Table 1

Adjusted HRs* and 95% CIs for ALS mortality by level of occupational formaldehyde exposure, National Longitudinal Mortality Study, men ages 25 years and older, 1973–2011

	Respondents	Person-years	ALS deaths	HR (95% CI)*
Intensity
Unexposed	607 416	9 815 195	372	1.0 (Reference)
Low	97 301	1 641 068	55	0.99 (0.74 to 1.30)
Medium	86 766	1 427 789	43	0.63 (0.44 to 0.90)
High	3058	46 188	2	1.53 (0.40 to 5.80)
Intensity, exposed restricted to probability=high
Unexposed	607 416	9 815 195	372	1.0 (Reference)
Low	0	0	0	–
Medium	361	6954	0	–
High	493	8539	2	4.43 (1.16 to 16.85)
Probability
Unexposed	607 416	9 815 195	372	1.0 (Reference)
Low	98 228	1 681 862	51	0.85 (0.63 to 1.15)
Medium	88 043	1 417 659	47	0.76 (0.54 to 1.06)
High	854	15 493	2	2.98 (0.78 to 11.30)
Probability, excluding first 5 years of follow-up
Unexposed	492 489	9 501 370	331	1.0 (Reference)
Low	82 155	1 637 260	47	0.87 (0.64 to 1.18)
Medium	71 598	1 372 603	39	0.77 (0.54 to 1.10)
High	758	15 230	2	3.49 (0.92 to 13.26)
Probability, follow-up to age 75 only
Unexposed	604 116	9 794 521	332	1.0 (Reference)
Low	97 959	1 680 822	41	0.79 (0.57 to 1.11)
Medium	86 760	1 407 671	40	0.66 (0.44 to 0.99)
High	832	15 315	2	4.13 (1.09 to 15.69)
Probability, respondents 35≤age≤75 at enrolment
Unexposed	427 530	6 493 151	332	1.0 (Reference)
Low	65 736	1 046 575	47	0.91 (0.67 to 1.24)
Medium	60 675	921 096	43	0.79 (0.56 to 1.12)
High	568	9731	2	3.41 (0.89 to 13.01)
Probability, respondents 50≤age≤75 at enrolment
Unexposed	175 376	2 441 370	197	1.0 (Reference)
Low	25 611	377 534	31	1.00 (0.67 to 1.49)
Medium	27 247	393 151	27	0.75 (0.47 to 1.19)
High	270	4125	2	4.76 (1.16 to 19.49)
Probability, respondents employed at enrolment
Unexposed	548 645	8 876 712	331	1.0 (Reference)
Low	85 041	1 459 452	45	0.88 (0.65 to 1.21)
Medium	76 249	1 238 082	38	0.71 (0.50 to 1.03)
High	770	14 063	2	3.26 (0.86 to 12.38)

*Adjusted for race/ethnicity, education and household income as a percentage of the poverty line.
ALS, amyotrophic lateral sclerosis.