TABLE 2.

IC₅₀ and RBA Values for Competitive Ligands for the Trout Liver ER

Treatment	Abbreviation	IC50 (M)a	RBA (%)b	Classificationc
Xenoestrogens
Estradiol	E2	1.39 × 10−8	100	S
Diethylstilbestrol	DES	7.59 × 10−9	186	S
Ethynylestradiol	EE2	5.89 × 10−8	23.7	S
Genistein	GEN	1.01 × 10−6	1.38	M
4-Nonylphenol	NP	8.42 × 10−4	0.0017	W
Indole-3-carbinol	I3C	4.81 × 10−3	0.0003	W
3,3′-Diindolylmethane	DIM	1.76 × 10−3	0.0008	W
Perfluoroalkyl carboxylic acids
Perfluoropentanoic acid	PFPA	2.89 × 10−3	0.0005	VW
Perfluorohexanoic acid	PFHxA	1.22 × 10−3	0.0011	W
Perfluoroheptanoic acid	PFHpA	1.78 × 10−3	0.0008	VW
Perfluorooctanoic acid	PFOA	1.82 × 10−3	0.0008	VW
Perfluorononanoic acid	PFNA	1.63 × 10−3	0.0009	VW
Perfluorodecanoic acid	PFDA	2.34 × 10−4	0.0060	W
Perfluoroundecanoic acid	PFUnDA	1.01 × 10−3	0.0014	W
Perfluorododecanoic acid	PFDoDA	6.51 × 10−4	0.0021	W
Perfluorotridecanoic acid	PFTrDA	5.22 × 10−4	0.0027	W
Perfluorotetradecanoic acid	PFTDA	L	L
Perfluoroalkyl sulfonates
Perfluorooctane sulfonic acid potassium salt	PFOS	2.01 × 10−4	0.0069	W
Perfluorodecane sulfonic acid ammonium salt	PFDS	1.52 × 10−4	0.0092	W
Fluorotelomers
6:2 Fluorotelomer alcohol	6:2FtOH	ND	ND
8:2 Fluorotelomer alcohol	8:2FtOH	ND	ND
8:2 Fluorotelomer acrylate	8:2FtOAcr	ND	ND

Note. ND, no significant displacement; L, less than 50% displacement.

^aIC₅₀ is the competitor concentration that causes 50% displacement of [³H]-E2.

^bRBA values were calculated by normalizing IC₅₀ values to that of E2 which was set at 100%.

^cLetters indicate classification of RBA values into four broad groups indicating calculated affinity for trout liver ER as follows: S, strong binding (RBA > 10%); M, moderate binding (RBA 0.1–10%); W, weak binding (RBA 0.001–0.1%); and VW, very weak binding (RBA < 0.001%).