Developmental Toxicity of n-Butanol in Chick Embryos: Dose-Dependent Effects on Morphology, Behavior, Oxidative Stress, Tissue Integrity, and Post-Hatching Feeding and Locomotor Behavior Disruption Induced by n-Butanol.

n-Butanol is extensively used in industrial, food, pharmaceutical, and petrochemical sectors, raising concerns about environmental and developmental exposure. However, evidence regarding its developmental toxicity remains limited. This study investigated the teratogenic and toxicological effects of n-butanol using a chick embryo (Gallus gallus domesticus) model, with emphasis on dose-dependent morphological alterations, feeding, and locomotory behavioral outcomes, oxidative stress responses, and histopathological damage. Fifty fertilized eggs were randomly assigned to five groups (n = 10 per group): a control group (received an equivalent sterile saline) and four treatment groups receiving n-butanol at doses of 10, 12, 14, and 20 μL per egg, via in ovo injection. Embryonic development was evaluated through morphometric measurements, including body length, limb length, head and beak dimensions, crown-rump length, and body weight. Oxidative stress was assessed in cardiac and hepatic tissues by determining DPPH radical scavenging activity and the activities of superoxide dismutase (SOD) and catalase (CAT), complemented by histopathological examination. Exposure to n-butanol resulted in a significant, dose-dependent reduction in most morphometric parameters (p < 0.0001), whereas head circumference remained unaffected. Antioxidant enzyme activities were markedly altered, indicating enhanced oxidative stress at higher exposure levels. Histopathological analysis revealed pronounced structural damage in liver and heart tissues, accompanied by behavioral abnormalities and limb deformities at elevated doses. Overall, these findings demonstrate that n-butanol induces developmental toxicity in chick embryos in a dose-dependent manner, likely mediated through oxidative stress and tissue injury. The chick embryo model proved to be a sensitive and effective system for evaluating developmental and environmental toxicants, highlighting potential risks associated with n-butanol exposure.