Microplastics in Soft Drinks and Ice Packs: What One Study Found

A 2025 study published in Scientific Reports set out to answer a simple question: if you pour yourself a carbonated soft drink over ice, how many plastic particles come with it? The researchers measured a mean of 183.1 microplastic particles per liter in the soft drinks they sampled and 178.9 particles per liter in commercial ice packs.[Scientific Reports, 2025]

Those are numbers from a specific market — carbonated drinks and ice packs sold across ten supermarkets in Mashhad, Iran — not a universal figure. But the study is notable for two reasons. It is among the first to examine microplastics in commercial ice packs, a widely used product that has been largely overlooked. And it traces the contamination back to a specific, mundane source: the packaging itself.[Scientific Reports, 2025]

How the researchers counted the particles

The team collected 29 samples: 15 soft drinks across three leading carbonated brands (labeled A, B, and C) and 14 ice pack samples. Each sample was salted to float out plastic, digested with hydrogen peroxide to break down organic matter, then filtered and examined under a stereomicroscope.[Scientific Reports, 2025]

To confirm that a suspicious particle was actually plastic — rather than, say, a stray fiber — they used Fourier-transform infrared spectroscopy (FTIR) and only classified a particle as microplastic if its spectrum matched a reference standard by 70% or more. Scanning electron microscopy provided close-up images of the particle surfaces.[Scientific Reports, 2025]

They also ran a laboratory blank prepared with filtered water alongside the real samples. That blank came back clean, which supports the case that the particles they counted came from the drinks and not from the lab air.[Scientific Reports, 2025]

The particles came from the packaging, not the drink

The single most useful finding here is about origin. FTIR analysis showed the microplastics were roughly 80% polypropylene and 20% PET. Those two polymers map neatly onto the two parts of a bottle: PET is the rigid bottle body, and polypropylene is the cap. Based on that split, the study attributes about 80% of the particles to the cap and 20% to the bottle body.[Scientific Reports, 2025]

80%

That points a finger at friction. Fragments — jagged, irregular pieces — made up 54% of the microplastics in soft drinks and 53% in ice packs, with fibers accounting for most of the rest. The authors link the abundance of fragments to the degradation of larger plastic parts like bottle caps during packaging and opening, where machinery and cap-on-bottle contact can shed particles.[Scientific Reports, 2025]

There is a telling detail buried in the comparison between drinks and ice packs. The soft drinks carried a mean particle concentration 20.4% higher than the ice packs, but that difference was not statistically significant. The authors read this as evidence that contamination depends mainly on packaging factors, not on the beverage type, since both product categories used similar PET packaging under comparable storage conditions.[Scientific Reports, 2025]

Most particles were small — and small is the part that matters

Across all samples, particle sizes ranged from 4.54 to 1,490 μm. That is a wide spread, but the distribution skewed small: 54% of the particles in beverages fell between 4.54 and 135 μm.[Scientific Reports, 2025]

Size is not a footnote here. The authors note that particles smaller than 5 μm show higher absorption in gastrointestinal, alveolar, and dermal tissue, and that microplastics under 150 μm are of particular concern because of greater bioavailability and their ability to move around the body. Over half the particles they detected fell under that 150 μm threshold.[Scientific Reports, 2025]

How much a person actually takes in

To translate particle counts into exposure, the researchers calculated an estimated daily intake (EDI) using standard intake rates for soft drinks. Adults came out at 5.49 particles per kilogram of body weight per day; children at 2.19.[Scientific Reports, 2025]

The adult figure being higher than the child figure reflects the intake-rate assumptions used, and the authors caution that exposure varies with lifestyle, region, and consumption habits. When they compared their EDI to studies from South Africa and Turkey, the numbers differed substantially — a reminder that these values are shaped by local packaging, consumption patterns, and the detection method used, not just the biology of exposure.[Scientific Reports, 2025]

The contamination was high — but the ecological risk score was low

Here the study contains a genuine tension worth sitting with. The researchers scored contamination two ways. The microplastic contamination factor (MPCF) compares each brand to a baseline; Brand C scored highest at 9.34, with all three brands landing in the study’s “very high pollution” band. But the microplastic pollution load index (MPLI), which rolls the brands together, averaged 8.26 — placing the samples in Ecological Risk Level 1, the lowest of four levels.[Scientific Reports, 2025]

It is also worth being clear about what this study did and did not show on health. It documents particles and estimates intake. The health effects it discusses — inflammation, oxidative stress, DNA damage, the “Trojan horse” effect where microplastics carry other toxins into the body — come from prior in vitro and animal work, not from measuring outcomes in the people drinking these beverages. The authors themselves write that robust evidence on real-world human consequences remains limited and that the findings need cautious interpretation.[Scientific Reports, 2025]

What the study suggests you can do

The researchers are direct about the practical implication. Because contamination tracked with packaging rather than with the drink, they suggest that raising awareness may encourage consumers to shift toward safer alternatives such as reusable glass or metal containers.[Scientific Reports, 2025]

On the policy side, they call for regulators to set maximum permissible microplastic concentrations for beverages, expand monitoring, and certify microplastic-free packaging — noting that no such standards currently exist for the food industry.[Scientific Reports, 2025]

For a reader, the honest takeaway is narrower than the headline number might suggest. One study, one city, three soft drink brands, and one ice pack brand cannot tell you what is in your specific drink. What it does show, credibly, is that plastic packaging — especially the cap — sheds measurable particles into what it contains, that most of those particles are small enough to be biologically relevant, and that the science on downstream health effects is still being written.