Occurrence and health risk assessment of microplastics in beverages and ice packs

Abstract

Microplastics (MPs) are increasingly recognized as pervasive pollutants in food and beverage products, posing potential risks to human health and ecosystems. The purpose of this research is to investigate the presence and concentration of MPs in various beverages and ice packs through quantitative analysis, and to evaluate the potential health risks associated with human exposure to these contaminants. Samples underwent filtration and organic matter digestion with hydrogen peroxide, followed by analysis using stereomicroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The results indicated mean microplastic (MP) concentrations of 183.1 particles/L in beverages and 178.9 particles/L in ice packs, predominantly composed of polypropylene (PP) (80%) and poly (ethylene terephthalate) (PET) (20%). Morphologically, fragments comprised 54% of MPs in beverages and 53% in ice packs, while fibers accounted for 46% and 47%, respectively, with particle sizes ranging from 4.54 to 1,490 μm. Transparent MPs dominated (90%), likely due to prevalent packaging materials. The estimated daily intake (EDI) was higher in adults (5.49 particles/kg/day) than in children (2.19 particles/kg/day), with ingestion being the primary route of exposure. Microplastic contamination in beverage samples was assessed using the microplastic contamination factor (MPCF) and the microplastic pollution load index (MPLI). Brand C showed the highest contamination (MPCF: 9.34), while the average MPLI (8.26) indicated ecological risk level 1. This study confirms the widespread presence of microplastics in carbonated soft drinks and ice packs. Consequently, further research is essential to evaluate the long-term health effects and to develop strategies for reducing plastic usage in food packaging.

Introduction

Plastic has become an indispensable part of modern life, with its production and consumption rising sharply over the past five decades¹. Global plastic production is projected to triple—from 391 million tons in 2021 to 1,100 million tons by 2050—leading to a substantial increase in MP pollution^2,3. This surge has resulted in the widespread accumulation of plastic waste across various ecosystems⁴. Estimates suggest that the world’s oceans contain between 5 and 51 trillion plastic particles. However, more recent assessments indicate this number could be as high as 170 trillion^5,6. Once discarded, plastic waste undergoes weathering due to physical, chemical, and biological processes, breaking down into smaller fragments at the micro- and nanoscale^7,8. Microplastics, in particular, have emerged as one of the most widespread environmental pollutants linked to human activity, leading some to characterize the present era as the “Age of Plastics”⁹. Due to their minuscule size (less than 5 mm in diameter), microplastics can bypass water filtration systems and have been detected in a wide range of environments, from the deepest ocean trenches to forests, deserts, and coastal sediments¹⁰. Their non-biodegradable nature further exacerbates their persistence, raising significant concerns about their long-term accumulation in the environment¹¹.

The presence of microplastics (MPs) in the food chain and their potential health effects is a global concern¹². Humans are primarily exposed to MPs through the consumption of contaminated food and water, inhalation of airborne particles both indoors and outdoors, and dermal contact with personal care products, clothing, and household dust. As a result, significant amounts of microplastics have been detected in human blood, urine, and feces¹⁴.

Numerous studies have reported the contamination of seafood products, such as fish^15,16, shellfish^17,18, shrimp^19,20, squid, marine plankton, and crustaceans²¹, with MPs. The presence of MPs in these organisms is primarily attributed to increasing marine pollution from land-based plastic waste entering the ocean, with a smaller contribution from plastic equipment used in marine industries, particularly in fishing²².

Microplastics have also been detected in fruits and vegetables^23,24, including pears²⁴, tomatoes and cherry tomatoes²⁵, as well as in vegetables and cereals such as wheat^26,27, rice²⁸, green onions²⁹, corn³⁰, Italian lettuce³⁰, carrots³¹, and broad beans³². The concentration of MPs in soil is estimated to be 4 to 23 times higher than in oceans, largely due to the use of fertilizers and certain agricultural practices, thereby posing contamination risks to crops³⁰.

Other food items, such as salt³³, sugar³⁴, honey^34–36, tea³⁷, coffee³⁸, and dairy products such as milk³⁹ and yogurt⁴⁰, have also been frequently found to contain MP particles. Drinking water⁴¹ and commercially bottled mineral water^42–44 are likewise not exempt from contamination.

These findings suggest that MPs may enter the food chain at various stages, including production, processing, packaging, and storage⁴⁵. Furthermore, evidence indicates that meat, canned fish, and certain condiments are also susceptible to MP contamination⁴⁶. Packaged dairy products and sauces, due to their chemical properties, may further facilitate the migration of plastic particles into the food matrix⁴⁷.

