SHANGHAI - Three companies were responsible for an incident last year in which dozens of children developed lead poisoning, according to a report by the municipal government.

In late September, 49 children, mainly between the ages of one and three, were found with elevated blood lead levels. They were among the 1,306 children living in the Kangqiao area of the city's Pudong district who had pre-school physical exams.

With excessive lead in their blood, 7-year-old Gu Hao (left) and his 21-month-old sister Gu Xinyu receive treatment in September at Shanghai's Xinhua Hospital, which is affiliated with Shanghai Jiaotong University's School of Medicine. [Zhang Long / for China Daily ]

The children were sent for treatment, and environmental and health authorities carried out an investigation.

The investigation found that the children were exposed to high levels of airborne lead in their living environments, according to the government report released on Saturday.

The report said a battery plant, an auto parts manufacturer and a recycling company were connected to the lead poisoning.

The report said Shanghai Johnson Controls International Battery Co Ltd was identified as the major source of lead contamination in Kangqiao. It said the company expanded its production without government permits, and discharged excess airborne lead.

Shanghai Xinmingyuan Automobile Parts Co Ltd was found to have made an unauthorized change in its production technology involving lead.

Excessive levels of lead and zinc were found in the soil near the plant of Shanghai Kangshuo Waste Recycling Co, which recycles used goods and materials.

Production involving lead at Shanghai Johnson Controls and Shanghai Xinmingyuan Automobile Parts has been shut down. The companies were ordered to take responsibility for the pollution.

Shanghai Kangshuo Waste Recycling Co, which had since relocated, was ordered to carry out soil remediation.

Three of the children remain in the hospital. The report said the children were in stable condition and their conditions had gradually improved.

The Shanghai Pudong district government said it would thoroughly assess the environmental conditions in the Kangqiao area and adjust the industrial structure of companies that use lead in their production processes.

The municipal government plans to develop emissions standards for battery plants and strengthen monitoring of such facilities to avoid a repeat of this problem.

In recent years, there have been several reported cases of children being poisoned by lead from battery plants.

Also this month, more than 90 children in Dongtang town, Renhua county of South China's Guangdong province, were found to have elevated levels of lead in their blood. Local environmental authorities are still investigating the cause.