Over the past 30 years, China has experienced the largest rural-to- urban human migration in history with its urban population growing from 191 million in 1980 to 622 million in 2009. In a study published in the latest edition of The Lancet, researchers from Emory University examined some of the public health consequences of this rapid urbanization, including higher disease rates and greater health care disparities.

Using the criteria that defined urban in China’s 2000 census, Justin V. Remais, PhD, assistant professor of environmental health at Emory’s Rollins School of Public Health and colleagues examined the growth of urban areas, including both the rise in population density and geographical expansion within these areas.

In 2011, the proportion of the population living in urban areas overtook that living in rural areas for the first time ever in China and an additional 200 million rural-to-urban migrants are anticipated during the next 10 years.

Researchers found that while there are health benefits of urbanization because of better access to services, education and higher incomes, the health risks are significant.

A major threat is the absence of continuous health-care coverage of rural-to-urban migrants putting many at risk of a dual infectious disease burden.

"Migrants can be exposed to pathogens associated with rural poverty like parasitic worms found in the soil, while also being susceptible to urban diseases found in crowded environments such as tuberculosis," says Remais. "This is especially concerning when we know many of these people will not receive continuous care as they make the move from country to city."

Remais and his colleagues also cite changes in nutrition and lifestyle choices in urban areas as major public health challenges, along with environmental concerns.

"Urbanization has led to changes in patterns of human activity, diet, and social structures in China, with profound implications for non-communicable diseases—e.g., diabetes, cardiovascular disease, cancer and neuro-psychiatric disorders," the authors write.

"The increasing population pressure on cities exacerbates environmental pollution, as for instance more urban-dwellers means more cars on the road, which contributes greatly to poor air quality in cities. Road traffic and occupational accidents are major sources of ill health as well, especially for rural-to-urban migrants."

The authors call for innovative health policies that address the needs of migrants while providing health services for people, especially older people and the very young, who remain in rural areas. They say health care providers and policymakers in China must be aware of the health risks that accompany rapid urbanization, particularly given the decades of urbanization still ahead.  

Full study available via The Lancet.