Annual human consumption is estimated at 46,000 to 52,000 particles, with a weekly intake averaging 220,386 particles, reinforcing food as a major exposure pathway⁶. These tiny plastics can enter the bloodstream and reach vital organs such as the lungs and liver⁴⁸. In vitro studies have shown that MPs can penetrate cell membranes, trigger the production of reactive oxygen species, cause inflammation, and induce neurotoxic effects^49,50. These pollutants may also harm the digestive system, leading to oxidative stress, intestinal blockages, and damage to the intestinal barrier^51,52. These disruptions can impair mucus secretion, exacerbate inflammation, and unbalance gut microbiota, potentially affecting metabolism⁵³. Additionally, microplastics serve as carriers of hazardous chemicals such as endocrine-disrupting phthalates and bisphenol A, along with toxic metals like lead, cadmium, and arsenic. These contaminants have been linked to impaired growth, reproductive issues, and disruptions in physiological functions, raising serious long-term health concerns^54–56.

The detection of MPs in freshwater and drinking water has raised concerns about their presence in bottled beverages as well⁵⁷. Beverages are an essential part of the human diet across various demographic groups, making them a significant pathway for MP exposure^58,59. The beverage industry encompasses a wide range of products, including alcoholic options such as beer, wine, and spirits, as well as non-alcoholic choices like tea, coffee, milk, soft drinks, energy drinks, and both carbonated and non-carbonated sweetened beverages⁶⁰. Notably, soft drinks represent approximately 40% of global beverage consumption⁶¹. Global soft drink consumption has reached an astounding 48,288.4 million liters, equivalent to an average of 92.4 L per person⁵⁹.

Currently, there are no established standards or regulatory limits for the presence of MPs in the food industry. Although numerous studies have investigated MP contamination in beverages, particularly soft drinks, across countries such as Iran⁶, Turkey^14,62, Hong Kong³, China⁴⁹, Thailand⁶³, Mexico^58,64, Italy⁵⁹, Poland⁶⁵, Germany⁶⁶, South Africa^60,67, and Ecuador⁶⁸, this study is among the first to examine microplastic contamination in commercial ice packs—a widely used yet largely overlooked product.

Given the potential health risks associated with MPs and the widespread consumption of plastic-packaged beverages in Iran, a comprehensive analysis of MP contamination in commercially available drinks is essential. This study aims to quantitatively assess the prevalence, physical properties, and morphological characteristics of MPs—including their type, shape, size, and color—in soft drinks and ice packs readily available in the Iranian market. Furthermore, it seeks to calculate the microplastic contamination factor (MPCF) and microplastic load index (MPLI), EDI of MPs, and compare the findings with similar studies on MP contamination.

Materials and methods

Materials

Hydrogen peroxide (H2O2, 30% w/w), NaCl and ethanol (75%) were purchased from Merck company, Germany.

Microplastic sampling from soft drinks and ice packs

To assess MP contamination in widely consumed beverages and ice packs in Mashhad, Iran, a systematic sampling strategy was developed based on established methodologies for MP analysis in food and beverages⁵⁸. A preliminary market survey was conducted across ten major supermarkets and retail outlets, selected from five distinct geographical zones to ensure broad representation of consumer habits and regional variability. Based on sales volume, retail display frequency, and consumer purchasing trends, three leading carbonated soft drink brands (designated A, B, and C) and one dominant ice pack brand were selected for analysis. These product categories were prioritized due to their high consumption rates and packaging in plastic materials, PET bottles with polypropylene (PP) caps, which are known sources of MP contamination. A total of 29 samples were collected: 15 soft drink samples (five per brand) and 14 ice pack samples (four to five per type), randomly purchased from stores within each zone to minimize sampling bias. All samples were collected within a one-week period, stored at room temperature, and analyzed within ten days to ensure consistency and minimize the risk of degradation or external contamination.

Extraction of MPs

Each bottle was gently shaken, and 500 mL of the beverage was transferred into a 1-liter glass beaker. To this, 180 g of sodium chloride (NaCl) were added to create a saturated solution. The NaCl was dissolved at 90 °C for 30 min with continuous stirring using a non-plastic magnetic stirrer. The solution was then transferred into a separatory funnel, and the beaker was rinsed three times with NaCl solution, with the rinses added to the funnel. The mixture was left undisturbed overnight for sedimentation.

After sedimentation, the lower phase was drained, while the upper phase containing floating particles was mixed with 100 mL of filtered 30% hydrogen peroxide (H₂O₂) to break down organic matter and pigments. This mixture was left overnight. The solution was then filtered using a vacuum filtration system equipped with cellulose filters (47 mm diameter, 0.45 μm pore size) at 0.5 bar pressure. The separatory funnel was rinsed three times with ultrapure filtered water, and these rinses were also passed through the same filter. If filters became clogged, new filters were used to complete the process.

Once filtration was complete, the filters were carefully transferred to petri dishes using stainless steel tweezers and left to dry at room temperature for 24 h. After drying, the filters were prepared for the identification and separation of MPs⁵⁹.

