Table 4.

Cancer incidence risk in relation to estimated pentachlorophenol and tetrachlorophenol exposure in sawmill workers, British Columbia, Canada.^a

		Pentachlorophenol exposure						Tetrachlorophenol exposure
		No latency			20-year latency			No latency			20-year latency
Cancer	Exposure-years	Obs	RR	95% CI	Obs	RR	95% CI	Obs	RR	95% CI	Obs	RR	95% CI
Non-Hodgkin lymphoma	< 1	38	1.0	(Referent)	46	1.0	(Referent)	50	1.0	(Referent)	78	1.0	(Referent)
	1–2	13	1.3	0.70–2.5	13	1.8	0.59–3.5	11	0.90	0.47–1.8	8	1.7	0.78–3.5
	2–5	24	1.9	1.1–3.3	21	2.1	1.1–3.7	20	1.3	0.80–2.3	5	1.3	0.49–3.3
	≥ 5	17	1.7	0.91–3.2	12	2.0	0.97–4.1	11	1.5	0.79–3.0	1	1.5	0.20–11.1
	(Trendb)			(0.06)			(0.02)			(0.14)			(0.32)
Multiple myeloma	< 1	6	1.0	(Referent)	8	1.0	(Referent)	15	1.0	(Referent)	19	1.0	(Referent)
	1–2	4	2.1	0.57–7.6	3	1.7	0.43–7.0	1	0.27	0.04–2.0	3	1.7	0.48–5.9
	2–5	4	1.3	0.34–5.0	6	2.1	0.62–7.0	5	1.1	0.38–2.9	3	1.8	0.48–6.7
	≥ 5	11	4.2	1.4–12.9	8	3.8	1.2–12.3	4	1.8	0.58–5.6	0
	(Trend)			(0.02)			(0.03)			(0.48)			(0.30)
Soft-tissue sarcoma	< 1	18	1.0	(Referent)	20	1.0	(Referent)	16	1.0	(Referent)	23	1.0	(Referent)
	1–2	3	0.64	0.18–2.2	1	0.34	0.04–2.6	3	0.77	0.23–2.66	0
	2–5	2	0.18	0.04–0.85	2	0.33	0.07–1.6	4	0.66	0.22–1.99	0
	≥ 5	0			0			0			0
	(Trend)			(0.11)			(0.12)			(0.43)			(1.0)
Liver	< 1	3	1.0	(Referent)	19	1.0	(Referent)	11	1.0	(Referent)	19	1.0	(Referent)
	1–2	4	4.1	0.89–18.8	1	0.61	0.08–4.7	7	2.7	1.0–6.9	1	0.61	0.08–4.7
	2–5	12	8.5	2.2–32.4	1	0.44	0.44–3.5	3	0.52	0.14–1.88	1	0.44	0.05–3.5
	≥ 5	2	1.4	0.21–9.2	0			0			0
	(Trend)			(0.18)			(0.38)			(0.58)			(0.38)

Obs, number of observed cases. Analyses based on Poisson regression using the lowest exposure group as the referent group, adjusting for age and time period.

^aData from Demers et al. 2006.

^bTrend p-value.