Mismanaged waste is causing hundreds of thousands of people to die each year in the developing world from easily preventable causes, and plastic waste is adding a new and dangerous dimension to the problem, a report has found.

Municipal waste frequently goes uncollected in poorer countries and its buildup fuels the spread of disease. Between 400,000 and 1 million people are dying as a result of such mismanaged waste, according to the charity Tearfund.

While mismanaged waste has been a problem for decades, the growth of plastic pollution, , which does not break down in the environment, is adding a fresh set of problems to an already dire situation. Plastic waste is blocking waterways and causing flooding, which in turn spreads waterborne diseases. When people burn the waste to get rid of it, it releases harmful toxins and causes air pollution.

Every second, a double-decker busload of plastic waste is burned or dumped in developing countries, the report found. When some plastics deteriorate, they can leach harmful chemicals into the environment and break down into microplastics, with effects that are still poorly understood and largely undocumented in poorer countries.

Sir David Attenborough, whose Blue Planet II series drew global attention to the problem of plastic waste, called for urgent action from the companies responsible for producing plastic that then turns into waste, and for support to help countries struggling against the tide of pollution.

“It’s high time we turned our attention fully to one of the most pressing problems of today – averting the plastic pollution crisis – not only for the health of our planet, but for the wellbeing of people around the world,” he said. “This report is one of the first to highlight the impacts of plastic pollution not just on wildlife but also on the world’s poorest people.”

Among the other harmful impacts of plastic pollution in poorer countries are the loss of fishing, as marine animals ingest the plastic; damage to agriculture, as up to a third of cattle and half of goats in developing countries have consumed significant amounts of plastic, harming their health as it leads to potentially fatal bloating; and large amounts of plastic waste washing up on shorelines and coral reefs deterring tourists, on whom many poorer countries rely.

While most attention has focused on the effects of marine plastic pollution in the natural world, its effects on people are equally problematic. About 8m tonnes of plastic waste are dumped into the seas each year, according to the UN, and there are few ways of retrieving it.

Last week countries around the world – but without the US – signed up through a UN to a plan to reduce the flow of plastic waste to developing countries. Although there have been signs of some companies making attempts to tackle the problem, these have been described by campaigners as a drop in the ocean.

“We need leadership from those who are responsible for introducing plastic to countries where it cannot be adequately managed, and we need international action to support the communities and governments most acutely affected by this crisis,” said Attenborough, who is a vice-president of the conservation charity Fauna & Flora International, which collaborated on the report.

At least 2 billion people around the world do not have their rubbish collected, and piles of it can build up in waterways, causing pollution, or rot in areas near where people live. Living near rubbish doubles the risk of contracting diarrhoea, the report found, which is a major cause of death in the developing world.

Hundreds of thousands of people around the world make a living from collecting waste, in some cases by collecting cans or bottles that can be recycled or returned, or, more dangerously, as “waste pickers” who live on rubbish dumps and scavenge what they can.

This is hazardous work, not only because of the pollution to which people are exposed but also because of the risk of physical injury, not least because poorly managed dumps are often affected by landslides and even explosions from the buildup of gases.

Ruth Valerio, the global advocacy and influencing director of Tearfund, said the organisation was calling on four multinationals that produce huge amounts of plastic packaging – Coca-Cola, Nestlé, PepsiCo and Unilever – to take responsibility for their products throughout the supply chain, and provide ways for the waste to be managed.