Maternal exposure to perfluorobutane sulfonate (PFBS) during pregnancy: evidence of adverse maternal and fetoplacental effects in New Zealand White (NZW) rabbits

Abstract

Perfluorobutanesulfonic acid (PFBS) is a replacement for perfluorooctanesulfonic acid (PFOS) that is increasingly detected in drinking water and human serum. Higher PFBS exposure is associated with risk for preeclampsia, the leading cause of maternal and infant morbidity and mortality in the United States. This study investigated relevant maternal and fetal health outcomes after gestational exposure to PFBS in a New Zealand White rabbit model. Nulliparous female rabbits were supplied drinking water containing 0 mg/l (control), 10 mg/l (low), or 100 mg/l (high) PFBS. Maternal blood pressure, body weights, liver and kidney weights histopathology, clinical chemistry panels, and thyroid hormone levels were evaluated. Fetal endpoints evaluated at necropsy included viability, body weights, crown-rump length, and liver and kidney histopathology, whereas placenta endpoints included weight, morphology, histopathology, and full transcriptome RNA sequencing. PFBS-high dose dams exhibited significant changes in blood pressure markers, seen through increased pulse pressure and renal resistive index measures, as well as kidney histopathological changes. Fetuses from these dams showed decreased crown-rump length. Statistical analysis of placental weight via a mixed model statistical approach identified a significant interaction term between PFBS high dose and fetal sex, suggesting a sex-specific effect on placental weight. RNA sequencing identified the dysregulation of angiotensin (AGT) in PFBS high-dose placentas. These results suggest that PFBS exposure during gestation leads to adverse maternal outcomes, such as renal injury and hypertension, and fetal outcomes, including decreased growth parameters and adverse placenta function. These outcomes raise concerns about pregnant women's exposure to PFBS and pregnancy outcomes.

Keywords: birth outcomes; developmental and reproductive toxicology; per- and polyfluoroalkyl substances (PFAS); perfluorobutanesulfonic acid (PFBS); placenta; rabbit.

Figure 1.

Chemical structure of legacy perfluorooctanesulfonic acid (PFOS) and perfluorobutane sulfonate (PFBS).

Figure 2.

New Zealand White rabbits were exposed to control or PFBS-contaminated drinking water for 32 days over the course of the study. Blood and baseline measurements, including body weight and blood pressure, were taken at timepoint 0. Only body weight measurements and blood were taken at timepoints 1 and 2, whereas blood was collected and measurements of body weight and blood pressure were assessed again at timepoint 3. Rabbits were bred 7 days after exposure began, and an ultrasound to confirm pregnancy occurred at approximately gestational day (GD) 15. Rabbits were necropsied before parturition on GD 25. Abbreviation: PFBS, perfluorobutanesulfonic acid.

Figure 3.

Maternal blood pressure measures, illustrated as pulse pressure (A) and renal resistive index measure (B). All data illustrated as percent change from baseline to the last study day, and analyzed via 1-way ANOVA with Dunnett’s test for multiple comparisons.  p < .05 is considered significant.

Figure 4.

Maternal kidney and liver histopathology. A, Representative images of maternal kidney histopathology results under light microscopy. Kidney from a PFBS-high dose exposed dam shows a mild case of nephropathy relative to the control. Arrows designate basophilic tubules. B, Livers of exposed dams showed minimal changes in cytoplasmic vacuolation (arrow) at low incidence. Abbreviation: ND, not detected.

Figure 5.

Fetal body weight and crown-rump length at necropsy (GD 25). Best fit mixed model showing beta estimates and 95% confidence intervals for fixed effects of PFBS exposure and litter size on (A) fetal body weight (BW) and (B) crown-rump length (CRL) (*p < .05). PFBS-H = 100 mg/l PFBS group, PFBS-L = 10 mg/l PFBS group; effect estimates are centered around the control group (white vertical line at y = 0). Abbreviation: GD, gestational day.

Figure 6.

Maternal PFBS exposure effects on whole placenta and body weight to placenta ratio at necropsy (GD 25). Mixed models showing beta estimates and 95% confidence intervals for fixed effects of PFBS exposure, fetal sex, litter size, and the interaction effect of PFBS treatment and fetal sex on (A) whole PW and (B) fetal BW:PW ratio, with plots of interaction term between PFBS-high and fetal sex. (*p < .05, **p < .01). PFBS-H = 100 mg/l PFBS group, PFBS-L = 10 mg/l PFBS group; effect estimates are centered around the control group (white vertical line at y = 0). Abbreviation: GD, gestational day.

Figure 7.

Gene expression differences in the placenta following PFBS exposure. Genes studied were involved in thyroid hormone transport and metabolism in the placenta. Data were analyzed using a 1-way ANOVA with Tukey’s multiple comparison test; p < .05 is considered significant. Abbreviation: PFBS, perfluorobutanesulfonic acid.