“There is evidence of declining trends in T levels among men in recent decades, as well as trends in related conditions at multiple life stages and in both sexes,” explained John D. Meeker, ScD, of the University of Michigan in Ann Arbor, and colleagues in the Journal of Clinical Endocrinology & Metabolism.
“There is also animal and limited human evidence that exposure to phthalates […] is associated with reduced androgen levels and associated disorders.”
To assess the association between urinary concentrations of phthalate metabolites and serum testosterone levels in patients, the investigators conducted a cross-sectional study using data from the United States National Health and Nutritional Examination Survey for 2011 to 2012.
There was a strong and consistent inverse relationship between urinary concentrations of phthalate metabolites and serum testosterone levels in female patients aged 40 to 60 years, the researchers found.
Among male patients aged 6 to 12 years, an interquartile range increase in metabolites of di-2-ethylhexyl phthalate was associated with greater decline in serum testosterone levels (29% decrease; 95% CI: 6% to 47% decrease).
Among patients aged 40 to 60 years, significant associations or trends for decline in serum testosterone levels were found only for increasing urinary concentrations of metabolites of di-2-ethylhexyl phthalate and dibutyl phthalate.
“Because T plays an important role in all life stages for both sexes, future efforts should focus on better defining these relationships and their broader impacts,” concluded the researchers.