Table 2.

Leukemia cancer risk in styrene job/exposure categories.

Study	Job/Exposure Category	Observed	Risk Estimatea	95% CIb
Reinforced Plastic Industry (RPC)c
Kolstad et al. (1994, 1995)	1–49% employees in reinforced plastics	28	1.15	0.77–1.67
	50–100% employees in reinforced plastics	14	1.38	0.75–2.32
	Total Reinforced plastics	42	1.22	0.88–1.65
	No reinforced plastics	13	0.86	0.46–1.47
	Production unclassified	6	2.37	0.87–5.16
Kogevinas et al. (1993, 1994)	Laminators	3	0.48	0.10–1.39
	Unspecified Tasks	16	1.4	0.79–2.28
	Other exposed Jobs	4	0.94	0.26–2.40
	Unexposed	4	0.99	0.27–2.54
	Total	28	1.04	0.69–1.50
Wong et al. (1994)d	Open mold processing	1	0.9
	Mixing and closed mold processing	0	‒
	Finishing operations	2	0.8
	Plant supports	1	0.56
	Maintenance and preparation	1	0.48
	Supervisory and professional	1	1.33
	Total	11e	0.74	0.37–1.32
Ruder et al. (2004)	High Exposure	1	0.46f	0.01–2.58
	Low Exposure	4	0.64f	0.17–1.63
	Total	5	0.59f	0.19–1.38
Styrene-Butadiene Rubber Industry (SBR)c
Sathiakumar et al. (2005)	Production, polymerization	18	2.04	1.21–3.22
	Production, coagulation	10	2.31	1.11–4.25
	Production, finishing	19	1.56	0.94–2.44
	Maintenance, shop	4	0.93	0.25–2.38
	Maintenance, field	10	0.84	0.40–1.55
	Labor, production	4	1.23	0.34–3.15
	Labor, maintenance	15	2.03	1.14–3.35
	Laboratories	14	3.26	1.78–5.46
	Other operations	6	0.69	0.25–1.50
McMichael et al.(1976)g	Compounding, mixing: cement mixing		1.3	1.0–1.8
	Extrusion, tread cementing		3.2	2.4–5.0
	Inspection, finishing, repair		3.7	2.8–5.3
	Synthetic plant		3.9	2.6–8.0
Polystyrene/Styrene Production Industry (PS)c
Bond et al. (1992)d	Styrene monomer and finishing	1	‒h
	Styrene-butadiene latex production	1	‒h
	Product research and development	1	‒h
	Polymerization, coloring, extrusion	6	1.65
	Total	9	1.18	0.54–2.24
Hodgson and Jones (1985)	Exposed workers	0	‒
	Unexposed workers	0	‒
	Total	1f	‒h
Nicholson et al. (1978)	Total	1	1/0.79
Environmental Exposurec
Loughlin et al. (1999)	Men	6	1.82	0.67–3.96
	Women	1	0.45	0.01–2.48

^aRisk estimates were reported as one of the following: standardized mortality ratio (SMR), standardized incidence ratio (SIR), relative risk (RR), or standardized risk ratio (SRR). Some values were divided by 100 for comparison.

^b95% CI = 95% confidence interval.

^cStatistically significant findings indicated in bold.

^dIf 95% CI was not provided, statistical significance was indicated in study.

^eThe total includes the entire study cohort, it is not the sum of all the observed cases by exposure category.

^fCompared to the US population. Similar results when compared to Washington state population.

^gMcMichael et al. (1976) calculated 99.9% CIs and did not report non-significant associations.

^hSMR not calculated by authors if observed <3.