RT Journal Article SR Electronic T1 Duration of exposure as a surrogate for dose in the examination of dose response relations. JF British Journal of Industrial Medicine JO Br J Ind Med FD BMJ Publishing Group Ltd SP 427 OP 429 DO 10.1136/oem.43.6.427 VO 43 IS 6 A1 Johnson, E S YR 1986 UL http://oem.bmj.com/content/43/6/427.abstract AB