Arsenic is an element of which the various forms (species) have a widely differing toxicity. Inorganic As (III) is highly toxic, e.g. amounts 0.15-0.3 g are acutely lethal to humans whereas As (V) is less toxic and organic arsenic compounds such as arsenobetaine and choline have no effect on the human body. Therefore it is of paramount importance to determine the form and binding in which the arsenic is present ("speciation") before concluding on the hazard of disposal or of removing an arsenic-contaminated food from the market. As2O3 is used as herbicide, pesticide, fungicide and desinfecting agent in sheep growing; Na-arsenite is still in use to disinfect soils. As2O5 is used in the cotton industry and to protect wood. In view of the different toxicological behaviour of various As containing compounds and their different toxicity it is necessary to determine the speciation rather than the total contents. This holds especially for fish intended for human consumption; high contents of As are tolerable if all arsenic is in the form of arsenobetaine. The fate of arsenic-containing herbicides and pesticides in the environment and the conversion of these compounds is of particular interest to the herbicide-industry but requires the development of suitable speciation methodology. The programme will include the methodologies for the determination of:
As(V) and As(III); mono and dimethylarsenic acids and salts; arsenocholine and arsenobetaine
Then the study will continue with the extraction from real samples (mussel tissue, fish, soil, sediments). It is intended to certify up to 4 materials.
Four intercomparisons on solutions of As compounds have been conducted.
Funding SchemeCSC - Cost-sharing contracts
SO14 3ZH Southampton