The effects of Las Vegas Wash water containing elevated levels of perchlorate (CLO4-) on development and metamorphosis in the Northern Leopard Frog (Rana pipiens).

The greater Las Vegas metropolitan area is a rapidly growing urban center in the southwestern United States which serves as home to approximately 1.2 million permanent residents. The cities of Las Vegas, North Las Vegas and Henderson constitute the majority of the population in the Las Vegas Valley which is surrounded by Mt. Charleston, Black Mountain, Sunrise Mountain and the Spring Mountains. The Las Vegas Valley is a 1600 square mile area drained by the Las Vegas Wash (hereafter referred to as the Wash), which flows directly into Lake Mead.

Several industrial areas exist along the Wash and have released or spilled environmental contaminants into this area. Of particular concern is the release of ammonium perchlorate, an oxidizer used in the production of rocket fuel. This has resulted in concentrations of perchlorate (CLO4-) in the Wash water that far exceed the 18 ppb EPA limits .

Perchlorate, in the mammalian system, is known to actively inhibit the uptake of iodide by the thyroid gland and to deplete the internal stores of thyroidal iodide. This mechanism of action has been related to measurable adverse effects such as hypothyroidism, hypertrophy, and hyperplasia of thyroid follicular cells.

In amphibians, large doses of perchlorate salts (such as potassium and sodium perchlorate) are known to block metamorphosis. Many of the steps which regulate metamorphosis in amphibians are controlled by the presence of the appropriate level of thyroid hormones at crucial times during development. Thus, it should be no surprise that high concentrations of these chemicals could alter normal development and metamorphosis. However, the effects of environmentally relevant concentrations of perchlorate in surface waters, such as the Las Vegas Wash, have not been accurately assessed. Thus, the major objective of this project is as follows:

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1. To determine if Las Vegas Wash water containing elevated concentrations of perchlorate can alter the normal development and metamorphosis of the Southern Leopard Frog (Rana pipiens).

Faculty:
Shawn Gerstenberger
Stanly Hillyard

Graduate Student:
Andrea Golli

Undergraduate Students:
Lindy Horn
Jaclyn Petrello
Eric Loomis
Jason Barangan
Sherri Powell
Beth Domowicz

Department of Environmental and Occupational Health : Office BHS 510
Phone: (702) 895-5420 : Fax: (702) 895-5573
School of Public Health : University of Nevada, Las Vegas
Copyright 2005 School of Public Health, UNLV