Gender and racial/ethnic differences in the associations of urinary phthalate metabolites with markers of diabetes risk: National Health and Nutrition Examination Survey 2001-2008.
BACKGROUND
Phthalates are ubiquitous endocrine disrupting chemicals associated with diabetes. Although women and minorities are more likely to be exposed to phthalates, no prior studies have examined phthalate exposure and markers of diabetes risk evaluating effect modification by gender and race/ethnicity.


METHODS
We analyzed CDC data for 8 urinary phthalate metabolites from 3,083 non-diabetic, non-pregnant participants aged 12- < 80 years in the National Health and Nutrition Examination Survey (NHANES) 2001-2008. We used median regression to assess the associations between urinary phthalate metabolites and fasting blood glucose (FBG), fasting insulin and Homeostatic Model Assessment of insulin resistance (HOMA-IR), controlling for urinary creatinine as well as several sociodemographic and behavioral factors. Stratified analyses were conducted to compare the gender- and race/ethnicity-specific patterns for the associations.


RESULTS
Urinary levels of several phthalate metabolites, including MBzP, MnBP, MiBP, MCPP and ∑DEHP showed significant positive associations with FBG, fasting insulin and HOMA-IR. No clear difference was noted between men and women. Mexican-Americans and non-Hispanic blacks had stronger dose-response relationships for MnBP, MiBP, MCPP and ∑DEHP compared to non-Hispanic whites. For example, the highest quartile of MiBP relative to its lowest quartile showed a median FBG increase of 5.82 mg/dL (95% CI: 3.77, 7.87) in Mexican-Americans, 3.63 mg/dL (95% CI: 1.23, 6.03) in blacks and 1.79 mg/dL (95% CI: -0.29, 3.87) in whites.


CONCLUSIONS
The findings suggest that certain populations may be more vulnerable to phthalates with respect to disturbances in glucose homeostasis. Whether endocrine disrupting chemicals contribute to gender and racial/ethnic differences in diabetes risk will be an important area for further study.
Tianyi
T
Huang
Aditi R
AR
Saxena
Elvira
E
Isganaitis
Division of Women's Health, Department of Medicine, Connors Center for Women's Health and Gender Biology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02120, USA. tjames-todd@bics.bwh.harvard.edu.
Tamarra
T
James-Todd
D000293:Adolescent; D000328:Adult; D000368:Aged; D044383:Black People; D001786:Blood Glucose / Q000032:analysis; D002648:Child; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000453:epidemiology / Q000208:ethnology* / Q000652:urine; D052244:Endocrine Disruptors / Q000652:urine*; D004784:Environmental Monitoring; D004785:Environmental Pollutants / Q000652:urine*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D017058:Mexican Americans; D008875:Middle Aged; D009749:Nutrition Surveys; D010795:Phthalic Acids / Q000652:urine*; D012306:Risk; D012737:Sex Factors; D044465:White People; D055815:Young Adult
D001786:Blood Glucose; D052244:Endocrine Disruptors; D004785:Environmental Pollutants; D007328:Insulin; D010795:Phthalic Acids; C032279:phthalic acid