Some of humanity's daily tragedies stand out because they inflict wantonly futile suffering; others awake the persistent tug of collective conscience. The calamity in Bangladesh, where the collapse of a building has claimed at least 270 lives, surely did both.
One moment, the Rana Plaza in Dhaka was packed with thousands of human beings, filling eight floors of shops, offices and factories. The next instant, the shoddy construction gave way under its own weight, pulverising itself into a shattered wreck, crushing and maiming soft human bodies under hard concrete.
As the cries of the trapped and the injured rose above a scene resembling a bomb site, the Bangladeshi Government on Thursday declared a day of national mourning.
Yet just about all of us are linked to this tragedy in some way. The building now in ruins once housed four garment factories with one purpose - to provide cheap clothes for mainly Western customers.
Among the garment makers in the building were Phantom Apparels, Phantom Tac, Ether Tex, New Wave Style and New Wave Bottoms. Together, they produced several million shirts, pants and other garments a year.
The New Wave companies, according to their website, make clothing for major brands including Dress Barn of the US, Canada's The Children's Place, Britain's Primark, Spain's Mango and the Asian arm of Benetton, based in Hong Kong.
Benetton says people involved in the collapse were not Benetton suppliers. Mango said it had only discussed production of a test sample of clothing with one of the factories.
Wal-Mart, the world's largest retailer, says it is investigating whether any of the factories in the building were producing garments for it at the time of the collapse.
An Associated Press reporter found in the rubble clothing labelled Saddlebred, Easycare Oxford, Next, Tweeti.com, LcWaikiki.
Britain's Primark acknowledged it was using a factory in Rana Plaza, but many other retailers distanced themselves from the disaster, saying they were not involved with the factories at the time of the collapse or had not recently ordered garments from them.
Primark, a bargain clothing chain with 161 branches in Britain, and Bonmarche, with 360 stores, may not have known it, but they were buying products made by people working in a death trap.
On Tuesday, cracks were noticed in the Rana Plaza. Police were called and they ordered an evacuation. But New Wave ordered its workers - most of them women - to carry on as normal. The management said other engineers had checked the building and declared it safe. The employees were also told that if they did not come to work on Wednesday, they would risk dismissal. When the workers turned up on Wednesday, the building edifice collapsed on top of them. In Bangladesh, women often bring their children to work. Many of New Wave's employees had done so. The infants would stay in creches on the second, sixth and seventh floors; every one of those floors collapsed.
Not all businesses in Rana Plaza shared New Wave's cavalier attitude. A branch of BRAC bank told its employees to go home when the alarm was raised on Tuesday, and they stayed away on Wednesday.
We don't know how many women working to fulfil contracts placed by Primark and Bonmarche have been killed. The same will also be true of their children.
Both British companies acknowledged that New Wave was among their suppliers. Both voiced distress over the tragedy and said they would offer whatever help was possible.
But yesterday, Primark went to ground and declined to respond to any questions. In particular, the company did not say whether it knew anything about the state of Rana Plaza before the disaster.The Bangladeshi Government has acknowledged that perhaps 90 per cent of Dhaka's high-rise buildings do not meet local construction standards, let alone international rules.
Can Primark and Bonmarche fairly be held accountable for working conditions in their supply chain? Campaigners say retailers do carry a burden of responsibility. If you are going to make money by selling products on the high street, you have an obligation to ensure a basic minimum of decency in the conditions in which they are produced.
"Legally, as businesses in the UK, the responsibility of the retailers is only to their shareholders," says Clare Lissaman from the Ethical Fashion Forum. "But morally, if they are making their money off the backs of people who are dying, then absolutely they have a responsibility."
By outsourcing production to developing countries, Primark and Bonmarche can sell clothes so cheaply that Western consumers may regard them as disposable items. How can a man's polo shirt go for £4 - about the same as a child's meal at McDonald's - or a pair of chinos sell for £10?
We complain bitterly when safe, but unlabelled, horse meat makes its way into the supply chain. But we tend not to display the same curiosity about how clothes begin. Lurking in many minds might be the thought that Bangladeshi women died making the £1.50 T-shirt worn by your child.
How should the dutiful and humane consumer react? The most sensible conclusion is to accept that responsibility is shared between companies and consumers. Put simply, all of us have a duty. If Primark and Bonmarche are responsible for the conditions in which their goods are produced, so are we.
Commercial pressure lies at the heart of the problem. Retailers want suppliers to deliver quickly and cheaply, creating dangerous incentives.
Sustainable fashion consultant Amisha Ghadiali calls this the "too fast, too cheap" problem. "How do you hold retailers to account? They're always going to say 'we didn't know ... '. But it's their responsibility to have a budget and to look at how corners are going to be cut."
In Bangladesh, the Government cannot be relied upon to prevent corner-cutting. It has labour laws and building safety standards but the corruption pervading a weak and inefficient state means they are rarely enforced.
One step could be taken. Last year, the US owner of Calvin Klein and a German retailer signed the Bangladesh Fire and Building Safety Agreement, providing for independent inspection of every factory used by a supplier.
Neither Primark nor Bonmarche has signed up.
They should both sign up immediately. And perhaps we, as consumers, should recognise our responsibilities - which might mean using our purchasing power to force their hand.