Worse, there is no firm definition of exactly what a PFAS is—at least in the United States. The Paris-based Organization for Economic Cooperation and Development (OECD), which works with 38 member nations including the U.S. to foster international cooperation and economic growth, defines PFAS as industrial chemicals that have at least one fully fluorinated carbon atom—which is a carbon atom with two or three fluorine atoms attached to it. There are about 15,000 species of chemicals that meet that standard. But the EPA has pushed back, broadening the definition to two fully fluorinated carbon atoms. “The final definition does not include substances that only have a single fluorinated carbon,” the agency wrote in its formal report in 2023—during Joe Biden’s presidency. That change is worrying.
A minimum of 2 fully fluorinated carbon atoms instead of 1 is NOT broadening the definition. That’s narrowing it.
A minimum of 2 fully fluorinated carbon atoms instead of 1 is NOT broadening the definition. That’s narrowing it.
Think of the definition as a sluice gate. When you allow more things through, you’re opening it wider, therefore broadening the definition. I know it’s counter-intuitive sometimes to think of it like that. Narrowing the definition would be to let fewer things through, thus closing the gate.
Edit:
Reading through the discourse below, I think I see the points made. It might should be reversed.
Allowing more things through, if I understand your analogy correctly in this case, is broadening the exceptions – things not matched by the definition.
But, I’ll bite, let’s dive in. In a Venn diagram, substances with a minimum of 2 fully fluorinated carbon atoms is a subset of substances with a minimum of 1fully fluorinated carbon atoms, yes?
Similarly, M&Ms with only red and green colors is a subset of M&Ms of any color, yes? If a person was to change their personal definition of acceptable M&Ms from any color to only red and/or green, would you call that broadening that definition?
The EPA definition would exclude chemicals like trifluoroethanol, so the EPA’s definition is narrower, not broader.
From a strict organic chemistry perspective, trifluoroethanol contains a perfluorinated methyl group, and methyl is a type of alkyl, therefore it must be considered a PerFluoro Alkyl Substance.
From the first article:
A minimum of 2 fully fluorinated carbon atoms instead of 1 is NOT broadening the definition. That’s narrowing it.
Think of the definition as a sluice gate. When you allow more things through, you’re opening it wider, therefore broadening the definition. I know it’s counter-intuitive sometimes to think of it like that. Narrowing the definition would be to let fewer things through, thus closing the gate.
Edit: Reading through the discourse below, I think I see the points made. It might should be reversed.
Allowing more things through, if I understand your analogy correctly in this case, is broadening the exceptions – things not matched by the definition.
But, I’ll bite, let’s dive in. In a Venn diagram, substances with a minimum of 2 fully fluorinated carbon atoms is a subset of substances with a minimum of 1fully fluorinated carbon atoms, yes? Similarly, M&Ms with only red and green colors is a subset of M&Ms of any color, yes? If a person was to change their personal definition of acceptable M&Ms from any color to only red and/or green, would you call that broadening that definition?
But wouldn’t requireing two fluoridated carbon atoms instead of just one to qualify as PFAS, encompass less chemicals, thus narrowing the definition?
The EPA definition would exclude chemicals like trifluoroethanol, so the EPA’s definition is narrower, not broader.
From a strict organic chemistry perspective, trifluoroethanol contains a perfluorinated methyl group, and methyl is a type of alkyl, therefore it must be considered a PerFluoro Alkyl Substance.