Microplastics identification and quantification

All beverage and ice pack samples were subjected to careful visual inspection using a stereoscope (Leica EZ4W, Germany) to assess the shape and color of the filtered material for potential MPs. The surface characteristics of MPs were thoroughly analyzed using scanning electron microscopy (SEM) to reveal intricate details about their physical structure. This analysis was conducted with a Carl Zeiss EVO18 instrument (United Kingdom) at multiple magnifications, operating at an accelerating voltage of 1.00 kV. High-resolution images captured at 5,000× and 10,000× magnifications provided a comprehensive examination of surface topography and morphological features, highlighting imperfections such as cracks, ridges, and rough textures—key indicators of MP degradation and origin. To confirm the identity of MP particles, FT-IR spectroscopy was employed, comparing sample spectra to reference standards. Only particles with a spectral match of 70% or higher were classified as MPs⁶². Additionally, the elemental composition of MPs was analyzed using SEM-EDX on an Auriga 3916-FESEM system (Carl Zeiss, Jena, Germany) at LANE, CINVESTAV-IPN.

Measures to prevent contamination

To minimize the risk of MP contamination from external sources, several precautionary measures were implemented. The experiments were conducted in a controlled laboratory environment with closed windows and restricted human movement. Before testing, all surfaces were meticulously cleaned with 75.0% ethanol-moistened paper towels. Laboratory personnel followed strict contamination-control protocols, wearing cotton lab coats and powder-free latex gloves at all times. To further prevent contamination, all equipment used was non-plastic and underwent triple rinsing with deionized water before use. When not in operation, equipment was covered with aluminum foil. Additionally, all liquids involved in the experiments were pre-filtered through cellulose filters (Ø = 47 mm, pore size = 0.45 μm) to eliminate potential MP introduction¹⁴. To address potential contamination, a laboratory blank prepared with filtered Milli-Q water was analyzed alongside the beverage and ice pack samples. The results confirmed the absence of MPs on the filters of the blank samples⁵⁸. The experiments were conducted under a laboratory hood to minimize airborne contamination, and all glassware and equipment were similarly covered with aluminum foil during periods of inactivity. These rigorous precautions, combined with careful material selection and meticulous handling, effectively minimized the risk of MP contamination and ensured the integrity of the analysis¹⁴.

Health risk assessment

To assess an individual’s exposure to MPs through beverage consumption, Eq. (1) was employed⁴², :

1

Estimated daily intake represents the estimated daily intake of MPs (particles/kg/day), C denotes the average MP concentration (particles/L), and IR indicates the intake rate of soft drinks (L/kg/day). The intake rates are specified as 0.03 L/kg/day for adults (assuming a body weight of 70 kg) and 0.012 L/kg/day for children (assuming a body weight of 20 kg)⁶⁹.

Assessment of MP pollution in soft drinks

The microplastic contamination factor and microplastic load index for soft drinks were calculated based on the methodology outlined by Altunısik (2023)⁶². The MPCF quantifies the extent of MP pollution present in the analyzed soft drinks, measured against baseline levels. The MPCF and MPLI were calculated using Eqs. (2) and (3), respectively.

2

3

The number of MPs detected in each soft drink sample is represented as MP_i ​, while MP₀​ denotes the baseline minimum average MP concentration previously reported in soft drinks. The total number of soft drinks evaluated is indicated by n. To categorize pollution levels, MPCF was classified into four: low pollution (MPCF < 1), moderate pollution (1 ≤ MPCF < 3), significant pollution (3 ≤ MPCF < 6), and very high pollution (MPCF > 6)⁶. Similarly, MPLI was used to assess environmental risk, classified into four levels: Risk Level 1 (MPLI < 10), Risk Level 2 (10 ≤ MPLI < 20), Risk Level 3 (20 ≤ MPLI < 30), and Risk Level 4 (MPLI > 30). These indices provide a systematic framework for evaluating the extent of MP contamination in soft drinks and its potential environmental impact⁶⁰.

Statistical analysis

Numerical data are presented as means ± standard deviations (SD). Statistical analyses were performed using SPSS Version 26. The Shapiro-Wilk test was used to assess data normality, while the Levene test evaluated variance homogeneity. A parametric independent-samples t-test was conducted to assess significant differences in MP concentrations among beverages from different brands, as well as between the two groups: soft drinks and ice packs. Additionally, a one-way analysis of variance (ANOVA) was performed to compare the mean total MP counts across three distinct types of soft drinks and three distinct types of ice packs. A P-value < 0.05 (within a 95% confidence interval) was considered statistically significant.

