Latest Scientific studies have taken a new turn towards
marine life.Thesestudies are showing results related to male fish developing characters
like female fish.The main cause of this settlement of characters in the opposite sex is
pollution.It is now believed that waste chemicals which make their
turn towards the aquatic world are the major cause of this very problem.
Hundreds of widely used man-made chemicals - including pesticides, industrial compounds,
dioxins and ingredients of plastics and detergents - are believed to mimic estrogen or
block testosterone, disrupting the endocrine system that is critical to sexual
Other recent studies had found scattered populations of animals with sexual defects living
in highly polluted waters, but the new research suggests that the problems are more
widespread than previously detected.The British researchers said they uncovered "very
compelling evidence" that
sewage-treatment plants routinely release hormonelike compounds into rivers that are
feminizing "a surprisingly large proportion" of wild fish.The incidence and
severity of intersexuality . . . is both alarming and intriguing.
This study is now being widespread in Great Britain where all the eight rivers are facing
this fish faminization.Some male fish have such mixed-up hormones that they are born with
ovaries and eggs instead of sperm ducts. In two of the eight rivers downstream of
sewage-treatment plants, all of the male fish sampled had feminized reproductive tracts.
The other six rivers
had rates from 20 percent to 80 percent. So scientists suspect damage to sex hormones is
so pervasive that it could be happening in many rivers around the world. Hormonal havoc,
however, has previously been reported in alligators, birds, river otters, carp and other
wildlife in isolated locations.
Adult animals are unharmed by hormone-imitating pollutants. The damage is done to the next
generation. Mothers pass the excessive amounts of estrogen to their embryos or fetuses,
which cannot distinguish between fake estrogens
and real ones. When this estrogen boost comes during a critical phase of sexual
development, genetic signals go haywire and males are born with feminized genitalia or
other reproductive problems. Both in vitro assays and
in vivo approaches have been developed to evaluate estrogenic effects of these toxicants.
The occurence of the female specific egg yolk precursor protein vitellogenin (Vtg) in the
plasma of male fish has widely been used as an indicator or biomarker of xenoestrogen
exposure Hormones play the same vital sexual role in humans as they do in fish and other
animals. Although people are exposed through food and water to the same pollutants as
water-inhabiting animals, they encounter much lower doses, so any effects on humans may be
Scientists wonder how minute concentrations of fake hormones in the environment - which
are hundreds of times less potent than natural estrogen - could have such a severe impact.
They do not know which chemicals are to blame, since sewage is everything that is washed
The culprits could be anything from the urine of women excreting artificial hormones from
birth-control pills, to pesticides or plastics. Evidence is emerging that wildlife is
being feminized in waters where modern environmental practices and laws are followed and
the ecosystem appears
The reproductive damage might have dire consequences for an ecosystem, because if males
are sterile, an entire animal population might gradually be depleted. Fish, in particular,
are an important link in the world's food chain.
"What we still don't know is if these intersex fish are reproductive or not. That's
the bottom line, some of them have no sperm ducts, so obviously they can't reproduce.
Because females are more critical to reproduction than males, populations can regenerate
themselves even if only a few males are fertile. Over the generations, though, if
feminization remains unchecked, fisheries could collapse.