title: Association of cadmium and arsenic exposure with salivary telomere length in adolescents in Terai, Nepal.
abstract: Cadmium and arsenic are ubiquitous metals commonly found in the environment which can harm human health. A growing body of research shows telomere length as a potential biomarker of future disease risk. Few studies have examined the effects of metals on telomere length and none have focused on adolescents.
  
  
  
  In this study, the impact of cadmium and arsenic on salivary telomere length was studied in adolescents in Terai, Nepal.
  
  
  
  Adolescents aged 12-16 years old (n=351)were recruited where questionnaire interviews and both saliva and urine collection took place. Telomere length was determined by quantitative polymerase chain reaction using DNA extracted from saliva. Urinary cadmium and arsenic concentration were measured by inductively coupled plasma mass spectrometry. Multivariable linear regression was used to examine associations between urinary metals and salivary telomere length.
  
  
  
  The geometric means and standard deviations of cadmium and arsenic were 0.33±0.33μg/g creatinine and 196.0±301.1μg/g creatinine, respectively. Urinary cadmium concentration was negatively associated with salivary telomere length after adjustment for confounders (β=-0.24, 95% CI -0.42,-0.07). Arsenic showed positive associations with telomere length but did not reach statistical significance.
  
  
  
  This is the first study to demonstrate that cadmium may shorten adolescent telomeres, even at exposure levels that may be considered low. These results agree with prior experimental and adult epidemiological studies, and also help identify the mechanism of DNA damage by cadmium. This study expanded current evidence on the harmful effects of cadmium exposure on telomere length even to adolescents.
authors.affiliation: Department of Human Ecology, School of International Health, Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-0033, Japan. Electronic address: tokif@humeco.m.u-tokyo.ac.jp.
authors.forename: Toki
authors.initials: T
authors.lastname: Fillman
authors.affiliation: Department of Human Ecology, School of International Health, Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-0033, Japan. Electronic address: hana-shimizu@umin.ac.jp.
authors.forename: Hana
authors.initials: H
authors.lastname: Shimizu-Furusawa
authors.affiliation: Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan. Electronic address: chrisng-tky@umin.ac.jp.
authors.forename: Chris Fook Sheng
authors.initials: CFS
authors.lastname: Ng
authors.affiliation: Basu Laboratory, CINE Building, Macdonald Campus, Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada. Electronic address: rp.parajuli@mcgill.ca.
authors.forename: Rajendra Prasad
authors.initials: RP
authors.lastname: Parajuli
authors.affiliation: Department of Human Ecology, School of International Health, Graduate School of Medicine, University of Tokyo, 7-3-1, Hongo, Bunkyo-Ku, Tokyo, 113-0033, Japan. Electronic address: chiho@humeco.m.u-tokyo.ac.jp.
authors.forename: Chiho
authors.initials: C
authors.lastname: Watanabe
mesh_terms: D000293:Adolescent; D001151:Arsenic / Q000652:urine*; D002104:Cadmium / Q000652:urine*; D002648:Child; D004781:Environmental Exposure; D005260:Female; D060587:Groundwater / Q000032:analysis; D006801:Humans; D008297:Male; D009390:Nepal; D012463:Saliva / Q000166:cytology; D016615:Telomere / Q000187:drug effects* / Q000502:physiology; D014874:Water Pollutants, Chemical / Q000633:toxicity* / Q000652:urine*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium; D001151:Arsenic
keywords: Adolescents; Arsenic; Cadmium; Nepal; Salivary telomere length