Correlation patterns between multiple chemicals measured through human biomonitoring to describe changes over time

摘要

While mixture toxicology and mixture risk assessment have been on the research and policy agenda for decades, assessment of the actual exposure of the population to mixtures of chemicals has received rather little attention. Within the HBM4EU project, individual human biomonitoring (HBM) data of multiple chemicals was analysed to better understand the patterns in correlation and network structures over time. These analyses are informative in understanding the common exposure patterns over time to combinations of chemicals. Three Flemish birth cohorts (FLEHSI-II-III) were included; recruited in ～2003, 2008 and 2013 from the general population. Heavy metals (Cd, Pb), p,p'-DDE, HCB and PCBs (PCB138, PCB153, PCB180) were measured in cord blood at all three points in time. Additionally, in 2008 and 2013 the heavy metals (As, Cu, Mn, Tl, MeHg (in hair)) and PFASs (PFOA, PFOS) were measured. Besides the Flemish data, preliminary comparative results of the cross-sectional population-representative German Environmental Survey for Children and Adolescents (GerES V) will be presented. At first, correlation structures within and across the datasets were assessed visually with Circos plots. Next, partial correlations were calculated to measure strength and direction between two chemicals whilst controlling for the effect of the other chemicals in the data. Based on the partial correlations, the best undirected graph networks were estimated using sparsity parameters. 'Undirected graphs' is an approach to describe the conditional independence among many variables. Within the networks, groups of closely related chemicals were identified (communities), which can provide insight into the existence of groupings. Changes over time were assessed with differentia) network analysis, assessing the similarities and differences between network structures and the communities. Here, differences are changes in correlation strength and direction between chemicals.