Table 5– Effect of time since last exposure and age at first exposure according to total duration of exposure on pleural mesothelioma risk, adjusted for age, cumulative index of exposure, total duration of exposure and birth cohort among exposed male subjects in a case–control study of occupational asbestos exposure and pleural mesothelioma in 1,041 cases and 1,425 controls in France in 1987–2006

Total duration of exposure yrs	Model 1^#		Model 2^¶
Total duration of exposure yrs	Times since last exposure yrs⁺	OR (95% CI)	Age at first exposure yrs^§	OR (95% CI)
<30	10	1.5 (0.8–2.4)	15	1.1 (0.4–2.9)
	20	2.0 (1.0–3.9)	20	1.3 (0.4–1.3)
	30	2.4 (1.2–4.7)	25	1.0 (0.3–2.9)
	40	2.3 (1.1–4.8)	30	0.6 (0.2–2.0)
	50	1.9 (0.7–5.0)	35	0.5 (0.1–1.7)

≥30	10	1.3 (0.72–2.4)	15	1.1 (0.3–3.8)
	20	3.1 (1.23–7.6)	20	0.7 (0.2–2.6)
	30	4.5 (0.89–22.3)	25	0.3 (0.1–1.2)
	40		30	0.2 (0.0–0.7)
	50		35	0.1 (0.0–0.5)

^#: logistic regression model with mean index of exposure (three-knot restricted cubic spline (RCS)), total duration of exposure (three-knot RCS), time since last exposure (four-knot RCS), age (three-knot RCS), birth year (three-knot RCS) and stratified on total duration of exposure shorter/longer than 30 yrs. ^¶: logistic regression model with mean index of exposure (three-knot RCS), total duration of exposure (three-knot RCS), age at first exposure (five-knot RCS), age (three-knot RCS), birth year (three-knot RCS), and stratified on total duration of exposure class. ⁺: relative to time since last exposure of 0 yrs. ^§: relative to age at first exposure of 10 yrs.