Kiambu Governor Kimani Wamatangi has called on residents to be vigilant after a truck carrying sodium cyanide along the Nairobi-Nakuru highway overturned.
The incident is said to have happened at the Kambembe area in Rironi causing spillage of the highly toxic substance.
Wamatangi said the chemical being transported was highly poisonous and hazardous with far-reaching health effects.
While addressing the press on Monday, the governor said the chemical has fatal consequences.
According to him, there are 12 drums of the chemicals that are still missing.
"We can't tell whether they are still within the Rironi or Limuru area or whether they have found their way as far as across the other 12 sub counties of Kimabu or even beyond," he said.
Wamatangi called on the residents to report any information about those hiding the chemicals.
"If by any chance there is a member of the public involved, it is important for you to know that already, you would have exposed yourself to the dangerous effects of that chemical," he said.
"Anyone that was involved should voluntarily surrender themselves to the nearest health facility and have themselves examined and for possible treatment to prevent any further harm."
The governor said that it is highly possible that part of the chemical was spread by rain to vicinity areas.
He said that it was important for the residents to be highly cautious.
Governor Wamatangi added that the county has despatched health personnel to observe the state of health of the residents.
Wamatangi said that enforcement officers should ensure that no one is allowed to pass or cross a check mounted in the Kiambu area.
He said the move would help to expose the residents to the chemicals.
"If anyone is seen transporting anything in a drum or containers, we want to urge the enforcement agencies to ensure no one is allowed to pass or cross a check to ensure no one is transporting chemicals," he said.
He said that the chemicals are valueless because they cannot be sold by an ordinary person.
Wamatangi said that Kiambu residents should take urgent precautionary measures.
"If you see that drum or you know where it is, don't carry it yourself, report to us because you don't have the kits, dress and precautionary to carry it to the police station or the county government offices. Wherever it is, report, we shall come to collect it," he added.
Wamatangi warned the transporters and companies in the field of the chemicals on transportation on the roads.
He said it is irresponsible that chemicals and substances of such high risk and highly poisonous should be transported in that manner.
The governor said that such vehicles should be transported with extra care that also includes escort.