A CASE of cyanide poisoning was among 169 serious environmental incidents reported to public health chiefs last year.

It is unclear whether anyone died as a result of exposure to the chemical, which can be highly toxic. Breathing in cyanide at a high dose can result in seizures, coma, cardiac arrest, and death within seconds.

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Hydrogen cyanide released as a gas from pellets of Zyklon-B was widely used to carry out mass murder in Nazi concentration camps during the Holocaust.

It can also be used to lace liquids with fatal effects. A highly-publicised murder trial in Indonesia in 2016 heard how 27-year-old Mirna Salihin was killed after drinking a Vietnamese iced coffee which her friend had spiked with cyanide.

At lower doses, exposure to is characterised by weakness, giddiness, headaches, vertigo, confusion, a perceived difficulty in breathing, and then loss of consciousness.

No details of the circumstances of the Scottish case have been disclosed, however.

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It is the first chemical incident involving cyanide to be reported in Scotland for more than four years.

A total of seven cyanide hazards were recorded in Scotland between 2002 and 2018.

The cyanide incident was listed in the Scottish Environmental Incident Surveillance System (SEISS) annual report, compiled by Health Protection Scotland (HPS).

The report found that there had been 111 chemical incidents in Scotland in 2018 - including the cyanide incident - and 58 involving microbiological agents. There were no radiation exposure incidents.

HPS said harm to humans had occurred in 18 of the 169 reported environmental incidents, with a total of 71 reported casualties and five deaths.

The most common chemical incidents reported to HPS involved dangers from smoke and asbestos, accounting for 32 environmental incidents. This included fumes from gorse fires.

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Leaks of methane, ammonia, chlorine, sulphuric acid, and carbon monoxide were also among the most common reports. An incident involving mercury released from a broken thermometer was also reported.

There were also two cases of acetone being used to manufacture explosives in residential properties, and one incident involved acetone being used to cause self harm.

The vast majority of microbiological incidents related to toxic contamination of lochs and water bodies with cyanobacteria - also known as blue-green algae.