The harbourside district of Mosman, parts of the eastern suburbs and the Blue Mountains are among the most lead-polluted areas in greater Sydney, with new data revealing the city's toxic footprint extends well beyond the industrial inner west.

It comes as research raises fresh concerns about the risks of eating home-grown vegetables and eggs from backyard chickens in highly lead-contaminated areas.

Toxic Sydney: map shows the percentages of homes where lead has been found above safe guidelines in soil sampled. Supplied by Macquarie University / VegeSafe Credit:Macquarie University/VegeSafe

High lead levels can cause irreversible harm in children, putting them at risk of behavioural problems, reduced attention span and a lowered IQ.

They are also at heightened risk of exposure through hand-to-mouth contact with household dust.