Table 5 Mortality from cancers* for which a reduction in mortality was reported in the Shanghai cohort in relation to length of employment in carding and other jobs: observed (O) and expected (E) cases, standardised mortality ratio (SMR), and 95% CI

Length of employment (months)		Carding (n = 1045)	Other jobs (n = 2916)
6.5–70	O/E	3/3.9	7/7.1
	SMR	0.77	0.98
	CI	0.15 to 2.25	0.50 to 2.58
71–147	O/E	12/7.75	20/16.2
	SMR	1.55	1.23
	CI	0.80 to 2.70	0.78 to 2.82
148–476	O/E	10/10.3	24/24.3
	SMR	0.97	0.99
	CI	0.46 to 1.78	0.30 to 1.35

*Oesophagus, stomach, rectum, liver, pancreas, breast.