The relationship between phthalates and obesity: serum and urine concentrations of phthalates.

Background: A limited number of human and animal studies suggest that a relationship exists between phthalates and obesity, although this is not supported by all research. The purpose of this study was to investigate the relationship between Body Mass Index (BMI) and the levels of phthalates in human blood and urine samples.

Methods: Sixty-four overweight or 132 obese individuals (total=196) of different ages (min-max, 17-62; mean ± SD, 42.07±11.3) and genders (F:M 97:99) enrolled in the study. BMI and waist circumference were measured to diagnose obesity. Venous blood samples were taken after overnight fasting. To compare the urine phthalates among participants, single spot urine (at least 10 mL) was collected from the subject after blood samples were taken. Urine and blood phthalate concentrations were measured using gas chromatography.

Results: Total blood/urinary phthalate levels significantly increased in proportion to the degree of obesity. There was a high correlation between the level of total phthalates in serum and BMI (ρ=0.697, P<0.001), and between total urinary phthalate levels and BMI (ρ=0.707, P<0.001).

Conclusions: This is the first study to have shown that both blood and urinary phthalates increased in proportion to BMI. The results show a strong association between obesity and phthalates.