Chris Hughes of Ricardo explains how a new tool will offer consistent guidance in environmental persistence assessment for the industry
New software for persistence assessment
Chris Hughes of Ricardo explains how a new tool will offer consistent guidance in environmental persistence assessment for the industry
The persistence of chemicals in the environment plays a key role in determining exposure to people and other organisms . This makes it an important component in risk assessment and regulation . Recently , there has been significantly increased awareness of issues around chemical persistence , including global plastic pollution and the presence of per- and poly-fluoroalkyl substances ( PFAS ) or ‘ forever chemicals ’ in the environment .
This has triggered numerous global policy initiatives . The EU ’ s Chemicals Strategy for Sustainability , for example , has proposed new measures for persistent , mobile and toxic ( PMT ) substances , and introduced requirements to carry out persistence assessments under the Classification , Labelling & Packaging ( CLP ) regulation .
Additional regulatory measures have created dual challenges for the chemicals industry : a significantly greater demand for chemical biodegradation testing ; and many more substances coming into scope for highly complex and detailed persistence assessments . This is bringing ongoing implementation challenges into sharp focus , including the notable gaps in available guidance .
Figure 2 - Scheme for determining persistence assessment conclusions within the PAT
Persistence assessment
Persistence assessment is a regulatory process whereby the intrinsic potential of a chemical to resist degradation processes in the environment is evaluated . In doing so , more persistent chemicals are identified and prioritised for potential further regulatory action . The rationale is that these chemicals present the potential for increased and poorly reversible exposure , and hence risk .
Persistence assessment is a cornerstone of regulatory frameworks , such as EU REACH , where persistence is evaluated alongside toxicity and bioaccumulation potential , with persistent , bioaccumulative and toxic ( PBT ), and very persistent , very bioaccumulative ( vPvB ) substances qualifying as substances of very high concern ( SVHCs ).
Persistence is typically evaluated by comparing degradation halflives to set criteria in individual compartments . There are three key issues with this approach : 1 . Observed half-lives are highly variable and depend on many factors 2 . Some substances have properties that lead to problems in measuring their half-lives 3 . Half-lives in individual environmental compartments may not describe well the overall half-life of a substance in the whole environment
Figure 1 - Figure 1 – Overall PAT workflow
22 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981