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Endocrine Disrupting Chemicals: Recent Meeting of Experts and EC Chief Scientific Adviser Meeting

December 5th, 2013

In late October 2013 a meeting on endocrine disrupting chemicals (EDCs) was held between the EC chief scientific advisor and a group of experts.

EDCs interact with hormonal receptors in animals and man, and there may be long term health effects that have yet to be identified. Vulnerability to EDCs might be much greater during reproductive development. EDCs have been much debated, with disagreement about whether or not there is a threshold below which EDCs do not have effects. Most toxicological endpoints have such thresholds, and these are the values on which Derived-No-Effect-Levels (DNELs), used for risk assessment under REACH, are based; however some effects, such as mutagenicity, are considered to be non-threshold.  

The meeting was held to identify both consensus and uncertainties, but not policy. Full minutes are available here; the main conclusions are summarised below. EU legislation including REACH does not currently reflect the OECD test for endocrine disruption. There is pressure for less animal testing but a need for more evidence regarding EDCs.

Main conclusions: 

1.       There is agreement on definition (provided by WHO, used by EFSA), which must be interpreted in relation to EDC criteria.

2.       Debate about thresholds is on-going:

  • There is uncertainty on whether thresholds exist.
  • Thresholds cannot be defined using only whole organism experiments.
  • Better and quantitative understanding of mechanisms is needed.

3.    Non-monotonic dose-response:

  • EDCs may have a non-monotonic dose-response curve (U or sideways S shaped), where effect decreases with increasing dose for some of the dose-response curve.
  • It is not known how often adverse non-monotonic effects occur.

4.    Guidelines:

  • Not all potential endocrine effects are covered by current guidelines.
  • Test strategies need to be designed to find non-monotonic effects – some such designs have been proposed but none have been agreed on.
  • More methods are needed to evaluate possible effects relevant for humans, especially hormonal cancer induction or long term effects.