A lot to digest: are nanoplastics bad for human health?
Microplastics can break down into nanoplastics, which can permeate human cells
A giant larvacean (the blue, tadpole-like animal) beats its tail, pumping water and microplastic beads (red dots) through its inner filter. Image: Monterey Bay Aquarium Research Institute
When we see pictures of beaches and seas choked with plastic, the impact of our throwaway culture sinks home. But the plastic we do not see is probably doing more harm, Irish scientist warn.
Tiny pieces are going on to farmland and flowing into rivers and lakes. These microplastics are ending up in earthworms, birds, fish and our drinking water. A major source is sludge, which is the solid stuff leftover after sewage treatment.
EU policy on recycling favours using sludge as fertiliser, and 80 per cent of Ireland’s is reused in agriculture, particularly in the southeast. An Irish study last year found about 4,000-15,000 microplastic pieces per kilogram of sludge from sewage plants. “This is probably an underestimate,” says Dr Anne Marie Mahon at the Galway-Mayo Institute of Technology, who led this research.
Some sewage works break it into ever smaller pieces. “Some treatments exacerbate the problems. Particles are broken up so you can’t see them, and they can be ingested by worms and eaten by birds,” says Mahon.
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