An investigation has been launched into how medical records ended up strewn across a country lane.
Confidential paperwork included outpatient forms and GP letters
The confidential paperwork from two London hospitals detailed serious illnesses suffered by patients.
Whipps Cross University Hospital in Leytonstone, east London, and St Bartholomew's Hospital in the City, have both launched investigations.
The medical records, which included outpatient forms, were found in Northaw near Potters Bar in Hertfordshire.
Judy Almond, from Coopers Lane, said she was surprised by what she found.
"It really shook me because it has the names of the people on it and I imagine the numbers are their hospital numbers," she said.
Residents have been complaining about documents flying off lorries for the last 18 months.
Martin Keane, from Coopers Lane, said: "I saw this lorry going past with paper flying out of the back.
"It continued on down the road with paper littering the whole of Coopers Lane."
A spokesman for Whipps Cross Hospital said: "The Trust employs an external contractor to carry out this work on its behalf following a strict protocol."
"An investigation to establish if and when a failure of the procedure has taken place has been instigated."
Barts and the London NHS Trust said its confidential waste is destroyed at a "highly secure" facility in east London.
A spokesman said: "The Trust has launched a high level investigation into how some materials were found in Hertfordshire, but until the documents are recovered it is impossible to determine exactly how this breach occurred."
Residents believe the lorries were heading towards a waste processing plant in Coopers Lane.
Chas Storer Ltd, which owns the site, said it does shred confidential papers at the plant but does not believe its vehicles are involved. It has launched an investigation.