There are more than 10,000 PFAS, per- and polyfluoroalkyl substances, and they’re used almost everywhere. Stop playing whack-a-mole with them, says Lara Williams for Bloomberg Opinion. LONDON: The more you learn about PFAS – per- and polyfluoroalkyl substances – the worse it gets. Though improvements in monitoring and remediation techniques are welcome, what the world needs first and foremost is a universal ban on the chemicals. In fact, we needed it yesterday. There are more than 10,000 PFAS,