Problems faced when evaluating the bioaccumulation potential of substances under REACH

Area of Science:

• Environmental Chemistry
• Chemical Regulation
• Ecotoxicology

Background:

• The European chemical legislation REACH identifies persistent, bioaccumulative, and toxic (PBT) substances due to potential long-term environmental effects.
• REACH Annex XIII defines PBT criteria, with bioconcentration factor (BCF) as the primary measure for bioaccumulation potential.
• Standardized aquatic exposure tests reliably assess BCF for neutral, lipophilic organic substances.

Purpose of the Study:

• To review current limitations in REACH bioaccumulation assessments.
• To propose refinements for evaluating bioaccumulation potential, especially for challenging substance groups.
• To enhance the identification and regulation of PBT substances under REACH.

Main Methods:

• Analysis of current REACH guidelines and Annex XIII criteria for bioaccumulation assessment.
• Evaluation of standardized aquatic test systems and their limitations.
• Review of alternative test results and indications for bioaccumulation (e.g., bioaccumulation factor, biomagnification, trophic magnification).

Main Results:

• Current test systems struggle with highly hydrophobic, amphiphilic, and nonlipophilic compounds.
• Existing methods may not fully capture complex bioaccumulation mechanisms beyond lipophilicity.
• Alternative data are currently only accepted as supporting evidence, limiting comprehensive assessment.

Conclusions:

• Refinements in bioaccumulation assessment are needed for certain substance groups under REACH.
• Developing and integrating alternative test systems and considering additive accumulation mechanisms are crucial.
• Improved evaluation strategies will enhance the accurate identification and regulation of PBT substances.