Rocket Fuel Masculinizes Fish

Rocket fuel masculinizes fish

A contaminant widely found across the U.S. turns female fish into males.

Researchers have found that perchlorate, a component of rocket fuel, interferes with the endocrine systems of fish. A study published in Environmental Toxicology and Chemistry reports that the chemical affected the sexual development of the threespine stickleback, a common lab fish.

The female fish exposed to perchlorate produced both male and female sexual organs and began behaving like their brethren. The females’ male organs even produced sperm that were capable of fertilization, although the embryos later died.

The doses used in the study were well above what has been found in the environment, but researchers say the study shows that the chemical may be having effects that have not yet been examined. Earlier studies have shown that perchlorate interferes with thyroid hormone production.

For more than a decade, the U.S. EPA has been studying safe exposure standards for perchlorate. Beginning in the 1940s, tons of the chemical were disposed of at military sites across the U.S., where it seeped into groundwater and has since been found in milk. EPA set a reference dose in January 2005, after a National Academies of Sciences report, that temporarily serves as the measure for safe drinking-water levels.

doi: 10.1897/05-454R.1
Environmental Toxicology and Chemistry: No. 25, pp. 2087–2096.

doi: 10.1897/05-454R.1
Environmental Toxicology and Chemistry: Vol. 25, No. 8, pp. 2087–2096.


Richard R. Bernhardt,1 Frank A. von Hippel,1 and William A. Cresko2

1. Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, Alaska 99508-4614, USA 2. Center for Ecology and Evolutionary Biology, University of Oregon, Eugene, Oregon 97403, USA

(Received 2 August 2005; Accepted 9 January 2006)

Abstract–Recently, concern regarding perchlorate contamination has arisen in many contexts. Perchlorate has many military, commercial, and domestic applications, and it has been found in milk, drinking and irrigation water, and produce. Perchlorate is harmful at low levels, yet it remains unregulated in the United States while the U.S. Environmental Protection Agency attempts to establish acceptable exposure levels. The present study investigated potential reproductive effects on vertebrates using a model fish species, the threespine stickleback (Gasterosteus aculeatus). Sticklebacks were raised from syngamy through sexual maturity in untreated water and in three target concentrations of sodium perchlorate–treated water. Perchlorate was found to interfere with the expression of nuptial coloration, courtship behavior, and normal sexual development. Genetic testing revealed that some females were masculinized to the extent that they produced both sperm and eggs, and histological analysis showed that these individuals had intersexual gonads (ovotestes) containing both oocytes and cells undergoing spermatogenesis. In vitro fertilizations revealed that those gametes were capable of self- and cross-fertilization. However, crosses using sperm derived from genetic females died either during the blastula phase or near the onset of organogenesis. Sperm derived from genetic males produced viable fry when crossed with eggs derived from genetic females from all treatments. To our knowledge, the present study provides the first evidence that perchlorate produces androgenic effects and is capable of inducing functional hermaphroditism in a nonhermaphroditic vertebrate.

Keywords–––Perchlorate     Hermaphroditism     Threespine stickleback     Gasterosteus aculeatus     Endocrine disruption

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