About 200 schools and kindergartens in the town have been closed after a lorry dumped toxic waste in a local river last week.
The number of those needing medical treatment has been rising. On March 15, the figure reached 2,355, including 113 still in hospital.
Prime Minister Mahathir Mohamad visited victims in hospital the previous day and urged competent agencies to promptly handle consequence of the incident.
The Malaysian military has been deployed along with hazardous waste experts to respond to the emergency and clean up the river.
Local media have reported the waste was a type of oil used to lubricate ship's engines which emitted methane and benzene fumes. Up to 40 tonnes of the toxic substance is believed to have been tipped into the river.
Three men have been arrested over the dumping of the waste and face up to five years in jail if convicted of breaking environmental protection laws.