Results and discussion

Characterization

Scanning electron microscopy

Figure 1 presents the surface morphology of MPs analyzed using SEM, highlighting MP fibers and fragments. As shown in Figs. 1a–d, the majority of the detected MPs were in the form of fibers. These fibers exhibit elongated cylindrical shapes with soft, flexible, and smooth surfaces. Their irregular edges suggest mechanical fragmentation of larger plastic materials. Additionally, surface textures such as cracks and grooves indicate polymer aging and oxidative degradation^42,70. These structures often display signs of mechanical abrasion, including etching and fragmentation, with lengths ranging from 1.528 mm to 44.84 μm. Furthermore, as shown in Figs. 1e–f, some MPs appeared as irregular fragments with jagged edges and rough surfaces, characterized by small pores and coarse textures. These features suggest physical degradation, likely resulting from mechanical stress or prolonged environmental exposure, possibly within beverage matrices or ice packs^71,72.

Fig. 1.

SEM images of MPs. Fiber (a–d) and fragment (e-f).

Energy dispersive spectroscopy

Figure 2 presents the EDS analysis of MP samples. The results indicate that MPs predominantly contain elements such as carbon (C) and oxygen (O), which is consistent with the composition of PET and PP types. Peaks of chlorine (Cl), sodium (Na), and gold (Au) were also detected, likely originating from sample preparation, environmental exposure, or additives. The presence of Cl suggests potential contamination of PET and PP or the adsorption of chlorinated compounds during processing, while Na may indicate exposure to saline environments or food additives^64,73–75.

Fig. 2.

EDS images of the elemental composition of sample MPs.

Fourier transform infrared spectroscopy

Figure 3 presents FTIR spectra that provide precise molecular signatures for characterizing the polymeric composition of MP samples, enabling accurate identification and structural differentiation. Based on Fig. 3a, distinct absorption bands were observed at 2950 cm⁻¹ and 2870 cm⁻¹, corresponding to the asymmetric and symmetric stretching vibrations of CH₃ groups, respectively. Additionally, peaks at 2920 cm⁻¹ and 2840 cm⁻¹ were detected, indicative of CH₂ stretching modes. Further peaks at 1460 cm⁻¹ and 1375 cm⁻¹ were attributed to the bending vibrations of CH₂ and CH₃ groups, respectively. These spectral features are characteristic of a specific type of MP, namely PP. This identification aligns with findings from comparable studies, which have identified PP as the predominant polymer in MPs detected in sampled commercial beverages in Thailand⁶⁸, Spanish beverage brands⁷⁶, and Turkish beverages⁶², thereby corroborating the observed trend. Conversely, Fig. 3b exhibits distinct spectral signatures with absorption bands at 3050–3100 cm⁻¹ (aromatic C-H stretching), 2950–2850 cm⁻¹ (aliphatic C-H stretching), 1710 cm⁻¹ (C = O stretching), 1500–1600 cm⁻¹ (aromatic C = C stretching), and 1250–1100 cm⁻¹ (C-O stretching). These vibrational modes, supported by prior research⁶³, are characteristic of PET MPs. Quantitative analysis revealed that PP constitutes approximately 80% of the identified polymers, while PET accounts for the remaining 20%. The predominance of PP underscores its widespread use in flexible packaging applications, whereas the presence of PET aligns with its common utilization in the production of rigid bottles. This compositional distribution highlights the significant role of plastic packaging materials, such as flexible films and bottle caps, in environmental contamination.

Fig. 3.

FTIR spectra of MPs in different samples.

Microscopic observations

Figure 4 presents microscopic images of MPs. As shown in Fig. 4, MPs appear in both fiber and fragment forms under a stereomicroscope.

Fig. 4.

MPs identified in beverages appear in two forms: fragments and fibers.

