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Upper Midwest Environmental Sciences Center

Fisheries Restoration

Determining exposure parameters that maximize eugenol residues in the fillet tissue and determining the sample times that will adequately characterize the depletion of eugenol residues from the fillet tissue of rainbow trout exposed to AQUI-S® 20E

Principal Investigator: Jeff Meinertz

Impact of UMESC Science

The results from this study will provide the base for future human food safety studies that are required by the U.S. Food and Drug Administration to approve an immediate release fish sedative.  These data will support the potential approval of an immediate release fish sedative that can be efficiently used by fishery managers throughout the U.S.

Introduction

There is a critical need in U.S. public aquaculture and fishery management programs for an immediate-release sedative, i.e. a compound that would safely and effectively sedate fish and subsequently allow for their immediate release. Such a sedative would have applications for nearly all freshwater fish species where it could be used during any field procedures involving the handling of fish (e.g. spawning and tagging).

Currently, tricane methanesulphonate (MS-222) is the only fish sedative approved by the U.S. Food and Drug Administration (FDA). Use of MS-222 is constrained by a FDA imposed 21-day withdrawal period meaning fish exposed to MS-222 cannot be made available for human consumption for at least 21 days.  This restriction was established because of a lack of mammalian toxicological data as it related to MS-222 residues in fish fillet tissue after an exposure. The withdrawal period was established to allow time for all MS-222 residues to deplete from the fillet tissue.  Generating the data that would be required to reduce the withdrawal time for MS-222 exposed fish is cost prohibitive.

In lieu of reducing the withdrawal time for MS-222 exposed fish, AQUI-S® 20E (active ingredient, eugenol; AQUI-S® New Zealand Ltd., Lower Hut, New Zealand) is the candidate sedative that is currently being pursued for approval as an immediate-release sedative.  As part of the approval process, a eugenol total residue depletion study is needed to characterize the depletion, distribution, and identity of eugenol residues in fillet tissue. Data from the total residue depletion study will be used to select a marker residue for eugenol. The marker will be the parent compound, metabolite, or combination of residues that persist in the skin-on fillet tissue for an appreciable period of time.  After selecting the marker, depletion of the marker residue will be characterized allowing the FDA to establish a withdrawal time for eugenol ensuring all eugenol residues reach safe concentrations before fish become available for human consumption.

There is a lack of information concerning eugenol depletion from freshwater fish. Therefore before the total residue depletion study can be conducted, pivotal work will be conducted to determine the exposure concentration and duration that will maximize eugenol residue concentrations in rainbow trout skin-on fillet tissue. Additionally, pivotal work will be conducted to determine the sample times that will adequately describe eugenol residue depletion. Water temperature for this study will be based on the results of Meinertz et al. (2006) where the fillet tissue concentrations of isoeugenol, a compound similar to eugenol, were determined in rainbow trout exposed to isoeugenol in 3 water temperatures, 7, 12, and 17°C.  Although not significantly different than the isoeugenol concentrations in fillet tissue from fish exposed in water at 12°C, the greatest isoeugenol concentrations were found in the fillet tissue from fish exposed in water at 17°C. Therefore, the water temperature used in this study will be 17°C.

Objective

Determine exposure parameters that maximize eugenol residues in the fillet tissue and determine the sample times that will adequately characterize the depletion of eugenol residues from the fillet tissue of rainbow trout exposed to AQUI-S® 20E.

References

Meinertz, J.R., S.L. Greseth, T.M. Schreier, J.A. Bernardy, and W.H. Gingerich.  2006.  Isoeugenol concentrations in rainbow trout (Oncorhynchus mykiss) skin on fillet tissue after exposure to AQUI-S® at different temperatures, durations, and concentrations.  Aquaculture 254: 347-354.


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