In January 2022, an international team of researchers sounded the alarm about the impact of manufactured chemicals and their “cocktail” effects on the entire earth system. Scientists have concluded that humanity has crossed the planetary threshold to properly assess the production and emissions of new pollutants.
Among these contaminants are endocrine disruptors (flame retardants used as flame retardants, bisphenol A found in some plastics, pharmaceutical products) that are known to specifically affect the hormonal system of animals and humans and thus cause health problems. These pollutants are found in our food, drinks, furniture, rivers and lakes; in short, they are everywhere.
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Unlike most pollutants (such as metals), whose toxicity increases with increasing amounts, endocrine disruptors often act in the opposite way, that is, they have a harmful effect at very low concentrations. This feature makes their regulation very difficult.
I am a Research Professor at the National Institute for Scientific Research (INRS) and Chair of Research in Ecotoxigenomics and Endocrine Disorders in Canada. Together with my colleague Isabelle Plant, who specializes in research on environmental causes of breast cancer at INRS, we co-founded the CIAPE Cross-Industry Endocrine Disruptor Analysis Center in 2020.
CIAPE members have just published a special issue on endocrine disruptors in a specialized scientific journal. Environmental studies. This edition includes 14 papers documenting all scientific and environmental health advances related to endocrine disruptors. Here we summarize some of the main points related to their ubiquity, detection, elimination and regulation.
Tracking the impact of pollutants on human health
A review of the group’s literature by epidemiology researcher Vicky Ho of the University of Montreal emphasized the importance of epidemiological studies (the study of health problems in human populations, their frequency, their distribution in time and space) in characterizing the health effects of endocrine disruptors. human populations.
For example, a South Korean study found that persistent organic pollutants such as polychlorinated biphenyls (PCBs) (insulating fluids) in the blood tripled the risk of prostate cancer. Another study found that high levels of brominated flame retardants (flame retardants found in upholstered furniture, for example) in the serum of young girls were associated with earlier menstruation.
However, it is difficult to link health problems to exposure to specific disruptors because people are exposed to a mixture of pollutants throughout their lives, making epidemiological studies very difficult. Professor Ho and her team, however, recommend integrating human epidemiology into toxicology (the study of the harmful effects of chemicals on living organisms) and ecotoxicology (the study of pollutants and their effects on the environment) studies when assessing the risk of chemicals.
Our drugs end up in the environment
Pharmaceuticals have become products of (over)consumption, some of which are used daily. The volume of their consumption is such that they end up in sewage and rivers with urine and faeces excreted by people and farm animals.
The chemical structure of hormones has been well preserved over the course of evolution (testosterone has been found in both fish, frogs, birds, mammals, and humans). Thus, hormonal drugs, or drugs designed to affect our hormones, act on other animals, sometimes causing adverse effects.
Pascal Voden, a physiology researcher at the University of Tours, and his team found that antibiotics, antidepressants, and non-steroidal anti-inflammatory drugs (ibuprofen, naproxen) have neurological effects, especially on animal brain development and behavior.
Screening for abnormal endocrine water activity
Endocrine disruptors have a diverse chemical structure, heterogeneous chemical and physical properties, and the ability to distribute in various environmental matrices, including human tissues, which makes them difficult to detect. However, their characterization has advanced significantly in recent decades with the development of advanced and highly sensitive assays to detect low levels of endocrine disruptors in water, soil, air, sediment, food, blood, breast milk, placenta, etc. Therefore, they can now even be detected in infinitesimal concentrations, paving the way for better regulation and international governance, according to a research team led by Professor Emeritus Chris Metcalfe of Trent University.
The presence of a number of endocrine disruptors in our environment, such as sewage, also complicates the study of their toxicity and health effects. For example, individual concentrations of various contaminants may be low in municipal effluents, making it impossible to observe estrogenic (estrogen-like) activity from individual studies of these compounds. On the other hand, when the effects of all contaminants add up, wastewater may exhibit general estrogenic activity.
Chemical analysis of such samples is difficult, and the use of bioassays (tests that use living organisms or isolated cells) can help solve such a problem. We have found that it is indeed possible to test whether municipal, hospital or industrial effluents have general endocrine disruptive activity using, for example, cell assays (using laboratory-maintained cell lines that are hypersensitive to endocrine disruptors).
These high-throughput tests both test the efficiency of wastewater treatment systems and monitor the environment, according to work by Julie Robitaille of INRS. Governmental and international bodies must now set environmental criteria (toxicity thresholds) based on available scientific evidence to protect our ecosystems and human health.
Removal of endocrine disruptors from wastewater
The removal of contaminants from wastewater is one of the main tasks of wastewater treatment plants. There are many different processes for treating contaminated water, each with its own advantages and limitations.
In our literature review led by Professor of Sanitation and Decontamination Jean-Francois Blé of INRS, we found that despite the variety of treatment processes available, some treatment plants still fail to eliminate 100% of endocrine disruptors.
On the other hand, some processes, such as ozonation at the end of wastewater treatment, can completely remove BPA (or BPA, found in plastic bottles in particular) present in the water. In addition, the city of Montreal will soon begin work to provide the city with an ozonation process to disinfect wastewater. Mr Blais and his team believe it is important to characterize the types and concentrations of contaminants present in wastewater for each municipality before selecting the best treatment options.
Rethinking pollution risk analysis
Our work has shown that the “Integrated Approaches to Testing and Evaluation” initiative proposed by the Organization for Economic Co-operation and Development (OECD) will be an excellent first step towards a fully integrated approach to existing pollutant data, including endocrine disruptors. This initiative aims to bring together research findings from around the world to better understand the impact of pollutants and establish appropriate regulation.
Canada is currently upgrading its risk assessment process to include comprehensive testing and assessment approaches.
The main takeaway is that the global community needs a scalable risk assessment platform that integrates existing data and all new real-time data on these environmental pollutants. To do this, risk assessment must become more dynamic and malleable over time.
In other words, newly acquired knowledge should be readily available for use in risk assessment models so that the use or production of a new or existing chemical can be restricted or even banned in a shorter period of time based on hard evidence. including disruption of our hormonal system.
Such a scalable and integrated platform should accelerate the transfer of knowledge from the scientific community to society, which is currently a major barrier to creating a safer environment.