. Author manuscript; available in PMC: 2021 Jan 1.

Published in final edited form as: Int J Hyg Environ Health. 2019 Aug 20;223(1):256–266. doi: 10.1016/j.ijheh.2019.07.012

Table 4.

Unadjusted associations between age and select serum PFAS¹ (N=213).

PFAS	Percent Change in PFAS for each 1-year increase in age
PFAS	Coefficient (95% CI)	R² (adj.)	p-value
PFHxS	2.63 (1.71, 3.67)	0.12	< 0.001
Total PFOS	2.63 (1.92, 3.46)	0.19	< 0.001
Total PFOA¹	1.82 (1.11, 2.53)	0.10	< 0.001
PFNA	1.11 (0.50, 1.61)	0.06	< 0.001
PFHpS²	3.15 (2.33, 3.87)	0.11	< 0.001

Abbreviations: PFAS, poly- and perfluoroalkyl substance; N, number of observations; CI, confidence interval; R²(adj.), adjusted coefficient of determination; PFHxS, perfluorohexane sulfonate; Total PFOS, sum of linear perfluorooctane sulfonate and sum of perfluoromethylheptane sulfonate isomers; PFOA, sum of linear and branched perfluorooctanoate; PFNA, perfluorononanoate; PFHpS, perfluoroheptane sulfonate.

PFAS were natural log-transformed for the analysis, however, results presented above have been back transformed and represent the percent change.

There were no branched perfluorooctanoates (PFOA) detected in any samples, therefore the “Total PFOA” value is equal to the concentration of linear PFOA.

Computed using Tobit regression to account for ~18% left-censored data.