I'm not a regulatory expert, but that comment was made to compare with what we know about toxicology for lead, arsenic, and mercury. There are almost no recorded cases where the threshold value has increased; it has always decreased. We've never gathered more data and concluded that it was less toxic than we thought in the end. There are always other effects and other studies.
In the case of PFAS, we currently have data and we're going to accumulate new data, and that data will certainly show us that the effects are being felt at lower and lower thresholds.
At the moment, the thresholds have been established, at least in the United States, as the commissioner mentioned, based on a cost-benefit analysis. So they analyze the number of human lives that will be saved or improved, and they assign a value in millions of dollars to the costs incurred and the savings realized.
PFAS are some of the most difficult molecules to remove. As the technology and the means available to remove PFAS improve and cost a little less, we will have to redo a cost-benefit analysis and it will become more profitable to have stricter regulations and lower our thresholds.