The State Authority said, the waste was dumped by a truck on a river south of Johor state last week. Disposal of waste triggers toxic smoke.
More than 500 people suffer from symptoms of poisoning such as nausea and vomiting after accidentally inhaling toxic vapors originating from waste disposal.
Hundreds of people affected by sewage disposal have received treatment at various hospitals in Johor. About 110 victims, the majority of whom were school students, must be hospitalized. Until now, the Malaysian Government has not been able to ascertain the type of toxic gas that has triggered poisoning and school closure.
Meanwhile, Malaysian Education Minister Maszlee Malik said, in order to prevent more victims he ordered the closure of hundreds of schools.
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"The Ministry of Education decided to close 111 schools in the Pasir Gudang area (Johor)," said Maszlee.
At present the authorities have arrested three people responsible for waste disposal. They will soon be tried on charges of violating the environmental protection law. If proven guilty the perpetrators face a three-year prison sentence.