Natural and technological disasters can lead to the release of toxic chemicals with the potential to harm large numbers of people. When a natural gas well in Gaoqiao, China erupted in 2003, the release of hydrogen sulphide killed more than 240 people. A further 9000 people attended hospital and 64 000 people had to be evacuated from the area.
Poisoning may also be an indirect consequence of a disaster. After Hurricane Katrina hit New Orleans in 2005, there was an increase in cases of carbon monoxide poisoning – this was due to the incorrect use of portable gasoline-powered generators during power outages.
A relatively common form of mass poisoning involves methanol. This may be added to illicit or informally-produced alcoholic drinks in order to boost the alcohol content. In 2005, for example, at least 21 people died in Turkey after drinking a counterfeit brand of raki. In 2006, in Nicaragua, 788 people were poisoned by methanol and 44 died after drinking contaminated guaron – a brandy-like liquor.
Sometimes there is no overt chemical release, and it is only when people start showing signs and symptoms of poisoning that the possibility of a release is suspected. Examples include mass chronic arsenic poisoning in Bangladesh from tube wells drawing on contaminated water, and an outbreak of tropane alkaloid poisoning in Slovenia caused by contamination of buckwheat flour with seeds from Datura stramonium.