The tests on samples of Chinese grenade-shaped toys that caused health problems to 37 students in Dak Nong Province have shown that they contain sodium bicarbonate and citric acid, local police reported.

>> 7 students re-hospitalized due to grenade-shaped Chinese toys >> 37 students suffer from harmful Chinese grenade-shaped toys

On Thursday, police in Dak Song District in the Central Highland province of Dak Nong announced the results of the tests taken on samples of grenade-shaped Chinese toys that explode when slapped or stamped on.

The tests had been carried out by the Sub-Institute of Criminal Sciences.

Accordingly, sodium bicarbonate and citric acid were identified in the samples, but they are not listed as banned toxic substances, police said.

When force is applied to the toy—a rather flat plastic bag with many Chinese characters on it--the two chemicals, each of which is contained in a small pack within the bag, interact to form CO2 that explodes due to high pressure created from the force, investigators explained.

As previously reported, a lot of students form Chu Van An Primary School in the province were hospitalized on January 16 after playing with this toy, which exploded in their faces and produced a pungent odor.  

Some children are looking at a Chinese grenade-shaped toy that is easy to explode when slapped or stamped on (Tuoi Tre)

As a result, 37 students who inhaled or were exposed to the odor suffered from difficulty breathing, chest pain, muscular contractions, headaches, rashes, and bloody feces. Many of the students even passed out.

They were taken to the Dak Song General Hospital for treatment. Many victims had to be put on respirators or were given intravenous transfusions, doctors said.

After one day of treatment, all 37 students had recovered and were discharged, but seven of them were taken to Dak Nong General Hospital again on the afternoon of January 19 after they suffered from the same symptoms they experienced several days before.

After receiving intensive treatment, three of the students were discharged while the others remained in the hospital for further treatment.

Many students told police that they had bought the toys from a shop near the entrance of the school for only VND1,000 (US$0.05). The police later examined the shop and seized all of the grenade-shaped toys found within.