Shape of MPs

Figure 5 shows the distribution of MP shapes in soft drinks and ice packs. Based on microscopic observations, the MPs identified in this study were primarily in the shapes of fragments and fibers. The results revealed that in soft drinks, fragments accounted for 54% of the MPs, followed by fibers at 45%. In ice packs, the distribution followed a similar trend. As depicted in Fig. 5, the average fiber concentration per liter was nearly identical between the ice pack and soft drink groups. However, the average fragment concentration per liter was slightly higher in the soft drink group compared to the ice pack group. The increased presence of fragments in certain cases is associated with the degradation of larger plastic products, such as bottle caps, during packaging or opening processes. Friction and abrasion resulting from machinery or bottle contact may also contribute to the release of these particles^43,77. The mean total MP concentration was 20.4% higher in the soft drink group than in the ice pack group, but the difference wasn’t statistically significant (P-value > 0.05). This is likely because both used similar PET packaging and experienced comparable storage conditions that promote MP release. The results suggest that MP contamination mainly depends on packaging factors, not the type of beverage, aligning with findings from Akhbarizadeh et al. (2023)⁷⁷. Additionally, one-way ANOVA analysis revealed a statistically significant difference in the mean fiber concentration per liter among soft drink brands (P-value < 0.05). Follow-up analysis using the Least Significant Difference (LSD) test indicated that this difference was primarily driven by a notable variation between Brand A and the other two brands (B and C). Generally, the mean total MP concentration varied significantly across the three soft drink brands (P-value < 0.05), with post-hoc analysis attributing this significant disparity to the difference between Brands A and C. Specifically, Brand A exhibited the highest fiber concentration (50%), followed by Brand C (47%) and Brand B (32%). The high abundance of fibers in bottled water is often linked to airborne contamination during production and analysis stages, where inadequate control of the environment, equipment, and packaging materials plays a critical role^78,79. In contrast, no significant differences were observed in fiber, fragment, or total MP concentrations among the different types of ice packs (P-value > 0.05). Several recent studies, consistent with the present research, have reported fragments as the dominant MP type in drinking water. For instance, the prevalence of fragments in specific food matrices, such as canned foods and drinking water, has been well-documented by Ibetu et al. (2021)⁸⁰ and Mason et al. (2018)⁴⁴. Conversely, some studies have identified fibers as the predominant MP morphology in diverse food matrices, including drinking water, tap water, beer, and carbonated beverages^58,81,82.

Fig. 5.

Various shapes of MPs observed in beverages and ice packs.

Abundance of microplastics

In this study, a total of 3,000 MP particles were identified in soft drinks and 2,800 particles in ice packs across 29 selected samples. Based on Table 1, the results indicate that the soft drink samples exhibited a mean concentration of 183.1 ± 28.3 particles per liter (p/L). Among the 3,000 particles identified in soft drinks, 1,243 were designated as fibers, exhibiting concentrations between 38 and 127 fibers per liter, whereas 1,503 were classified as fragments, with concentrations spanning 74 to 124 fragments per liter. For the ice pack samples, a mean concentration of 178.9 ± 36.4 particles per liter (p/L) was recorded. Of the 2,800 particles observed in ice packs, 1,170 were categorized as fibers (ranging from 59 to 118 fibers per liter), and 1,334 were identified as fragments (ranging from 48 to 135 fragments per liter). Multiple factors potentially influence the MP concentrations in beverages and ice packs, accounting for the variability in MP prevalence across different brands. Crucial determinants likely include the chemical makeup and characteristics of the packaging materials, such as the polymer types employed, alongside the packaging methodologies implemented. Moreover, mechanical stresses experienced during transport and handling may promote the liberation and transfer of MP particles into the contents of the containers. Additional pivotal factors include carbonation levels, the acidity of the beverages, and storage temperatures, all of which could affect the degree of MP contamination^42,49,83. A similar study reported a significantly high MP concentration of 281.4 ± 61.3 particles per liter in carbonated beverages packaged in PET bottles⁴⁹. Conversely, Lam et al. (2024) identified MPs in all 50 evaluated packaged soft drinks, reporting a concentration of 41.2 ± 42.1 MPs per liter³. Similarly, another study revealed that MPs were present in 100% of soft drink samples, with a median concentration of 8.90 MPs per liter (range: 5–15 MPs/liter)⁶². Furthermore, Crosta et al. (2023) reported a mean MP concentration of 9.2 ± 1.8 particles per liter in beverages, a value significantly lower than that observed in the present study. These differences may be attributed to variations in regional packaging regulations, production practices, and environmental conditions⁵⁹.

Table 1.

Reported MP concentrations in commercial beverages across different countries and packaging types.

Location	Beverage category	Packaging type	MP (particles/L)	Size (µm)	Reference
China	Chilled carbonated beverages	PP bottles, PET, PE bottles.	260.52-281.38	1 μm-5 mm	49
Ecuador	Citrus refreshing drinks	PET, Tetra Pak	32	2.5–6742.5	68
Italy	RTD teas Soft drinks	PET bottles	7.1 9.9	Lower limit: 0.45	59
Mexico	RTD teas Energy drinks	Glass bottles; PET bottles PET bottles	11.0 14.0	100.0–3000.0	58
Turkey	Soft drinks	Aseptic cartons; PET bottles	40.0 8.9	25.0–2000.0	62
	Sparkling soft drinks	------	10.3	0.97 ± 0.47	14
Hong Kong	Juice drinks RTD teas Soda waters Soft drinks Sports and energy drinks	Aluminum cans; aseptic cartons; glass bottles; PET bottles	30.0 36.4 49.3 32.5 32.4	30.0–5000.0	3
Thailand	Soft drinks	Can Glass PET	2–39 12–39 2–25	50–100	63
Spain	Commercial beverages	PET and glass bottles	17.2	783	76
Iran	Soft drinks Iced pack	PET bottles	183.1 178.9	4.54 to 1,490	This study

