Welcome to London Arsenic Group

The London Arsenic Group (LAG) brings together expertise from the fields of sedimentary geochemistry, hydrochemistry, hydrogeology, environmental mineralogy and analytical geochemistry. We seek to understand the source, mobility, and fate, of arsenic in the environment. We exist to bring a multi-disciplinary approach to this issue and provide a focus for exchange of views.

Arsenic is a poison and carcinogen. Arsenic is most damaging as the inorganic form, with recent work suggesting As(III) and As(V) are equally toxic. The USEPA has recently adopted an MAC of 10 microgrammes per litre for the concentration of arsenic in drinking water, based on a legal requirement to follow a linear dose-response curve for arsenic toxicity in the absence of compelling evidence that other models (such as hormesis) apply. Arsenic occurs in small amounts in food, frequently as organic arsenic (arsenobetaine, arsenosugars etc.), which are less toxic than inorganic arsenic. In nature, arsenic exists overwhelmingly either in substitution for sulfur in iron sulfides, or sorbed to iron oxyhydroxides. Arsenic is released to the environment by weathering of the former, or reduction of the latter. These mechanisms explain most occurrences of arsenic in the environment at concentrations that might cause environmental harm. 

Global Extent

Known areas with natural arsenic contamination (Ravenscroft et al., 2008)


Natural arsenic contamination (area marked red) at global scale