Residents living near the site of the Grangemouth Port chemical leak have raised concerns about a lack of information on the incident.
Several residents said they were not aware of what had happened until Thursday morning.
A number of people have said officials and emergency services should have made a greater effort to inform them.
However, Central Scotland Police said that information was given out as soon as it was "practical to do so".
They added that as a precautionary measure, a 500m exclusion zone has been set up around the tank where the chemical leaked.
The incident happened away from Scotland's largest oil refinery in Grangemouth which is run by Innovene.
Liz Sinclair, who lives near the entrance to the dockyard, said she first became aware of the incident - which happened at about 1600 BST on Wednesday - from a news report on Thursday morning.
Pale straw-coloured liquid
Used in making plastics and resins
Volatile between 30C and 95C
Exposure caused by breathing in vapours or contact with skin
Can cause irritation to eyes and nose
Little information on long-term health effects
She said: "I am deeply concerned that, although it was described as a major incident, there were no warnings issued to residents.
"I was at home all evening, windows open because it was warm, and heard no recorded warnings, no siren, no announcements of any kind."
Ms Sinclair said she was glad that the situation was brought under control, but added: "It leaves me with definite concerns that, should a similar event occur in the future, I may be endangered through lack of information, action and support from my local authority."
Another resident, Stuart Dales, who also lives close to the docks, on Grangeburn Road, claimed that nobody was alerted to the chemical leak.
Mr Dales said he first learned of the incident through a neighbour who works at the docks, adding: "No police came round to inform anyone and no sirens went off.
"All you could see were fire engines, and that in itself is a regular occurrence."
The chemical, which was inside a storage tank on a quayside within the docks area, was divinylbenzene.
It is delivered on a regular basis and had been unloaded from a cargo vessel. It was due to be delivered to Rohm and Haas, which has a facility in Grangemouth.
Friends of the Earth Scotland chief executive, Duncan McLaren, said residents should have been better informed.
"I'm very disturbed that the public weren't informed much more directly about this incident," he said.
The emergency was dealt with by Central Scotland Police, Central Scotland Fire and Rescue Service, Falkirk Council, Sepa, the Health and Safety Executive, Forth Valley Health Board, Forth Ports, the Scottish Executive and industry partners.
The action taken was established under the Central Scotland Strategic Co-ordinating Group protocols.
In a news release issued on Thursday afternoon, Central Scotland Police said: "Efforts are being made to minimise any disruption to members of the public.
"Police are advising the public to continue with their normal business and will provide updates as the situation develops.
"Information is made available to the public as soon as it is practical to do so."
Dr Mel Cooke, director of chemical regulation advice company Alchemy Compliance, said divinylbenzene was a substance which is used to make plastics.
He told BBC Scotland's Newsdrive programme: "It's actually quite a reactive substance, the problem is that it can react with itself and normally large quantities of the material have to have a second chemical added to it, an inhibitor, to stop it reacting and producing large amounts of heat.
"If the substance is heated it could boil or produce large amounts of vapour.
"There's not a great deal known about the health affects of the vapour, it's not a particularly toxic substance, but it would cause irritation of the particularly sensitive parts of the body, the eyes, the nose and throat if it were breathed in."
Dr Cooke said that divinylbenzene is particularly toxic to fish and does not biodegrade quickly in the environment.
He said the investigation would be likely to focus on whether there was heating which could have caused the leak.
He added: "One possibility is that if the material is placed in an unclean storage unit it may react with residues of material that are already in there, there are a number of possibilities, but if it began to react with itself or some other material that would cause a large amount of vapour and the pressure could cause an uncontrolled release."