Evaluating PFAS substitutes based on toxicity characteristics




Robert DeMott

PhD, DABT, Managing Principal
T: +1 813 628 4325

Ensuring against regrettable substitutions

Ensuring against “regrettable substitution” outcomes is a key focus as products are re-formulated.   Product stewardship teams recognize the need to put various alternatives through a complex screen to look at toxicity, persistence and other hazard characteristics comprehensively. The optimal alternative for reducing persistence, for example, may not have optimal toxicity characteristics. 

When evaluating innovative alternative ingredients, a typical challenge is the limited information base available. Ramboll worked with a product stewardship team to look at how modifications to PFAS ingredients would change their human health and environmental toxicology characteristics. Our goal was to provide a prioritization approach identifying types of chemistry changes expected to result in reduced toxicity. This tool helped the team ensure against regrettable substitution when reformulating PFAS-containing products.

Selecting suitable read-across surrogates 

Expertise with chemical properties affecting toxicity and the types of responses to PFAS compounds allowed us to use available testing information to evaluate a series of modifications to fluorotelomers and to demonstrate how carbon chain length reduction, frequently helpful with regard to reducing persistence, has to be coupled with other chemical properties to achieve improved toxicity characteristics. 

We solved the challenge of limited toxicity information by identifying patterns for PFAS with similarities in key portions of their structure and focusing the selection of suitable read-across surrogates based on these similarities. Using this approach, we were able to characterize both groupings of PFAS expected to have similar toxicity and specific chemical modifications that could be associated with undesirable toxicity outcomes.

Results that matter

Ramboll’s expansion of the client’s decision matrix allowed them to rank various product reformulations based on both persistence and toxicity factors. This resulted in the identification of substitute ingredients with preferred characteristics from a group of fluorotelomers with similar terminal chemical structures and the de-selection of several modified short-chain PFAS.


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