ECHA provides clarification for the degradation and mutagenicity studies

ECHA elucidates the rules on accepting adaptations for degradation testing and requiring combined studies for mutagenicity. It also suggests companies should consider these changes while deciding whether to update their registrations. 

Chemical Safety Assessment does not permit registrants to exclude the standard information on degradation of the substance from column 1 under REACH (Annex IX, section 9.2., column 2). Instead, biotic degradation testing must be proposed by companies if the chemical safety assessment indicates the need to further investigate the degradation of the substance and its degradation products. The choice of the appropriate tests depends on the results of the chemical safety assessment 

For adaptation of the degradation tests listed in column 1, companies apply the specific rules for adaptation listed in REACH Annex IX, sections 9.2.1.2-4 and 9.2.3, column 2, along with the general rules for adaptations, listed in Annex XI. As explained in Annex IX and XI, exposure-based adaptations can also be considered when human/environmental exposure is absent or so low that additional hazard information will not lead to improved risk management. But the legal basis for such adaptation must be well-defined. Also, It has been suggested by ECHA that for all adaptations, sufficient justification and documentation are needed while considering the whole lifecycle of the substance. 

Furthermore, for mutagenicity studies, a combined comet assay and micronucleus test is required for the substances registered over one tonne per year under Annex VII and also for annexes VIII, IX and X. 

The combination study will be requested if there is: for mutagenic studies 

• a positive Ames test – which checks the potential of chemicals to create mutations in bacteria. 
• an indication of a chromosomal aberration concern; and 
• no other adequate and appropriate in vivo genotoxicity data in the registration. 

This combined study can be helpful to lessen animal testing while providing useful information on the potential of a substance to induce chromosomal aberrations or gene mutation in vivo.