Bone Abstracts

Objectives: In the modern society, all individuals are exposed throughout life to a variety of chemicals, which may contribute significantly to the human disease burden. Most of these chemicals are transferred to the fetus in-utero and to the infant via mother’s milk. Until recently, few studies have addressed effects of chemicals on the development of mineralized tissues following exposure during these early stages of life. In this experimental study, we analysed consequences of human relevant chemical exposure on developing bone.

Methods: Pregnant Sprague–Dawley rats were exposed to a mixture of polychlorinated biphenyls (PCBs), pesticides and mercury, or to the PCB- and mercury components of the mixture alone, from gestational day 1 to prenatal day 23. Tibias from male and female offspring at postnatal day 21 were analysed using peripheral quantitative computed tomography.

Results: Exposure to the mixture resulted in bone with smaller mid-diaphysis cross-sectional area, but higher cortical thickness. Further, the trabecular bone area was smaller, while the trabecular bone mineral density was higher. The increase in trabecular bone mineral density was larger in the female offspring, while the effects on bone geometry were generally more pronounced in the males. Offspring exposed to PCBs alone showed the same trend of bone alterations as caused by the mixture, although less pronounced and with no increase of cortical thickness. In contrast, exposure to mercury alone resulted in increased cortical thickness, but had no effect on trabecular bone mineral density.

Conclusion: Higher trabecular bone mineral density and increased cortical thickness were the most notable alterations of bone following early life exposure to a mixture of chemicals mimicking the human exposure situation. The functional consequences of these observations should be further investigated in order to identify preventive measures.