Investigators have detained 19 people and are questioning 78 to find out how melamine was added to milk supplied to Sanlu Group Co., China's biggest milk powder producer, officials said at a news conference. They said some tainted powder was exported to Taiwan but none was sent to other foreign markets.
In Taiwan, authorities seized thousands of bags of Chinese milk powder. There was no word on whether any was consumed in Taiwan.
Chinese officials defended the speed of their response to the country's latest product safety disaster. They said authorities were only told of the contamination Monday, even though Sanlu received complaints as early as March and its tests found melamine in August.
"For a comparatively long time, the Sanlu Group failed to report this incident to the government," said Health Minister Gao Qiang. "The Sanlu Group should shoulder major responsibility for this."
Gao gave no indication what penalties Sanlu might face but said those to blame would "be dealt with severely."
Officials are investigating whether word of the contamination was suppressed, said Vice Gov. Yang Chongyong of Hebei province, where Sanlu Group is located.
"We will look into whether government at any level was negligent or whether any officials tried to withhold information," Yang said. "If we find anyone did this, they will be held accountable."
Yang said he did not know the identities of the people detained but said investigators were looking into whether dairy farmers added the chemical.
Gao said it might have been done to fool quality tests after water was added to fraudulently increase the milk's volume. Melamine is rich in nitrogen, and standard tests for protein in food ingredients measure nitrogen levels.
The number of cases of kidney stones in babies who were fed Sanlu milk has risen to 432 in areas scattered around China, Gao said. He said Beijing was sending experts to treat them and will pay for their care.
"We are confident that with timely diagnosis and treatment, these infant patients will recover soon," he said.
The incident reflects China's enduring problems with product safety despite a shake-up of its regulatory system after a spate of warnings and recalls about tainted toothpaste, faulty tires and other goods.
The biggest group of victims is in China itself, where shoddy or counterfeit products are common. Infants, hospital patients and others have been killed or injured by tainted or fake milk, medicines, liquor and other products.
Authorities have seized 2,176 tons of Sanlu formula and ordered a recall totaling 8,218 tons, Yang said. That was far more than the 700 tons in Sanlu's initial recall announcement on Thursday. Yang gave no indication whether the recall might increase.
Beijing has launched an emergency inspection of all 175 companies in China that produce infant formula, Gao said.
In Taiwan, Liu Fang-ming of the Taoyuan county government said the Chinese shipment of milk powder, which arrived in June, was 55,115 pounds. Liu said only 21,660 pounds had been recovered.
Taiwan and China split in 1949 amid civil war and have no formal relations, but indirect trade is booming. Gao said Beijing informed Taiwan through the agencies that maintain informal contact between the two governments.
Xinhua cited a Gansu provincial health department spokesman as saying he received reports on July 16 that 16 infants under a year old, all of whom drank Sanlu milk, were suffering a rare kidney ailment. He said the Health Ministry launched an epidemic survey.
"However, there seemed no food and safety survey had been done. Otherwise, the health, and even lives, of many infants could have been saved," Xinhua said.
A Sanlu manager quoted by the newspaper Beijing News said the dairy received complaints in March and June but could not track down the problem.
"We finally imported foreign equipment in August and finally found the milk powder contained melamine," said the manager, identified only by the surname Wang.
Sanlu buys milk from a nationwide network of suppliers that includes 60,000 family farms, according to its Web site.
This is China's second high-profile case in four years involving harmful baby formula.
In 2004, more than 200 infants suffered malnutrition and at least 12 died after being fed phony formula with no nutrients. Some 40 companies were found to be making phony formula and 47 people were arrested.
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