Chlorine, the poison gas of the First World War, was involved in 181 accidents in the United States in 2009 alone, resulting in 56 injuries, according to a special report from the environmental journalism ngo Environmental Health News. The article reports that there have been hundreds more such accidents over the last decade, resulting in dozens of injuries and at least 13 deaths.
Chlorine is a widely used industrial substance, used at water treatment plants and in all kinds of manufacturing. One of the accidents reported by EHN took place at a recycling plant when workers cut into a tank that was supposed to be empty but which contained chlorine. Another took place at a fruit cannery where tomatoes were washed with chlorine dioxide.
Similar data for Canada is not publically available. GallonDaily is planning to ask the Ontario Ministry of the Environment for data on the number of spills involving release of chlorine which took place in that province over the last decade. We will publish the data if we receive it.
The EHN report is available at http://www.environmentalhealthnews.org/ehs/news/2011/chlorine-accidents/