title: Urinary metals and heart rate variability: a cross-sectional study of urban adults in Wuhan, China.
abstract: BACKGROUND
  Epidemiological studies have suggested an association between external estimates of exposure to metals in air particles and altered heart rate variability (HRV). However, studies on the association between internal assessments of metals exposure and HRV are limited.
  
  
  OBJECTIVE
  The purpose of this study was to examine the potential association between urinary metals and HRV among residents of an urban community in Wuhan, China.
  
  
  METHODS
  We performed a cross-sectional analysis of 23 urinary metals and 5-min HRV indices (SDNN, standard deviation of normal-to-normal intervals; r-MSSD, root mean square of successive differences in adjacent normal-to-normal intervals; LF, low frequency; HF, high frequency; TP, total power) using baseline data on 2,004 adult residents of Wuhan.
  
  
  RESULTS
  After adjusting for other metals, creatinine, and other covariates, natural log-transformed urine titanium concentration was positively associated with all HRV indices (all p < 0.05). Moreover, we estimated negative associations between cadmium and r-MSSD, LF, HF, and TP; between lead and r-MSSD, HF, and TP; and between iron, copper, and arsenic and HF, SDNN, and LF, respectively, based on models adjusted for other metals, creatinine, and covariates (all p < 0.10). Several associations differed according to cardiovascular disease risk factors. For example, negative associations between cadmium and r-MSSD were stronger among participants ≤ 52 years of age (vs. > 52), current smokers (vs. nonsmokers), body mass index < 25 kg/m2 (vs. ≥ 25), and among those who were not hypertensive.
  
  
  CONCLUSIONS
  Urine concentrations of several metals were associated with HRV parameters in our cross-sectional study population. These findings need replication in other studies with adequate sample sizes.
authors.affiliation: Department of Occupational and Environmental Health, and Ministry of Education Key Lab for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Xiaosheng
authors.initials: X
authors.lastname: He
authors.forename: Mu
authors.initials: M
authors.lastname: Chen
authors.forename: Siyun
authors.initials: S
authors.lastname: Deng
authors.forename: Gaokun
authors.initials: G
authors.lastname: Qiu
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Li
authors.forename: Chuanyao
authors.initials: C
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Qifei
authors.initials: Q
authors.lastname: Deng
authors.forename: Suli
authors.initials: S
authors.lastname: Huang
authors.forename: Tian
authors.initials: T
authors.lastname: Wang
authors.forename: Xiayun
authors.initials: X
authors.lastname: Dai
authors.forename: Binyao
authors.initials: B
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.forename: Meian
authors.initials: M
authors.lastname: He
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Zhang
authors.forename: Weihong
authors.initials: W
authors.lastname: Chen
authors.forename: Haidong
authors.initials: H
authors.lastname: Kan
authors.forename: Tangchun
authors.initials: T
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D015716:Electrocardiography, Ambulatory; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis / Q000706:statistics & numerical data*; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006973:Hypertension; D008297:Male; D008670:Metals / Q000652:urine*; D008875:Middle Aged; D012307:Risk Factors; D012907:Smoking; D014505:Urban Population
chemical_list: D004785:Environmental Pollutants; D008670:Metals