More Bullbleep on Depleted Uranium

According to a recent article in The Guardian on alleged health problems caused by depleted uranium:

It is 50 years since Tony Ciarfello and his friends used the yard of a depleted uranium weapons factory as their playground in Colonie, a suburb of Albany in upstate New York state. 'There wasn't no fence at the back of the plant,' remembers Ciarfello. 'Inside was a big open ground and nobody would chase us away. We used to play baseball and hang by the stream running through it. We even used to fish in it - though we noticed the fish had big pink lumps on them.'

Today there are lumps on Ciarfello's chest - strange, round tumours that protrude about an inch. 'No one seems to know what they are,' he says. 'I've also had a brain aneurysm caused by a suspected tumour. I'm constantly fatigued and for years I've had terrible pains, deep inside my leg bones. I fall over without warning and I've got a heart condition.' Ciarfello's illnesses have rendered him unable to work for years. Aged 57 and a father of five, he looks much older.

I then started looking to other descriptions of the same research and found the following:

During the 1960s and ‘70s an estimated 5 tonnes of uranium was emitted into the environment, in a residential area of Colonie, NY, USA. Local residents are concerned that they were exposed to airborne particulate, and have campaigned for a health study. The current research could provide valuable baseline data for such a study.

The researchers led by Professor Randall Parrish collected hundreds of soil and dust samples last July, with the help of local residents and Dr John Arnason of SUNY at Albany. Soils and dusts have been examined using scanning electron microscopy, and reveal micrometer diameter uranium-rich particulate (invisible to the naked eye). These particles may be resuspended and inhaled. The samples have also been analysed by mass spectrometry, revealing contamination several hundreds of times greater than background near source, and trace contamination 35 cm below surface and as far afield as 5.8 km.

Can you see what is wrong here? At a density of 2.8 g/cm³ and a concentration of 4 ppm of uranium, there are over 400 tons of natural uranium less than 5.8 km from the plant up to a depth of 35 cm. If they could identify that trace contamination, the plant must have been in a uranium-free area in the first place.