Bisphenol A and health across species: a One Health review with emphasis on companion animals

Bisphenol A (BPA) is a high-volume industrial chemical used in polycarbonate plastics and epoxy resins that has become a pervasive environmental contaminant. Human exposure occurs primarily through diet, with inhalation and dermal routes as secondary pathways. After absorption, BPA rapidly enters systemic circulation and traverses the blood–placenta and blood–brain barriers, raising concern for fetal and neonatal vulnerability. Toxicologically, BPA acts as an endocrine-disrupting chemical with estrogenic, anti-androgenic, and thyroid-disrupting activities, binding nuclear and membrane receptors to perturb hormonal homeostasis. Accumulating evidence links chronic exposure to endocrine-related disorders (e.g., infertility, breast cancer, obesity, and ADHD), neurotoxicity with adverse neurodevelopmental and cognitive outcomes, and metabolic dysregulation including hepatic steatosis. While human biomonitoring studies, murine in vivo models, and in vitro assays have characterized exposure, mechanisms, and health endpoints, much less is known about BPA in companion animals that share human environments. Emerging data in dogs (and to a lesser extent cats) demonstrate short-term internal exposure and acute biological responses—such as altered serum BPA level, endocrine changes, and microbiome shifts—but the long-term consequences, epigenetic alterations, immune and stress-response markers, and multigenerational effects remain insufficiently defined. Framed within a One Health perspective, this review synthesizes current evidence across humans, experimental animals, and cells, and critically appraises the nascent literature in companion animals. We highlight key knowledge gaps and propose a research agenda emphasizing standardized exposure assessment, longitudinal cohorts, species-appropriate biomarkers, and integrative omics to strengthen causal inference and risk assessment. Understanding BPA’s impacts in companion animals living alongside humans may yield sensitive sentinels and translational insights to guide public-health policy and mitigation strategies.