The sheepshead minnow (Cyprinodon variegatus Lacépède), an estuarine fish species, was exposed to 17alpha-ethynylestradiol (EE2) at nominal test concentrations of 0.2, 2, 20, 200, 400, 800, 1,600, and 3,200 ng/L. Fish were exposed for up to 59 d, from subadult stages to sexual maturity, under flow-through conditions. The exposure period was followed by an evaluation of reproductive success and survival of progeny. The reproductive success of exposed sheepshead minnows, as determined from data on egg production from two subsequent spawning trials, was reduced in fish exposed to 200 ng/L EE2 and, in one spawning trial, in the 20-ng/L treatment. Hatching success was reduced in the progeny of fish exposed to 200 ng/L EE2, but survival was good among fry that successfully hatched. Histological examination indicated generalized edema, damage to gill epithelia, hepatic toxicity, fibrosis of the testis, and evidence of sex reversal, including testes-ova and spermatagonia-like cells in ovaries. The maximum acceptable toxicant concentration (MATC) for gonadal development in males was within the normal range of EE2 concentrations in sewage treatment plant effluents. The exposure regimen and choice of test organism, combined with histological examination, allowed independent evaluation of ecologically significant acute, reproductive and estrogenic endpoints. Estrogen receptor-mediated effects occurred at concentrations where reproductive effects were measurable under standard reproduction assays. The sheepshead minnow appears to be a sensitive in vivo model for partial life-cycle testing of compounds that have the potential to disrupt the endocrine system as well as reproduction in estuarine and coastal marine fish species.

The sheepshead minnow (Cyprinodon variegatus Lacépède), an estuarine fish species, was exposed to 17alpha-ethynylestradiol (EE2) at nominal test concentrations of 0.2, 2, 20, 200, 400, 800, 1,600, and 3,200 ng/L. Fish were exposed for up to 59 d, from subadult stages to sexual maturity, under flow-through conditions. The exposure period was followed by an evaluation of reproductive success and survival of progeny. The reproductive success of exposed sheepshead minnows, as determined from data on egg production from two subsequent spawning trials, was reduced in fish exposed to 200 ng/L EE2 and, in one spawning trial, in the 20-ng/L treatment. Hatching success was reduced in the progeny of fish exposed to 200 ng/L EE2, but survival was good among fry that successfully hatched. Histological examination indicated generalized edema, damage to gill epithelia, hepatic toxicity, fibrosis of the testis, and evidence of sex reversal, including testes-ova and spermatagonia-like cells in ovaries. The maximum acceptable toxicant concentration (MATC) for gonadal development in males was within the normal range of EE2 concentrations in sewage treatment plant effluents. The exposure regimen and choice of test organism, combined with histological examination, allowed independent evaluation of ecologically significant acute, reproductive and estrogenic endpoints. Estrogen receptor-mediated effects occurred at concentrations where reproductive effects were measurable under standard reproduction assays. The sheepshead minnow appears to be a sensitive in vivo model for partial life-cycle testing of compounds that have the potential to disrupt the endocrine system as well as reproduction in estuarine and coastal marine fish species.

Orimulsion “First Generation,” commonly known as Orimulsion®-100, is a commercial boiler fuel presently used at power plants worldwide (e.g., Canada, Denmark, Japan, Italy, Lithuania, and China). This fuel is manufactured by PDVSA-BITOR (PDVSA, Petroleos de Venezuela South America) from the vast bitumen reserves of the Orinoco Belt, Venezuela. Orimulsion® is a liquid fossil fuel made up of 70% bitumen, and 30% water. Orimulsion®-400 is part of the “New Generation” of Orimulsion-type fuels being developed by PDVSA-BITOR; this formulation includes modifications which enhance the fuel's combustion and transport, while continuing to improve its environmental and economic benefits. The characteristics of Orimulsion® fuels are conducive to the conversion to this fuel in any kind of boiler designed to burn Fuel Oil No. 6 or coal. The introduction of this fuel alternative for utility repowering will have a significant impact on power generation worldwide. The environmental fate and effects of Orimulsion®-400 has been studied by several groups of scientists (e.g., Battelle, 1998; Bjornstead et al., 1998; Environment Canada, 1998; Esclapés et al., 7997, 1998; Johnson et al., 1998a), and this paper is an overview of these studies. This presentation includes: chemical and physical properties of the fuel; behavior of bitumen particles in freshwater and seawater; environmental toxicity studies using Orimulsion®-400 and its new surfactant package; and spill prevention and cleanup methods.

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