Metals as endocrine disruptors and the related health effects

Abstract

Quite a few metals, both synthetic and naturally occurring, may disrupt hormonal homeostasis and/or developmental processes. These include bio-accumulated ones such as cadmium (Cd), lead (Pb), methyl-mercury (MeHg), and abandoned organotin, which may stay in human bodies for months to years; others such as inorganic arsenic (iAs), manganese (Mn), chromium (Cr), and copper (Cu) have half-lives of hours to several days. People exposed to these metals mainly through ingestions of contaminated drinking water and food (i.e. grains, fish), and inhalation of polluted air. The disturbed systems might consist of endocrine (i.e. iAs inducing type 2 diabetes, Pb affecting on reproductive health), neurological (Pb, MeHg and their neurocognitive and behavioral effects, Mn on peripheral neurological disorder), and maybe immune (allergy). Increased risk of some cancers was suggested such as gynecological ones at endometrium, ovary, etc.Certain metals such as Pb and MeHg have been proved to cross the placenta and/or brain barriers and affect the next generations’ health through the organ dysfunction and/or epigenetic changes. Exposure to Pb and iAs was found associated with spontaneous abortion, stillbirth and neonatal deaths; while maternal exposure to arsenic was associated with impaired glucose tolerance.Human survey for MeHg exposure was found higher than in the US and Europe, but similar to in Asia such as Japan. We reported MeHg was associated with type 2 diabetes with an odds ratio (OR) of 1.64. From our 15-year and 6-wave follow-up analyses, prenatal exposure to iAs was found to significantly associate with an increased risk of asthma (OR = 4.28, for greater than the median level); children's exposure was associated with an increased risk of allergic rhinitis (OR = 2.26).More investigations are warranted particularly with considerations of co-exposure to prevalent organic EDCs (i.e. phthalate, persistent organic pollutants) at various doses.