: Yao
authors.affiliation: Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, PR China. Electronic address: daijy@ioz.ac.cn.
authors.forename: Jiayin
authors.initials: J
authors.lastname: Dai
mesh_terms: D000328:Adult; D002681:China / Q000453:epidemiology; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000652:urine; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D010795:Phthalic Acids / Q000652:urine*; D012661:Semen; D055101:Semen Analysis / Q000706:statistics & numerical data*; D013076:Sperm Count; D013081:Sperm Motility
chemical_list: C540838:5-hydroxymethyl-2'-deoxycytidine; D010795:Phthalic Acids; D003841:Deoxycytidine; C032279:phthalic acid; C016569:5-methyldeoxycytidine
keywords: 5hmdC; 5mdC; DNA methylation; Hydroxymethylation; Phthalate metabolites; Semen quality