The cost of collecting hospital medical waste in Scotland has more than doubled since the collapse of Healthcare Environmental Services, figures show.
The Lanarkshire-based company went to the wall after becoming embroiled in a waste stockpiling scandal.
Contingency measures to remove waste from every hospital, GP surgery, dental practice and pharmacy in Scotland were put in place.
But this has resulted in a "significant increased cost".
Contractors are receiving more than £460,000 per week to dispose of the hazardous materials following the collapse of Healthcare Environmental Services (HES), according to a Freedom of Information request made by the Press Association.
But Garry Pettigrew, the ex-boss of HES, which went into liquidation four months after all of its staff were made redundant, has claimed his firm charged a maximum of £11m per year – about £211,500 per week – for the collections.
The Scottish government said the contingency measures in place were robust and "ensure that the environment and human health are appropriately protected".
However, leading bacteriologist Prof Hugh Pennington, of Aberdeen University, expressed concerns about both the safety risks and the value for money under the contingency plans and called for an inquiry into the situation.
He said: "On the face of it it does sound as if there wasn't a contingency plan that was going to deliver value for money and there was a contingency plan that certainly wasn't as safe, from what I've heard, as the work that was being done before.
"If it's costing twice as much then the public is being put at a disadvantage.
"Waste is being generated 24/7 and has to be got rid of, safely as well.
"If what I've been told is true people are being put, unnecessarily, at a greater risk than they should be."
Scottish Labour health spokeswoman Health Monica Lennon added: "Professor Pennington is right to raise concerns and the SNP government would be foolish to dismiss these. HES treated their staff appallingly and tax payers are having to clean up the financial and environmental mess left behind."
'Significant increased cost'
The FoI response from NHS Scotland shows that about £7m was spent on contingency waste measures in just 15 weeks – equivalent to about £465,000 per week.
The bulk of this went on "operational and logistics" measures for collecting the waste, while £2.2m went on disposal costs.
Emails between NHS officials discussing waste contingency plans, which were also released under FoI, make reference to the "significant increased cost compared to previously".
Correspondence also shows some GP practices did not have any collections for nearly a month between December last year and January, resulting in "lots of bags of smelly waste lying in corridors or stored in cupboards etc which is unacceptable and also a hazard".