The Internet is a mine of useful information, a repository of knowledge that makes the Library of Alexandria look like a leaflet. So naturally, we're using all that information to try and kill ourselves – and to kill others. The thought of would-be terrorists downloading the explosive equivalents of a Haynes manual is pretty scary, but do such things exist? And are would-be bombers really using the Internet to download the recipe for ricin and peruse the pages of the Anarchist Cookbook?

Factor in the eBooks and sites that tell you how to make bombs, booby-traps or botnets, the ease with which you can track and trace individuals, and all the other dubious joys of the information revolution, and we face an obvious question: is there such a thing as too much information?

Since January, Japan has seen more than 40 suicides linked to websites that explain how to make poisonous hydrogen sulphide gas from bath salts and detergent. Police have asked ISP's to block access to such sites – but when one site is blocked, another springs up in its place.

In April 2008, 19-year-old Bristolian Andrew Ibrahim was charged under the Terrorism Act after police found the explosive hexamethylene triperoxide diamine (HTMD) in his house. You can make HTMD in the bath from common household chemicals.

In 2007, the FBI foiled a plot to explode gas pipelines at John F Kennedy Airport. The charge sheet notes that one of the accused, Abdul Kadir, repeatedly urged his co-conspirators to use Google Earth's satellite imagery ofthe airport to identify "the fuel tank locations and air traffic control tower… [and] the distance between the street and the fuel tanks." In the same year, The Times reported that Iraqi insurgents also used Google Earth toplan their attacks on British bases in Basra.

Jeremy Binnie is News and Analysis Editor at Jane's Terrorism and Insurgency Centre. He notes that the most easily found ricin recipe is useless and that many terror manuals have a tenuous grasp of reality. "We've reviewed Arabic-language manuals available on jihadist websites, and they are often vague, if not technically inaccurate," he says. "Much of the information is derived from the Anarchist Cookbook and its imitators, or US survivalist manuals, and are really of little use as online tutorials – the ricin recipe being an excellent example. The threat from this poison was massively over‑hyped by the media. This also applies to manuals on making chemical, biological and radiological weapons."

The Anarchist Cookbook is famously flawed – it contains instructions on isolating the non-existent drug Bananadine from banana skins – and contains a number of serious and potentially dangerous or even deadly errors. As the Anarchist Cookbook FAQ notes: "People strongly advise you to stay away from [the book] if you enjoy having your limbs." And that's assuming you've actually found the right book, because over the years all kinds of nonsense has been labelled as the Anarchist Cookbook and circulated online.

Bomb making

Even when the online information is accurate, that doesn't necessarily mean that it's useful. Recipes for TATP (Acetone Peroxide), a favourite of would‑be bombers and apparently used in the 7/7 London bombings, are widely available – but you've got to be mad to make it, because it's exceptionally unstable. As one website puts it, TATP "makes nitro-glycerine look safe."

Getting key ingredients could be difficult too. In 2006, the Fertiliser Industry Assurance Scheme was launched to ensure that ammonium nitrate-based fertiliser – a key component of explosives and a key ingredient in many online bomb-making recipes – was only sold to established account holders or people who could prove their identities. The National Counter-Terrorism Security Office (NaCTSO) publishes guidelines for farmers and tours trade shows to encourage legitimate users to keep their supplies secure.