Abstract
Polycyclic aromatic hydrocarbons (PAHs) are known environmental pollutants. Studies are very limited regarding the impacts of paternal PAHs exposure on birth outcomes as well as the underpinning mechanisms in human. In this study, 302 reproductive-aged males (22–46 years old) were enrolled and demographic informatics data were obtained by questionnaires. The levels of urinary hydroxylated PAHs (OH-PAHs) were assessed by ultra-high performance liquid chromatography-tandem mass spectrometry; and methylation levels of the imprinting genes H19, Meg3, and Peg3 of sperm DNA were evaluated via bisulfite pyrosequencing. The analysis of the correlation between OH-PAHs levels and methylation levels of imprinting genes showed that OH-PAHs are correlated with some CpG sites in H19, Peg3, and Meg3. To further investigate an association of urinary OH-PAHs with birth outcomes, follow-up study of wives of these subjects has been performed for 1–3 years. As the result, a total of 157 babies were born. The birth outcomes parameters including birth weight (BW), length (BL), and ponderal index (PI) were recorded. The further analysis of generalized estimating equation indicated a negative correlation between urinary total OH-PAHs levels and newborn BW (β = −0.081, p = 0.020); but this association has not been found for BL and PI. Furthermore, a logistic regression analysis was employed for examining associations of the methylation of imprinting genes with birth outcomes parameters, which indicated a negative correlation between BW and H19, namely, each unit percent (%) elevation in methylation of H19 (but not Peg3 and Meg3) was significantly associated with a 0.135 g reduction of BW (β = −0.135; 95% CI 0.781–0.978). Putting together, these results show that paternal non-occupational environmental exposure to PAHs is associated with newborn BW. And imprinting gene H19 methylation may be involved in the underlying mechanisms. This study in human population adds a support for previous animal study and implies that environmental impact on the offspring through paternal pathway.
Highlights
The impacts of environmental pollutants on reproduction and development in humans have been of increasing concern (Nassar et al, 2010; Shirangi et al, 2011)
The results from our previous animal study indicated that paternal exposure to BaP, an important component of Polycyclic aromatic hydrocarbons (PAHs), induced changes in methylation levels of the four imprinting genes in sperm DNA and these alterations pasted to their F1 and F2 male offspring (Zhang et al, 2019)
We found that a positive correlation between paternal urinary OH-PAHs level and some CpG sites in H19, Peg3, and Meg3
Summary
The impacts of environmental pollutants on reproduction and development in humans have been of increasing concern (Nassar et al, 2010; Shirangi et al, 2011). Further human studies showed direct maternal exposure to PAHs of pregnant women was associated with adverse birth outcomes (Dejmek et al, 2000; Choi et al, 2006, 2008; Lamichhane et al, 2016), including delayed intrauterine growth and preterm deliveries (Singh et al, 2008; Wilhelm et al, 2011; Guo et al, 2012), reduced newborn weights, head circumferences, and lengths (Dejmek et al, 2000; Perera et al, 2005; Choi et al, 2006; Tang et al, 2006; Jedrychowski et al, 2012, 2017; Duarte-Salles et al, 2013; Langlois et al, 2014; Padula et al, 2014). The mechanisms underlying the impact of paternal PAHs exposure on their offspring have not been fully characterized
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