Microplastics

Microplastics are solid plastic particles smaller than 5 mm, encompassing nanoplastics at the sub-micron scale, originating from the fragmentation of larger plastic debris, synthetic textiles, tyre wear and personal-care products. They have been detected in human blood, placental tissue, breast milk and, in a 2024 NEJM study by Marfella and colleagues, within carotid artery atheromas — patients with detectable plaque microplastics had a significantly higher risk of myocardial infarction, stroke and death over a median 34-month follow-up. Proposed mechanisms of harm include local inflammatory responses, endocrine disruption via adsorbed chemical additives such as phthalates and bisphenols, and oxidative stress, though dose-response relationships in humans remain poorly characterised. Clinical significance and safe threshold levels have not yet been established, and no validated reduction strategy exists beyond minimising dietary and inhalation exposure.