Labour has accused the Government of being “asleep at the wheel” when it comes to coastal landfill sites facing erosion and flooding.
Over 1,000 are thought to be at risk of spilling their toxic contents into the sea which could then damage ecosystems, wildlife or people.
Waste is already spilling into the sea in 25 council districts, while repairing or moving landfill contents to safer areas is thought to cost millions of pounds.
Thousands more sites are situated in flood plains away from the coast with many left unsealed because they were in use before strict regulation was introduced.
One particular cluster in Chertsey, Surrey, is believed to have been responsible for causing terminal illnesses and the death of a seven-year-old boy, Zane Gbangbola.
Years of investigation and campaigning by his parents has revealed the presence of a landfill next to their home thought to contain military waste from a nearby tank factory.
Hydrogen cyanide, a toxic nerve agent, was found in their home hours after flood water ran past the landfill and into the family’s basement, which Kye Gbangbola, Zane’s father, said not only killed his son but left himself paralysed.
He and Zane’s mother, Nicole Lawler, have been calling for an independent inquiry that would examine evidence excluded at the coroner’s inquest.
The Government has so far declined any such inquiry.
Labour has previously backed opening a new investigation and is now accusing the Government of being silent on what the Coastal Landfill Working Group describes as a “silent, ticking time bomb”.
Emma Hardy, Labour’s minister for coastal communities, said: “The next pollution crisis is just round the corner – with a mountain of plastic and chemicals at risk of collapsing into the sea on an industrial scale.
“Yet this Conservative Government is asleep at the wheel with absolutely no interest in tackling the problem.
“The Government must immediately start working with local councils to tackle this growing threat. If they don’t, our beautiful seas and beaches will be buried under an avalanche of waste and toxic chemicals.”
The party said it would establish a Flood Resilience Task Force that would meet every winter ahead of the extreme weather.
It would co-ordinate preparation efforts for coastal erosion and flooding between central government, local authorities, communities and emergency services.
The Government has been contacted for comment.