Accident prevention relies on a proper understanding of relevant hazards so that appropriate controls can be put in place to safeguard those who are potentially endangered. Setting deaths from war, natural events and domestic accidents to one side, industrial chemicals in their manufacture, transport, storage and use arguably contribute significantly to society＇s accident toll. National and international regimes have been developed over the years to characterise the properties of these hazardous materials so that risks to society and workforces handling such ＇dangerous goods＇ are reduced. Sometimes it has taken a disaster to show that a hazard formerly unrecognised did in fact exist; sometimes the closer scrutiny of test methods has shown that a dangerous property may have gone unrecognised; sometimes misuse of materials precipitated controls, However, in all the deliberations surrounding hazardous materials characterisation, accident investigation and prevention, and development of controls, suitable exchange of information and viewpoints between experts is necessary to promote development and adoption of international conventions. These international protocols are normally agreed by policy makers who have technical advisers to support their negotiations. These technical advisers need to meet in an appropriate forum to develop an understanding of all the relevant factors and to test ideas; often such group discussions pave the way to agreements being reached at formal policy negotiations, to solutions being provided for certain disasters, to better methods of testing. The International Group of Experts on the Explosion Risks of Unstable Substances (OECD-IGUS) created by the OECD is one such group. It first met in 1962. Set up initially to harmonise test methods used by countries to identify and quantify the explosive properties of unstable materials, it has continued over the years to offer scientists who are advisers to their governments (and others) a forum to exchange data and information primarily in support of the development of classifications regimes to protect society from the hazards of unstable substances and remove barriers to international trade but also in understanding and quantifying the resulting effects--such as explosion--from accidents involving these and other ＇dangerous goods＇. This paper describes some of the accidents which show the need for international controls for ＇dangerous goods＇ and some of the contributions made by OECD-IGUS (often referred to as ＇IGUS＇) to their developments.