The 266 factory workers who were found to have excessive blood cadmium levels in northwest China's Gansu Province are still being treated and would need three months to fully recover, the local government said Saturday.

The workers, from a zinc smelting factory owned by the Gansu Baohui Industrial Group Co. Ltd. in Huixian county, were all diagnosed over the past month, after the first case was detected on October 23, the county government said in a statement.

Of the 71 workers who were hospitalized at the People's Hospital in Huixian County, nine had excessive cadmium levels in both their blood and urine, said the hospital's vice president Cao Weizhi.

Cao said most of the patients were local peasants and nine were women. "They need medication and diet intervention. Their blood cadmium levels will hopefully fall after three months of treatment."

Another 195 workers are receiving treatment at the factory with the instructions of industrial disease specialists in Xi'an, capital of the neighboring Shaanxi Province.

An initial investigation showed inadequate protection was to blame for the incident.

The zinc smelting factory with 869 employees was ordered to stop production after the incident.

Its management has promised to pay all the workers their wages in full during the suspension, plus additional food allowances for the patients.

Acute exposure to cadmium fumes may cause flu-like symptoms, including chills, fever and muscle aches. More severe exposure can cause tracheo-bronchitis, pneumonitis, and pulmonary edema.