An amputated foot is not considered a "serious injury" under the O'Farrell government's changes to WorkCover, a parliamentary inquiry has heard.

In addition, it is taking WorkCover up to four months to review claims by injured workers - far exceeding its statutory limit of 30 days, the NSW Legislative Council's Law and Justice Committee heard on Friday.

Injured workers are losing entitlements ... Greens MLC David Shoebridge. Credit:Simon Alekna

The O'Farrell government's WorkCover changes, which started in 2012, were designed to lower the costs of the workplace compensation agency.

Since the changes were introduced, the number of injured workers receiving benefits under WorkCover has dropped sharply, from about 70,500 in 2012 to about 60,000 in 2013.