Dispersed black carbon mediates intergenerational BDE-47 toxicity in zebrafish by regulating steroidogenesis: Attenuated parental toxicity with exacerbated offspring impairment

Persistent organic pollutants (POPs) are a class of long-lasting, high-risk contaminants in aquatic environments, and their toxicity is modulated by fluctuations in environmental factors. Dispersed black carbon (DBC) is a prevalent particulate matter in water bodies that exhibits a strong adsorption capacity, which can alter the bioavailability and toxicity of pollutants. This study investigated the intergenerational toxicity mechanisms of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47), a representative POPs, through a 60-day exposure experiment. BDE-47 was administered at concentrations of 0, 2, 20, and 200 μg/L, with DBC at 0.5 mg/L, to assess its interference. The results demonstrate that DBC can adsorb BDE-47 efficiently, with an adsorption capacity of 34.6 mg/g, thereby modifying its bioavailability. Through a 60-day exposure experiment on adult zebrafish, we established that BDE-47 induces sex-specific toxicity. Females showed higher survival rates than males, but surviving females displayed more severe tissue damage and behavioral impairments. DBC-mediated adsorption mitigated the BDE-47-induced toxic effects in adult zebrafish via the modulation of steroidogenic pathways. Specifically, DBC increased gonad weight by 27.6 %, reduced the occurrence of atretic follicles, and elevated sperm count. At the molecular level, DBC alleviated the transcriptional dysregulation of key steroidogenic genes, notably upregulating the expression of Cyp17a1 and Star by approximately two-fold and three-fold, respectively. Conversely, in a 7-day assessment of offspring (F1), DBC enhanced the toxicity of BDE-47 in offspring, exacerbating tachycardia and behavioral disturbances in offspring fish. Based on evidence from gonadal histopathology, steroid synthesis gene dysregulation, and the behavioral phenotypes of the offspring, this study discovered the intergenerational paradox of particle-mediated POPs toxicity, namely that DBC reduces the bioavailability of BDE-47 in adult zebrafish but exacerbates intergenerational health risks. The research results emphasize that under the mediation of DBC, the persistent impact of POPs on aquatic ecosystems has intensified. • BDE-47 caused higher male mortality but more severe sublethal effects in females. • DBC adsorbs BDE-47 (34.6 mg/g), lowering its bioavailability and changing its toxicity. • DBC protects exposed parents but worsens BDE-47 toxicity in offspring. • DBC protects adults by reducing gonadal damage and steroidogenic gene dysregulation. • DBC amplifies POPs' intergenerational health risks and aquatic ecosystem impacts.