Research
A Section 508–conformant HTML version of this article is available at http://dx.doi.org/10.1289/ehp.1307563.
Urinary Metals and Heart Rate Variability: A Cross-Sectional Study of Urban Adults in Wuhan, China Wei Feng,1,2* Xiaosheng He,1,2* Mu Chen,1,2,3,4* Siyun Deng,1,2 Gaokun Qiu,1,2 Xiaoliang Li,1,2 Chuanyao Liu,1,2 Jun Li,1,2 Qifei Deng,1,2 Suli Huang,1,2 Tian Wang,1,2 Xiayun Dai,1,2 Binyao Yang,1,2 Jing Yuan,1,2 Meian He,1,2 Xiaomin Zhang,1,2 Weihong Chen,1,2 Haidong Kan,5 and Tangchun Wu1,2 1Department
of Occupational and Environmental Health, and 2Ministry of Education Key Lab for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; 3Department of Nutrition, and 4Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA; 5School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China *These authors contributed equally to this work.
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. Objectives: 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 1.70 mmol/L at the study examination, or a previous diagnosis by a physician), diabetes (fasting glucose ≥ 7.0 mmol/L or a previous diagnosis), and urinary creatinine. Because urinary creatinine levels are usually used as an index of standardization for urinary metabolite levels of chemicals to correct for variable dilutions among spot samples, we also investigated HRV associations with ln-transformed urine metal concentrations using creatinine-standardized values (micrograms per millimole creatinine). However, the potential bias of creatinine-standardized urinary chemical concentrations used as independent variables in regression models was well documented (Barr et al. 2005; Schisterman et al. 2005), so we focused primarily on the creatinine-adjusted estimates. We also checked the consistency of estimators by robust chisquare testing based on a previously published method (Cantoni and Ronchetti 2001) if the distributions of log-transformed HRV indices were still skewed (identified by p
A Section 508–conformant HTML version of this article is available at http://dx.doi.org/10.1289/ehp.1307563.
Urinary Metals and Heart Rate Variability: A Cross-Sectional Study of Urban Adults in Wuhan, China Wei Feng,1,2* Xiaosheng He,1,2* Mu Chen,1,2,3,4* Siyun Deng,1,2 Gaokun Qiu,1,2 Xiaoliang Li,1,2 Chuanyao Liu,1,2 Jun Li,1,2 Qifei Deng,1,2 Suli Huang,1,2 Tian Wang,1,2 Xiayun Dai,1,2 Binyao Yang,1,2 Jing Yuan,1,2 Meian He,1,2 Xiaomin Zhang,1,2 Weihong Chen,1,2 Haidong Kan,5 and Tangchun Wu1,2 1Department
of Occupational and Environmental Health, and 2Ministry of Education Key Lab for Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; 3Department of Nutrition, and 4Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA; 5School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China *These authors contributed equally to this work.
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. Objectives: 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 1.70 mmol/L at the study examination, or a previous diagnosis by a physician), diabetes (fasting glucose ≥ 7.0 mmol/L or a previous diagnosis), and urinary creatinine. Because urinary creatinine levels are usually used as an index of standardization for urinary metabolite levels of chemicals to correct for variable dilutions among spot samples, we also investigated HRV associations with ln-transformed urine metal concentrations using creatinine-standardized values (micrograms per millimole creatinine). However, the potential bias of creatinine-standardized urinary chemical concentrations used as independent variables in regression models was well documented (Barr et al. 2005; Schisterman et al. 2005), so we focused primarily on the creatinine-adjusted estimates. We also checked the consistency of estimators by robust chisquare testing based on a previously published method (Cantoni and Ronchetti 2001) if the distributions of log-transformed HRV indices were still skewed (identified by p
