Influence of Tetrabromobisphenol A, with or without Concurrent Triclosan, upon Bisphenol A and Estradiol Concentrations in Mice

BACKGROUND: Humans are commonly exposed to multiple environmental chemicals, including tetrabromobisphenol A (TBBPA; a flame retardant), triclosan (an antimicrobial agent), and bisphenol A (BPA; polycarbonate plastics). These chemicals are readily absorbed and may interact with each other. OBJECTIVES: We sought to determine whether TBBPA, given alone or in combination with triclosan, can modulate the concentrations of BPA and [Formula: see text] (E2). METHODS: Female and male CF-1 mice were each given a subcutaneous injection of [Formula: see text] TBBPA, with or without concurrent [Formula: see text] triclosan, followed by dietary administration of [Formula: see text] body weight [Formula: see text]. Radioactivity was measured in blood serum and tissues through liquid scintillation counting. In subsequent experiments, female and male CF-1 mice were each given a subcutaneous injection of 0 or [Formula: see text] TBBPA and E2 was measured in urine 2–12 h after injection. RESULTS: Doses as low as [Formula: see text] TBBPA significantly elevated [Formula: see text] concentrations in the uterus and ovaries of females; in the testes, epididymides, vesicular-coagulating glands, and preputial glands of males; and in blood serum, heart, lungs, and kidneys of both sexes; urinary E2 concentrations were also elevated. Lower doses of TBBPA or triclosan that had no effects on their own elevated [Formula: see text] concentrations when the two substances were given concurrently. CONCLUSION: These data indicate that TBBPA, triclosan, and BPA interact in vivo, consistent with evidence that TBBPA and triclosan inhibit enzymes that are critical for BPA and E2 metabolism. https://doi.org/10.1289/EHP1329