Twelve kinds of common cooking in Hanoi are contaminated with lead, the National Institute of Nutrition said last week after a one-year study.

The research conducted between March 2009 and March 2010 at four major districts in Hanoi showed that 12 tainted kinds of food include water morning glory, rice, pork, beef, chicken, shrimp, oranges, mandarins, tomatoes, eggs, powdered and fresh milk.

The report states that rice, pork, water morning glory, shrimp, oranges and mandarins had the highest content of lead.

The researchers took the samples of food from four major markets and supermarkets based on the daily menu for children aged between two and three years old in several city-based kindergartens.

The content of lead in the 12 kinds of food exceeded the level allowed by the Health Ministry, even when the vegetables were carefully washed before cooking, according to the report.

The report concluded that food may have been contaminated because of dust from construction, traffic vehicles and water pollution in residential areas.

Le Thi Hong Hao, deputy director of the National Institute for Food Safety and Hygiene Tests said people, especially children, can suffer from kidney failure and cerebral edema if eating lead-tainted food.