Prenatal Phthalate Exposure and Childhood Obesity


Diethyl phthalate

My team just published a paper assessing the links between prenatal exposures to phthalates and childhood body size at age 5 and 7.  Using data from the Columbia Center for Children’s Environment Health we measured nine metabolites of six phthalates (di-(2-ethylhexyl) phthalate (DEHP), di-n-octyl-, di-iso-butyl-, di-n-butyl-, butylbenzyl-, and diethyl phthalates) in urine samples collected from pregnant women during their third trimester.  Body size and body composition data were collected from their children at ages 5 and 7.

Because the 9 metabolites represent a fairly complex, inter-correlated mixture of chemicals we applied Principal Component Analyses to identify major patterns of metabolite concentrations in the maternal urine samples.  Two prominent patterns of metabolite concentrations were identified: 1) a pattern representing variation in DEHP metabolite concentrations, and, 2) a pattern representing variation in non-DEHP phthalate metabolite concentrations.   In boys, higher concentrations of non-DEHP metabolites in maternal urine were associated with lower BMI z-score, lower fat percentage and smaller waist circumference. Among boys, body size outcomes were not associated with higher DEHP metabolite concentrations and among girls body size outcomes were not associated with either pattern of phthalate metabolites in maternal urine.

These findings were actually contrary to our hypotheses, past cross-sectional studies have suggested that phthalate exposures are associated with higher risk for obesity.


Obesity and Prostate Cancer Risk

I just published a new paper linking obesity to an increased risk of prostate cancer after an initial benign biopsy that is getting some nice media attention.  Our work shows that among men who have had a prostate biopsy that was negative for cancer, obese men, as compared to normal weight men, had a significantly higher risk of being diagnosed with prostate cancer in the years following that initial biopsy.  This risk was particularly high for a diagnosis occurring in the first four years after biopsy.  We also found that obesity was associated with the presence of pre-cancerous cells in the initial biopsy.

We know that obese men have a higher risk of dying of prostate cancer, but medical science hasn’t determined whether obesity puts men at a higher risk of developing prostate cancer or makes it more difficult to survive prostate cancer (or both).  This new work, particularly the finding that obesity is associated with the presence of pre-cancerous cells in otherwise benign biopsy specimens, suggests that obesity may be involved in the development of prostate cancer., and the Huffington Post have reported on the research and the NY Times is scheduled to write about it in the Tuesday Science Times.


New article on the utility of BMI as a health indicator

Two of my students and I just published a paper on the utility of body mass index (BMI) as an indicator of health.  There have been several critiques of BMI lately in the popular press that have suggested that alternative measures of body size are much better at predicting health status.  We decided to take a look at this and compared BMI to several alternative measures of body size as predictors of cholesterol, blood pressure and fasting glucose. We found that none of the alternative measures were consistently better than BMI.  So despite the recent criticism, it appears that BMI is a measure that we should be taken seriously as an indicator of obesity and obesity related health risks.

Steve Mooney wrote a nice companion piece for the 2×2 health blog and the article was featured in the NY Times Science Times