New views on the hypothesis of respiratory cancer risk from soluble nickel exposure; and reconsideration of this risk's historical sources in nickel refineries

Table 2 Characteristics of KNR epidemiological studies by treatment of worker exposure

First Author (Year)	Follow up period	Year first employed	Number of workers	Cases of lung cancer	Qualifications for study entry^a
I. Studies using rule based allocation of workers to process department
Pedersen (1973) [1]^b	1953–71	1910–60	1,916	48	≥ 3 years employment; alive on Jan. 1, 1953
Magnus (1982) [2]^b	1953–79	1916–65	2,247	82	≥ 3 years employment; alive on Jan. 1, 1953
II. Studies using ICNCM Job Exposure Matrix developed by protocol
ICNCM (1990)[3]^b	1953–84	1946–69	3,250	77	≥ 1 year employment; alive on Jan. 1, 1953
Andersen (1996) [4]^b	1953–93	1916–40	379	203	≥ 3 years employment; alive on Jan. 1, 1953
		1946–83	4,385		≥ 1 year employment; alive on Jan. 1, 1953
III. Studies using revised Job Exposure Matrix
Grimsrud (2002)[6]^c	Dec '52-Aug '95	1910–94	5,389	227	≥ 1 year employment; alive on Jan. 1, 1953
Grimsrud (2003)[7]^b	1953–2000	1910–89	5,297	267	≥ 1 year employment; alive on Jan. 1, 1953
Grimsrud (2005)[8]^c	Dec '52-Aug '95	1910–94	5,389	227	≥ 1 year employment; alive on Jan. 1, 1953

^a A worker qualified on Jan. 1, 1953, or on the first succeeding date when he had the minimum qualifying employment. ^b Cohort study
^c Case control study