0 8 Abnormal abnormal JJ 9 18 apoptosis apoptosis NN 19 22 and and CC 23 27 cell cell NN 28 33 cycle cycle NN 34 45 progression progression NN 46 48 in in IN 49 55 humans human NNS 56 63 exposed expose VBN 64 66 to to TO 67 73 methyl methyl NN 74 88 tertiary-butyl tertiary-butyl NN 89 94 ether ether NN 95 98 and and CC 99 106 benzene benzene NN 107 120 contaminating contaminating NN 121 126 water water NN 126 127 . . . 129 130 1 1 LS 130 131 . . . 132 134 In in IN 135 139 this this DT 140 145 study study NN 146 148 we we PRP 149 161 hypothesized hypothesize VBD 162 166 that that IN 167 169 in in IN 170 181 individuals individual NNS 182 186 with with IN 187 194 certain certain JJ 195 202 genetic genetic JJ 203 209 makeup makeup NN 209 210 , , , 211 215 MTBE MTBE NNP 215 216 , , , 217 224 benzene benzene NN 225 227 or or CC 228 233 their their PRP$ 234 245 metabolites metabolite NNS 246 249 act act VBP 250 252 as as IN 253 260 adducts adduct NNS 261 264 and and CC 265 268 may may MD 269 275 induce induce VB 276 286 programmed program VBN 287 291 cell cell NN 292 297 death death NN 297 298 . . . 299 300 2 2 LS 300 301 . . . 302 305 Our our PRP$ 306 311 study study NN 312 320 involved involve VBD 321 322 a a DT 323 328 group group NN 329 331 of of IN 332 334 60 60 CD 335 339 male male JJ 340 343 and and CC 344 350 female female JJ 351 359 subjects subject NNS 360 363 who who WP 364 368 were be VBD 369 376 exposed expose VBN 377 379 to to TO 380 384 MTBE mtbe NN 385 388 and and CC 389 409 benzene-contaminated benzene-contaminated JJ 410 415 water water NN 416 430 concentrations concentration NNS 431 433 up up IN 434 436 to to TO 437 439 76 76 CD 440 443 PPB ppb NN 444 447 for for IN 448 452 MTBE MTBE NNP 453 456 and and CC 457 459 14 14 CD 460 463 PPB ppb NN 464 467 for for IN 468 475 benzene benzene NN 475 476 , , , 477 480 for for IN 481 482 a a DT 483 489 period period NN 490 492 of of IN 493 494 5 5 CD 495 497 to to TO 498 499 8 8 CD 500 505 years year NNS 505 506 . . . 507 510 For for IN 511 521 comparison comparison NN 521 522 , , , 523 525 we we PRP 526 535 recruited recruit VBD 536 537 a a DT 538 545 control control NN 546 551 group group NN 552 562 consisting consist VBG 563 565 of of IN 566 568 32 32 CD 569 576 healthy healthy JJ 577 582 males male NNS 583 586 and and CC 587 594 females female NNS 595 599 with with IN 600 607 similar similar JJ 608 611 age age NN 612 624 distribution distribution NN 625 628 and and CC 629 636 without without IN 637 638 a a DT 639 646 history history NN 647 649 of of IN 650 658 exposure exposure NN 659 661 to to TO 662 666 MTBE mtbe NN 667 669 or or CC 670 677 benzene benzene NN 677 678 . . . 679 680 3 3 LS 680 681 . . . 682 692 Peripheral peripheral JJ 693 698 blood blood NN 699 710 lymphocytes lymphocyte NNS 711 712 ( ( ( 712 715 PBL PBL NNP 715 716 ) ) ) 717 719 of of IN 720 724 both both DT 725 731 groups group NNS 732 736 were be VBD 737 743 tested test VBN 744 747 for for IN 748 751 the the DT 752 762 percentage percentage NN 763 765 of of IN 766 775 apoptotic apoptotic JJ 776 781 cells cell NNS 782 785 and and CC 786 790 cell cell NN 791 796 cycle cycle NN 797 808 progression progression NN 809 814 using use VBG 815 819 flow flow NN 820 829 cytometry cytometry NN 829 830 . . . 831 832 4 4 LS 832 833 . . . 834 838 When when WRB 839 848 apoptotic apoptotic JJ 849 860 lymphocytes lymphocyte NNS 861 865 from from IN 866 873 exposed expose VBN 874 885 individuals individual NNS 886 890 were be VBD 891 899 compared compare VBN 900 902 to to TO 903 912 apoptotic apoptotic JJ 913 924 lymphocytes lymphocyte NNS 925 929 from from IN 930 933 the the DT 934 941 control control NN 942 947 group group NN 947 948 , , , 949 974 statistically-significant statistically-significant JJ 975 986 differences difference NNS 987 994 between between IN 995 999 each each DT 1000 1004 mean mean JJ 1005 1010 group group NN 1011 1015 were be VBD 1016 1024 detected detect VBN 1025 1026 ( ( ( 1026 1030 26.4 26.4 CD 1031 1034 +/- +/- CC 1035 1038 1.8 1.8 CD 1039 1042 and and CC 1043 1047 12.1 12.1 CD 1048 1051 +/- +/- CC 1052 1055 1.3 1.3 CD 1055 1056 , , , 1057 1069 respectively respectively RB 1069 1070 ) ) ) 1070 1071 , , , 1072 1082 indicating indicate VBG 1083 1085 an an DT 1086 1095 increased increase VBN 1096 1100 rate rate NN 1101 1103 of of IN 1104 1113 apoptosis apoptosis NN 1114 1116 in in IN 1117 1121 80.5 80.5 CD 1121 1122 % % NN 1123 1125 of of IN 1126 1133 exposed expose VBN 1134 1145 individuals individual NNS 1146 1147 ( ( ( 1147 1148 P p NN 1149 1150 < < SYM 1151 1157 0.0001 0.0001 CD 1157 1158 , , , 1159 1171 Mann-Whitney Mann-Whitney NNP 1172 1178 U-Test U-Test NNP 1178 1179 ) ) ) 1179 1180 . . . 