Influence of temperature and storage time on microplastic release from packaged sausages

Abstract

This study investigated the microplastics (MPs) release in chicken sausages before and after packaging for 180 days of storage at -18 °C–4 °C. Samples were digested in 10% KOH at 50 °C, filtered (0.6 μm), and MPs characteristics (color, shape and size) were determined by optical microscope. The polymer type and elemental composition of MPs were determined by Confocal-Raman-Spectroscopy and SEM-EDX, respectively. MPs release was significantly higher at 4 °C than at -18 °C. The isolated MPs were in fibrous shape ranging from 50 to 1500 μm in length; and transparent color constituted the predominant fraction. Detected polymers were polypropylene, polycarbonate and polyamide. The highest estimated daily intake (EDI) corresponded to sausages held at 4 °C with 55% meat content. MPs release was influenced by meat percentage, storage time and temperature. These findings underline the need for further research on the long-term health implications of MPs exposure through processed meat products.

Introduction

Plastics due to durability and cost-effectiveness, light weight, easy application, and high performance are widely used in the production of clothing, transportation, cosmetics and, hygiene products, especially in food packaging¹. The widespread use of plastic resulted in the formation of Microplastics (MPs), small particles ranging from 1 μm to 5 mm. These particles are generated by various environmental factors including ultraviolet radiation, mechanical effects, temperature fluctuations, biological activities, erosion and weathering, and atmospheric pollutants². Studies indicate that while larger MPs (> 150 μm) are secreted in feces, smaller particles (0.1–10 μm) can penetrate the blood-brain and placental barriers. MPs of 15–20 μm, considered highly toxic, can enter the circulatory and lymphatic systems³. The distribution of MPs in body resulted in oxidative stress and inflammation, which leads to cytotoxic effects and manifests as organ-specific damage, including liver inflammation, kidney dysfunction, heart circulatory issues, and endocrine disruption causing infertility and metabolic disorders^4,5. Also, MPs could be carrier of toxic materials (heavy metals, benzo(α) pyrene and phthalates) which could be toxicant for vital human body resulted in endocrine disruption, abnormal growth patterns, and oxidative stress⁶.

Plants are susceptible to MPs contamination through several agricultural pathways including irrigation with contaminated water, soil, and the use of plastic mulches to preserve agricultural soil. Also, MPs can enter animal products like poultry and livestock from contaminated soil, water, feed stocks⁷, processing methods (cutting boards), food packaging⁸. In recent years, consumption of fast foods including sausages has been increased⁹. The sausage production involved preparation (meat cutting, addition of ice, additives and spices, stuffing), packaging, and heat processing of packed sausages (72 °C for 2 h) which rise concerns about the probability of MPs contamination¹⁰. Sausages could be an excellent model system for a broader category of processed foods which can provide insights on MPs release relevant to other similar products. In some studies, the effect of temperature in release of MPs from different packaging including food and drink containers¹¹, and take-out food containers¹² has been well documented. Although, there is a lack of data concerning about (1) how internal product composition (e.g., meat content and additive profile) influences MPs release, (2) the long-term release under actual food storage conditions, and (3) the MPs risks posed by processed meat products, which undergo extensive mechanical processing and packaging. It should be mentioned that the selection of 70 and 55% sausages were due to the fact that 70% sausage is a common benchmark for many premium or standard meat products. The 55% sausage was selected to represent economic value or highly processed products, which often contain a higher proportion of non-meat ingredients (fillers, binders, extenders) where the potential for MPs contamination from these additives might be higher. Therefore, the present study evaluates the simultaneous influence of formulation (55% and 70% meat content) and extended storage (1 to 180 days) at two standard temperatures (4 and − 18 °C) on MPs release in sausages. The selection of the temperature (4 and − 18 °C) and time (1, 7, 14, 21, 28 and 180 days) was owing to model the realistic and recommended storage conditions for food product to understand the MPs release during storage. Therefore, the current study was aimed to investigate the effect of meat percentage (70% and 55%) and temperature (-18 °C and 4 °C) on MPs release in sausage during 180 days’ storage.

