Exposure of pregnant women to air pollution could affect the development of the sex organs of their sons in ways that have been linked to fertility later in life.
Fine particulate matter is released from fossil fuel combustion, for example, by car engines, and exposure has previously been linked to sperm motility in adult men (see BioNews 1133). USA-based researchers have now shown that exposure to particulate matter during weeks eight to 14 of pregnancy, when the anatomy of different-sex fetuses starts to differentiate, is linked to changes in the distance of the anus to the genitals of babies. This distance has been shown to be a good indicator of the levels of sex-differentiating hormones during development.
'These findings suggest air pollution may interfere with normal hormone activity during critical periods of prenatal and early infant development, and we suspect that disruption may have long-term consequences for reproductive health,' said Professor Emily Barrett, professor of biostatistics and epidemiology at the Rutgers School of Public Health, New Jersey and lead author of the study published in the journal Environmental Health Perspectives.
Previous research has inconclusively linked shorter distance between the anus and genitals in males to lower semen quality and reduced fertility. Prenatal exposure to diesel fumes has been shown to affect levels of the hormones associated with sex organ differentiation and development in rodents.
To determine whether air pollution from the combustion of fossil fuels could have the same effect on humans, researchers looked at a USA-based multicentre cohort of 687 mother-baby dyads, including 268 male offspring.
Researchers estimated the exposure of the pregnant mother to particulate matter during early pregnancy and then of the baby during the first months of life when sex hormone changes occur.
Exposure to particulate matter during early pregnancy was associated with a shorter, less masculinised distance between the anus and genitals in males at birth but longer distances at one year of age. Exposure to particulate matter during the first months of life was also associated with a shorter, less masculinised distance between the anus and genitals in males.
Results were less significant in females, with only a small association found between increased distance between the anus and genitals and particulate matter exposure in the third trimester.
Authors have made clear that the effects found were small, amounting to just a 1mm difference in male babies born following higher exposure to particulate matter in utero, representing a two percent smaller distance than the average male newborn.
They warn that though these differences are small on an individual level, they might be important on a population level.
'When we see shorter anogenital lengths, it's telling us there is lower testosterone activity in the womb … and it may have implications for fertility and reproductive health down the road,' Professor Barratt told the Guardian.
Sources and References
-
Associations of exposure to air pollution during the male programming window and mini-puberty with anogenital distance and penile width at birth and at 1 year of age in the multicenter U.S. TIDES cohort
-
Exposure to air pollution in utero may affect reproductive system development
-
Prenatal exposure to air pollution may hurt reproductive health in adult men, study finds
-
Air pollution may be interfering with prenatal hormone activity
-
Air pollution exposure in utero disrupts human reproduction
Leave a Reply
You must be logged in to post a comment.