Association of Maternal Polybrominated Diphenyl Ether (PBDE) Exposure with Cryptorchidism

Presentation Number: FRI 112
Date of Presentation: April 1st, 2016

Cynthia Gates Goodyer*1, Shirley Poon2, Katarina Aleksa2, Laura Hou3, Veronica Atehortua3, Amanda Carnevale4, Roman Jednak5, Sherif Emil5, Darius Bagli2, Sumit Dave6, Barbara Hales3 and Jonathan Chevrier3
1McGill University, Montreal, QC, Canada, 2Toronto Hospital for Sick Children, 3McGill University, 4University of Toronto, 5McGill University Health Center, 6London Health Sciences Centre

Abstract

Polybrominated diphenyl ethers (PBDEs) are flame retardants used throughout North America during the past four decades. They have been added to many household products, including appliances, electronics, foam upholstery and building materials. PBDEs leach out as these products age and are found in dust of the home and workplace; PBDEs have also migrated into the environment and entered the food chain. Thus, individuals are exposed through both dust and diet.  Epidemiological studies suggest that PBDEs can disrupt endocrine systems (thyroid, estrogen, androgen), leading to alterations in thyroid function, growth and development, including of the reproductive system.  Cryptorchidism is the failure of one or both testicles to descend into the scrotum during in utero development of the male fetus.  This is a common urogenital abnormality observed in otherwise normal term male newborns (1.8-9%)1. Animal and clinical studies have demonstrated that normal migration of the testes is dependent on both specific genes (INSL3, RXFP2) and the in utero hormonal (androgenic) environment1-3.  In the present study, we examined whether there is a link between maternal exposure to PBDEs and the risk of having a male child with undescended testes (cryptorchidism).

Control (n=158) and case (n=137) participants were recruited through pediatric urology and surgery clinics in Montreal QC, Toronto ON and London ON as well as a community pediatric practice in Montreal; inclusion criteria were a full-term normal birth, child age (3-18 months), surgically-defined cryptorchidism in case infants and absence of genitourinary abnormalities in controls. Seven BDEs (BDE-28, 47, 99, 100, 153, 154, 209) were measured by GC-MS in maternal and child hair samples4-6; mothers completed a demographics/lifestyle questionnaire.

The geometric mean (GM) of ∑PBDEs for maternal hair was 45.35 pg/mg for controls and 50.27 for cases; four BDEs were significantly higher in cases than controls (BDE-99, p<0.01; BDE-100, p<0.01; BDE-153, p<0.05; BDE-154, p<0.04). The GM of ∑PBDEs for infant hair was 65.37 pg/mg for controls and 67.95 for cases. Logistic regression analysis revealed that every 10-fold increase in maternal hair BDE-99 (OR=2.41; 95% CI=1.25, 4.65; p<0.01) and BDE-100 (OR=2.32; 95% CI=1.24, 4.34; p<0.01) was associated with more than a doubling in the risk of having a male infant with cryptorchidism; BDE-154 was marginally significant (OR=1.72; 95% CI=0.98, 3.02; p<0.06). Confounders taken into account included maternal age, ethnicity, income and familial history of cryptorchidism amongst others. Paired maternal-infant hair samples showed moderate correlations for each of the BDEs (r=0.34-0.71; p<0.01-0.001).

Our results suggest that maternal exposure to BDE-99 and BDE-100 may be associated with abnormal migration of testes in the male fetus. This may be due to the anti-androgenic properties of these PBDEs7-10.

 

Nothing to Disclose: CGG, SP, KA, LH, VA, AC, RJ, SE, DB, SD, BH, JC