Table 2.

Biological exposures and lung cancer risk

Exposure	Cumulative exposure	Cases	Controls	OR^*	95% CI
Organic dust	Never	6,487	8,940	1.00	Reference
	1^st Quartile	1,549	1,770	1.05	0.96–1.15
	2^nd Quartile	1,875	1,914	1.15	1.06–1.25
	3^rd Quartile	1,634	1,804	1.12	1.03–1.22
	4^th Quartile	1,755	1,845	1.24	1.14–1.35
	Test for trend, p-value^†			<.001
Endotoxin	Never	8,509	11,305	1.00	Reference
	1^st Quartile	1,241	1,276	1.08	0.98–1.19
	2^nd Quartile	1,113	1,175	1.08	0.98–1.20
	3^rd Quartile	1,230	1,268	1.12	1.02–1.23
	4^th Quartile	1,207	1,249	1.23	1.12–1.36
	Test for trend, p-value^†			<.001
Contact with animals	Never	11,158	14,001	1.00	Reference
	1^st Quartile	661	627	1.10	0.97–1.26
	2^nd Quartile	463	512	1.05	0.90–1.21
	3^rd Quartile	488	563	1.07	0.93–1.24
	4^th Quartile	530	570	1.15	1.00–1.32
	Test for trend, p-value^†			0.081

ORs are adjusted for age, sex, study, cigarette pack-years, time-since-quitting smoking, and ever employment in a ‘list A job’

^†

P-values for trend result from logistic regression model with exposure as continuous variable