In a small study of 28 women, researchers in Belgium have found black carbon particles on the foetal side of the placenta in women exposed to air pollution during pregnancy. These particles are released largely from the combustion of fossil fuels and are thought to impact pregnancies through pre-term births or low birthweights. Using high-resolution images, researchers were able to detect black carbon in all 28 placentas, with those women who were exposed to high levels of residential air pollution during pregnancy having higher levels.

The research, published in Nature Communications has attracted a strong response from around the world, including here in New Zealand.

Dr Ian Longley, Principal Scientist – Air Quality, National Institute of Water & Atmospheric Research (NIWA) says it is reasonable to assume that the exposures in the Belgian cohort would be comparable to what you would find in urban New Zealand.

Associate Professor Jennifer Salmond from the School of Environment at the University of Auckland says in high income countries like New Zealand, urban air quality is often dominated by traffic emissions which are also an important source of black carbon.

“This is true for Auckland. In such cities, we know that concentrations of air pollution vary significantly in time and space and we see steep gradients in concentration near busy roads. We also know that for adults in cities like Auckland, daily exposure is primarily determined by time spent in the commuter microenvironment. However, in the specific case of black carbon the importance of exposure the indoor environment is largely unquantified and poorly understood. Sources of black carbon in the indoor environment include wood burning stoves.”

“Children are particularly vulnerable to poor air quality during fetal development and in the first few years of life when exposure can result in life long changes to development and permanent damage to lung tissue. Although previous studies have shown that it is possible for fetal development to be affected by poor air quality, this study is important because it is the first study to demonstrate that black carbon can cross into the placenta,” says Salmond.

Associate Professor Christine Jasoni, Director of the Brain Health Research Centre at the University of Otago says perhaps the most alarming aspect of this study is that black carbon particles from air that is not even considered to be particularly polluted by WHO standards is nevertheless accumulating in the placenta, where it could be affecting the health of the unborn child across its entire life.

However, Salmond says linking the exposure of the mother to a specific air pollutant such as black carbon, with specific health outcomes of the foetus (and children as they grow up), is very difficult.

Indeed, the authors of the study agree that additional research is required to understand whether the accumulation of black carbon particles in placental tissue may be responsible for the adverse effects associated with air pollution exposure during pregnancy.



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