More than 40 children in an industrial district of China’s Guangdong Province were found to have lead poisoning, state-media reported.

Authorities on Monday started health checks on all children living near a battery factory in Yinyuan district. That’s according to a statement from authorities in Qingyuan municipality where Yinyuan is located.

The factory, called Aokelai Power Company, was shut down on Saturday. The city’s environmental bureau ordered it to be closed after tests showed excessive amounts of lead in its discharge water.

Lead poisoning can cause irreversible neurological damage and other serious health problems.

In recent months, there have been similar reports of lead poisoning in Yunnan, Fujian, and Shaanxi provinces affecting more than 3,000 children. And in some regions, anger over lead poisoning has sparked protests.