"Concentrations of 17α-estradiol and the contraceptive 17α-ethinylestradiol were in most of these samples below the limit of detection." From my post above. NOT found in sewer plant discharges, limit of detection quite low.
The low-levels study you cite is from the Netherlands, 2000.
Another study showing levels are irrelevant (length of time exposed is the factor) is from England, 2002.
You apples, me oranges:
In fish younger than 3 years of age, intersex was found to be a rare condition, thus indicating that the expression of this condition is progressive and appears at, or after, the onset of puberty in roach. Incidence and severity of the intersex condition were related more to the duration of exposure to effluent than to the year of hatching or to the prevailing environmental conditions in the study rivers (Environment Agency 2002a).
No, it does not say levels are irrelevant, in fact they are not mentioned in your clip.
Another clip from your link says “Direct-exposure studies with early life-stage roach (from fertilized egg and juveniles) confirm that effluents induce a number of feminizing effects, including vitellogenin induction and duct disruption, in a concentration-dependent manner. “
Time*concentration will be the critical factor, I think; if the observed effects don't follow the amount of exposure (time*concentration) then there may be threshold effects, or it's a proof of homeopathy or hormesis (which I doubt).
I need to do “real work” for a while, but I'll keep a back-burner pot going looking for data on synthetic estrogen concentrations (there are too many sources of natural hormones).