Everyone in the United States is exposed to hundreds of environmental chemicals every day. One class of chemicals has recently become more concerning, per- and poly-fluoroalkyl substances (PFAS). PFAS are chemicals found in nonstick cookware and food packaging materials, such as pizza boxes and microwave popcorn bags. Historically, chemical companies dumped PFAS into lakes and rivers and in turn, we ate fish and other contaminated animal products. For pregnant people, PFAS exposure can lead to preterm deliveries (delivery before 37-weeks gestation) and underweight babies.
Environmental chemicals, including PFAS, are also found in fast foods and personal care products. People in lower socioeconomic groups are more likely to eat fast foods and use personal care products that contain chemicals because these products tend to be less expensive. Lower-income groups are also more likely to experience social stressors, such as anxiety, financial hardship, and food insecurity. This double jeopardy exposure to both environmental chemicals and social stressors creates cumulative negative health impacts.
While we know that PFAS are harmful to both mom and baby, we do not have a good understanding of how this might be happening. We hypothesized that PFAS may be leading to preterm delivery through changes in the hypothalamic pituitary adrenal (HPA) axis. Psychological stress can activate the HPA axis during pregnancy and signal the production of corticotropin-releasing hormone (CRH). High levels of CRH can ultimately lead to delivery before 37-weeks gestation. In our study, we looked at the relationship between PFAS and CRH during pregnancy.
We collected blood samples from pregnant people in the San Francisco Bay Area and measured the blood samples for CRH and five different PFAS chemicals. We found that all five PFAS were detected in everyone enrolled in our study. We also asked pregnant people questions to measure certain social stressors, particularly food insecurity, financial strain, depression, perceived stress, and stressful life events. We examined if experiencing either PFAS alone or social stressors alone leads to increases in CRH. We also looked to see if there was a stronger effect if participants had both high levels of PFAS and experienced stress.
We found that pregnant people who had higher levels of PFNA and PFOA, two specific PFAS chemicals, also had higher levels of CRH. People who experienced stressful life events, such as job loss or a family death, also had higher CRH levels. Among people who reported experiencing stressful life events, depression, food insecurity, and financial strain, high levels of PFNA were associated with much higher levels of CRH. In our statistical analysis, we adjusted for socioeconomic status to ensure that any effect we observed could be attributed to social stress.
Our findings show that exposure to PFAS and social stress during pregnancy is associated with higher CRH, a stress biomarker that can lead to preterm birth. We also found that psychological stressors enhance the negative health effects of PFAS. Going forward, it is important for researchers to consider that there may be a double jeopardy effect of environmental chemicals and social stressors. When setting regulatory standards, policy makers should also consider that some groups are particularly vulnerable to the health effects of PFAS, particularly PFNA.
About the author
Stephanie Eick, MPH, PhD is a postdoctoral scholar for the PRHE research team. She received her PhD in Epidemiology from the University of Georgia and her MPH in Epidemiology from the Rollins School of Public Health at Emory University. As a postdoc, she works on the NIH’s Environmental Influences on Child Health Outcomes (ECHO) study at UCSF. She is particularly interested in biologic mechanisms that link chemicals and psychosocial stressors to adverse pregnancy and child health outcomes.
Co-authors on this paper are Stephanie M. Eick, Dana E. Goin, Lara Cushing, Erin DeMicco, Sabrina Smith, June-Soo Park, Amy M. Padula, Tracey J. Woodruff & Rachel Morello-Frosch.