Respiratory disease affects millions of people worldwide. Since many of these diseases originate early in life, it is important to evaluate the factors that can influence the risk of developing respiratory problems. This was reflected in a number of presentations at the 28th European Respiratory Society (ERS) International Congress, which was held in Paris, France on 15–19 September, 2018.
Among the research presented at ERS was an analysis of data from RHINESSA (Respiratory Health in Northern Europe, Spain and Australia, www.rhinessa.net), a large international study that has been investigating factors affecting lung health in children and adults. The study evaluated the average exposure of ‘greenness’, as assessed by means of a Normalised Difference Vegetation Index, which uses satellite images to quantify the amount of vegetation in an area, in 5,415 participants. In addition, investigators analysed exposure to air pollution in 4,414 participants. Preliminary results have shown that exposure to particulate matter and nitrogen dioxide increased the probability of late onset asthma by 6–23%, whereas exposure to greenness before the age of 10 was associated with a 71% lower probability of wheeze, and exposure to greenness between the ages of 11 and 18 was associated with a 29% lower probability of respiratory symptoms and a 39% lower probability of wheeze. It is hoped that these findings will allow clinicians and policy-makers to recognise the importance of exposure to pollution and access to green spaces, and use these data to advise patients and ultimately improve public health.1,2
It has long been known that exposure to certain chemicals in the womb may be associated with childhood respiratory diseases such as wheezing, asthma and chest infections. A new study presented at ERS is the first to show a link between objective measures of lung strength and capacity, and low-level exposure to organochlorine compounds, which include pesticides such as DDT, as well as electrical insulators and other industrial products. Although the use of organochlorine chemicals were banned in the 1970s, their slow degradation and accumulation in fatty tissue means that people are still exposed to them through food. The study involved 1,308 babies who were born in the Valencia, Gipuzkoa, and Sabadell regions of Spain between 2004 and 2008. Investigators measured the levels of 7 different organochlorine compounds in the pregnant mother's blood or in blood taken from the umbilical cord. The children’s lung function was evaluated at 4 and 7 years. In particular, exposure to DDE, a breakdown product of DDT, was associated with poorer lung function in children at both 4 and 7 years old.3,4 Women of reproductive age can reduce their exposure of these chemicals by limiting their intake of food that contain organochlorine compounds such as oily fish and fatty meat.4
While it is known that air pollution affects foetal development, the mechanism underlying this effect is not fully understood. In a study presented at ERS, carbon particles from burning fossil fuel have been found in placentas for the first time. The study involved the placentas of five women, all of whom were non-smokers, had uncomplicated pregnancies and gave birth to healthy babies. Researchers examined 3,500 placental cells under a microscope and discovered 60 cells that between them contained 72 small black areas, believed to be carbon particles. Each placenta contained approximately 5 µm2 of this black substance. A further study of placental macrophages under an electron microscope also showed particles that appeared to be black carbon. It is hoped that this study will raise awareness of the harmful effects of air pollution in pregnant women.5,6
Bacterial infections during and before birth are also known to cause respiratory problems in infants. A study investigated the presence of Ureaplasma bacteria, which are found in the birth canal and associated with respiratory infection in newborns,7 in the noses and trachea of 121 premature babies born between 24–28 months' gestation, and followed up for their first year of life. Ureaplasma was found in 36% of all the babies in the study, but this rose to 45% among the most premature babies born between 24–26 weeks' gestation. Compared with babies without the infection or those who only had the bacteria in their nose, babies who had Ureaplasma in their trachea at birth were less likely to survive (71% compared with 90% and 100%, respectively), and were more likely to develop bronchopulmonary dysplasia and other respiratory problems during their first year of life (67% compared with 50% and 21%, respectively). Half of the babies with Ureaplasma were treated with a 3-day course of azithromycin (20 mg per kg of the baby's weight per day), while the others were given a placebo. This was found to be safe and effective in terms of eradicating Ureaplasma bacteria.8,9 While the study did not provide sufficient evidence to suggest that routine screening and treatment for Ureaplasma should be carried out in premature babies, further large clinical trials are warranted.9
The real need for prenatal screening for Chlamydia trachomatis has been highlighted in previous studies.10 A new study of 2,294 children found an association between maternal C. trachomatis infection during pregnancy and early childhood wheezing and school-age asthma. Further studies are needed to investigate the underlying mechanisms and clinical implications of this finding.11
These presentations have highlighted the challenges posed both by exposure to environmental pollutants and infection to childhood respiratory development There is a need for additional studies on birth cohorts to monitor the relationship between the exposure of pregnant women to pollutants and the respiratory development of their children.
1. European Respiratory Society (ERS). Green space near home during childhood is linked to fewer respiratory problems in adulthood. Available at: https://erscongress.org/about-ers-2018/media-centre/press-releases/143-press-releases/618-green-space-childhood-lung-problems.html (accessed 8 October 2018).
2. Kuiper IN, Svanes C, Abramson MJ, et al. Lung health in adulthood after childhood exposure to air pollution and greenness. Presented at the 28th European Respiratory Society International Congress, 15–19 September, 2018, Paris, France. Abstract OA5186.
3. Casas M, Abellan A, Garcia R, et al. Prenatal exposure to organochlorine compounds and lung function until early adulthood. Presented at the 28th European Respiratory Society International Congress, 15–19 September, 2018, Paris, France. Abstract PA5015.
4. European Respiratory Society (ERS). Exposure to organochlorine pesticides in the womb linked to poorer lung function in childhood. Available at: https://erscongress.org/about-ers-2018/media-centre/press-releases/143-press-releases/616-organochlorine-pesticides-womb-childhood-lungs.html (accessed 8 October 2018).
5. Liu N, Miyashita L, McPhail G, et al. Do inhaled carbonaceous particles translocate from the lung to the placenta? Presented at the 28th European Respiratory Society International Congress, 15–19 September, 2018, Paris, France. Abstract PA360.
6. European Respiratory Society (ERS). First evidence that soot from polluted air is reaching placenta. Available at: https://erscongress.org/about-ers-2018/media-centre/press-releases/143-press-releases/612-soot-pollution-placenta.html (accessed 9 October 2018).
7. Viscardi RM. Ureaplasma species: role in neonatal morbidities and outcomes. Arch Dis Child Fetal Neonatal Ed. 2014;99:F87–92.
8. Viscardi RM, Terrin M, Magder L, et al. Azithromycin (AZM) reduces death or severe respiratory morbidity at 12 month adjusted age (AA) in Ureaplasma-positive intubated preterms. Presented at the 28th European Respiratory Society International Congress, 15–19 September, 2018, Paris, France. Abstract OA301.
9. European Respiratory Society (ERS). Bacteria passed on in the womb is linked to premature birth and breathing difficulties but could be safely treated with antibiotics. Available at: https://erscongress.org/about-ers-2018/media-centre/press-releases/143-press-releases/609-bacteria-passed-in-womb.html (accessed 9 October 2018).
10. Angelova M, Kovachev E, Tsankova V, et al. Role and importance of chlamydia trachomatis in pregnant patients. Open Access Maced J Med Sci. 2016;4:410–2.
11. van Meel ER, Moll HA, Reiss IK, et al. Associations of maternal Chlamydia trachomatis infection with wheezing,lung function and asthma in children. Presented at the 28th European Respiratory Society International Congress, 15–19 September, 2018, Paris, France. Abstract PA5013.