Table 3

Exposure to organic dust and lung cancer risk

Subjects	Cumulative exposure to organic dust	Cases	Controls	OR^* (95% CI)
All	Never	6487	8940	1.00 (reference)
	First quartile	1549	1770	1.05 (0.96 to 1.15)
	Second quartile	1875	1914	1.15 (1.06 to 1.25)
	Third quartile	1634	1804	1.12 (1.03 to 1.22)
	Fourth quartile	1755	1845	1.24 (1.14 to 1.35)
	Test for trend, p value^†			<0.001
Never smokers	Never	487	2971	1.00 (reference)
	First quartile	105	498	0.98 (0.76 to 1.26)
	Second quartile	128	576	1.07 (0.84 to 1.35)
	Third quartile	129	540	1.20 (0.95 to 1.51)
	Fourth quartile	115	592	0.98 (0.76 to 1.25)
	Test for trend, p value^†			0.440
Workers never employed in a ‘list A job’	Never	6018	8598	1.00 (reference)
	First quartile	1335	1586	1.06 (0.97 to 1.17)
	Second quartile	1607	1694	1.19 (1.09 to 1.30)
	Third quartile	1397	1604	1.14 (1.04 to 1.24)
	Fourth quartile	1576	1706	1.25 (1.14 to 1.36)
	Test for trend, p value^†			<0.001

* ORs are adjusted for age, sex, study, cigarette pack-years, time since quitting smoking (if appropriate), and ever employment in a ‘list A job’.
† p Values for trend result from a logistic regression model with exposure as a continuous variable.