Inspectors found a string of environmental breaches at a clinical waste firm which made all of its staff redundant.
Healthcare Environmental Services (HES) told workers they were losing their jobs after it was embroiled in a waste stockpiling scandal.
Environmental regulators inspected HES sites in Dundee and Shotts this week.
They found both were failing to comply with enforcement notices over the proper storage of waste.
One former worker said the North Lanarkshire waste processing and incineration plant was at capacity.
They said: "Stuff has been stacking up for weeks, it is mostly from third party contracts so I am not surprised Sepa has been back round. I don't know what happens to it now but if it sits there for weeks or months then there will be issues with smells and the like."
In September, the Scottish Environment Protection Agency (Sepa) flagged up issues at a waste transfer station in Dundee and the plant in Shotts resulting in enforcement notices being issued.
Further notices relating to the storage of waste were issued earlier this month and inspections this week revealed these had not been complied with.
In a letter given to employees on Thursday morning, managing director Garry Pettigrew said the firm had ceased trading due to circumstances "outwith our control".
About 150 people are employed at the firm's base in Shotts, and almost 400 at depots throughout the UK.
Employees had earlier been sent text messages warning them they might not be paid this week, with HES claiming its bank had refused to release funds.
They were then called to meetings, where they were handed redundancy notices.
The letter said: "I write to you to inform you that your position in the company will be made redundant with immediate effect.
"I apologise that there have been no previous consultations on this matter, however there are unforeseen circumstances that have proven to be outwith our control."
It said the company had been "exploring all avenues, both politically and commercially, through enterprise schemes and sales of parts and the whole of the business to try to secure the future of the employees and the company".
But it added: "We have been given no assistance at any time, from the politicians or enterprise bodies in England or Scotland, we have been unable to resolve matters, and accordingly the company will cease trading on December 27, 2018."
The company had responsibility for disposing of clinical waste from every hospital, GP's surgery, dental practice and pharmacy in Scotland.
But it lost 17 contracts with NHS trusts in England earlier this year as a criminal inquiry was launched into a build up of waste at some of its depots.
HES has claimed its reputation was destroyed by the UK government, and said a shortage of incinerators rather than its actions was to blame for the problems.
Earlier this month the firm was also informed it would lose its NHS Scotland contract in April of next year, and subsequently said its banking facilities had been cut off.
Speaking as he left the Shotts base, worker Gary Hawthorn said: "We knew it was coming, the writing has been on the wall for the past four months and they are still in denial saying it is not their fault, it is everybody else's.
"Gutted really, a lot of time and effort, a lot of overtime, expecting wages to arrive and they don't arrive, that puts our families in a position now."
On 12 December National Services Scotland (NSS) said it had taken responsibility for waste from every hospital, GP surgery, dental practice and pharmacy to cope with a potential backlog of clinical waste after HES withdrew its service.
The Scottish government said it had contacted HES and offered to provide support to employees through its initiative for responding to redundancy situations, Partnership Action for Continuing Employment (Pace).
Business Minister Jamie Hepburn added: "After previously not engaging with this offer of support we hope that the company will now do so to assist their employees."
A spokeswoman for NHS National Services Scotland (NSS) said contingency measures were in place to collect waste previously collected by HES.
A spokeswoman for the Department for Health and Social Care in England said HES had "made a number of unfounded allegations against the government which are completely untrue".
A Sepa spokesman said: "Sepa is continuing to robustly regulate and monitor the two HES sites in Dundee and Shotts to ensure the environment and communities remain safeguarded.
"Following the issue of two enforcement notices in September, Sepa served further enforcement notices on HES earlier this month. These are to ensure each facility complies with permit conditions for the storage of waste.
"Inspections by Sepa this week have established that HES has not fully met the requirements of our latest enforcement notices, and Sepa is continuing to robustly regulate the company."
The spokesman said if HES entered into liquidation then responsibility for complying with the enforcement notice would fall to any insolvency practitioner appointed.
The BBC has approached HES for a comment.