The associated long-term disturbance of diethyl phosphonate on the growth phenotype, gut microbiota and SCFAs of offspring rats.

Diethyl ethylphosphonate (DEEP) is a new type of highly effective organophosphorus flame retardant that is widely used in various industrial products, but there have been no reports on its potential health risks. In this study, we exposed pregnant rats to different DEEP doses (23.3 mg·kg-1·BW-1 and 233 mg·kg-1·BW-1) via gavage during gestation and lactation, and measured the DEEP content in the placenta of pregnant rats. We also looked into the impacts of varying DEEP doses on the growth phenotype, gut microbiota, and metabolite SCFAs of female and male offspring. According to the findings, DEEP exceeded the detection limit in the high-dose exposure group. Maternal high-dose DEEP exposure reduced body weight in both immature male and female offspring. Compared to the low-dose exposure, high-dose DEEP significantly decreased the richness and diversity of both male and female offspring gut microbiota. Low-dose exposure increased the Pseudomonadota and decreased the Bacillota. In immature female offspring, high-dose exposure increased the genus Lactobacillus and Bacteroides and reduced Clostridium, Adlercreutzia, and Segatella. The proportions of fecal acetic and butyric acid in male and female immature offspring were elevated after maternal high-dose exposure. But the fecal butyric acid in adult offspring decreased after maternal low-dose exposure during gestation. PICURSt2 analysis confirmed that changes in gut microbiota composition altered its function. In the correlation analysis, SCFAs showed significant positive or negative correlation with 11 genera. This study helped to elucidate the long-term effects of maternal DEEP exposure and provided a basis for assessing the health risk management of analogous flame retardants.