Following an investigation by ITV News, the UK’s recycling industry is calling for better regulation of the international trade in second-hand clothing.
The Textile Recycling Association says the Environment Agency should do more to prevent "people operating under the radar".
It comes after our cameras filmed piles of discarded clothes in Ghana left on illegal dumps and even polluting the sea.
The figures we have obtained tell their own story.
ITV News found that 63, 418,990kg of old clothes from the UK were sent to be sold in Ghana last year - our analysis shows that's doubled in a decade.
Overall, exported cast-off clothing from the UK is up 35% in the same period.
The value of what we send has halved from as little as £200 a tonne to just £100 in just 12 months, according to industry documents we've seen.
There are fears that the fall in value means unscrupulous dealers will send ever-increasing volumes in order to maintain their incomes.
That could open the door for even more low quality items being exported.
When we put clothes into a recycling scheme, we expect it be part of the solution - not part of the problem.
Yet our new evidence shows exports of second hand clothes to developing countries are becoming an unmanageable deluge.
Even insiders want more regulation of what we send to countries like Ghana.
ITV News Consumer Editor Chris Choi explains how to make more sustainable choices:
One trader of used clothes to Africa spoke to me anonymously about commercial pressures leading to a deluge of poor quality garments: "Yes there are people doing that already.
"That's why the dumps are there."
Much of the used clothing we donate to charities, councils and retailers' schemes gets sold to traders.
Some export up to 60% of the garments, but reputable traders sift out poor quality items first so dumping and waste are far less likely.
But according to Alan Wheeler of the Textile Recycling Association, a lack of regulation is leading to "people operating under the radar".
He says "we need checks both in the recipient country, but also government officials in this country should be paying closer scrutiny".
Checks of the containers would expose any operators who are sending out unsuitable clothes.
The Department for Environment, Food and Rural Affairs told us where there is evidence of illegal activity, officers carry out inspections at sites and ports to stop, correct or return loads.
A spokesperson said "we are working to bring in new laws so the fashion industry makes sustainable choices, as well as exploring tighter regulations for clothing exports".
The UK's 70% recycling rates for clothes is one of the best in the world, making an estimated £100 million for charity.
However, we can't just shove things into collection bags and hope for the best.
The best advice is to donate to reputable charities, to local councils or retailer return schemes.
Recycling your cast-offs does a lot of good: environmentally, it's keeping 650,000 tonnes from UK landfill and economically it is helping developing countries create work and income.
But we've found that lack of checks leaves an open door for unscrupulous traders around the world to sell unsuitable clothes to developing countries.