Traffic fumes increase diabetes risk in children

Living near a busy road and increased levels of pollution from cars and lorries significantly raised the risk of insulin resistance in ten-year-olds, scientists found.

The condition, which reduces the body’s ability to control blood sugar with the hormone insulin, is a recognised precursor of Type 2 diabetes.

Researchers in Germany looked at the effect of two kinds of traffic pollution on 397 children. Blood tests were taken and measurements made of pollution emissions in areas where the children lived.

For every defined step-rise in levels of nitrogen dioxide (NO2) and sooty particulate matter (PM) from diesel exhausts, the risk of insulin resistance increased by 17 per cent and 19 per cent respectively. The risk also rose by 7 per cent every 500 metres closer to a major road a child lived.

Study leader Dr Joachim Heinrich, from the German Research Centre for Environmental Health in Neuherberg, said: “To our knowledge, this is the first prospective study that investigated the relationship of long-term traffic-related air pollution and insulin resistance in children.

“Insulin resistance levels tended to increase with increasing air pollution exposure, and this observation remained robust after adjustment for several confounding factors, including socioeconomic status, BMI [body mass index] and passive smoking.”

The findings appear in the latest edition of the journal Diabetologia.

Previous research has linked air pollution, especially sooty particulates, with heart disease and premature death.

However, studies looking at associations between long-term exposure to traffic pollution and Type 2 diabetes in adults have been inconclusive.

The researchers are continuing to study the children, whose progress will be monitored for 15 years. They want to see how the children fare as they grow older and become adults. Individuals who stay in the area where they grew up and those who move will also be compared.

“The results of this study support the notion that the development of diabetes in adults might have its origin in early life including environmental exposures.”

Environmental health expert Professor Frank Kelly, from King’s College London, pointed out that children were especially vulnerable to air pollution.

“They have a larger lung-to-body volume ratio, their airway epithelium is more permeable to air pollutants, and the lung defence mechanisms against particulate matter pollution and gaseous pollution are not fully evolved,” he said.

“Breathing the same pollutant concentrations, children may have a two to four-fold higher dose reaching the lung compared with adults.”