Article 2 chromosome damage controlled study 2 human 2 1,3 butadiene 1 1,3-butadiene 1 5 methyltetrahydrofolic acid 1 5,10 methylenetetrahydrofolate reductase (FADH2) 1 China 1 Chromosomal damage 1 DNA damage 1 DNA methylation 1 DNA methylation age 1 DT40 cell line 1 Folate metabolism 1 MTHFR 1 Polymorphism 1 Western blotting 1 adult 1 animal cell 1 butadiene diepoxide 1 cell culture 1 cell death 1 cell growth 1 cell nucleus 1 cell viability 1 chromosome aberration 1 chromosome breakage 1 clinical article 1 female 1