The EPA approach to approving new chemicals for commerce ignores risks and violates the nation’s primary chemicals law, environmental health advocates are arguing.

The Environmental Protection Agency’s approach glosses over the different ways companies make and use the same chemical, even though the differences may alter the chemical’s health effects, the Natural Resources Defense Council alleged in an opening brief filed May 1 in a federal appeals court.

In January, the NRDC filed its challenge to EPA’s framework...