The Guardian view on microplastics research: questioning results is good for science, but has political consequences | Editorial

It is true that science is self-correcting. Over the long term this means that we can generally trust its results – but up close, correction can be a messy process. The Guardian reported last week that 20 recent studies measuring the amount of micro- and nanoplastics in the human body have been criticised in the scientific literature for methodological issues, calling their results into question. In one sense this is the usual process playing out as it should. However, the scale of the potential error – one scientist estimates that half the high-impact papers in the field are affected – suggests a systemic problem that should have been prevented.

The risk is that in a febrile political atmosphere in which trust in science is being actively eroded on issues from climate change to vaccinations, even minor scientific conflicts can be used to sow further doubt. Given that there is immense public and media interest in plastic pollution, it is unfortunate that scientists working in this area did not show more caution.

The questions raised are mainly about the measurement of quantities of micro- or nanoplastic in the human body. In particular, one method, pyrolysis-gas chromatography-mass spectrometry, may have either been used or interpreted incorrectly. There is still robust evidence via other methods – such as electron microscopy and Fourier transform infrared spectroscopy – that these small-scale plastics are in our organs. What is in doubt now is how much.

Many, though not all, of the studies in question were conducted mainly by medical researchers, and published in medical journals. It is possible that there was a lack of rigour or technical expertise in chemistry. Some scientists have noted that this is a young field, and best practices are still being established.

But extraordinary claims require extraordinary evidence, and public interest in this field means that results will be seen as extraordinary in the wider world, whether or not researchers think they are. Until clear and widely agreed standards are established for these plastic measurements, great care – and perhaps wider consultation and peer review – should be taken before results are published, and reported in the media. Hopefully the spotlight trained on the field last week will prompt reflection and future caution.

There is, of course, a long-established playbook for magnifying and misrepresenting scientific conflicts – with attempts to discredit the science of global heating a case in point. This is not fair, but it is the world we live in. Scientists are confident that there will be some consensus on the scale of plastics in our bodies soon – probably within a few years. But even when the science becomes clearer, this row will probably be referenced by bad actors to discredit future results. After all, the plastic industry is downstream of the fossil fuel industry and employs many of the same lobbying techniques.

Concerns about plastic pollution have thus far transcended traditional political boundaries. Hopefully that will remain true. More worrying than the situation in Europe is the Trump-captured scientific system in the US. Last year an executive order entitled Restoring Gold Standard Science warned that strict criteria will be used to disqualify studies from being used as evidence for government policy. Many are concerned that even normal debates and differences of view between researchers could be used to reject wide swathes of well-agreed fact. In effect, science’s treasured self-correcting method could be turned against it.