TY - JOUR T1 - Exposure JF - Canadian Medical Association Journal JO - CMAJ SP - 697 LP - 697 DO - 10.1503/cmaj.110273 VL - 183 IS - 6 A2 - , Y1 - 2011/04/05 UR - http://www.cmaj.ca/content/183/6/697.abstract ER -