Nearly a quarter of infants in the Chinese capital Beijing consumed milk formula tainted with melamine before the products were taken off store shelves.
The state Xinhua news agency reported that a government survey of more than 307,000 Beijing families with children under the age of three found that over 75,000 babies had been fed contaminated milk formula.
The survey involved door-to-door screening and was ordered by the Beijing Municipal Health Bureau and carried out from September 20 to October 24.
Four children have died and thousands of others have fallen ill from drinking milk formula adulterated with melamine, which was subsequently found in other drinks and foods, prompting Chinese-made products to be pulled from shelves worldwide.
More than 3,000 children remain in hospital in China.
Chinese officials have promised that all milk products on the country's store shelves are now safe and vowed to bring its food products up to international standards.
China is reviewing a tougher draft food safety law following criticism from the United Nations over its sluggish response to the health scandal.