For those he used lead white, a traditional oil pigment he reckoned would show up in an x-ray due to the heavy metal content.

FORBES: Masterpieces For Everyone? The Case Of The Socialist Art Forger Tom Keating [Book Excerpt]

There are "real concerns" about the impact on the Danube, he says, as "it will increase the heavy metal content of the water and it might have adverse effects on fish".

BBC: How toxic is Hungary's red sludge?