Wastewater lowers fish egg production more than thought
David Buchwalter, P.h.D.
Environmental Health News
05/01/2009
The hormones that humans excrete and flush down the toilet can harm fish reproduction more than previously thought.
A British study shows that wastewater released from sewage treatment plants has a bigger impact than prior research suggests on egg production – and the long-term reproductive health – of fish living in the treated water.
This study was unique in that it looked at real effluents with their mixtures of different types and amounts of hormones. The authors showed that common methods used to assess the level of hormonal disruption may underestimate true reproductive impairment caused by estrogenic compounds.
In this study, the exposures altered egg production more than would be predicted by two standard measures of estrogen action: the amount of the egg protein vitellogenin produced by male fish when exposed to estrogens and estrogen-like substances and egg production after exposure to the potent, natural estrogen ethinylestradiol (EE).
Previous studies have shown that exposure to individual estrogen hormones commonly found in wastewater effluents can negatively impact fish reproduction by affecting offspring survival and reversing sex in the adults. In the wild, researchers find fish that have both male and female sex organs and male fish that have more female-like ducts and reproductive tissue. These changes more than likely hamper reproduction.
The study's authors monitored egg production in mating pairs of fathead minnows – a widely used species in toxicology studies. The fish were held for three weeks in effluents (full strength or diliuted to 25 or 50 percent) collected from three different treatment facilities. Eggs were collected daily and compared to the pair's egg production prior to exposure...