1181 1185 MTBE MTBE NNP 1186 1189 and and CC 1190 1205 benzene-induced benzene-induced JJ 1206 1215 apoptosis apoptosis NN 1216 1218 is be VBZ 1219 1229 attributed attribute VBN 1230 1232 to to TO 1233 1234 a a DT 1235 1243 discrete discrete JJ 1244 1249 block block NN 1250 1256 within within IN 1257 1260 the the DT 1261 1265 cell cell NN 1266 1271 cycle cycle NN 1272 1283 progression progression NN 1283 1284 . . . 1285 1292 Because because IN 1293 1297 cell cell NN 1298 1303 cycle cycle NN 1304 1312 analysis analysis NN 1313 1319 showed show VBD 1320 1324 that that IN 1325 1327 in in IN 1328 1331 PBL PBL NNP 1332 1336 from from IN 1337 1355 chemically-exposed chemically-exposed JJ 1356 1367 individuals individual NNS 1367 1368 , , , 1369 1376 between between IN 1377 1382 20-50 20-50 CD 1382 1383 % % NN 1384 1386 of of IN 1387 1392 cells cell NNS 1393 1397 were be VBD 1398 1409 accumulated accumulate VBN 1410 1412 at at IN 1413 1416 the the DT 1417 1423 S-G2/M S-G2/M NNP 1424 1434 boundaries boundary NNS 1434 1435 . . . 1436 1437 5 5 LS 1437 1438 . . . 1439 1442 One one CD 1443 1445 of of IN 1446 1449 the the DT 1450 1459 signaling signal VBG 1460 1469 molecules molecule NNS 1470 1475 which which WDT 1476 1484 mediates mediate VBZ 1485 1495 programmed program VBN 1496 1500 cell cell NN 1501 1506 death death NN 1507 1509 is be VBZ 1510 1517 nuclear nuclear JJ 1518 1524 factor factor NN 1525 1532 Kappa-B Kappa-B NNP 1533 1534 ( ( ( 1534 1542 NF-kappa NF-kappa NNP 1543 1544 B B NNP 1544 1545 ) ) ) 1545 1546 . . . 1547 1555 NF-kappa NF-kappa NNP 1556 1557 B B NNP 1558 1561 was be VBD 1562 1570 examined examine VBN 1571 1573 as as IN 1574 1577 one one CD 1578 1580 of of IN 1581 1584 the the DT 1585 1589 many many JJ 1590 1599 molecular molecular JJ 1600 1610 mechanisms mechanism NNS 1611 1614 for for IN 1615 1624 mediating mediate VBG 1625 1629 cell cell NN 1630 1635 death death NN 1636 1638 by by IN 1639 1643 MTBE MTBE NNP 1644 1647 and and CC 1648 1655 benzene benzene NN 1655 1656 . . . 1657 1663 Indeed indeed RB 1663 1664 , , , 1665 1673 addition addition NN 1674 1676 of of IN 1677 1687 inhibitors inhibitor NNS 1688 1690 of of IN 1691 1699 NF-kappa NF-kappa NNP 1700 1701 B B NNP 1702 1712 activation activation NN 1713 1724 pyrrolidine pyrrolidine NN 1725 1740 dithiocarbamate dithiocarbamate NN 1741 1742 ( ( ( 1742 1746 PDTC PDTC NNP 1746 1747 ) ) ) 1747 1748 , , , 1749 1751 to to TO 1752 1755 the the DT 1756 1767 lymphocytes lymphocyte NNS 1768 1770 of of IN 1771 1774 the the DT 1775 1793 chemically-exposed chemically-exposed JJ 1794 1799 group group NN 1800 1803 was be VBD 1804 1811 capable capable JJ 1812 1814 of of IN 1815 1825 inhibiting inhibit VBG 1826 1836 programmed program VBN 1837 1841 cell cell NN 1842 1847 death death NN 1848 1850 by by IN 1851 1853 40 40 CD 1853 1854 % % NN 1854 1855 . . . 1856 1860 This this DT 1861 1869 reversal reversal NN 1870 1872 of of IN 1873 1882 apoptosis apoptosis NN 1883 1889 almost almost RB 1890 1892 to to TO 1893 1896 the the DT 1897 1904 control control NN 1905 1910 level level NN 1911 1913 by by IN 1914 1923 inhibitor inhibitor NN 1924 1926 of of IN 1927 1935 NF-kappa NF-kappa NNP 1936 1937 B B NNP 1938 1948 activation activation NN 1949 1952 may may MD 1953 1961 indicate indicate VB 1962 1973 involvement involvement NN 1974 1976 of of IN 1977 1981 this this DT 1982 1991 signaling signal VBG 1992 2000 molecule molecule NN 2001 2003 in in IN 2004 2008 MTBE MTBE NNP 2009 2012 and and CC 2013 2020 benzene benzene NN 2021 2030 induction induction NN 2031 2033 of of IN 2034 2044 programmed program VBN 2045 2049 cell cell NN 2050 2055 death death NN 2055 2056 . . .