Aims
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals widely used in consumer products. PFAS can accumulate in animal tissues, resulting in biomagnification and adverse effects on wildlife. In bird species, PFAS are transferred from mothers to eggs along with essential nutrients, affecting embryo development. However, the extent of maternal PFAS offloading across different species and compounds remains poorly understood. Therefore, this study aimed to quantify the transfer rate of PFAS in wild birds and investigate potential sources of variation.
Methods
We conducted a systematic review and meta-analysis following established guidelines and procedural steps. Through a rigorous search and screening process, we identified relevant primary studies that measured PFAS concentration in both adults and offspring. Data extraction from the selected studies included statistical information, chemical compound details, and bird species characteristics. We build a meta-analytic model to estimate the overall transfer rate expressed as the logarithm of the response ratio. Finally, meta-regression analyses investigated the moderating effect of predictors, such as compounds' physicochemical properties and birds' biological traits.
Results
Our findings revealed that PFAS concentration was 34% higher in offspring than in mothers. We identified several significant moderators of transfer, including the carbon chain length of PFAS compounds, molecular weight, and clutch size. Specifically, longer and heavier compounds showed preferential offloading, while a larger clutch size was associated with decreased PFAS transfer.
Conclusions
This study provides novel insights into the factors influencing the transfer of PFAS from mothers to offspring in wild bird species. Given the crucial role of birds in maintaining ecological balance, these findings have important implications for developing strategies to mitigate the impacts of PFAS on wildlife, ecosystems, and human health.