Materials and methods

Chemical and reagents

Analytical-grade potassium hydroxide (KOH) pellets (Merck/Germany, prepared 10% (w/w) KOH aqueous solution), copper adhesive, and Whatman filter paper (0.6 μm pore size) (Cytiva/Germany) were prepared. Also, standard MPs (polycarbonate, polypropylene, and polyamide with size of 45–53 μm) were prepared.

Quality assurance and control

To minimize aerial deposition of fibers, particles, and airborne contamination, all sample preparation steps were performed under a certified laminar flow hood. Also, Researchers wore 100% cotton lab coats, which are known to shed fewer synthetic fibers than polyester blends. To avoid cross-contamination, all solutions (Potassium hydroxide solution 10%, ethanol and distilled water) were filtered through a filter membrane (Whatman filters with a diameter of 0.6 μm). Also, the working surface was cleaned with filtered ethanol and all glassware’s were thoroughly rinsed three times with filtered distilled water before each use¹³.

Sample preparation

Sausage was prepared with 2% chicken meat (70 and 55%) according to Iran National Standards Organization 2303¹⁴ (INSO, 1402). The samples were packed in commercial 5-layer polyamide coatings and heated at 75–80 °C for 2 h. The commercial 5-layer polyamide/ Ethylene Vinyl Alcohol/ Polyethylene coatings are multilayer polymer films commonly used for sausage and processed-meat products. They typically consist of alternating layers of polyamide which have high mechanical strength, puncture resistance, and a strong barrier against oxygen.

Additive and sausage sampling

All ingredients used to prepare sausages including water, raw chicken meat, spices and oil were collected for analysis. The additives used in the preparation of the sausages included water, ice, vegetable oil, salt, egg white, wheat flour, starch, sodium polyphosphate, gluten, spices, garlic, nitrite, and ascorbic acid in the amounts specified by the Iran National Standards Organization (INSO, 1402).

Approximately, 20 mL aliquots of the water, 10 mL of the vegetable oil, 5 g of additive, and 5 g of raw chicken meat were gathered in solvent-rinsed amber-glass containers before production, transported on ice to the laboratory and stored at -20 °C until analysis. Sausages samples including before and after packaging (200 ± 5 g of each sausage) was stored at both 4 °C and − 18 °C. Sub-samples (5 g, 3 samples) were aseptically cut and placed in solvent-rinsed glass jars for MPs analysis on days 1, 7, 14, 21, 28 and 180.

Sample analysis for MPs

Sample preparation and filtration

Sub-samples of sausage, chicken, and additives were taken for digestion and filtration. Preliminary experiments (1–20 g) demonstrated ≥ 95% MPs recovery for masses ≥ 5 g; however, 10 g and 20 g yielded viscous solution that obstructed the 0.6 μm filter. Therefore, 5 g was selected as the standard test portion for sausage analysis. To remove organic components, sausage, chicken, and additives samples were mixed with 40 mL of KOH (10%) and kept at 50 °C until the digestion was completed. The complete digestion was confirmed by both visual and chemical endpoints, specifically indicated by a clear and transparent solution, and the absence of visible solid organic matter (ranging from 72 to 96 h). To determine MPs particles in water samples, approximately 20 ml of water was passed through a filtration setup equipped with a vacuum pump, and the sampling was performed in triplicates. The digested samples were filtered using a filtration device connected to a vacuum pump. The filters were placed in a glass plate in an air-free place until they were dried¹⁵.

To confirm that the digestion procedure did not compromise the integrity of MPs, positive controls (2.0 × 10³ microspheres mL^− 1, 1 ml) spiked with PC, PP, PA polymer (certified reference microspheres 45–53 μm in ultrapure water) was processed in parallel, consistently yielding high recovery rates (> 95%).

Detection of MPs characteristics by optical microscope

The MPs characteristic (color, shape, and size) and numbers were investigated under a microscope at 32× magnification using a 100 µ insulin needle to confirm the nature of MPs¹⁶.

