Phthalate exposure in pregnant women with systemic lupus erythematous (SLE)

Abstract

TPS 632: Health effects of flame retardants and plasticizers, Johan Friso Foyer, Floor 1, August 27, 2019, 3:00 PM - 4:30 PM Background: Environmental chemicals might contribute to the pathogenesis of autoimmune diseases in combination with established genetic factors. Phthalate exposure in pregnant women may influence fetal growth and birth outcomes. Hence, we assessed phthalate exposure in pregnant women with systemic lupus erythematous (SLE) and compared levels with nationally-representative and pregnant populations. Methods: Participants were 50 pregnant women from the New York City (NYC) sample of PROMISSE (2003-2010), a multi-ethnic/racial cohort designed to prospectively assess adverse pregnancy outcomes in SLE women with inactive or mild/moderate disease activity. We measured urinary concentrations of 21 phthalate metabolites during each trimester and compared median concentrations with 1) 15-to-50 year-old women in the National Health and Nutrition Examination Survey (NHANES) 2003-2010; and 2) a contemporary population-based cohort of pregnant women in NYC (n=240). Results: Intraclass correlations for three measurements across pregnancy varied between r=0 [mono-carboxy isooctyl phthalate (mCIOP)] and r=0.57 [mono-n-butyl-phthalate (mBP)]. Mono-(3-carboxypropyl) phthalate (mCPP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (mEHHP), mono-(2-ethyl-5-carboxypentyl) phthalate (mECPP), mono-(2-ethyl-5-oxohexyl) phthalate (mEOHP), mCIOP, and mono-carboxy isononyl phthalate (mCINP) were detected in all pregnant women, comparable to NHANES. Metabolites of di-(2-propylheptyl) phthalate (DPHP) and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) were detected in 4-55% of participant. Compared to NHANES, pregnant women with SLE had higher first trimester concentration of mono-(2-ethylhexyl) phthalate (MEHP) [median=3.9 ng/mL interquartile range (IQR)=6.0 vs 2.5 ng/mL, IQR=5.45], mono-isobutyl phthalate (mIBP) (median=12.8 vs 7.6 ng/mL), mono-isononyl phthalate (mINP) (median=2.7 vs. 0.87 ng/mL), and mCIOP (median=14.9 vs 6.9 ng/mL). Concentrations of other phthalate metabolites were comparable between groups. Pregnant women with SLE had higher phthalate levels than the NYC cohort. Conclusions: Pregnant women with SLE had higher concentrations of certain phthalate metabolites than controls. This cross-sectional analysis cannot rule out that SLE might influence phthalate metabolism. Sociodemographic and lifestyles factors might also explain the results; therefore, further investigation is needed.