Table 2 Case-control studies of benzene exposure and non-Hodgkin’s lymphoma (NHL)

Author, year (Reference)	RR	CI_low	CI_up	Type	N	Location	Exposure	Exposure category	Self-report	Outcome	Source
Bernard et al 198438	0.49	0.21	2.00	cc	unk	Yorkshire	Benzene use	All	Yes	NHL incidence	Cancer registry/hospital controls
Blair et al 199339	1.5	0.7	3.1	cc	12	Iowa/Minnesota	Higher intensity	High	Yes	NHL incidence	Cancer registry/RDD & HCFA
Dryver et al 200440	1.95	0.90	4.21	cc	15	Sweden	High exposure aromatic HCs	High	Yes	NHL incidence	Cancer registry/Sweden ID no.
Fabbro-Peray et al 200141	5.7	1.4	23.2	cc	8	France	Cumulative >810 days exposed	High	Yes	NHL incidence	Hospitals/electoral lists
Franceschi et al 198942	1.14	0.57	2.28	cc	15	Italy	Benzene and solvents	All	Yes	NHL incidence	Hospitals/hospital controls
Fritschi et al 200543	0.31	0.06	1.50	cc	2	Australia	Substantial (>10 TLV >5 days × 5 yrs)	High	Yes	NHL incidence	Cancer registry/electoral lists
Gerin et al 199829	0.8	0.4	1.6	cc	9	Montreal	Medium/high	High	Yes	NHL incidence	Hospitals/electoral lists
Glass et al 200344	1.48	0.30	7.16	ncc	2	Australia	Cumulative exposure >16 ppm-yrs	High	No	NHL incidence	Nested in cohort
Kato et al 200545	1.52	0.41	5.70	cc	7	New York	Occupational exposure	All	Yes	NHL incidence	Cancer registry/DMV & HCFA
Mao et al 200046 men	1.2	0.8	1.9	cc	36	Canada	Occupational exposure	All	Yes	NHL incidence	Cancer registry/insurance & RDD
Mao et al 200046 women	0.6	0.2	1.8	cc	5	Canada	Occupational exposure	All	Yes	NHL incidence	Cancer registry/insurance & RDD
Miligi et al 200630	1.6	1.0	2.4	cc	58	Italy	Medium/high intensity	High	Yes	NHL incidence	Hospital & cancer registry/population sample
Persson & Fredrikson 199947	0.8	0.1	3.8	cc	3	Sweden	Occupational 1 year, 5–45 years earlier	All	Yes	NHL incidence	Hospitals/population registers
Scherr et al 199248	1.2	0.5	2.6	cc	unk	Boston	Benzene	All	Yes	NHL incidence	Hospitals/town residency lists
Schnatter et al 199649	0.93	0.08	7.19	ncc	2	Canada	Intensity (mean ppm) 0.20–0.49 ppm	High	No	NHL mortality	Nested in cohort (petroleum workers)
Seidler et al 200750	1.0	0.4	2.3	cc	11	Germany	Cumulative >130 ppm-yr	High	Yes	NHL incidence	Hospitals and physicians/population registry

cc, case-control; CI_low, lower 95 CI; CI_up, upper 95 CI; DMV, Department of Motor Vehicles; exposure, the exposure category selected for this meta-analysis; exposure category, described as “High” if results for a high exposure category were used; HC, hydrocarbon; HCFA, Health Core Financing Administration; LR, lymphosarcoma and reticulosarcoma; N, number of cases in the selected exposure category; ncc, nested case control; RDD, random digit dialling; self-report, “Yes” means exposure history based primarily on self-reported work history; source, the source of cases and controls in case-control studies; TLV, threshold limit value; unk, unknown.