Report of the Scientific Committe of AESAN related to the risk assessment associated to the possible presence of arsenic in algae intended to human consumption

Globalisation contributed to the introduction of novel foods into the Spanish diet, among the seaweed,  
able to accumulate toxic elements and among them arsenic (As). It is considered necessary to obtain information on the As contents in seaweeds that can be considered safe.  
Arsenic is a metalloid with four oxidation states, that give rise to a high variety of compounds having different physical and chemical characteristics. The As species differ also in their biological and toxicological properties, depending not only of the valence state, but also of the inorganic and organic forms. The latter have the lowest toxic potential, being therefore the adverse effects determined mainly by the inorganic As fraction, being As (III) toxicity higher than those of As(V).  
Arsenic specie affects the absorption, distribution, metabolism and excretion. As methylated forms  
(MMA and DMA), the main forms present in many seaweeds are considered of a lower toxicity, the  
binding to tissues is lower and the elimination quicker than those of non-methylated species.  
Organoarseniacal compounds are metabolised in a lower extent and rapidly excreted.  
Regarding As toxicity, symptomatology of acute intoxication via oral exposition include; diarrhoea, gastrointestinal colic type pains, anorexia, weight lose, severe vomiting, muscular cramps, heart disorders,  
central nervous system disorders, irritability increase, exanthem and hair lose. These symptoms are observed in adults after a 3 mg As intake per day during several weeks. Chronic exposure causes skin lesions, hipo and hiperpigmentation (blackfoot disease), vaso-occlusive and gangrenous disorders, peripherical neuropaties, encephalopathy, alteration of hemo group metabolism, hepathomegalia, bone marrow depression, diabetes and impairment of renal function (necrosis).   
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