Size of microplastics

The particle size of MPs is a critical factor influencing human health risks. Studies show that MP particles smaller than 5 μm have higher absorption rates in gastrointestinal, alveolar, and dermal epithelia, increasing their potential to cause toxicological effects⁸⁴. Furthermore, microplastics under 150 μm are especially concerning due to their greater bioavailability and ability to translocate systemically⁸⁵. Figure 6 illustrates the size distribution of MPs, revealing significant variation across brands and packaging types. Across all beverages examined, MP sizes ranged from 4.54 to 1,490 μm, with 54% of particles falling between 4.54 and 135 μm. These particles were uniformly distributed throughout the samples, reaching a concentration of 100 particles per liter, predominantly below 135 micrometers, a pattern suggestive of contributions from packaging degradation or external contamination. In addition, 45% of MPs exhibited a broader size range, spanning approximately 55 to over 1,490 μm, with notably longer fibers observed in Beverage A. This prevalence of larger fibers may stem from specific packaging materials, processing techniques, or chemical properties influencing fiber reformation. Similarly, in ice packs, 53% of MPs consisted of particles ranging from 4.5 to 125 μm, while 46% displayed a wider distribution from 8.3 to 1,470 μm. The largest particles, exceeding 1,400 μm, were primarily detected in Ice Pack D, whereas Ice Pack E exhibited a more extensive size spectrum. The presence of larger fibers in ice packs suggests reduced mechanical degradation compared to liquid environments, likely attributable to diminished turbulence and physical interaction. The MP size distribution identified in this study corroborates findings from prior research, such as Shruti et al. (2020)⁵⁸ and Altunışık et al. (2023), which reported beverage MP sizes predominantly between 100 and 1,000 micrometers⁶². Likewise, A study observed MPs in beer samples ranging from 100 to 5,000 micrometers, reflecting trends broadly consistent with the current results⁸⁶. In contrast, exceptionally long fibers (2,224.25 μm) in soft drinks⁶⁸ and a significantly smaller MP size range (≤ 1.5–5 μm)⁸⁷ have been reported, diverging from the present findings. Variations in MP size distribution across food and beverage matrices are likely attributable to differences in characterization techniques, underscoring the critical need for methodological standardization to enhance our understanding and mitigate MP contamination in consumer products⁶⁴.

Fig. 6.

Size distribution of MPs in different brands of soft drinks and ice packs.

Color of microplastics

The color of MPs can provide valuable information about their origin, polymer composition, and potential sources of contamination^84,88,89. Figure 7 illustrates the color distribution of MPs identified in the analyzed samples. The findings reveal that 90% of the detected MPs were transparent, with the remaining 10% exhibiting color, predominantly red (7%), blue (1%), and green (1%). The prevalence of transparent MPs in this study likely reflects the widespread use of unpigmented PP in packaging materials. In contrast, the presence of colored MPs—red, blue, and green—may be attributed to pigments commonly incorporated into caps, bottle neck rings, or other packaging components, which can fragment and disperse during manufacturing, transportation, or consumer handling⁹⁰. The predominance of transparent MPs in this study aligns with observations from prior research^62,76. Additionally, A study revealed that MP fibers in bottled water matched the colors of the bottles (transparent, blue, green) and caps (opaque blue, green, red), indicating a strong connection between packaging materials and MP coloration⁶⁵. Notably, transparent red fibers were found despite the absence of red caps, pointing to contamination during manufacturing rather than post-packaging. The study suggests that environmental factors, like bottle agitation, may increase the release of colored MPs from packaging⁹⁰. However, some studies report a higher prevalence of colored MPs, presenting a contrast to the findings of this investigation. For example, A study identified seven distinct MP colors in beverages, with blue predominating at 70%, followed by green (24%), and other hues including transparent, black, red, yellow, and white¹⁴. Crosta et al. (2023) further reported black MPs as the most frequent type (53%), followed by blue (15%), with transparent MPs comprising only 9%⁵⁹. These discrepancies suggest that MP coloration may vary significantly depending on the sample matrix, contamination sources, or analytical methodologies employed⁸⁶.

Fig. 7.

Color distribution of MPs in drinks and ice packs.

Bottle MP sources

Studies indicate that microplastics found in packaged beverages primarily originate from different components of the container, with PET associated with the bottle body and PP linked to the cap^1–3. As a result, based on the data in Figs. 8 and 80% of the identified microplastics are related to the cap material (PP) and 20% to the bottle body (PET).

Fig. 8.

Composition of microplastic particles in soft drinks according to polymer type.

Risk assessment

EDI for adults and children

Table 2 presents EDI of MPs for two distinct age groups: children and adults. According to the data, children exhibit an EDI of 2.19 particles/kg.day, which is notably lower than that of adults, whose average EDI stands at 5.49 particles/kg.day. This disparity suggests distinct consumption patterns across age groups, potentially influenced by a variety of factors.

