Letter to the Editor: Re: Neurobehavioral Deficits, Diseases, and Associated Costs of Exposure to Endocrine-Disrupting Chemicals in the European Union

ERGO: Breaking Down the Wall between Human Health and Environmental Testing of Endocrine Disrupters

ERGO (EndocRine Guideline Optimization) is the acronym of a European Union-funded research and innovation action, that aims to break down the wall between mammalian and non-mammalian vertebrate regulatory testing of endocrine disruptors (EDs), by identifying, developing and aligning thyroid-related biomarkers and endpoints (B/E) for the linkage of effects between vertebrate classes. To achieve this, an adverse outcome pathway (AOP) network covering various modes of thyroid hormone disruption (THD) in multiple vertebrate classes will be developed. The AOP development will be based on existing and new data from in vitro and in vivo experiments with fish, amphibians and mammals, using a battery of different THDs. This will provide the scientifically plausible and evidence-based foundation for the selection of B/E and assays in lower vertebrates, predictive of human health outcomes. These assays will be prioritized for validation at OECD (Organization for Economic Cooperation and Development) level. ERGO will re-think ED testing strategies from in silico methods to in vivo testing and develop, optimize and validate existing in vivo and early life-stage OECD guidelines, as well as new in vitro protocols for THD. This strategy will reduce requirements for animal testing by preventing duplication of testing in mammals and non-mammalian vertebrates and increase the screening capacity to enable more chemicals to be tested for ED properties.

Human cost burden of exposure to endocrine disrupting chemicals. A critical review

Recently published papers have alleged that exposures to endocrine disrupting chemicals (EDCs) are causing substantial disease burdens in the EU and US and are consequently costing society hundreds of billions of dollars annually. To date, these cost estimates have not undergone adequate scientific scrutiny, but nevertheless are being used aggressively in advocacy campaigns in an attempt to fundamentally change how chemicals are tested, evaluated and regulated. Consequently, we critically evaluated the underlying methodology and assumptions employed by the chief architects of the disease burden cost estimates. Since the vast majority of their assigned disease burden costs are driven by the assumption that "loss of IQ" and "increased prevalence of intellectual disability" are caused by exposures to organophosphate pesticides (OPPs) and brominated flame retardants (PBDEs), we have taken special care in describing and evaluating the underlying toxicology and epidemiology evidence that was relied upon. Unfortunately, our review uncovered substantial flaws in the approach taken and the conclusions that were drawn. Indeed, the authors of these papers assumed causal relationships between putative exposures to EDCs and selected diseases, i.e., "loss of IQ" and "increased prevalence of intellectual disability", despite not having established them via a thorough evaluation of the strengths and weaknesses of the underlying animal toxicology and human epidemiology evidence. Consequently, the assigned disease burden costs are highly speculative and should not be considered in the weight of evidence approach underlying any serious policy discussions serving to protect the public and regulate chemicals considered as EDCs.