GUANGZHOU -?Four people were killed and more than 30 hospitalized after being poisoned by toxic glue in Guangzhou, capital of South China's Guangdong province, local authorities said Thursday.

A total of 38 people are suspected to have suffered from acute dichloroethane poisoning between September 28, 2011 and February 20 this year, according to the safety supervision bureau of the municipal government of Guangzhou.

The victims worked at 38 shoe and leather workshops in the city's Baiyun and Liwan districts, with 36 of the workshops found to be operating without a license.

Low-quality glue and poor ventilation contributed to the acute poisoning cases, the bureau said.

After an initial investigation, local police detained 21 people for selling toxic glue or illegally storing hazardous chemicals. A further investigation into the case is under way.

Dichloroethane, a carcinogen and a main ingredient in glue, can enter the body through the respiratory tract, alimentary tract and skin.