Endocrine-disrupting chemicals may lower bone mineral density in adolescent boys
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Adolescent boys exposed to higher levels of two types of endocrine-disrupting chemicals may have lower areal bone mineral density, according to study data published in The Journal of Clinical Endocrinology & Metabolism.
“Per- and polyfluoroalkyl substances (PFAS) and phthalates are detectable in the blood of almost all individuals in the U.S., but few studies have looked at how these chemicals could be impacting our bone health,” Abby Fleisch, MD, MPH, environmental health researcher at the Center for Outcomes Research and Evaluation at Maine Medical Center Research Institute and a pediatric endocrinologist at Maine Medical Center in Portland, told Healio. “Because bone accrual primarily occurs during adolescence, if replicated, our findings may have implications for lifelong bone health.”
Fleisch and colleagues analyzed data from 848 adolescents aged 12 to 19 years who participated in the 2011-2016 National Health and Nutrition Examination Survey (mean age, 15 years; 47% female). Participants completed in-person interviews, provided urine and blood samples to measure serum PFAS and phthalate biomarker concentrations and underwent a DXA scan to measure areal BMD. Five types of serum PFAS and seven urinary phthalate metabolites were analyzed in the study. Linear regression was used to examine associations between each PFAS and phthalate biomarker and areal BMD z score. Bayesian kernel machine regression was performed to examine the overall association between the PFAS and phthalate biomarker mixture and areal BMD z score.
In multivariable single-chemical models, a decrease in areal BMD z score was observed with each doubling of serum perfluorooctanoate (mean difference, –0.24; 95% CI, –0.41 to –0.06) and urinary monobutyl phthalate (mean difference, –0.09; 95% CI, –0.17 to 0) in males. No other significant associations were found.
In Bayesian kernel machine regression mixture models, higher levels of serum perfluorooctanoate and perfluorooctanoic sulfonate, and urinary monobutyl phthalates and mono-isobutyl phthalates were linearly associated with lower areal BMD z score for boys. Sigma di-2-ethylhexyl phthalates and monobenzyl phthalates were nonlinearly associated with areal BMD z score for boys, with those having the lowest and highest concentrations of the chemicals having the lowest areal BMD z-score.
There were no significant associations between any single chemicals and areal BMD z score for adolescent girls. In mixture models, serum perfluorooctanoate and urinary mono-isobutyl phthalates were associated with higher areal BMD in females, whereas urinary monobutyl phthalates were associated with a lower areal BMD z score.
“Our findings have public health implications because reducing exposure to PFAS and phthalates may improve peak bone accrual in adolescent males and set the stage for improved bone health across the life span,” the researchers wrote. “Exposure to PFAS and phthalates can be reduced through avoidance of impacted consumer products or, more equitably, through public policies requiring substitution of these chemicals with safer alternatives.”
Fleisch said prospective studies examining long-term exposure to endocrine-disrupting chemicals and its effect on bone health are needed to further build on the findings.
For more information:
Abby Fleisch, MD, MPH, can be reached at abby.fleisch@mainehealth.org.
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