Endocrine disruption in teleosts and amphibians is mediated by anthropogenic and natural environmental factors: implications for risk assessment

Abstract

Environmental variation in the Anthropocene involves several factors that interfere with endocrine systems of wildlife and humans, presenting a planetary boundary of still unknown dimensions. Here, we focus on chemical compounds and other impacts of anthropogenic and natural origins that are adversely affecting reproduction and development. The main sink of these endocrine disruptors (EDs) is surface waters, where they mostly endanger aquatic vertebrates, like teleost fish and amphibians. For regulatory purposes, EDs are categorized into EATS modalities (oestrogenic, androgenic, thyroidal, steroidogenesis), only addressing endocrine systems being assessable by validated tests. However, there is evidence that non-EATS modalities—and even natural sources, such as decomposition products of plants or parasitic infections—can affect vertebrate endocrine systems. Recently, the disturbance of natural circadian light rhythms by artificial light at night (ALAN) has been identified as another ED. Reviewing the knowledge about EDs affecting teleosts and amphibians leads to implications for risk assessment. The generally accepted WHO-definition for EDs, which focuses exclusively on ‘exogenous substances' and neglects parasitic infections or ALAN, seems to require some adaptation. Natural EDs have been involved in coevolutionary processes for ages without resulting in a general loss of biodiversity. Therefore, to address the ‘One Health’-principle, future research and regulatory efforts should focus on minimizing anthropogenic factors for endocrine disruption. This article is part of the theme issue ‘Endocrine responses to environmental variation: conceptual approaches and recent developments’.

Endocrine responses to environmental variation

“…Similarly, environmental concentrations of EDCs, such as bisphenols derived from plastic waste and manufacture, are increasing at an alarming rate worldwide [ 18 , 54 , 55 ]. EDCs interact with nuclear receptors such as thyroid and glucocorticoid receptors to activate or block endocrine signals [ 25 , 56 , 57 ].…”

“…EDCs interact with nuclear receptors such as thyroid and glucocorticoid receptors to activate or block endocrine signals [ 25 , 56 , 57 ]. EDCs thereby impair essential biological functions across a broad range of taxa [ 58 ] and have the potential to disrupt ecosystems, particularly in aquatic environments [ 18 ]. Environmental exposures throughout the lifetime define the chemical exposome of an organism [ 59 ].…”

“…Anthropogenic endocrine disruption modifies endocrine-mediated responses to natural variation and links the fields of environmental science and toxicology to ecology and conservation biology [ 16 , 17 ]. Understanding of how anthropogenic impacts such as climate change, artificial light-at-night (ALAN) and endocrine disrupting chemicals (EDCs) alter evolved responses of animals is only now emerging [ 18 ]. There needs to be a collaborative effort to understand their impacts on non-human animals in the context of their natural and urbanized environments.…”