Spotted in that British tabloid, the BBC.
For those curious, there isn't a significant amount of real heavy metals either:
The Hungarian Academy of Science said sludge samples taken two days ago showed that the muck's heavy metal concentrations do "not come close" to levels considered dangerous to the environment. But the academy said Thursday it still considered the sludge dangerous — apparently due to its caustic characteristics.
The only hazard is the extreme alkalinity which makes the sludge corrosive. Note the CaO and Na2O content; both decompose to extremely basic hydroxides, Ca(OH)2 and NaOH, when exposed to water. Apparently a deadly sea of lye sweeping away villages isn't newsworthy enough for BBC readers without some ludicrous cancer angle being invented.