A Taiwanese-funded battery plant in east China's Jiangsu Province is being probed after its employees were found to have excessive levels of lead in their blood.

More than 70 employees, or one-third of the total number of people employed by the Changzhou Ri Cun Battery Technology Co., Ltd., have been found to have extremely high levels of lead in their blood, according to sources close to the employees.

Medical tests showed that the employees typically had lead levels between 280 and 480 micrograms per liter of blood. "Normal" levels are below 100 micrograms of lead per liter of blood, according to national diagnostic standards.

Excessive amounts of lead in the blood harm the nervous and reproductive systems and can cause high blood pressure and anemia. In severe cases, it can lead to convulsions, comas and death.

The poisoning cases were exposed after a pregnant female employee named Zhang Xiaoyu fainted during her shift near the end of last month. She went to a local hospital, where she was found to have nearly double the normal amount of lead in her blood.

"The doctor told me I was poisoned by lead, and that my baby must be aborted," Zhang said.

Another employee, Meng Chunbao, believes that the factory's managers may have known about the problem but were trying to cover it up.

Meng said that after finding out that his own blood contained a high level of lead, he went to a deputy general manager to discuss the issue. During the meeting, the manager gave him 1,000 yuan (about 154 U.S. dollars) and asked him to keep the issue under wraps.

Meng went on to tell his colleagues about his blood test results, which ultimately lead to the exposure of the widespread poisoning. Company employees have said that although the company arranges for the employees to take medical tests every year, their medical reports are never given to them.

A joint investigation led by the management board of the Xinbei Industrial Park, where the plant is located, has been started.

The management board has sealed up the company's raw materials and semi-finished products and ordered the company to suspend production for the time being.

It has also told the company to arrange for medical tests for the employees and to compensate those who are found to have excessive levels of blood lead.

Lead poisoning is endemic in economically booming regions in east China.

Authorities in east China's Zhejiang Province have ordered thorough safety checks for all of the province's 273 battery factories after 332 people, including 99 children, living near a battery plant were found to have excessive levels of lead in their blood in March of this year.