GOPENG (THE STAR/ASIA NEWS NETWORK) - There is no proof to show that the toxic waste incident at Johor's Sungai Kim Kim four months ago caused a 12-year-old boy to suffer from myokymia, an ailment that causes parts of the body to tremble.

Malaysian Deputy Health Minister Lee Boon Chye said the authorities conducted background checks on Irfan Wafiy Idham Wazir and found that he was born prematurely and had a history of fits since he was four.

"He was assessed by a paediatric neurologist. There's been no evidence so far to show it is related to the incident," Dr Lee said on Saturday (July 6).

"We know that myokymia is a disease that can be caused due to a brain tumour, brain infection or injury," he added.

Ifran - a pupil at Sekolah Kebangsaan Taman Bukit Dahlia - developed the Parkinson's-like condition after experiencing breathing difficulties in March.

It is believed that he had sniffed poisonous gases at the school in Johor, following which he was admitted to Sultan Ismail Hospital, Bernama reported.

Irfan, the fourth of five siblings, was in hospital for 10 days, during which his health progressively deteriorated.

He was subsequently diagnosed with myokymia after he was referred to the Kuala Lumpur Hospital.

On March 7, 105 students and residents near Sungai Kim Kim experienced symptoms including nausea, headaches, unconsciousness and breathing difficulties after chemicals were dumped in the river.

Then, on March 11, a second wave of people fell sick, with as many as 1,000 hospitalised within the course of several days, including eight in the intensive care unit.