Mean (standard deviation) and frequency distribution were calculated to describe the demographic and socioenvironmental characteristics of the study population. When appropriate, median and interquartile ranges are presented. For statistical comparison, the units of pesticide concentrations in hair and meconium were expressed in mg mL1 to be uniform with the concentration unit in blood. The prevalence of exposure for each pesticide was compared among the five matrices by the Cochran Q test. A significant Cochran Q test was followed by the McNemar tests to compare the prevalences for pairs of matrices. Agreement between matrices for prevalence was assessed with Cohen’s Kappa. The concentrations of pesticides among all matrices were compared using the Friedman test. A significant Friedman test was followed by Wilcoxon Signed Rank tests to compare the concentrations for pairs of matrices. When appropriate, exact p-values were calculated for the Cochran Q, McNemar, Friedman and Wilcoxon Signed Rank tests using StatXact (StatXact Version 7.0.0 (2005) [Computer software]. Cambridge, MA: Cytel Inc.). A p-value of p0.05 was set as the level of statistical significance