Table 2.

Baseline levels of perfluoroalkyl substances in $n=310$ overweight and obese adolescents recruited from Southern California between 2001 and 2012 (SOLAR cohort) and in $n=135$ young adults recruited from Southern California between 2014 and 2018 (CHS cohort).

Perfluoroalkyl substance	SOLAR cohort		CHS cohort		SOLAR vs. CHS $p$-valuesb
	Females ($n=132$)	Males ($n=178$)	Females ($n=59$)	Males ($n=76$)	Overall	Females	Males
PFOS (ng/mL)	11.3 (9.3, 13.6)	10.9 (9.1, 13.0)	3.5 (3.1, 4.0)	5.4 (4.8, 6.0)	8 $\times {10}^{–27}$	1.8 $\times {10}^{–19}$	6.3 $\times {10}^{–11}$
PFHxS (ng/mL)	1.1 (0.8, 1.4)	1.1 (0.8, 1.3)	0.8 (0.6, 1.0)	1.4 (1.2, 1.7)	0.87	0.05	0.04
PFNA (ng/mL)	0.58 (0.53, 0.64)	0.64 (0.60, 0.69)	0.35 (0.33, 0.38)	0.39 (0.37, 0.41)	2 $\times {10}^{–34}$	7.8 $\times {10}^{–14}$	6.3 $\times {10}^{–23}$
PFDA (% above LOD)a	55 (42)	81 (46)	22 (37)	31 (41)	0.42	0.68	0.58

Note: Data presented as geometric mean (95% confidence interval) or $n$ (%). CHS, Children’s Health Study; LOD, limit of detection; PFDA, perfluorodecanoic acid; PFHxS, perfluorohexane sulfonic acid; PFNA, perfluorononanoic acid; PFOS, perfluorooctane sulfonate; SOLAR, Study of Latino Adolescents at Risk of Type 2 Diabetes.

^aProportion of samples below the LOD was too high to provide a valid estimate of the geometric mean. LOD for PFOS, PFHxS, PFNA, and PFDA were 0.02, 0.03, 0.1, and $0.2\text{\hspace{0.17em}ng}/\mathrm{mL}$, respectively.

^b$p$-Values to test for differences in the geometric means between cohorts were calculated using independent $t$-tests on log-transformed PFAS concentrations. For PFDA, differences in the proportion of samples above the LOD between cohorts were tested using chi-square tests.