HEALTH

Endocrine disruptors in our food?

Tadpole expressing a green fluorescent biomarker to reveal the presence of a hormonal disruptor. © WatchFrog
Tadpole expressing a green fluorescent biomarker to reveal the presence of a hormonal disruptor. © WatchFrog
Jan-Åke Gustafsson, professor at the Karolinska Institute (SE)  and Cascade coordinator. © Anders Kallersand
Jan-Åke Gustafsson, professor at the Karolinska Institute (SE) and Cascade coordinator. © Anders Kallersand
Gian-Paolo Rando and Balai Ramachandran are members of Professor  Adriana Maggi’s team (at the back in the photo) at the Centre of Excellence on Neurodegenerative Diseases at Milan University. They are working on links between oestrogens and breast cancer.   © Anders Kallersand
Gian-Paolo Rando and Balai Ramachandran are members of Professor Adriana Maggi’s team (at the back in the photo) at the Centre of Excellence on Neurodegenerative Diseases at Milan University. They are working on links between oestrogens and breast cancer. © Anders Kallersand
Arnaud Pillon showing the effects of toxic substances on a mouse, visible through bioluminescence. © Anders Kallersand
Arnaud Pillon showing the effects of toxic substances on a mouse, visible through bioluminescence. © Anders Kallersand

Do we know what we eat? We are surrounded today by over 100 000 different chemicals, present in the air, the soil, the water - and in the food we eat. The Cascade network of excellence is studying the ability of certain of these molecules present in our food to disrupt our hormonal system.

Is breast milk safe for the health of your baby? As for you, what about bread, fruit and fish? These questions are more complex than they seem. One of the reasons is that certain compounds present in food may disrupt our endocrine system. These endocrine disrupting compounds (EDCs) are natural and synthetic compounds present in the environment that act by mimicking or interfering with endogenous hormones.(1)

On 2 October 2008, EDCs were the subject of an Open Forum organised in Brussels by a network of excellence (NoE) named Cascade, in cooperation with seven other projects funded by the European Union, all devoted to the study of different aspects of endocrine disruption (Athon, BioCop, Caesar, Crescendo, NewGeneris, ReProtect and SmeReceptor). Cascade networks over 200 researchers from 9 European countries dedicated to identifying and studying environmental pollutants present in food. Since its start in 2004, Cascade has produced more than a hundred peer-reviewed articles. “But producing knowledge is nothing if the information is not shared”, stresses Jill Jönsson, communication manager with Cascade. Among activities to disseminate the results, the project’s website lists all publications written within the project and gives everyone the opportunity to ask questions to experts.

Similarly, cooperation with other nations is clearly beneficial. “First, with the United States,” points out Andrea Tilche, head of the Environmental Technologies and Pollution Prevention Unit at the European Commission’s Directorate-General for Research (DG Research). The DG Research and the United States Environmental Protection Agency (EPA) have in fact just launched a coordinated call for research proposals on new methods for toxicological screening. The results of the selected projects are expected to enhance our capacity for fast screening of the toxicological properties of industrial chemicals. This would be very valuable in the context of stricter environmental regulations, such as REACH (Registration, Evaluation, Authorization and restriction of chemicals), the European legislation on chemicals that stipulates that up to 30 000 chemicals have to be registered by 2018.(2) “The next step will be to expand this cooperation to other nations, such as Japan, and to emerging countries like China,”continues Andra Tilche.

Why is this transatlantic cooperation important? “There are three main reasons for that”, answers Robert Kavlock, director of the National Center for Computational Toxicology at the EPA. “First, chemicals do not know boundaries: products produced in the United States end up in Europe and vice versa. Secondly, the action mechanisms of EDCs are complex and diverse, therefore requiring the collaboration of experts in different fields of research. Thirdly, technologies developed on both sides of the Atlantic are complementary.” International cooperation in the field of research on endocrine disruption is also a feature of the OECD (Organisation for Economic Co-operation and Development) validation process for the various tests, and also at the European Commission’s Joint Research Centre (JRC).

Shifting from the traditional toxicological paradigm

Endocrine disruptors behave as biological signals and, as such, can be misinterpreted by the organism. One of the problems resides in the fact that the effects of EDCs are hard to establish, mainly because they deviate from a traditional toxicological approach.

Firstly, the effects of exposure to EDCs, whether one-off or over time, may be latent, sometimes only observable years later. This is one of the reasons why it is only recently that epidemiological studies(3) implicating EDCs have produced results. “Besides, we also have to recognise that, until now, the hypothesis of endocrine disruption had scarcely been considered in epidemiological studies”, adds Nicolas Olea, professor at the Laboratory of Medical Investigation at the University of Granada (SP).

In addition, a minimum dose that would cause no adverse effects may not actually exist since, by definition, compounds mimicking biological molecules already present in the body will exceed a threshold level.

Finally, EDCs are rarely present in isolation in the environment. Knowing that the way they interact may be “additive, antagonist, synergetic or without any effect”, as Nicolas Olea points out, demonstrates the need to examine the different combinations of compounds rather than assaying each compound singly.

The precautionary principle

Being at the top of the food chain, humans are particularly vulnerable to chemicals present in food. Do bioaccumulation and biomagnification(4) also apply to EDCs? “The list of potential EDCs actually contains chemicals known for their bioaccumulation and biomagnification properties. Many organochlorine pesticides and PCBs (polychlorobiphenyls) belong to this group. For these, rules concerning persistent chemicals do apply. There are also several EDCs that are not persistent. In their case, problems related to their exposure are present on a daily basis,” explains Nicolas Olea.

In order to avoid exposure to EDCs, the consumer can choose food coming from the bottom of the food chain or certified organic food. “These recommendations are optimal for persistent EDCs. Other recommendations should be added for non-persistent EDCs,” continues Nicolas Olea. “For example, in order to avoid exposure to bisphenol A, it is recommended to limit the use of polycarbonate containers to under stringent conditions only (e.g. very hot liquid, microwave use). In fact, these are the recommendations of the Canadian Government regarding the use of baby bottles.(5) Common sense would also argue for breastfeeding, which should be even safer. However, things might not be so simple, since the mother’s milk may also contain environmental contaminants. This is something of a dilemma and one raised during the Forum by Jan-Åke Gustafsson, professor at the Department of Biosciences and Nutrition at the Karolinska Institute (SE), and coordinator of Cascade.

Research is still ongoing in the field of endocrine disruption. On the Cascade website, an opinion paper written after the Open Forum states the major challenges in the field of research on endocrine disruption. As for the consumer, while research on EDCs is in progress, the best solution might be to adopt the precautionary principle.

Isabelle Noirot

  1. See also issue 58 ofresearch*eu
  2. ec.europa.eu/environment/chemicals/reach/reach_intro.htm. See also issue 48 of RDT info
  3. Epidemiological studies are studies on populations, attempting to link the distribution of diseases to the factors that contributed to these diseases.
  4. Bioaccumulation is the accumulation of substances in an organism. It occurs when the substance is absorbed at a rate greater than that at which it is lost. Biomagnification is the bioaccumulation of a substance up the food chain.


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