Officials continue to search for the remaining 3,256 tonnes of carcinogenic cadmium waste illegally moved from Tak province, after tracing a total of 10,194 tonnes so far.
The first 2,440 tonnes were found at a smelting factory in Muang district of Samut Sakhon on Thursday, and on Saturday, a further 6,720 tonnes were discovered at a warehouse in tambon Khlong Kiew of Ban Bueng district of Chon Buri.
On Sunday, 1,034 tonnes were discovered at a warehouse in tambon Bang Nam Jued of Samut Sakhon's Muang district.
Industry Minister Pimphattra Wichaikul had originally led officials to inspect the smelting factory in Samut Sakhon where the carcinogenic cadmium waste was stored.
However, the minister said the quantities did not match the 13,450 tonnes shown in a document submitted by a company in Tak seeking permission to transport it to Samut Sakhon in August last year.
Ms Pimphattra said the chief of Tak's industry office has been transferred to work at the ministry pending the findings of the probe.
Officials said the cadmium tailings originated from a landfill in Tak province.
Mr Pimphattra said on Sunday the 1,034 tonnes found in tambon Bang Nam Jued of Samut Sakhon on Sunday were stored in piles, both inside and outside a foundry registered for copper melting.
She said the Department of Industrial Works and provincial industry offices have been told to locate the missing cadmium waste as quickly as possible.
The minister said the cadmium tailings seized during the raids will be sent to be buried at the original landfill in Tak to ease public concern.
On Saturday, police raided a warehouse in Ban Bueng district in Chon Buri and found 6,720 tonnes of cadmium waste in big bags. During the raid, police arrested the Chinese owner of the unregistered warehouse.
Officials quoted him as saying that he was a middleman who bought the tailings from another Chinese man in Samut Sakhon for 10,000 baht per tonne. He said the tailings were for resale in China.
Police charged the Chinese man with possessing hazardous substances and declared the warehouse off-limits.
Cadmium has many uses, notably in the production of rechargeable batteries, pigments, metal coatings, and plastics. However, its compounds are highly toxic to humans. Because of this risk, its disposal is tightly regulated.
Although the cadmium waste had been neutralised before being moved to the landfill in Tak, moving it from the landfill for melting elsewhere was illegal.
A worker at the factory in Samut Sakhon told police on Sunday that its owner gave him and his colleagues "medicine" to protect them from contamination.
On Thursday, Samut Sakhon governor Phon Damtham declared the smelting factory and the surrounding area off-limits for 90 days.
The government also ordered all the cadmium waste to be transported back to its origin within seven days and disposed within fifteen days.
The Pollution Control Department (PCD) collected samples of soil and air within a one-kilometre radius around the factory in Samut Sakhon and has not detected any cadmium contamination, said Preeyaporn Suwannaked, PCD director-general.
However, the department found high levels of contamination inside and in front of the factory, she said.