Internal memo shows Trump appointee targeting EPA program that assesses toxic chemicals

Published May 5, 2026 6:00AM (EDT)

EPA Administrator Lee Zeldin. (REBECCA DROKE/POOL/AFP via Getty Images)

This article originally appeared on ProPublica .

For decades, a small program in the Environmental Protection Agency conducted the painstaking scientific work of assessing the toxicity of chemicals.

The calculations done by scientists at IRIS, as it was commonly known, underpin vast numbers of chemical regulations, permits and other environmental rules in the U.S. and abroad.

Now the Trump administration is suggesting that their library of more than 500 chemical assessments can’t be trusted, opening the door to weakening hundreds of efforts to protect people from harmful chemicals at the state and federal level.…