A five-year medical study in 13 mainland cities has found that one-tenth of all birth defects in Jiangsu province are caused by environmental pollution, with half of the remaining cases partly caused by environmental issues, the South China Morning Post reported. The number of birth defects on the mainland rose by 50% to 1.2 million from 2001 to 2006, but Jiangsu was chosen as the focus for the study as it had the largest data pool. The research team, led by Hu Yali of Nanjing University, found that the most common birth defect was congenital heart disease, which is closely related to air pollution. Cleft lip was the second most common birth defect; congenital hydrocephalus – excessive fluid in infants’ brains – the third most common. The study found that low-income groups were at greater risk for birth defects. Hu’s team will receive the Chinese Medical Science and Technology Award in Beijing today.