The levels of TFR-F index and TBIC in FE and VF groups before intervention ( ( 1.59 0.37 ) , ( 1.63 0.40 ) and ( 9.04 2.71 ) , ( 9.26 2.33 ) mg/kg , respectively ) were all lower than those of after intervention ( TFR-F index : ( 1.84 0.51 ) , ( 1.87 0.45 ) and TBIC : ( 12.42 3.49 ) , ( 13.01 2.98 ) mg/kg ) ( t values were 3.93 , 3.78 , 7.57 and 9.41 , respectively , all P values were < 0.01 ) .