Table 2.

EDI of MPs in soft drinks for children and adults.

Brands	Mean MPs (particles/L)	EDI (particles/kg.day)
		Child	Adults
A B C Total of soft drinks	158.6 185 205.6 183.07	1.9 2.22 2.46 2.19	4.75 5.55 6.16 5.49

Similarly, Hassan et al. (2025) estimated the annual intake of MPs from beverages to be 2.34 particles/kg/day⁶⁷. A study reported that children consume higher quantities of MPs through soft drinks compared to adults, with an EDI ranging from 0.006 to 0.018 MP/kg body weight/day for children, whereas for adults, the range was 0.002 to 0.006 MP/kg body weight/day⁶². Also, in South Africa, the EDI for children from non-alcoholic beverages was recorded at 1.26 particles/kg/day, significantly higher than that for women (EDI = 0.45 particles/kg/day) and men (EDI = 0.63 particles/kg/day)⁶⁰. These findings contrast with the data presented in Table 2, suggesting that local and regional factors may significantly influence MP exposure levels. Socioeconomic variables such as lifestyle, ethnicity, gender, age, religion, and health status have been shown to shape beverage consumption patterns and, consequently, MP intake⁶⁰. Additionally, variations in EDI between European and Asian countries may be attributed to higher per capita beverage consumption and increased MP concentrations in the analyzed samples. Other contributing factors include the quality of packaging materials, storage conditions, demographic trends, consumption habits, and MP detection methodologies^62,77,77.

Determination of MPCF and MPLI in soft drink samples

In this study, MPCF and MPLI were employed to assess the degree of MP contamination in various beverage samples, with the results of Fig. 9. Findings from Fig. 9 indicate that Brand C exhibited the highest contamination level, with an MPCF of 9.34, followed by Brands B and A, which recorded values of 8.4 and 7.2, respectively. The average MPLI across all analyzed samples was 8.26, placing it within Ecological Risk Level 1 (MPLI < 10) according to the MPLI classification. This value significantly exceeds those reported in comparable studies from other countries investigating MP prevalence in carbonated drinks. Microplastics, primarily PP and PET from beverage packaging, can enter soft drinks during production or packaging. Additionally, unrecycled bottles contribute to environmental contamination through degradation⁹¹. These persistent particles infiltrate ecosystems via wastewater, surface runoff, atmospheric deposition, and inadequate waste management, spreading globally through wind and water currents⁹². Microplastics accumulate in soil, freshwater, marine sediments, and even polar regions, where they disrupt soil health, harm microbial communities, and affect over 1,300 species through ingestion—causing oxidative stress, reproductive harm, and endocrine disruption Acting as carriers for toxic pollutants, microplastics further amplify ecological risks⁷². Several studies reporting elevated contamination levels support the findings of this research. For example, Hassan (2025) identified remarkably high MPCF values in Bangladesh, attributing these levels to factors such as the extensive reuse of inadequately cleaned bottles, deterioration of plastic packaging materials, environmental pollution, poor manufacturing standards, and insufficient enforcement of regulations regarding MPs⁶⁷. Similarly, carbonated soft drinks from Thailand⁶³, Spain⁷⁶, Mexico⁵⁸, and Hong Kong³ have exhibited heightened MP contamination, as reflected in elevated MPCF values. According to Ramaremisa et al. (2025), non-alcoholic beverages exhibited MPCF values ranging from 0.22 to 4.31, with 70% classified as having low contamination and 20% showing moderate contamination, aligning with a Hazard Level 1 designation⁶⁰. In contrast, Basaran et al. (2024) recorded the lowest levels of MP contamination, which fell below the threshold for minimal pollution classification¹⁴. This variation in results highlights significant regional disparities in MP contamination in beverages worldwide, potentially influenced by factors such as production techniques, packaging integrity, and regulatory frameworks.

Fig. 9.

The mean MPLI in soft drink samples.

