As I recall, among experts this use of IQ testing is controversial.

That depends a lot on who you call expert. There are people with an ideological agenda against IQ and you may have read books arguing against IQ. That doesn't mean that's the psychometic community doesn't still consider IQ test to be valuable. It doesn't mean that IQ isn't a tool valued by organisation like the EPA.

The usage of the EPA is clearly not standard usage of what the test was desgined to do. If you want to argue that you oppose the usages of the test for purposes besides what the original purpose of the tests you attack the basis on which the EPA decision against mercury pollution rests.