UK scientists have finally found a use for toenail cuttings. Mark Button at the British Geological Survey in Nottingham, UK, and colleagues are using the clippings to detect human exposure to elevated environmental levels of arsenic.

Button's group collected toenails from residents living near a former arsenic mine in Devon, UK. They washed and acid digested the samples under microwave irradiation. They then analysed the samples using inductively coupled plasma mass spectrometry. The toenails showed significantly elevated arsenic levels compared to those seen in samples taken from people that had no contact with the element. 

Arsenic occurs naturally in the environment and people can be exposed to it in several ways, for example through contaminated water, food or soil. Chronic exposure is associated with increases in lung, liver, bladder and kidney cancers. 

Once ingested, arsenic is absorbed into the bloodstream and then accumulates in several body parts. Evidence disappears from blood and urine after a few days but arsenic accumulates long term in keratin rich materials such as hair and nails. This makes them potentially more useful as biomarkers of chronic arsenic exposure. Toenail samples in particular are an attractive possibility as they are easy to collect, store and transport and are less liable to contamination than hair samples. 

'This research', says Button, 'highlights the suitability of toenails as a biomarker of exposure to potentially harmful elements in areas such as the south-west of the UK where more extensive biomonitoring studies are long overdue.'

Richard Kelly

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