sentence: In pregnancies during 1968 – 1977 , the mean ( range ) concentrations of PeCDF , PCB-126 , and PCB-169 were 2899.3 ( 112.1 – 19942.7 ) , 336.4 ( 89.5 – 1705.3 ) , and 759.6 ( 67.6 – 4224.2 ) , respectively .