Table 1.

Participant characteristics overall ($n=576$) and by quartiles of total perfluorooctanoic acid (PFOA) plasma concentration in midchildhood.

	Overalla	Quartiles of PFOAb
		Q1	Q2	Q3	Q4
	$n=576$	$n=145$	$n=147$	$n=140$	$n=144$
	$\text{Mean}\pm \text{SD}$ or n (%)
Maternal/neighborhood characteristics
Maternal age at enrollment (y)	$31.8\pm 5.7$	$29.8\pm 6.5$	$31.6\pm 5.9$	$32.7\pm 5.0$	$33.1\pm 4.5$
College graduate (%)	364 (64)	59 (41)	89 (61)	101 (73)	115 (80)
Individual household income (%)
$<\$40,000$	85 (16)	39 (30)	20 (14)	15 (11)	11 (8)
$\$40,001–70,000$	89 (16)	25 (19)	23 (17)	22 (16)	19 (13)
$>\$70,000$	369 (68)	65 (51)	96 (69)	98 (73)	110 (79)
Census tract median household income (%)c
$<\$30,000$	35 (6)	15 (11)	12 (8)	4 (3)	4 (3)
$\$30,000–59,999$	248 (44)	84 (59)	61 (42)	57 (41)	46 (32)
$\$60,000–99,999$	244 (43)	39 (27)	64 (44)	71 (51)	70 (49)
$\ge \$100,000$	43 (7)	4 (3)	8 (6)	8 (6)	23 (16)
Child characteristics
Age (y)	$7.9\pm 0.8$	$8.2\pm 1.0$	$8.0\pm 0.8$	$7.8\pm 0.7$	$7.7\pm 0.6$
Female (%)	280 (49)	73 (50)	73 (50)	101 (45)	71 (49)
Race/ethnicity (%)
White	328 (57)	37 (26)	80 (54)	94 (68)	117 (81)
Black	129 (23)	66 (46)	32 (22)	21 (15)	10 (7)
Asian	14 (2)	6 (4)	2 (1)	2 (1)	4 (3)
Hispanic	34 (6)	13 (9)	13 (9)	6 (4)	2 (1)
Other	69 (12)	22 (15)	20 (14)	16 (12)	11 (8)
Dairy intake (servings per week)	$2.2\pm 1.5$	$2.0\pm 1.5$	$2.2\pm 1.5$	$2.3\pm 1.6$	$2.4\pm 1.5$
Physical activity (hours per week)	$1.9\pm 1.4$	$1.9\pm 1.5$	$1.7\pm 1.3$	$1.9\pm 1.2$	$1.9\pm 1.5$
Year of blood draw (%)c
2007	64 (11)	6 (4)	17 (12)	16 (11)	25 (17)
2008	203 (35)	21 (14)	39 (27)	62 (44)	81 (56)
2009	189 (33)	56 (39)	58 (39)	45 (32)	30 (21)
2010	120 (21)	62 (43)	33 (22)	17 (12)	8 (6)
aBMD z-score	$-0.86\pm 0.77$	$-0.73\pm 0.73$	$-0.81\pm 0.84$	$-0.95\pm 0.73$	$-0.93\pm 0.78$
BMC z-score	$-0.36\pm 0.74$	$-0.24\pm 0.70$	$-0.37\pm 0.84$	$-0.42\pm 0.69$	$-0.44\pm 0.70$

Note: aBMD, areal bone mineral density; BMC, bone mineral content; Q1, first/lowest quartile; SD, standard deviation.

^aMissing data for participants overall ($n=576$): 4 missing maternal education, 6 census tract median household income, 33 individual household income, 2 race/ethnicity, 22 dairy intake, and 22 physical activity.

^bPFOA quartile minimum and maximum values: limit of detection $\left(\text{LOD}\right)<0.1–3.0\text{\hspace{0.17em} ng}/\mathrm{mL}$ for Q1, $3.1–4.4\text{\hspace{0.17em} ng}/\mathrm{mL}$ for Q2, $4.5–6.1\text{\hspace{0.17em} ng}/\mathrm{mL}$ for Q3, and $6.2–14.3\text{\hspace{0.17em} ng}/\mathrm{mL}$ for Q4.

^cPercentages do not add up to 100% due to rounding.