Urinary phthalate metabolites and the risk of low bone mineral density and osteoporosis in older women.

Abstract

CONTEXT: Experimental studies have demonstrated that phthalate exposure is

associated with skeletal malformations and an imbalance in bone homeostasis.

However, few studies have evaluated the association between phthalates and human

bone health. OBJECTIVES: We evaluated whether urinary phthalate metabolites were

associated with total hip and femur neck bone mineral density (BMD) and

osteoporosis in postmenopausal women (>/=50 y old). DESIGN: We analyzed data from

the 2005-2008 National Health and Nutrition Examination Survey (NHANES) for 398

postmenopausal women >/= 50 years of age. Eleven phthalate metabolites were

selected with a detection rate >/= 60% and were categorized into quartiles. Total

hip and femur neck BMD measurements were obtained using dual-energy x-ray

absorptiometry bone densitometry. Osteoporosis was defined based on the World

Health Organization criteria, with thresholds of 0.64 and 0.56 g/cm(2) or less

for the total hip and femur neck, respectively. RESULTS: Increases in the urinary

mono-n-butyl phthalate, mono-(3-carboxypropyl) phthalate, and monobenzyl

phthalate quartiles were significantly associated with reduced total hip or femur

neck BMD. Postmenopausal women with the highest levels of mono-(3-carboxypropyl)

phthalate, mono(carboxyoctyl) phthalate, and the sum of the three

di(2-ethylhexyl) phthalate metabolites were more likely to have an increased risk

for total hip or femur neck osteoporosis than those with the lowest levels of

these metabolites. CONCLUSION: Urinary phthalate metabolites were associated with

low BMD and high osteoporosis risk in postmenopausal women. Our findings suggest

that background phthalate exposure may unfavorably affect bone homeostasis and

BMD in humans.