. 2023 Jul 17;131(7):077007. doi: 10.1289/EHP12603

Table 1.

Summary of selected characteristics among participants in a nested case–control study of serum PFAS and testicular germ cell tumors among U.S. Air Force servicemen, both overall (530 matched pairs) and for the subset with two prediagnostic serum samples (187 matched pairs).

	All participants			Subset of participants with two samples
	Cases	Controls	$p$ -Value	Cases	Controls	$p$ -Value
Age (y) at first serum collection [ $n$ (%)]	—	—	0.41	—	—	0.55
$less than 20$	141 (26.6)	134 (25.3)	—	60 (32.1)	58 (31.0)	—
20–24	194 (36.6)	220 (41.5)	—	75 (40.1)	88 (47.1)	—
25–29	95 (17.9)	76 (14.3)	—	37 (19.8)	26 (13.9)	—
30–34	64 (12.1)	66 (12.5)	—	11 (5.9)	12 (6.4)	—
35–39	36 (6.8)	34 (6.4)	—	4 (2.1)	3 (1.6)	—
Age (y) at second serum collection [ $n$ (%)]
$less than 20$	NA	NA	—	58 (31.0)	62 (33.2)	0.98
20–24	NA	NA	—	55 (29.4)	55 (29.4)	—
25–29	NA	NA	—	45 (24.1)	42 (22.5)	—
30–34	NA	NA	—	18 (9.6)	19 (10.2)	—
35–39	NA	NA	—	11 (5.9)	9 (4.8)	—
Age (y) at case diagnosis [ $n$ (%)]^a	—	—	1.00	—	—	1.00
$less than 20$	10 (1.9)	10 (1.9)	—	0	0	—
20–24	111 (20.9)	111 (20.9)	—	4 (2.1)	4 (2.1)	—
25–29	159 (30.0)	159 (30.0)	—	54 (28.9)	54 (28.9)	—
30–34	113 (21.3)	113 (21.3)	—	58 (31.0)	58 (31.0)	—
35–39	137 (25.9)	137 (25.9)	—	71 (38.0)	71 (38.0)	—
Race and ethnicity [ $n$ (%)]^a	—	—	1.00	—	—	1.00
Non-Hispanic White	422 (79.6)	422 (79.6)	—	146 (78.1)	146 (78.1)	—
Hispanic	57 (10.8)	57 (10.8)	—	26 (13.9)	26 (13.9)	—
Non-Hispanic Black	13 (2.5)	13 (2.5)	—	3 (1.6)	3 (1.6)	—
Asian/Pacific Islander	6 (1.1)	6 (1.1)	—	4 (2.1)	4 (2.1)	—
Native American/Alaskan Native	5 (0.9)	5 (0.9)	—	0 (0.0)	0 (0.0)	—
Other/unknown	27 (5.1)	27 (5.1)	—	8 (4.3)	8 (4.3)	—
Education [ $n$ (%)]	—	—	0.26	—	—	0.55
$\leq High school$	261 (49.3)	268 (50.6)	—	82 (43.9)	88 (47.1)	—
Some college	120 (22.6)	138 (26.0)	—	55 (29.4)	51 (27.3)	—
Bachelor’s degree	80 (15.1)	57 (10.8)	—	18 (9.6)	17 (9.1)	—
Advanced degree	68 (12.8)	66 (12.5)	—	32 (17.1)	31 (16.6)	—
Unknown	1 (0.2)	1 (0.2)	—	0	0	—
Grade	—	—	0.06	—	—	0.20
E01–E10 (Enlisted)	410 (77.4)	435 (82.1)	—	143 (76.5)	153 (81.8)	—
O01–O10 (Officer)	120 (22.6)	95 (17.9)	—	44 (23.5)	34 (18.2)	—
Number of military deployments	—	—	$less than 0.001$	—	—	0.23
0	296 (55.9)	222 (41.9)	—	64 (34.2)	52 (27.8)	—
1	114 (21.5)	121 (22.8)	—	47 (25.1)	43 (23.0)	—
$2 plus$	120 (22.6)	187 (35.3)	—	76 (40.6)	92 (49.2)	—
Calendar year started military service [median (min, max)]^a	1998 (1986, 2017)	1998 (1986, 2017)	0.95	1998 (1986, 2012)	1998 (1986, 2012)	0.98
Calendar year of sample collection [median (min, max)]^a
First/only sample	1999 (1988, 2017)	1999 (1989, 2017)	0.99	1999 (1989, 2012)	1999 (1989, 2012)	0.98
Second sample	NA	NA	—	2005 (1991, 2012)	2005 (1992, 2013)	0.97
Years of service at sample collection [median (min, max)]
First/only sample	0.3 ( $negative 0.2$ , 12.3)^b	0.4 ( $negative 0.2$ , 12.3)^b	0.49	0.3 ( $negative 0.2$ , 12.1)^b	0.4 ( $negative 0.1$ , 12.3)^b	0.64
Second sample	NA	NA	—	5.8 ( $negative 0.2$ , 21.8)^b	5.8 ( $negative 0.1$ , 25.0)^b	0.90
Years from sample collection to case diagnosis [median (min, max)]
First/only sample	5.0 (0.0, 19.8)	NA	—	10.3 (5.0, 19.8)	NA	—
Second sample	NA	NA	—	5.8 (4.8, 11.5)	NA	—
Tumor morphology [ $n$ (%)]
Seminoma	300 (56.6)	NA	—	125 (66.8)	NA	—
Nonseminoma	230 (43.4)	NA	—	62 (33.2)	NA	—

Note: —, no data; max, maximum; min, minimum; NA, not applicable; PFAS, per- and polyfluoroalkyl substances.

^{^a}

Control matching factor.

^{^b}

Negative values represent serum collection dates prior to the military service start date (cases: 115 first/only samples, 6 second samples; controls: 99 first/only samples, 5 second samples).