| Summary: | A study of 24 weeks duration was carried out in which oysters (Crassostrea gigas) were grown in four regimes. These were: (i) on phytoplankton cultured in a mixture of secondary treated sewage effluent and seawater for a period of 12 weeks followed by a second 12 week period of feeding on phytoplankton cultured in a "clean," inorganically enriched regime; (ii) as for (i) except that the secondary effluent was sand filtered prior to use; (iii) as for (ii) except that the effluent was charcoal filtered prior to use; and (iv) using "clean," inorganically enriched phytoplankton food for the 24 week duration. At intervals of two weeks, populations of oysters were removed for assay for trace metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) and organic contaminants (hydrocarbons, P . C.B.' s). No significant accumulation or depuration of any metal or organic contaminant was evident in any of the regimes. In terms of these contaminants all oysters are within acceptable edible standards as set by F.D.A. A series of experiments was carried out to examine the public health implications of enterovirus survival in a mollusc culture system fertilized with secondary treated sewage effluent. Using MS-2 bacteriophage and vaccine strain poliovirus it would appear that depuration could be effected in 20-25 days in C. gigas at l5°C. However this does NOT mean that such a time span would be adequate for other enteroviruses. Further work is required in this area. Supported by NOAA Office of Sea Grant, Department of Commerce, Grant No. 04-07-158-44104 .
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