You’re standing in a grocery store, two cans of competing brands of tuna in your hands. They both look the same, but where did the fish inside come from? The fishing industry in places such as Thailand is one of today’s largest domains of child labour and modern-day slavery. How do you make sure the tin you buy doesn’t support these human rights abuses?

The same technology that’s driven the cryptocurrency craze may hold the answer. It’s called blockchain, and it can help end forced labour.

Over 40 million people are slaves today—more than at any other point in human history—working in the dark corners of industries around the world. Supply chains for everything from tuna to fast fashion to the precious metals in our cell phones are notoriously complicated—and often murky—behemoths, allowing companies to cut corners and sacrifice human rights for the sake of profit.

World Vision Canada estimates that over $30 billion worth of goods involving child labour flood our market every year, hidden in the supply chain. While some companies have launched self-reporting applications, they can be fudged. In 2015, the U.K.’s largest tuna supplier launched a website enabling customers to follow the fish from boat to store, but omitted information on fish sourced from Thailand’s abuse-laden fishing industry.

Blockchain offers complete transparency.

Simply put, blockchain is a tamper-proof database. It creates a digital ledger of every transaction that is accessible to everyone, but isn’t controlled by any one company. Raw materials—from the cotton in your T-shirts to the tungsten in your electronics—get a code, like a digital passport. As the materials move along the supply chain, they automatically accrue stamps in their passport, allowing everyone to track each step in the process.

The result: there’s nowhere to hide shady business practices.

Now, imagine you’re back at the grocery store. You pull out your mobile phone and access the blockchain app piloted by London-based NGO Provenance, which records every step from catch to consumer. Simply scan a barcode to see the fisherman who reeled in the tuna, the plant that processed it and the truck it was transported on.

Some of the biggest companies in the world are beginning to implement this technology to make their own supply chains more transparent. Unilever is currently halfway through a year-long pilot project of their own, using blockchain to verify the sustainability of their tea from 10,000 farmers in Malawi.

We got our start working to end child labour and slavery more than 20 years ago. We kicked in doors to sweatshops and factories in India, Thailand and Nepal, and supported rehabilitation and education centres for those rescued from forced labour. We learned then that you can never close all the factories; as soon as we shuttered one, another would spring up. We need to address the supply side.

Consumers want to do their part. More than 80 per cent of Canadians wish there was more transparency in their products—and that offers us an opportunity to finally end forced labour.

Blockchain is the great disruptor. Let’s harness it for good.