Potential health consequences of consuming drinks and ice packs containing MPs

In this study, significant concentrations of MPs were detected in both carbonated beverages and ice packs, with a total of 3,000 particles in beverages and 2,800 particles in ice packs. The average concentration was 180 particles per liter, with particle sizes ranging from 4.54 to 1,490 μm. Based on these results, the presence of MPs in beverages and ice packs indicates that their consumption inevitably exposes humans to these contaminants. The ingestion of MPs through these sources is an emerging public health concern, primarily due to their widespread presence in consumer plastic packaging materials. Microplastics smaller than 150 μm can persist in the human body after ingestion, potentially accumulating in the gastrointestinal tract and leading to inflammation, oxidative stress, and DNA damage due to their non-degradable nature⁹³. Additionally, microplastics can act as carriers for toxic substances such as phthalates, benzo(a)pyrene, and heavy metals, enhancing their bioavailability and toxicity through the “Trojan horse” effect⁹⁴. These toxins may be transported to vital organs, including the liver, lungs, and brain, thereby exacerbating systemic exposure and potentially altering metabolic pathways¹². In vitro and animal studies suggest that microplastic penetration into cell membranes can stimulate the production of reactive oxygen species (ROS), activate inflammatory pathways such as NF-κB, suppress antioxidant defenses like NRF2, and trigger neurotoxic effects and apoptosis⁹⁵. Furthermore, preliminary evidence from animal models indicates a possible link between MP exposure and reduced fertility, as well as an increased risk of cancer, particularly in the gastrointestinal tract. This study highlights that MPs smaller than 150 μm exhibit higher bioavailability, thereby increasing toxicological risks⁹⁶. Although these findings suggest potential chronic health implications, the lack of long-term human data necessitates cautious interpretation. The current evidence underscores the urgent need for further research to elucidate dose-response dynamics and the consequences of chronic exposure, thereby informing public health strategies aimed at mitigating the risks associated with MP consumption from beverages and ice packs.

Conclusion & prospect

This study quantitatively confirmed the presence of MPs in commercially available carbonated beverages and ice packs in Mashhad, Iran. The findings indicated that the mean concentrations of MPs were 183.1 ± 28.3 particles per liter in beverages and 178.9 ± 36.4 particles per liter in ice packs, showing a comparable level of contamination across both product types. PP and PET were the dominant polymer types, accounting for 80% and 20% of the MPs, respectively. The detected MPs were almost equally distributed between fragments and fibers. Notably, over half of the detected particles were smaller than 150 μm, raising concerns due to their higher potential for bioavailability and systemic absorption. Despite these levels of contamination, risk assessments, including the MPCF and the MPLI, classified the environmental hazard as minimal (Level 1). The EDI of microplastics for adults was 5.49 particles/kg/day, while for children it was 2.19 particles/kg/day. Moreover, the findings indicated significant differences in MP concentrations among beverage brands. Brand A had the highest mean fiber concentration and total MP load compared to Brands B and C. Additionally, soft drinks exhibited a 20.4% higher mean MP concentration than ice packs. The MPCF ranged from 7.2 to 9.34 across beverage brands, and the average MPLI remained within risk Level 1, indicating minimal environmental hazard. 

Although the present study focused on a limited selection of beverage types and brands available in Iran, it provides valuable baseline data on microplastic (MP) contamination in the region. To enhance the comprehensiveness and generalizability of the findings, future research should include a broader range of beverage categories and brands.

Regarding health impacts, while the toxicological effects of MPs have been well-documented in laboratory and animal studies, robust evidence concerning their real-world consequences in human populations remains limited. Therefore, further epidemiological and clinical research is essential to clarify the health implications of MP exposure in real-life scenarios, including exposure thresholds, bioaccumulation patterns, and long-term physiological effects.

At the same time, the development of safer packaging materials and the implementation of standardized protocols for MP detection are critical for mitigating contamination risks and safeguarding consumer health. The findings of this study can play a pivotal role in influencing consumer behavior and shaping public health strategies in Iran, particularly by raising awareness of the potential health consequences of MP exposure, such as inflammation, oxidative stress, and long-term effects, including reduced fertility. This increased awareness may encourage consumers to shift toward safer alternatives, such as reusable glass or metal containers.

Moreover, public health authorities can build on previous environmental health initiatives to launch targeted educational campaigns aimed at reducing plastic consumption and promoting sustainable packaging. From an industry perspective, adopting biodegradable materials—such as polylactic acid and cellulose- or starch-based polymers, which align well with Iran’s agricultural capacities—offers an effective strategy to minimize MP release throughout the packaging lifecycle.

Finally, regulatory bodies, particularly the Ministry of Health and Medical Education, must take a proactive stance by establishing maximum permissible concentration standards for MPs in beverages (e.g., the 0.6 mg/kg threshold outlined by the European Union), expanding mandatory monitoring systems, and promoting certification for MP-free packaging. Achieving these goals will require coordinated collaboration among regulatory agencies, local industries, and academic institutions to ensure that all interventions are evidence-based, culturally appropriate, and economically feasible.

Another limitation of this study is the use of Whatman filter paper with a pore size of 0.45 μm, which may not have captured microplastics smaller than this threshold. Consequently, the total level of microplastic pollution may have been underestimated.

Author contributions

A.S: Methodology, investigation. F.B: Writing, original draft. E.E: Methodology. Z.B: Investigation, Methodology, Writing, review & editing, Supervision. M.D: Investigation.

Data availability

The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Competing interests

The authors declare no competing interests.