Endocrine disruptors are frequently discussed but what exactly are they? And what is the current position from a research and regulatory perspective? Here’s some food for thought.
Endocrine disruptors (ED) are substances or blends of substances that alter the way in which the hormone system functions. They can have adverse effects on the health of exposed individuals or that of their descendants.
These substances can interfere with all of the major functions of living organisms: growth, reproduction, behaviour, nutrition, metabolism, the nervous system and immune system. In fact sensitivity to these substances can vary depending on the time of life (foetal period, post-natal or pre-puberty, etc.).
According to a recent study carried out by the Institute for Risk Assessment Sciences, the socio-economic impact of endocrine disruptors on the health of EU citizens is estimated at 46 to 288 billion euros(1). Another set of studies conducted in 2015 had previously set the figure at 157 billion.
Exposure from extremely diverse sources
EDs figure largely in our everyday lives: phthalates in plastics (toys, packaging, food containers, etc.), bisphenols in plastics, thermal papers or flame retardants, parabens in cosmetics, organochlorine compounds in crop protection products, tin and derivatives used in solvents and combustion products [dioxins, furans, PAH (polynuclear aromatic hydrocarbons)]. Overall, almost 800 products have the potential to disrupt hormone sensors, hormone synthesis or hormone conversion. However, only a small fraction has been assessed to date. Exposure occurs in different ways (ingestion, inhalation, skin contact). Almost 80% of the exposure comes from food (such as pesticides, food additives, plasticisers used in packaging, etc.).
The effects are not necessarily correlated to the dose. They may be higher at a low dose (referred to by toxicologists as “non-monotonic dose response“). Exposure time per se is also an important factor for consideration. Not to be overlooked are blends of substances, which generate a cocktail effect warranting more extensive research.
Three main mechanisms of action
EDs act through three different types of mechanism. On the one hand, they may mimic the action of a hormone, so interfering with how the body/organism responds to that hormone (with unwanted reactions). On the other hand, they can block the action of a hormone by preventing it from targeting cells, thus blocking transmission of the hormone signal. Finally, they can disrupt the production, transport, elimination or regulation of a hormone or its receptor.
What is the regulatory framework?
Several European regulations cover endocrine disruptors, including REACH (with inclusion in the list of substances subject to authorisation: a substance is banned if it is deemed to be of “very high concern”); CLP regulation (regarding the classification, labelling and packaging of chemical substances and mixtures); and regulation governing crop protection products and biocides (which excludes certain substances).
France published its initial national strategy on endocrine disruptors in April 2014 in order “to reduce population and environmental exposure”. The second strategy – currently in the pipeline for the 2019-2022 period – focuses on three types of action: protection of the population (publication of the REACH list, communication campaign, training of health professionals and local authority personnel); action to protect the environment (exploratory analyses of fast-moving consumer goods intended for sensitive populations, measurement of the levels of permeation into various environments, heightening awareness of exposure via foods, encouraging voluntary commitments from industry and distributors to substitute products); and action to raise understanding [co-ordination to support research and innovation, extending monitoring to disorders other than those involved in reproduction (metabolism, the nervous system, etc.)].
Europe adopted a Community strategy in 1999 but is currently updating its approach, as outlined in a Commission memo dated 7 November 2018. The new strategy encompasses evaluation of the legislative framework in particular. However, in view of the fact that the framework proposed by the Commission does not confront this menace, the European Parliament adopted a resolution in April requesting the Commission to review its approach between now and June 2020. More specifically, it calls on the Commission to treat EDs as CMRs(2) in terms of legislation, to consider the effects of mixing and exposure to a combination of substances, to encourage research and trials, and to introduce appropriate bio-monitoring strategies, etc. This resolution was adopted by 447 votes out of a possible 502. So, watch this space.
1) Study cited in the European Parliament resolution towards a comprehensive European Union framework on endocrine disruptors (2019/2683/RSP) adopted on 18 April 2019.
2) CMR: substances carcinogenic, mutagenic or toxic to reproduction.