Familiar and novel reproductive endocrine disruptors: xenoestrogens, dioxins and nanoparticles.

Environmental contaminants are known to exert endocrine-disrupting effects on the reproductive axis of animals. Many of these molecules can affect steroid biosynthesis or estrogen-receptor signaling by behaving as estrogen-like molecules ("xenoestrogens"), or by exerting estrogenmodulatory effects. Exposure to some compounds has been correlated with the skewing of sex ratios in aquatic species, feminization and demasculinization of male animals, declines in human sperm counts, and overall diminution in fertility of birds, fish, and mammals. We herein devote space to several classes of endocrine-disrupting compounds (EDCs), including estrogenic substances such as bisphenol A (BPA), molecules that can behave at times anti-estrogenically while activating the aromatic hydrocarbon receptor (AHR), such as dioxins (a known human carcinogen), and novel, ubiquitous molecules such as nanoparticles, particularly gold nanoparticles (GNPs), that appear to alter the sexsteroid biosynthetic pathway.