Air Pollution May Be Interfering With Prenatal Hormone Activity

Air pollution and its effects on human respiratory health are well documented. Researchers from Rutgers University have now uncovered its potential impact on prenatal hormone health and infant reproductive development. The new paper, published in Environmental Health Perspectives, reports on how exposure in utero can have long-term consequences on human health.

Air pollution and human health

Previous studies have uncovered several links between air pollution exposure and its detrimental effects, leading to around 7 million deaths worldwide per year. Animal studies have shown gestational and perinatal exposure to diesel exhaust and concentrated particulate matter alter known markers of prenatal androgen activity in both sexes. Dr. Emily Barrett, a professor in the Department of Biostatistics and Epidemiology at the Rutgers School of Public Health and team suspected these effects may also be seen in humans.

The researchers used data from The Infant Development and Environment Study (TIDES), an ongoing longitudinal study of pregnant women and their children launched across four US cities in 2010, to investigate.

TIDES gathered data including anogenital distance (AGD), the length between the genitals and the anus, which can be used as a marker of semen quality, fertility and reproductive disorders. “When AGD is reduced in male offspring, it’s a sign that a toxic exposure is interfering with fetal testosterone production,” said Barett.

Data on AGD, recorded at birth in children and at one year of age in boys, were compared with levels of nitrogen dioxide (NO₂) and fine particulate matter, via an air pollution monitoring system that tracked the pollution levels in the residential areas of TIDES participants during pregnancy.

Higher PM2.5 exposure (particle pollution 2.5 micrometers or smaller released during the burning of gasoline, oil, diesel and wood) during the male programming window at the end of the first trimester – when the male fetus typically receives a surge of hormones – was associated with shorter AGD at birth. 

Similar results were observed when PM2.5 exposure was higher during mini puberty (a period in early infancy when hormone production is high). Increased NO₂ exposure was also associated with smaller penile width at one year of age. “These findings suggest air pollution may interfere with normal hormone activity during critical periods of prenatal and early infant development,” said Barrett.

The researchers also observed that AGD was inversely associated with PM2.5 exposure in females.

Lifelong impacts on human health

There is a shortage of studies identifying links between an altered infant AGD and adult health. However, some studies have suggested that adult AGD may be a marker for a wider array of reproductive health concerns, including endometriosis and polycystic ovary syndrome in females, as well as reduced semen quality and fertility in males.

Further longitudinal studies are needed to understand how these pollutants may have an impact on long-term human health and to clarify the mechanism behind these results.

“When these disruptors interfere with the body’s hormones, the result could be lifelong impacts on our health, from cancer risks to impaired ability to conceive a child,” Barrett concluded.

Reference: Barrett E, Sharghi S, Thurston S, et al. Associations of exposure to air pollution during the male programming window and mini-puberty with anogenital distance and penile width at birth and at one year of age in the multicenter U.S. TIDES Cohort. Environ Health Perspect. 2023. doi: 10.1289/EHP12627

This article is a rework of a press release issued by Rutgers University. Material has been edited for length and content.