With the world's population and consumption increasing, the waste heap is growing. More than 4bn tonnes of waste (municipal, industrial and hazardous) is generated annually worldwide. Where does it all go?

There is a major challenge in describing and quantifying the global waste trade. A limited number of countries monitor and make public their imports and exports. Definitions and reporting discipline can vary greatly across countries. There is also a large (and growing) illegal trade in waste, which is even more difficult to monitor. The market for waste is now worth an estimated $443bn (£283bn) a year, and this figure is growing because of increasing export volumes and rising prices.

The top destination for waste is China, which in 2010 imported around 7.4m tonnes of discarded plastic, 28m tonnes of waste paper and 5.8m tonnes of steel scrap. Between 2000 and 2008, European exports of plastic waste increased by 250% – and about 87% of these exports ended up in China (including Hong Kong).

The trade is being driven by tough EU legislation forcing local authorities and businesses to recycle more, and increasing landfill charges, making it cheaper to send the waste abroad. More than a third of the waste paper and plastic collected by British local authorities, supermarkets and businesses for recycling is sent to China.

According to a report to the secretariat of the Basel Convention in 2003, the Netherlands, Switzerland, Belgium and Germany were the highest exporters of waste, while Italy, France and, perhaps ironically, Germany, were the top waste importers.

Despite legislation banning the shipping of hazardous waste from the EU to non-OECD countries, an estimated 250,000 tonnes a year of used electrical products still flood to west Africa and Asia – hotspots are Ghana, Nigeria, India, Pakistan and China – under the guise of "used goods" or "charitable donations", allowing traders to elude these laws.

In these countries they may be dismantled by unprotected workers, often children, who remove small pieces of metal to be sold, and hard drives to extract personal information for fraudulent use. The remaining plastics and cables are often dumped or burned. More than 15 million people make money from waste-picking – almost all of them in developing countries.

Despite the difficulty in estimating the volume and value of the illegal waste trade, attempts by the UN Environment Programme and the Green Customs Initiative indicate that crime syndicates earn $20 to $30bn a year from waste crime. Inspections of 18 European seaports in 2005 found as much as 47% of waste destined for export was illegal.

According to an International Solid Waste Association report to be released in October, worldwide trade of recyclable plastics is estimated at a total of 12m tonnes a year, valued at $5bn. It flows mainly from affluent western and northern countries to Asia, especially China, which again enjoys the lion's share with about 70% of the global market. Europe is the major collective exporter with Hong Kong, the US, Japan, Germany and the UK representing the top five individual plastic scrap exporters.