While it may be a belated Christmas present for the petrochemical industry, your article (‘A bombshell’: doubt cast on discovery of microplastics throughout human body, 13 January) was less surprising to the scientific community, where constructive debate around microplastic detection in humans has been ongoing for some time. Such debate is entirely normal – and essential – for scientific inquiry.

New and novel methods must be tried, tested, critiqued, improved and tried again. Science is incremental and gradual – unlike the uncapped production and pollution of plastics, which contain thousands of hazardous chemicals. Decades of robust evidence demonstrates the harms that these inflict on people and planet.

While this debate expands with the claim in your report by a former chemist at one of the world’s leading petrochemical and plastics producers that doubts raised about studies on micro- and nanoplastics in the body amount to a “bombshell”, independent scientists are collectively striving for clarity on what is known and what is yet to be understood in this area.

In this light, it is worth reflecting on the state of public research. Ever scant resources drive less than healthy competition, pushing cash-strapped universities to enhance visibility through newsworthy findings. Meanwhile, a highly commercialised publishing industry – with thousands of journals making billions from gatekeeping publicly funded research while failing to compensate academic reviewers – is only too happy to oblige. The media are quick to jump on results, yet slower to cover more nuanced methodological debates. As always, the devil is in the detail.

While independent researchers continue to conduct rigorous, painstaking science and engage in constructive debate, often uncompensated, for the love of science and the benefit of society, the plastic crisis continues to grow around us each day, with irrefutable evidence of its negative impacts on humans, other animals and the environment. At what point will we move towards bold action? Joe Yates Hove, East Sussex

Your article is right to point out that there is work to be done in refining, standardising and harmonising the analytical techniques for examining microscopic particles in tissue samples. There is a need especially to distinguish microplastics from lipids. But that does not mean this whole area of science is rubbish.

Good researchers using well-validated techniques have directly observed microplastic particles in multiple human tissues under the microscope and have even identified which types of plastic are present in these particles.

Moreover, we now know a great deal about how the chemicals in microplastics harm health. Microplastic particles act as vectors, Trojan horses that transport toxic plastic chemicals such as phthalates, bisphenols and brominated flame retardants from the environment into the human body. Once in the body, these chemicals leach out of microplastic particles, enter the bloodstream, are distributed to tissues and cells, and cause diseases from cancer to heart disease, from IQ loss in children to decreased fertility.

This means that the presence of microplastics in the human body needs to be taken seriously, even though we don’t yet know all the ways in which they may harm health. They cannot be wished away.

Our newly launched Countdown on Health and Plastics, established under the sponsorship of the Lancet,* *will be coordinating global efforts to improve analyses of microplastics in human tissues and to increase knowledge of the possible impacts of microplastic particles on disease. Prof Philip J Landrigan Director, Global Observatory on Planetary Health

I and my colleagues in the Metabolomics Quality Assurance and Quality Control Consortium (mQACC) agree with the central message in your article; research on micro- and nanoplastics in human tissues requires exceptional analytical rigour, transparency and validation. Notwithstanding, we were concerned by the implication that shortcomings in some studies reflect a lack of analytical rigour within metabolomics as a discipline.

The mQACC consortium, which has more than 140 members around the world, works to define, establish, review and promote best-practice analytical chemistry as applied to metabolomics (the study of small molecules involved in metabolism). Robust study design, reliable analytical methods and careful data processing are essential to minimising errors and ensuring reliability of metabolomics data.

The metabolomics community is deeply rooted in analytical chemistry, and thus particular emphasis is placed on the need for high standards of identification and quantification. We acknowledge that some published studies have reported misidentifications, often resulting from overreliance on automated tools without sufficient expert review. The mission of mQACC is to provide clear, evidence-based guidance to reduce such issues and to strengthen confidence in metabolomics research. Over the last decade, such efforts have helped promote higher standards of analytical rigour within metabolomics.

We strongly support open and critical discussion of scientific research. However, individual studies that fall short of best practice do not represent the broader metabolomics scientific community that has long valued analytical rigour and has built structures to support and uphold it. Jennifer Kirwan Professor of veterinary metabolomics, University of Veterinary Medicine, Vienna, Austria

Your editorial (18 January) correctly states that the re-evaluation of publications on microplastics in human tissues is the scientific process playing out as it should. I think, though, that your comments about peer review and publication highlight an important misunderstanding about why and for whom research papers are written, and what peer review is for.

Research reports are published primarily for other researchers. Especially at the beginning of a field, foundational studies may be small, and “scruffy” in terms of methods, but worthy of publication because they highlight an important question and are a rallying cry for more researchers, with a broader range of collective expertise, to investigate thoroughly. Peer reviewers check that a report covers existing knowledge fairly, that it presents and analyses new data appropriately, and that the paper itself does not extend its conclusions beyond the data. Their job ends with the research report – they have no control over how press releases, AI summaries, bloggers and journalists transform what may be a nuanced report, whose uncertainties will be understood by other researchers, into an unjustified bald statement of fact.

In my research life (nothing to do with microplastics), I have read many contradictory research reports, each entirely worthy of publication, and often turning out to be contradictory only because, like blind men of the parable each feeling a different part of the elephant, each early report explored only a facet of something eventually understood to be bigger and more complex.

Scientific knowledge is always provisional, and research papers are not statements of eternal truth but contributions to an ongoing conversation between scientists. If the public is made sceptical of science by contradictory news reports, this may be because most newspapers say little about really solid areas of science and focus instead on the wild frontiers. Anybody reading this on an electronic device will have a vivid proof of the power and validity of mature science right in their hands. Jamie Davies Professor of experimental anatomy, University of Edinburgh