. Author manuscript; available in PMC: 2018 Oct 1.

Published in final edited form as: Eur J Epidemiol. 2017 Jun 5;32(10):893–899. doi: 10.1007/s10654-017-0249-8

Table 3.

Adjusted^* rate ratios and 95% confidence intervals (CI) for association between formaldehyde exposure (expected ppm), lagged three years, with ALS Jan 1 1982–Dec 31 2009.

Formaldehyde Exposure^**	Controls N (%)	Cases N (%)	RR^* (95% CI)
No Exposure	10934 (75)	2582 (71)	1.0 (ref)
Ever Exposure	3666 (25)	1068 (29)	1.3 (1.2–1.4)
1^st Quartile	935 (6.4)	262 (7.2)	1.3 (1.1–1.5)
2^nd Quartile	976 (6.7)	272 (7.5)	1.2 (1.1–1.4)
3^rd Quartile	873 (6.0)	268 (7.3)	1.4 (1.2–1.6)
4^th Quartile	882 (6.0)	266 (7.3)	1.3 (1.1–1.5)

All models adjusted for matching factors (age, sex and calendar date), residence, marital status, and SES.

^**

Quartiles of exposure determined from cases with non-zero exposure, with cutoffs: 0.013, 0.08, and 0.28 ppm.