Air pollution increases premature birth risk

Pollutants in the air increase the risk of premature birth

10/10/2011

Air pollution in the form of particulate matter increases the risk of premature birth by 30 percent. This is the conclusion of US researchers who have examined possible relationships between air pollution and the premature birth risk in the Los Angeles area.

For a long time, there was a suspicion that air pollution has a negative influence on the course of pregnancies. „It has been known for some time that there is a link between air pollution, low birth weight and premature birth“, Head of Studies Beate Ritz from the University of California, Los Angeles, said in the current issue of the journal „Environmental Health“. According to the expert, however, it has not been clear to date which pollutants are exactly the cause of the complaints. In their study, the US researchers have now been able to prove that especially the particulate matter contained polycyclic aromatic hydrocarbons (PAHs), an increase in premature births.

30 percent increased premature birth risk from PAH
Up to 30 percent increase the risk of a premature birth through the PAH contained in the particulate matter, the statement of the US scientists in the journal „Environmental Health“. Other air pollutants such as benzene or diesel soot in car exhaust gases increase the premature birth rate by another ten percent, study leader Beate Ritz explained. Thus, for the first time the pollutants, which significantly increase the risk of premature birth, named clearly, with the results of the US researchers show, „that PAHs from vehicle exhaust gases are of particular importance“, stressed Ritz. To check for a possible link between air pollution and premature birth, over a 22-month period, the researchers analyzed the data from seven Los Angeles County air pollution control laboratories and California health officials' data on births around the United States Measuring stations compared. The pollutants collected at the monitoring stations, such as nitrogen oxides, ozone, particulate matter and carbon monoxide, supplemented the researchers with information on toxic chemicals provided to them by the air quality monitoring of the South Coastal Air Quality Management. They also incorporated into the investigation a model of the traffic exhaust gases produced in the Los Angeles metropolitan area. Birth data were based on the California Health Department's figures, with approximately 276,000 recorded births taken into account for just 110,429 where the mothers' home was within five kilometers of an air quality meter.

The higher the air pollution, the higher the premature birth risk
The result of the investigation was clear: the higher the air pollution, the higher the risk of premature birth. According to their own statements, the researchers were able to establish clear relationships between the spatial and temporal concentration of air pollution and the occurrence of premature births. The underlying process is believed to be triggered by the pro-inflammatory effect of the PAHs and other particulate matter, said the US scientists. Thus, the organic components of the fine dust cause an increased release of inflammatory substances in the mucosal cells and weaken the self-healing powers of the organism at the same time, explained Beate Ritz and colleagues. In addition, individual components of fine dust can cause damage to the mitochondria - the tiny cell power plants of the human organism - emphasized the US researchers. In doing so, they referred to earlier laboratory studies that had established a clearly negative effect of certain particulate matter on the mitochondria.

However, the scientists not only registered a negative direct effect of the particulate matter on the course of pregnancy, but also referred to the influence of substances such as ammonium nitrate, which arise only in the reaction of various air pollutants. At high concentrations of ammonium nitrate, the proportion of premature births had risen by 21 percent, suggesting the assumption, „that secondary pollutants also adversely affect the health of unborn children“, emphasized study leader Beate Ritz. Overall, US researchers rated their findings as an important contribution to assessing and significantly reducing the impact of air pollution on public health. (Fp)

Picture: Günter Havlena