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Do Endocrine Disrupting Chemicals (EDCs) have a safe limit?

One of the big debates about endocrine disrupting chemicals is: Is there a threshold (a ‘safe level’) below which they don’t disrupt the endocrine (hormone) system?

The European Commission set up an expert advisory group on Endocrine Disrupters in 2011; CHEM Trust are part of this group. At their 5th meeting in February 2013 the experts discussed key scientific uncertainties when trying to determine thresholds for EDCs

The EU Commission’s Joint Research Centre (JRC) has finally published a report of this meeting, “Thresholds for Endocrine Disrupters and related Uncertainties”, which looks at the threshold issue in depth. Some key points from the report:

  • Most of the experts in the group agreed that thresholds of adversity for EDCs may be very low or absent during early development
  • Several experts also highlighted that it may be very difficult to determine thresholds with the current available standard tests.
  • Thresholds determined in laboratory experiments are not equivalent to the true biological threshold, as a study with more sensitive endpoints may lead to a lower threshold. This calls into question the reliability of current risk assessment approaches
  • Additional relevant uncertainties discussed ranged from low dose effects, non-monotonic dose response curves to mixture effects and critical windows of exposure.

Chemical Watch covered the report, including comments from CHEM Trust director Gwynne Lyons:

“The [JRC] report is a very considered piece,” says Gwynne Lyons, director of NGO ChemTrust and a member of the Endocrine Disruptors Expert Advisory Group (ED EAG). She highlights the fact that “several experts said that although thresholds may exist, it is going to be difficult to measure them with any confidence, given current test methods.”

Some NGOs are concerned that the lack of clarity in establishing whether or not thresholds exist may lead to lengthy delays in substituting EDCs. The review document quotes extensively another ED EAG report on identifying EDCs, which also covers thresholds (CW 25 March 2013).

Ms Lyons is now fearful that ECHA’s Risk Assessment Committee (Rac) “will ignore the carefully considered voice of the experts”.  “I think they will just have an eye on the difficulty of regulating, or requiring, industry to find safer alternatives and just go along with the normal risk assessment, using the outdated test methods that are not well targeted to pick up endocrine disruptors,” she says.

In CHEM Trust’s view, in the absence of evidence that thresholds exist, the EU and others should treat EDCs as non-threshold substances and work to ensure that they are substituted with safer alternatives.