. 2017 Sep 26;125(9):097020. doi: 10.1289/EHP1302

Table 1.

Population characteristics and serum polybrominated biphenyl (PBB) and polychlorinated biphenyl (PCB) concentrations by thyroid disease status among Michigan adults 2004–2015.

Characteristic	Total study sample	Thyroid disease^a $n = 135$ (17.9%)^b^,^c	No thyroid disease $n = 620$ (82.3%)^c^,^d	p-Value^e
Exposures [GM; ng/mL (ng/g lipid)]
PBB-153^f	0.17 (26.3)	0.22 (33.2)	0.16 (25.0)	0.07 (0.09)
PCB-118	0.05 (7.9)	0.08 (11.5)	0.05 (7.3)	$< 0.01$ ( $< 0.01$ )
PCB-138	0.17 (25.8)	0.22 (33.3)	0.16 (24.4)	$< 0.01$ ( $< 0.01$ )
PCB-153	0.19 (29.0)	0.24 (36.8)	0.18 (27.5)	$< 0.01$ ( $< 0.01$ )
PCB-180	0.14 (20.8)	0.18 (26.5)	0.13 (19.7)	$< 0.01$ ( $< 0.01$ )
$Σ PCB$ (di-ortho)^g	0.51 (76.9)	0.65 (97.7)	0.48 (73.0)	$< 0.01$ ( $< 0.01$ )
Sex [n (%)]
Female	455 (60.4)^g	113 (24.8)	344 (75.6)	$< 0.01$
Male	298 (39.6)^g	22 (7.4)	276 (92.6)
Age (y) at blood draw [n (%)]^h
18–29	100 (13.3)	3 (3.0)	97 (97.0)	$< 0.01$
30–39	176 (23.4)	19 (10.8)	157 (89.2)
40–49	153 (20.3)	32 (20.9)	121 (79.1)
50–59	150 (19.9)	33 (22.0)	117 (78.0)
$\geq 60$	186 (24.7)	49 (26.3)	137 (73.7)
Age (y) at PBB contamination [n (%)]
$\geq 16$ at contamination	226 (30.0)	58 (25.7)	168 (74.3)	$< 0.01$
0–15 at contamination	315 (41.8)	61 (19.4)	256 (81.3)
Born after contamination	212 (28.2)	16 (7.5)	196 (92.5)
Study years [n (%)]
2004–2006 onlyⁱ	70 (9.3)	4 (5.7)	66 (94.3)	$< 0.01$
2012–2015 only	674 (89.5)	128 (19.0)	546 (81.0)
2004–2006 and 2012–2015^c	9 (1.2)	3 (33.3)	8 (88.9)
Race/ethnicity [n (%)]
Non-Hispanic white	712 (96.1)	128 (18.0)	586 (82.3)	0.92
Hispanic white	22 (3.0)	3 (13.6)	19 (86.4)
Other	7 (0.9)	1 (14.3)	6 (85.7)
Missing	12	3	9
Body mass index^h^,^j [n (%)]
$\leq Normal$	155 (31.1)	16 (10.3)	140 (90.3)	0.02
Overweight	156 (31.3)	20 (12.8)	137 (87.8)
Obese	190 (38.2)	42 (22.1)	148 (77.9)
Missing	255	57	198
Smoking status^j [n (%)]
Current smokers	120 (16.1)	14 (11.7)	106 (88.3)	0.11
Former smokers	182 (24.4)	35 (19.2)	147 (80.8)
Never smokers	444 (59.5)	86 (19.4)	360 (81.1)
Missing	7	0	7

Note: GM, Geometric mean. Total study sample: $n = 753$ individuals, $n = 801$ samples.

^{^a}

Includes those who specified physician-diagnosed thyroid disease [ $n = 128$ (107 women; 21 men)] and those who had thyroid hormone concentrations outside clinically normal ranges [ $n = 7$ (6 women; 1 man)]; includes 8 women and 1 man who reported thyroid disease before PBB contamination; includes 13 (9.1%) hyperthyroid (13 individuals), 66 (46.2%) hypothyroid (60 individuals), 17 (11.9%) other types (15 individuals), and 47 (32.9%) not specified (47 individuals).

^{^b}

143 samples.

^{^c}

$n = 2$ women participated in 2004–2006 and again 2012–2015 and developed thyroid disease during that time; thus, these participants are counted in both categories, and percents sum to $> 100 %$ .

^{^d}

658 samples.

^{^e}

For comparison between thyroid disease versus no thyroid disease (statistical tests: Student’s t-test using natural log–transformed PBB and PCB levels; chi-squared test for categorical variables; Fisher’s exact test for categorical variables with sparse cells (expected value of $\geq 1$ cell is $n < 5$ ).

^{^f}

$n = 37$ women and 17 men with PBB-153 concentrations below the limit of detection (LOD); GMs for PBB-153 computed after multiple imputation for observations $< LOD$ .

^{^g}

$PCB - 138 + PCB - 153 + PCB - 180$ .

^{^h}

$n = 36$ individuals participated twice, and $n = 6$ individuals participated three times over time; thus, cell counts sum to $> 753$ , and percents sum to $> 100 %$ .

^ⁱ

Only women participated between 2004 and 2006.

^{^j}

Assessed at time of blood draw.