| Abnormal Bone Composition in Female Juvenile American Alligators from a Pesticide-Polluted Lake (Lake Apopka, Florida) P. Monica Lind,1 Matthew R. Milnes,2 Rebecca Lundberg,1 Dieldrich Bermudez,2 Jan Örberg,3 and Louis J. Guillette, Jr.2 1Institute of Environmental Medicine, Karolinska Institutet, Institute of Environmental Medicine, Stockholm, Sweden; 2Department of Zoology, University of Florida, Gainesville, Florida, USA; 3Department of Environmental Toxicology, Uppsala University, Uppsala, Sweden Abstract
Reproductive disorders have been found in pesticide-exposed alligators living in Lake Apopka, Florida (USA) . These disorders have been hypothesized to be caused by exposure to endocrine- disruptive estrogen-like contaminants. The aim of this study was to expand our analysis beyond previous studies by investigating whether bone tissue, known to be affected by sex steroid hormones, is a potential target of endocrine disruptors. Long bones from 16 juvenile female alligators from Lake Apopka (pesticide-contaminated lake) and Lake Woodruff (control lake) were evaluated by peripheral quantitative computed tomography. We observed significant differences in bone composition, with female alligators from the contaminated lake having greater trabecular bone mineral density (BMD) , total BMD, and trabecular mineral content compared with females from the control lake (p < 0.05) . Increased trabecular and total BMD measurements suggest that juvenile female alligators from Lake Apopka were exposed to contaminants that created an internal environment more estrogenic than that normally observed. This estrogenic environment could be caused by both natural and anthropogenic compounds. Effects on BMD indicate interference with bone homeostasis. We hypothesize that contaminants present in the lake inhibit the natural and continuous resorption of bone tissue, resulting in increased bone mass. Although this is the only study performed to date examining effects of environmental estrogenic compounds on alligator bones, it supports previous laboratory-based studies in rodents. Further, this study is important in demonstrating that the alterations in morphology and physiology induced in free-ranging individuals living in environments contaminated with endocrine-active compounds are not limited to a few systems or tissues ; rather, effects can be observed in many tissues affected by these hormones. Key words: alligator, bone mineral density (BMD) , EDCs, endocrine disruption, Lake Apopka, pesticides, pollution, pQCT. Environ Health Perspect 112:359-362 (2004) . doi:10.1289/ehp.6524 available via http://dx.doi.org/ [Online 1 December 2003]
Address correspondence to M. Lind, Karolinska Institutet, Institute of Environmental Medicine, P.O. Box 210, Nobels väg 13, plan 3, S-171 77 Stockholm, Sweden. Telephone: 46-8-524-87525. Fax: 46-8-343849. E-mail: Monica.Lind@imm.ki.se This work was funded in part by the Swedish Research Council of Environment, Agricultural Sciences and Spatial Planning (21.0/2002-0646) , and in part by grants to L.J.G. from the U.S. Environmental Protection Agency (CR821437 and R824760-01-0) . The authors declare they have no competing financial interests. Received 13 June 2003 ; accepted 1 December 2003.
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