In a wide-ranging analysis of the issue, the UK-based Institute of Development Studies (IDS) said that the implementation of ethical working codes had led to the introduction of training on emergency procedures, safer use of chemicals and better working hours.
But issues such as discrimination, regular employment and harsh treatment remain serious problems.
"There have been some improvements for workers in global supply chains, but significant challenges remain," said Dr Stephanie Barrientos of the IDS, which was commissioned by the Ethical Trading Initiative (ETI) to carry out the research into its members activities.
The ETI is a coalition of UK companies (retailers, brands and suppliers), NGOs and trade unions that are committed to implementing codes of labour practice aimed at improving labour conditions in their global supply chains.
Last year ETI corporate members collectively spent over 12.4 million on ethical trade, inspected over 10,000 suppliers and delivered 4,500 hours of ethical trade training. Members include high street names such as Marks and Spencer and Tesco.
"ETI member companies are clearly making a very real difference to the lives of poor workers and their families, and on a large scale - last year the scope of our members ethical trade activities reached at least three million workers," said ETI director Dan Rees.
"But many fundamental issues remain to be addressed. Notably, migrant and casual workers have so far achieved little benefit from ethical trade."
The growth of ethical business in part reflects changing European consumer attitudes to ethical food. Market analyst Mintel for example recently forecast that UK shoppers are set to spend over £2 billion on ethical foods this year alone, up by a massive 62 per cent since 2002.
Within the ethical foods market, Fairtrade remains the star performer in terms of sales growth. Fairtrade is set to be worth £230 million n the UK by the end of this year, experiencing some 265 per cent growth between 2002 and 2006 alone.
" People in Britain today are clearly moving towards more ethical lifestyles and are starting to realise that their actions all have consequences," said the report.
"As British shoppers increasingly look to shop with a clear conscience, Mintel forecasts that the market will continue to grow for the foreseeable future."
Of course, consumer will be quick to turn cynical if they find that products they are paying over the odds for are not as 'ethically sourced' as they were led to believe. The IDS report, which also covers non-food products, therefore provides a useful gauge as to how effective ethical codes of practice can be.
Examining a banana farm in Costa Rica for example, the team found that positive change was being driven by high levels of commitment by ETI companies and suppliers, along with frequent and consistent communication from buying companies on ethical trade.
In contrast, downward pressure on prices and lead times appeared to have the opposite effect: suppliers in all countries and sectors reported that this limited their ability to make improvements in labour practices.This point relates to the central problem of reconciling cheap food and ethical sourcing, according to Rees. "Companies must start to seriously address the impact that their core business practices are having on workers down the supply chain," he said.
"But we must all recognise that despite the growing pressures on UK retailers to address consumers ethical concerns, they face much greater pressure to deliver the cheapest products in the shortest possible time.
"Perhaps it is time for a more open and honest debate about the cost to workers of demand for cut price products."
Over 20,000 suppliers were covered in the study, which was launched yesterday. Nearly all suppliers had been informed that they were expected to comply with the code and around 9,000 had been assessed for code compliance. Most of these suppliers were located in the upper tiers of supply chains, for example packers and first-tier producers.