Early life exposure to environmental hazards and infant health

The impact of harmful environmental factors on human health has become a major concern, especially during the prenatal and early postnatal stages of development. Exposure to these factors can result in long-term effects that may affect future generations. Although numerous studies have investigated the effects of environmental hazards in high-income countries, there is an urgent requirement for more research in low-middle income countries, particularly those experiencing significant declines in air quality. This thesis is based on two population studies conducted in Jakarta, the capital city of Indonesia.

The first part of the study examines the influence of household hazards on infant growth in mothers during pregnancy. The findings indicate that infants born to mothers heavily exposed to secondhand smoke during pregnancy had a significantly smaller head circumference at birth (11.09mm) compared to infants from nonexposed mothers. This trend continued in the first six months of life. Additionally, we observed that infants born to mothers exposed to household pesticides during pregnancy had a considerably lower head circumference (-7.1 mm) compared to infants from nonexposed mothers. This effect was even more pronounced in a subset of infants from mothers exposed to pesticides other than mosquito insecticides (-22.1 mm).

The second part of the thesis focused on the impact of exposure to outdoor air pollution during the antenatal and perinatal periods on infant health. Antenatal exposure to soot and NOx was observed to correlate with reduced birth length. Specifically, for every 0.74 x 10-5 per m increase in soot concentration, there was a birth length reduction of 3.83 mm. Similarly, for every 4.68µg/m3 increase in NOx concentration, there was a birth length reduction of 2.82 mm. Exposure to PM2.5 and soot during the perinatal period was also related to a higher risk of upper respiratory tract infections (URTI). Specifically, for every increase of the interquartile range (IQR) in PM2.5, the odds of URTI increased by 1.50. Likewise, for every IQR increase in soot, the odds increased by 1.14. Additionally, exposure to outdoor fine particles (PM2.5 and soot) during pregnancy and early infancy was associated with higher systolic blood pressure in infants during the first six months of life. To be more specific, every 7.1 μg/m3 increase in perinatal PM2.5 exposure corresponded to a 2.3 mmHg increase in infant systolic blood pressure at one month old.

Our study provides evidence to inform policymakers about the negative effects of exposure to environmental hazards on children's health, especially for the fetus's fetal growth, immune system, and cardiovascular health. It also emphasizes the importance of collaboration among various stakeholders to effectively address environmental hazards. Furthermore, we have partnered with nongovernment organizations (NGOs) to raise awareness and advocate for policy changes in this regard. In line with our findings, we strongly recommend the establishment of a dedicated division for environmental health within both the government and university systems. These comprehensive efforts aim to improve children's health outcomes and actively contribute towards attaining the Sustainable Development Goals.