Bomb teams sent to schools 600 times in chemical alert
Bomb disposal teams were called out to almost 600 schools in the wake of government advice about a potentially hazardous chemical.
The warning about stocks of 2,4 dinitrophenylhydrazine (DNPH) sparked a flurry of calls to the Army, which carried out hundreds of explosions.
The Department for Education (DfE) said it worked with the Army to support schools with "necessary disposals".
Some schools were criticised for not warning the public about the blasts.
The controlled explosions were carried out between 21 October and 21 December 2016 after schools were advised to check the chemical by the government advisory science service CLEAPSS (Consortium of Local Education Authorities for the Provision of Science Services).
The Ministry of Defence (MoD) figures were released to the BBC under the Freedom of Information Act.
Controlled explosions were carried out on at least 589 occasions. On four occasions visits were "doubled up", meaning the issue had been previously reported and dealt with. On one occasion verbal advice was given.
The chemical 2,4-DNPH is sometimes used in chemistry lessons and safe if stored correctly, but dangerous if allowed to dry out.
It is known to pose a risk of explosion by shock, friction or fire and is usually kept inside a larger container holding water.
The advice was to contact CLEAPSS in the first instance, which would then advise on the best way for the chemical to be disposed of.
In some cases, schools were advised to contact the Armed Forces or police, or take no action if it was believed the chemical posed no risk.
What is 2,4-DNPH?
- 2,4-dinitrophenylhydrazine is used in chemistry lessons and is perfectly safe if stored correctly
- A-level syllabus, where 2,4-DNPH was used in organic chemistry, has changed
- Action needs to be taken if there is evidence it has dried out because it could cause burns
- Destroying it with an explosion is one option
Dr David Kinnison, a chemical safety advisor, said the number of occasions was not a surprise as schools "did exactly as they were instructed".
"As a safety professional, I would always err on the side of caution," he said.
"Yes, there could have been possible other ways of dealing with this, however, the schools were presented with this advice.
"The positive is that a material which potentially could be unsafe was made safe, [and] the bomb disposal squads have gained some valuable experience," Dr Kinnison added.
Controlled explosions to dispose of the chemical were carried out on hundreds of occasions at schools across the UK.
The MoD said it cost just under £90,000 for the tasks to be carried out at English schools. It is still calculating the cost for tasks carried out elsewhere in the UK.
It said: "In line with policy on military assistance to the civil authorities, MoD will seek to recover costs from relevant authorities as appropriate. The MOD holds no information on additional costs incurred elsewhere."
The Thomas Adams School in Wem, Shropshire, attracted criticism from residents for not providing a public warning of the blast, which was carried out while children were trick or treating.
A government spokesperson said: "We contacted schools last year to remind them of the importance of storing chemicals for practical science activities carefully.
"We've been working with the Armed Forces and the police to support schools with any necessary disposals."