Zinc from Oyster Tissue as Causative Factor in Mouse Deaths in Official Bioassay for Paralytic Shellfish Poison

Abstract

Toxicity (extreme weakness, body temperature drop, cyanosis, some slow deaths) in test mice, upon intraperitoneal injection of standardmethod paralytic shellfish poison (PSP) extracts of some PSP-free oysters, is consistent with the relatively high levels of zinc in these extracts. As a rough guideline, the threshold for a toxic response corresponds to a drained tissue zinc level of over 900 μg/g. The identification of zinc as the substance responsible has been supported by inducing toxicity in control extracts by spiking with nontoxic levels of zinc, and by eliminating toxicity from toxic extracts by chemical removal (precipitation, ion exchange) of metals.

Bioaccumulation of Trace Metals in Mussel (Mytilus galloprovincialis) from Mali Ston Bay during DSP Toxicity Episodes

“…Accumulation of trace metals and marine biotoxins in shellfish are studies that have mainly been carried out separately. However, some studies indicate the role of trace metals and emerging toxins, gymnodimines (GYMs) and spirolides (SPXs), on the false positive results of mouse bioassay test (MBA) for marine biotoxins [4,5,6].…”

“…To date, these toxins have not been included in the official shellfish monitoring, however, their existence can lead to incorrect results when applying an MBA. Besides, a mouse bioassay may give false positive results in the presence of other substances than biotoxins, such as higher contents of zinc or fatty acids [4,5,21,22,23,24].…”

From physical chemistry to mass spectrometry to government lab manager in half a century

“…To test this suggestion we exploited long‐forgotten principles from first‐year chemistry classes of qualitative inorganic analysis by selective precipitations of metal ions in unknown mixtures. And indeed removal of zinc from the oyster extracts (also done using ion‐exchange resins) completely eliminated the toxicity evidenced in the bioassays (McCulloch et al, ). The apparent crisis was the result of an understandably zealous commitment by DFO to avoid a second crisis of confidence in the shellfish industry.…”

VARIED ASSAYS FOR PSP TOXINS IN HEAT SHOCKED PHILIPPINE GREEN MUSSELS (PERNA VIRIDIS)

“…The presence of interfering factors like heavy metal pollutants was reported to induce mouse death with apparent neurotoxic symptoms similar to PSP in mouse bioassay. This affects the measurement of total toxicity in mammalian bioassay (McCulloch et al 1989). Barile (1990) confirmed the presence of heavy metal contamination in Philippine green mussel growing waters.…”