such as age,sample size,design quality,different ranges of iAs exposure levels,different assessments of iAs exposure,and other
variation of the covariates in studies,etc.Thus we used both meta-
regression and sensitivity analysis to explore the potential impor-
tant causes of the between-study heterogeneity.We did not find
that the covariates of publication year,number of deaths,study
duration periods,and study design had a significant impact on
between-study heterogeneity.