Table 7.

Serum levels of PFAA in cases and controls in the two recruitment periods

Parameters	2000–2003			2011–2014			P-value a	P-value b	P-value c
	Median serum levels			Median serum levels			all	cases	controls
	All	Cases	Controls	All	Cases	Controls
∑PFAA	49.11	55.30	25.65	27.91	31.18	27.91	0.159	0.007	0.669
∑PFCA	6.59	7.95	4.78	9.08	9.83	8.75	0.001	0.051	0.003
PFHpA	0.05	0.05	0.05	0.14	0.17	0.13	0.006	0.084	0.012
PFOA	2.27	2.50	1.62	1.49	1.68	1.45	0.419	0.074	0.558
PFNA	1.50	1.80	0.89	2.64	3.03	2.58	<0.001	0.001	<0.001
PFDA	0.96	1.20	0.49	1.34	1.34	1.34	<0.001	0.022	0.001
PFUnA	1.80	2.00	0.98	2.49	2.58	2.35	0.001	0.029	0.003
PFDoA	0.15	0.20	0.15	0.54	0.56	0.48	<0.001	<0.001	<0.001
∑PFSA	42.80	48.20	20.71	19.90	21.39	19.90	0.010	<0.001	0.818
PFHxS	2.84	3.50	1.38	1.11	1.47	1.08	<0.001	<0.001	0.158
PFOS	39.70	45.60	18.06	18.20	19.35	18.20	0.009	<0.001	0.796

The differences between the two recruitment periods were tested with independent samples t-test. ^aThe p-value form independent samples t-test on ln-transformed variables between all the participants; ^bThe p-value from independent samples t-test on ln-transformed variables between the cases; ^cThe p-value from independent samples t-test on ln-transformed variables between the controls; Bold text: significant finding; ∑PFCA: PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA and PFTrA; ∑PFSA: PFHxS, PFOS and PFOSA; ∑PFAA: ∑PFCA + ∑PFSA. The serum concentration of PFAS was measured in ng/ml