Subject: polar bears and PCBs; pseudohermaphrodites (fwd)

Mike Williamson (
Wed, 8 Jul 1998 12:37:00 -0400 (EDT)

Date: Fri, 3 Jul 1998 09:37:52 -0700
From: MARMAM Editors <marmamed@UVic.CA>
Reply-To: Marine Mammals Research and Conservation Discussion
Subject: polar bears and PCBs; pseudohermaphrodites (fwd)

     The following comes from _Science_, Volume 280, Number 5372, Issue of
     26 June 1998
     Polar Bears and PCBs

     Scientists in Norway have discovered seven female polar bears bearing
     both female and male genitals near the island of Svalbard
     (Spitsbergen) in the Barents Sea.The researchers say their prime
     suspect is polychlorinated biphenyls (PCBs) that concentrate in the
     bears' fat.

     Over the last 3 years, zoologists Andrew Derocher of the Norwegian
     Polar Institute in Tromso and Oystein Wiig of the University of Oslo
     have captured some 450 polar bears and tagged them to study population
     dynamics and monitor toxicants in their bodies. The
     pseudohermaphrodites, they found, are genetic females--some
     have had cubs--but they also have small penises in front of their

     There may be "a perfectly natural explanation" for this, says
     Derocher, whose paper will appear in the Journal of Wildlife Diseases.
     In many species, for example, adrenal or ovarian tumors in females can
     trigger the formation of anomalous sex organs in fetuses. But such
     cases are rare. And PCBs are known to end up in the bears' fishy diet
     after traveling long distances and condensing in the cold air.

     This is the latest in a string of reports implicating pollutants that
     mimic sex hormones in gender-bending effects on wildlife. Most of
     these reports have sparked considerable controversy. Although lab
     studies have shown that PCBs can interfere with sexual development in
     rats, they haven't led to the formation of coexisting male and female
     sex organs, says toxicologist Bram Brouwer of the Agricultural
     University in Wageningen, the Netherlands. Yet, he says, "it's not
     unreasonable tosuppose something like that could happen" in other
     species, including bears. Brouwer adds that he wouldn't rule out some
     other member of the family of so-called persistent organic pollutants
     as the culprit.

     Derocher has called in an endocrinologist for further investigations.
     One theory is that PCBs interfere with hormone-regulating enzymes
     called P450 cytochromes. Says Derocher: "We're hoping other
     researchers around the Arctic will start to examine their females as

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