Table 2.

Plasma Concentrations of 7 Perfluoroalkyl Substances^a in Subjects in a Subcohort of the Norwegian Mother and Child Cohort Study, 2003–2007

Perfluoroalkyl Substance	Abbreviated Name	% > LOQ	Chain Lengthb	Plasma Concentration (ng/mL) by Percentile
				5th	25th	50th	75th	95th	CVc
Perfluorooctanoic acid	PFOA	100.0	7	1.43	2.14	2.78	3.57	5.15	8.6
Perfluorononanoic acid	PFNA	99.7	8	0.24	0.39	0.54	0.74	1.12	13.3
Perfluorodecanoic acid	PFDA	71.1	9	<LOQ	<LOQ	0.10	0.18	0.34	27.0
Perfluoroundecanoic acid	PFUnDA	83.7	10	<LOQ	0.08	0.17	0.27	0.47	22.2
Perfluorohexane sulfonate	PFHxS	99.5	6	0.27	0.49	0.69	0.95	1.78	14.6
Perfluoroheptane sulfonate	PFHpS	83.6	7	<LOQ	0.09	0.15	0.23	0.37	29.8
Perfluorooctane sulfonate	PFOS	100.0	8	6.07	9.69	12.87	17.03	25.53	11.4

Abbreviations: CV, coefficient of variation; LOQ, limit of quantification.

^a The 7 perfluoroalkyl substances were those with concentrations that could be quantitated in more than 50% of samples.

^b Refers to the number of carbons in the fully-fluorinated alkyl chain.

^c Interassay coefficient of variation was calculated as (standard deviation/mean) × 100 for 25 pooled samples.