Environmental experts have warned of a toxic "ticking time bomb" putting Aussie lives at risk, because of poor regulation around coal ash waste.

National guidelines are desperately needed for the sector and energy companies should be forced to maintain a bond or financial assurance to ensure ash dumps are properly managed, according to Environmental Justice Australia.

The not-for-profit group of lawyers' new report, "Unearthing Australia's toxic coal ash legacy" released on Monday, wants to lay bare the environmental and health risks from the waste.

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"Coal ash is an enormous toxic legacy issue for Australia that largely flies under the radar, despite it being one of Australia's biggest waste problems and a huge risk to human and environmental health," report author and EJA lawyer Bronya Lipski said.

"Coal ash dumps are a ticking time bomb. All Australian governments need to act now, not wait for a disaster."

Dumps can be found in Victoria, NSW, Queensland, WA and SA and the ash accounts for nearly one-fifth of Australia's waste stream, the group says.

Coal ash linked to cancer

Coal ash contains toxic heavy metals which have been linked to asthma, heart disease, cancer, respiratory diseases, nervous system damage and stroke.

"At most coal-fired power stations, coal ash is mixed with saline wastewater and pumped into enormous dump sites creating a lethal cocktail of mercury, lead, arsenic, selenium and chromium," the report reads.

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"This toxic slurry can leak into aquifers and soil needed by farmers and the environment, and into rivers and lakes where our families fish and our children swim.

"When it is left to dry out, winds can blow the toxic dust onto nearby communities where people breathe toxic pollution deep into their lungs."

Poor government regulation and management of coal ash dumps - such as those near Vales Point and Eraring power stations - has led to contamination of groundwater, rivers, lakes and aquatic ecosystems as well as toxic air pollution from dried out dumps. https://t.co/l0ygGaoABw — Lock the Gate (@LockTheGate) July 1, 2019

The report makes seven recommendations, including for governments to hold immediate inquiries into the problem, create national rehabilitation plans, tougher groundwater regulations and financial security from energy companies.