Table 1

Observed (Obs) and expected (Exp) numbers of lung cancer and nasal cancer among Welsh nickel refinery workers according to period of first employment (data from Easton et al, 1992⁹ and Sorahan and Williams, 2005¹⁰)

Reference	Year of first employment		Lung cancer				Nasal cancer
Reference	Year of first employment	Follow up	Obs	Exp	SMR	95% CI	Obs	Exp	SMR	95% CI
SMR, standardised mortality ratio; CI, confidence interval.
Data from Easton et al (1992)⁹ on men employed between 1950 and 1964 and followed through 1985 are not shown, as most of them are included in Sorahan and Williams (2005).¹⁰
*Workers who started before 1950 were only followed through 1985.
Easton et al, 1992	1902–1919	1930–1985	83	13.46	617	494–769	55	0.15	37647	28461–49318
Easton et al, 1992	1920–1929	1930–1985	88	28.04	314	253–390	12	0.17	7255	3751–12696
Easton et al, 1992	1930–1939	1935–1985	20	14.45	138	84–213	1	0.07	1434	36–7987
Easton et al, 1992	1940–1949	1945–1985	14	11.88	118	64–198	0	0.06	–	–
Sorahan and Williams, 2005	1953–1992	1958–2000	28	20.17	139	92–201	1	0.10	995	25–5542
Combined	1930–1992	1930–2000*	62	46.50	133	103–172	2	0.23	870	105–3141