Dietary exposure of juvenile female mice to polyhalogenated seafood contaminants (HBCD, BDE-47, PCB-153, TCDD): Comparative assessment of effects in potential target tissues

- At the low observed adverse effect levels, effects and targets of four test contaminants in juvenile female mice are comparable.
- Each compound caused adverse changes in liver, thymus and thyroid; spleen was affected by BDE-47 and PCB-153.
- Effects on sex steroid serum levels are seen in response to HBCD, BDE-47 and TCDD.
- Based on the parameters assessed, the main toxicity targets are comparable between juvenile and adult mice.
- Additive effects should be considered; test contaminants elicited similar effects and may be all present in oily fish.

Fish represents source of nutrients and major dietary vehicle of lipophilic persistent contaminants. The study compared the effects of two legacy and two emerging fish pollutants (Hexabromocyclododecane HBCD; 2,2′,4,4′-Tetrabromodiphenyl ether BDE-47; 2,2′,4,4′,5,5′-Hexachlorobiphenyl PCB-153; 2,3,7,8-Tetrachlorodibenzo-p-doxin TCDD) in juvenile female mice exposed through a salmon based rodent diet for 28 days (dietary doses: HBCD 199 mg/kg bw/day; BDE-47 450 μg/kg bw/day; PCB-153 195 μg/kg bw/day; TCDD 90 ng/kg bw/day). Dose levels were comparable to previously reported developmental Lowest Observed Adverse Effect Levels. None of the treatments elicited signs of overt toxicity, but HBCD increased relative liver weight. All compounds caused changes in liver, thymus and thyroid; spleen was affected by BDE-47 and PCB-153; no effects were seen in uterus and adrenals. Strongest effects in thyroid follicles were elicited by PCB-153, in thymus and liver by BDE-47. HBCD and BDE-47 induced liver fatty changes, but appeared to be less potent in the other tissues. HBCD, BDE-47 and TCDD increased serum testosterone levels and the testosterone/estradiol ratio, suggesting a potential involvement of pathways related to sex steroid biosynthesis and/or metabolism. The results support the role of toxicological studies on juvenile rodents in the hazard characterization of chemicals, due to endocrine and/or immune effects.