The environmental watchdog has not declared some residential land contaminated where it found chemicals which may have posed health risks.

On Friday, the NSW government announced emeritus professors Stephen Leeder, a public health expert, and Chris Fell, a chemical engineer, will lead a review into the EPA's policies.

Polluted groundwater spread from this service station in Randwick and may have posed a "vapour risk" to residential properties, the Environment Protection Authority found. Credit:Peter Rae

It follows a Fairfax Media investigation that last week revealed the Environment Protection Authority was not declaring "significant contamination" on residential land to avoid lowering property prices.

In response, the EPA's chairman and chief executive, Barry Buffier, said if a property was "so badly impacted that it was a risk to human health, then it would be declared."