Association of exposure to phthalates with endometriosis and uterine leiomyomata: findings from NHANES, 1999-2004.
BACKGROUND
Phthalates are ubiquitous chemicals used in consumer products. Some phthalates are reproductive toxicants in experimental animals, but human data are limited.


OBJECTIVE
We conducted a cross-sectional study of urinary phthalate metabolite concentrations in relation to self-reported history of endometriosis and uterine leiomyomata among 1,227 women 20-54 years of age from three cycles of the National Health and Nutrition Examination Survey (NHANES), 1999-2004.


METHODS
We examined four phthalate metabolites: mono(2-ethylhexyl) phthalate (MEHP), monobutyl phthalate (MBP), monoethyl phthalate (MEP), and monobenzyl phthalate (MBzP). From the last two NHANES cycles, we also examined mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP). We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for potential confounders.


RESULTS
Eighty-seven (7%) and 151 (12%) women reported diagnoses of endometriosis and leiomyomata, respectively. The ORs comparing the highest versus lowest three quartiles of urinary MBP were 1.36 (95% CI, 0.77-2.41) for endometriosis, 1.56 (95% CI, 0.93-2.61) for leiomyomata, and 1.71 (95% CI, 1.07-2.75) for both conditions combined. The corresponding ORs for MEHP were 0.44 (95% CI, 0.19-1.02) for endometriosis, 0.63 (95% CI, 0.35-1.12) for leiomyomata, and 0.59 (95% CI, 0.37-0.95) for both conditions combined. Findings for MEHHP and MEOHP agreed with findings for MEHP with respect to endometriosis only. We observed null associations for MEP and MBzP. Associations were similar when we excluded women diagnosed > 7 years before their NHANES evaluation.


CONCLUSIONS
The positive associations for MBP and inverse associations for MEHP in relation to endometriosis and leiomyomata warrant investigation in prospective studies.
Weuve
Jennifer
J
Rush Institute for Healthy Aging, Rush University Medical Center, Chicago, Illinois 60612 , USA. Jennifer_Weuve@rush.edu
Hauser
Russ
R
Calafat
Antonia M
AM
Missmer
Stacey A
SA
Wise
Lauren A
LA
D000328:Adult; D003430:Cross-Sectional Studies; D004715:Endometriosis / Q000139:chemically induced / Q000453:epidemiology*; D004781:Environmental Exposure / Q000032:analysis*; D004785:Environmental Pollutants / Q000633:toxicity* / Q000652:urine; D005260:Female; D006801:Humans; D007889:Leiomyoma / Q000139:chemically induced / Q000453:epidemiology*; D016015:Logistic Models; D008875:Middle Aged; D009749:Nutrition Surveys; D016017:Odds Ratio; D010795:Phthalic Acids / Q000633:toxicity* / Q000652:urine; D011795:Surveys and Questionnaires; D014481:United States; D014594:Uterine Neoplasms / Q000139:chemically induced / Q000453:epidemiology*
D004785:Environmental Pollutants; D010795:Phthalic Acids; C032279:phthalic acid