A preliminary report into Ministry of Defence firing ranges and bomb testing areas at Shoeburyness has called for a more detailed study of contamination.
Investigators said the site was used by the Atomic Weapons Establishment (AWE) for assembling and testing components of Britain's first nuclear bombs.
Weapons are still tested and evaluated on the ranges in Essex and bomb disposal training is carried out.
The report, by independent consultants, recommends further investigation.
Consultants Carl Bro recommend investigation of the possible residual contamination from old firing points and burial pits.
A second phase of land quality assessment will include analysing soil samples and will take up to three years to complete.
Defence minister Don Touhig said: "I welcome the outcome of this report. The MoD conducts routine reviews of all its sites across its 240,000 hectare estate, but we recognise that Shoeburyness is of particular interest given its use for weapons test and evaluation.
"MoD Shoeburyness is an important national asset that needs to be maintained and sustained."