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VICTORIA LÓPEZ-RODAS Y COLS. AN. R. ACAD. NAC. FARM.

Toxins produced by harmful species are transferred to food chain and cause
numerous human intoxications with different clinical profile such as ciguatera fish
poisoning (CFP), paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning
(NSP), diarrhetic shellfish poisoning (DSP), and amnesic shellfish poisoning (ASP).
DSP is perhaps the main public health (and economic) problem in Spain and
Europe 1.

The principal measures to avoid DSP outbreaks are the monitoring of shellfish
harvesting areas and toxin analysis. European legislation allows up to 0,16 µg of
DSP toxins per gram of meat.

Nowadays, the debate raised by DSP is only as a toxin causing diarrhoea.
However, we think that the residual levels of DSP toxins ingested through shellfish
consumption could contribute to increase colorectal cancer incidence (CRC). An
epidemiological study to correlate dietary customs and tumour incidence shows a
statistically significant correlation (p < 0.001) between consumption of molluscs
and the incidence of colorectal cancer (coefficient determination = 0.50). An
increase of 7 times in shellfish consumption produced duplication in the risk ratio
of CRC in the Spanish population. Further analysis is necessary to conclusive
association between shellfish consumption and CRC. In a context of global change
that favours blooms of toxic microalgae a good approach for public health would
be to change legislation to reduce the presence of residual levels of DSP toxins OA
in shellfish. This point of view produces a conflict between the economic interests
of the sector and public health.

Keywords: HABs.—DSP.—Cancer risks.—Dinoflagellates.—Marine toxins.

RESUMEN

Proliferaciones algales tóxicas, mareas rojas y salud: envenenamiento
diarreico por moluscos y cáncer colorrectal

Las grandes proliferaciones de microalgas unicelulares se denominan mareas
rojas cuando cambian el color del agua del mar. Algunas de estas especies fito-
planctónicas producen potentes toxinas y/o condiciones ambientales anóxicas que
son capaces de provocar mortandades masivas de animales marinos. Los episodios
de proliferaciones de microalgas tóxicas se conocen en el mundo entero como
«harmful algal bloom» (HAB).

La mayoría de las especies tóxicas y formadoras de mareas rojas forman parte
del grupo de los dinoflagelados, los cuales presentan unas características nucleares
fascinantes (cromosomas permanentemente condensados organizados en hileras
amontonadas de arcos unidos en paralelo sin histonas). Se requiere un tiempo y
un esfuerzo considerable para identificar las especies de algas peligrosas bajo el
microscopio en los programas de monitorización. Por eso, en la actualidad, se está
incrementando el uso de sondas moleculares (anticuerpos, lectinas, DNA) que
marcan específicamente las células tóxicas diana de manera más eficaz.

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