Table 6 Comparison of summary risk estimates (SRRE) from single industry cohorts versus cohorts from multiple companies within Group I cohorts studies of occupational TCE exposure and non‐Hodgkin's lymphoma.

	Group I studies involving single industry cohorts*		Group I studies involving multiple industry cohorts†
	SRRE (95% CI)	p value for heterogeneity	SRRE (95% CI)	p value for heterogeneity
Total cohort	1.00 (0.80 to 1.24)	0.119	1.84 (1.10 to 3.07)	0.012
TCE exposed sub‐cohort	1.25 (0.87 to 1.79)	0.431	1.86 (1.27 to 2.71)	0.159
Highest TCE exposure	0.90 (0.50 to 1.65)	0.472	2.96 (1.20 to 7.32)	0.257
Lowest TCE exposure	1.00 (0.55 to 1.81)	0.31	2.45 (1.39 to 4.32)	0.47
Longest TCE exposure	1.21 (0.77 to 1.92)	0.535	1.81 (1.09 to 2.99)	0.248
Shortest TCE exposure	1.10 (0.69 to 1.75)	0.44	2.13 (0.86 to 5.26)	0.09

*Includes the following: Blair et al, 1998;²⁹ Boice et al, 1999;³⁵ Morgan et al, 1998.³⁰

†Includes the following: Anttila et al, 1995;²⁸ Axelson et al, 1994;²⁷ Hansen et al, 2001²⁵; Raaschou‐Nielsen et al, 2003.²⁶