John Mooney from Unison Scotland said care workers are leaving jobs in the sector to work at new supermarkets due to rising fuel costs.
“What you have is workers who have 20 visits per day in areas where they have no option but to use their car.
“We have members approaching us and saying that they simply can’t afford to go to work,” said Mr Mooney.
The union has previously called for the Scottish Government to increase fuel allowances for care workers following the sharp rise in fuel costs, but representatives say they were advised the issue was down to individual employers, of which there are around 1,200 in Scotland providing social care services.
Care workers are also ditching cars in favour of walking, Mr Mooney has warned.
“What we have is a situation where members are coming to us saying they have spoken to their employer about a schedule that covers walking only without them having to drive.
“That may be OK in the more populated areas but in Borders, Fife, Angus, these things just aren’t possible, the rural nature just means that they have to use their car.”
Mr Mooney warned that if action is not taken, the standards of social care will drop as more people are priced out of the profession.
“If you’re driving people out of providing care because of the cost or you’re making them contemplate changing the schedule or the route that they take, then essentially the standard of care is always going to drop, it’s going to be the vulnerable that pay.
“Members have come to us recently and said, ‘there’s a new supermarket opening up, the pay is more than what I’m getting paid’. That’s just one real-life example of people moving on to other areas because they just can’t afford to work in social care.”
One self-employed carer in the far north of Scotland told BBC Radio: “The rising cost of diesel is a big percentage of my income. And when the home energy bills come next winter, I am going to really struggle to keep a car on the road if there isn’t a cut to the price at the pumps.”
Mr Mooney added: “We really need the Scottish Government to step in.
“There are more than 1,200 social care employers in Scotland. The Scottish Government must put mechanisms in place to ensure that challenges faced by social care staff are adequately addressed to allow the continued delivery of essential services to the most vulnerable in society.”
Scottish Labour health spokesperson Jackie Baillie branded the situation as “shocking” and said the Scottish Government had failed to support care workers as fuel costs rise.
She said: “Social care workers are heroic frontline workers and should not be forced to shoulder the burden of the cost-of-living crisis.
“The SNP government has completely failed to support these workers and Labour’s calling for a travel allowance for social care workers to be increased by five pence per mile, as agreed for NHS workers.
“Without an allowance being introduced, we risk more staff leaving the profession and, consequently, lives being endangered.”