Plasma concentrations of mono-ortho-substituted dioxin-like polychlorinated biphenyls (DL-PCBs)
Aboriginal populations living in Canada's northern regions are exposed
to a number of persistent organic pollutants through their traditional
diet which includes substantial amounts of predator fish species.
Exposure to dioxin-like compounds (DLCs) can cause a variety of toxic
effects including adverse effects on bone tissue.
descriptive cross-sectional study was conducted to investigate the
relationship between plasma concentrations of DLCs and bone quality
parameters in Cree women of Eastern James Bay (Canada).
Two hundred and forty-nine Cree women from seven communities in Eastern
James Bay (Canada), aged 35 to 74 years old, participated in the study.
In order to determine the total DLC concentration in plasma samples of
participants, we measured the aryl hydrocarbon receptor-mediated
transcriptional activity elicited by plasma sample extracts using a
luciferase reporter gene assay.
Plasma concentrations of
mono-ortho-substituted dioxin-like polychlorinated biphenyls (DL-PCBs)
105, 118 and 156 were measured by gas chromatography--mass spectrometry.
Bone quality parameters (speed of sound, m/s; broadband ultrasound
attenuation, dB/MHz; stiffness index, %) were assessed by quantitative
ultrasound at the right calcaneus with the Achilles InSight system.
Several factors known to be associated with osteoporosis were
documented by questionnaire. Multiple linear regression models were
constructed for the three ultrasound parameters.
DL-PCBs 105 and 118 concentrations, but not the global DLC
concentration, were inversely associated with the stiffness index, even
after adjusting for several confounding factors.
index (log) decreased by -0.22% (p=0.0414) and -0.04% (p=0.0483) with an
increase of one mug/L in plasma concentrations of DL-PCB 105 and DL-PCB
118, respectively. Other factors, including age, height, smoking
status, menopausal status and the percentage of omega-6 polyunsaturated
fatty acids (PUFAs) in erythrocyte membranes were negatively associated
with one of the ultrasound parameters, while the percentage of omega-3
PUFAs in these membranes and levels of physical activity and education
were positively associated with them.
Our results show that an increase in plasma concentrations of DL-PCBs
105 and 118 was negatively associated with stiffness index, a measure of
bone quality/strength, in women of this population.
to environmental contaminants, future studies should also consider PUFA
intake as a factor influencing bone quality.