Embryonic Exposure to the Polybrominated Diphenyl Ether Mixture, DE-71, Affects Testes and Circulating Testosterone Concentrations in Adult American Kestrels (Falco sparverius)

Abstract

Polybrominated diphenyl ethers (PBDEs) are additive flame retardants that are environmentally persistent and bioaccumulative. The developmental effects of in ovo exposure to environmentally relevant levels of the PBDE technical mixture, DE-71, on male reproductive physiology in captive American kestrels (Falco sparverius) was determined. Males were exposed in ovo by direct maternal transfer to DE-71 at three mean concentrations of 289 ng/g ww (low exposure), 1131 ng/g ww (high-exposure), or background levels of 3 ng/g ww (control). As adults, males were paired with unexposed females for breeding and, 1 year later, sacrificed for testes evaluation. While breeding, high-exposure males demonstrated a trend of reduced circulating testosterone levels when their female mate commenced egg laying when compared with controls (p = 0.056). No differences in circulating free T₄ or T₃ were detected. Sperm numbers were elevated on the perivitelline layer of the first egg of both high- and low-exposure males when compared with controls (p = 0.021). High-exposure males had a higher gonadosomatic index (p = 0.046) and heavier right testis than controls (p = 0.034) with a similar trend for their left testis (p = 0.055). High-exposure males had more seminiferous tubules containing lumen than controls (p = 0.030), and in proportion to the total number of tubules, low-exposure males had more tubules containing lumen than did controls (p = 0.016). Only high-exposure males had fewer than half of tubules containing final spermatids (43%). The results of the present study demonstrate that embryonic exposure to technical DE-71 affects the reproductive tract of adult male kestrels.