Symantec has started its end-of-year lists a little early, revealing its dirtiest websites of 2009. This is a list of sites that contain malicious software, viruses and other nasty things that you really don't want to be exposing your computer to.

37% of the websites listed contain adult content, but others include laser engravers, glove retailers, gaming cheats and many otherwise-innocuous sites. Security risks are the most common issue on the sites, followed by viruses and then browser exploits.

The USA is the dirtiest country - most of the list comprises sites hosted in the States, but China, Germany and Canada were also problematic. The UK came in fifth. The average number of threats per site on the list was a whopping 18,000, with 40% of those having more than 20,000.

"As the results suggest, online threats are constantly evolving as cybercriminals continue to look for sneaky and more complex ways to trick people into giving out personal details, targeting their money, identity and assets" said Con Mallon, Symantec's EMEA consumer product marketing director.