As part of a major Ecologist investigation into the horticulture sector - focussing in particular on the often-unreported stories of those picking the fruit and vegetables we eat - I've just returned from southern Italy where a good deal of our tinned tomatoes (and other processed tomato products) originate.
Whilst there I was secretly taken to one of numerous slums hidden deep in Basilicata's arid countryside (similar places are dotted acoss Puglia and Campania too). The grim collection of shacks I visited are home to some of Europe's so-called 'tomato slaves' - mostly migrants from impoverished west African nations, a few from Eastern Europe - trying to scratch a living harvesting the region's abundant tomato crop.
I discovered that life for these men (from places such as Ghana, Burkina Faso and Ivory Coast), and as many as 50,000 others like them, is blighted by shocking levels of exploitation and abuse. Many workers - some of them illegal immigrants - are forced to toil for up to 14 hours a day picking tomatoes in harsh conditions (the heat can reach 40C) for poverty wages (sometimes as little as 17 pounds a day), frequently under the control of (sometimes brutal) gangmasters.
The workers live in appalling squalor. Home is often a derelict building - such as those I visited - many without power or any form of effective sanitation. As many as thirty people can be crammed into a single, filthy, one floor house. Some workers described how, at the height of the annual harvest season, people simply sleep outdoors, perhaps on a scavenged mattress or blanket.
What's shocking is that this is happening inside Europe. We're (unfortunately) all-too-used to horror stories blighting our food supply chains in less developed parts of the world (not that such cases are any more acceptable whether they are in Honduras or Kenya or Thailand, particularly where UK companies sell the goods in question) but most people will be particularly alarmed that this is happening on our own doorstep.
What's equally shocking is that the tomatoes being picked will be processed and shipped across Europe - including to Britain - to be sold in tins, as pastes, purees and passatas, or for use in pizza toppings, ready meals or other everyday food products. This means that virtually every household in the UK could have, at one point or another, unwittingly consumed a tomato harvested in such disturbing conditions.
Culture of impunity
Perhaps most shocking of all however is the apparent culture of impunity around the issue: some Italian farmers and industry insiders acknowledge the use of migrant labour in the tomato sector yet choose to ignore the exploitation and squalor. The current economic climate being what it is, they argue there's little choice but to keep overheads to a absolute minimum - and migrant labour is cheap labour.
All of the large processors and retailers I spoke to denied they were linked to the scandal and insisted strict codes of conduct and ethical audits are in place to prevent such abuses on their patch. One supermarket - Waitrose - announced an inquiry into the issue following our revelations (we don't yet know what they've found, if anything), the others said they were satisfied their products were not tainted by the problem.
Who is to blame then? The trade is dominated by just a handful of large companies who in turn sell to supermarkets, bulk wholesalers and specialist shops. But, in common with many consumer goods, the complex nature of the supply chain (more than 200 companies are apparently involved in processing Italy's tomato crop) and the scale of the problem make it difficult to establish for certain whether specific tomato products are tainted by exploitation. At least that's what campaigners say.
Unions and welfare groups are attempting to tackle the problem by getting all of the major players involved to sign up to an industry wide protocol, akin to a certification scheme, in order to agree minimum standards and an ethical code.
Although in theory this should help tackle the worst abuses, a stamp of approval from a certification scheme does not necessarily guarantee an ethical purchase: only in April an Ecologist investigation uncovered allegations of sexual abuse and poor conditions for workers at a Rainforest Alliance-certified tea plantation in Kenya http://www.theecologist.orgsupplying Unilever's PG Tips and Lipton brands.
Campaigners say they are expecting resistance to the industry protocol from some of those involved in the tomato business. But genuine progress will only be made when all parties - producers, processors and retailers - start acknowledging there's a serious problem connected to the sector, regardless of who specifically is to blame, rather than pretending it doesn't exist.
Until that happens the 'tomato slaves' I met, and all the others like them, will continue to toil, almost invisible to the outside world, and consumers will continue to have little idea of what really lies behind the food on their plates.