Detection of MPs polymer type by confocal raman spectroscopy

To determine the type of MPs, a Confocal Raman Spectroscopy was performed in the range of 400–1800 cm^{− 1} with a 633 nm laser diode. Also, images of the identified MPs are presented at two magnifications of ×10 and ×50¹⁷. For validation of polymer identification, all preprocessed spectra were compared against the Bio-Rad reference library using Lab Spec 6. A match-score threshold of greater than 80% was employed, and only spectra exceeding this criterion were accepted as reliable identifications. Spectra with lower match scores or ambiguous spectral characteristics were excluded from the quantitative analysis.

Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX)

Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX) is a technique for imaging a sample and characterizing the surface morphology of the sample. The voltage of 20 kV, the beam current to 1.00 nA, magnification to 500, and exposure time of 30 s was used.

Estimated Daily Intake (EDI)

The Estimated daily intake (EDI) can be used to determine the level of exposure to a pollutant. The daily intake of MPs in humans through the consumption of sausages was calculated by the following formula¹⁸.

Where IR, BW and C represent the sausage consumption per day (6 kg/year), the body weight (70 kg for adults and 16 kg for children), and the number of MPs in sausage (particles/kg), respectively.

Statistical analysis

Statistical analysis was performed using SPSS V18. Descriptive statistics (mean, standard deviation) and repeated measures tests were employed, with a significance level set at 0.05. Post hoc pairwise comparisons utilized paired-samples t-tests with Bonferroni correction.

Result and discussion

MPs in water

According to Table 1, three transparent fibers in 20 mL water, two 700 μm and one 400 μm in length, were identified as polypropylene by confocal Raman spectroscopy (library match ≥ 80%). The SEM images displayed grooves on the surfaces of MPs which revealed longitudinal scratches, consistent with mechanical abrasion (Figs. 1 and 2). The study of Pironti et al., on drinking water showed 700 MPs particles/L, which 90% were polypropylene and polyethylene fragments ranging from 50 to 150 μm¹⁹. Boyakanal et al., reported the presence of MPs in various water sources, predominantly as fibers and fragments composed of ethylene propylene and neoprene which attributed to the extensive use of polypropylene and other plastic polymers in the manufacture of bottles and food packaging²⁰. According to Danopoulos et al.,²¹, the MPs found in drinking water were composed of polyethylene terephthalate (PET) and polypropylene (PP), with sizes ranging from 1 to 100 μm²¹. Polypropylene, a frequently detected polymer in water, can be sourced from various origins, including agricultural activities and urban sewage²², industrial purification process²³, distribution system, and packaging materials.

Table 1.

The MPs in raw chicken meat, additives, and water used in sausage preparation.

Samples	Number, shape and size of MPs	Polymer Type
Raw chicken meat (5 g)	3 Transparent fiber (200, 300, and 600 μm)	Polypropylene, Polycarbonate
	1 black fiber (200 μm)
Additives (5 g)	6 transparent fiber (300, 400, 500, 600, 700, and 800 μm)	polypropylene
Water (20 ml)	2 transparent fiber (400 and 700 μm)	polypropylene

Fig. 1.

Images of selected MPs in sausages under optical microscope. Transparent Fiber (a), Transparent Fiber, 1200 μm (b, e), red fiber, 300 μm (c), black fiber, 700 μm (d), black fiber, 200 μm, (f).

Fig. 2.

Images and Raman Shift of MPs in sausage samples by confocal Raman spectroscopy. Polypropylene (A and B), Polycarbonate (C and D), Polyamide (E and F).

MPs in chicken meat

In the present study, 3 MPs particles were found in 5 g of raw chicken which were 2 transparent and 1 black fibers ranged from 200 to 600 μm (Fig. 1). According to Fig. 2, the MPs polymer types were polypropylene and polycarbonate (Table 1). In Velebit et al., study, the MPs particles in packaged chicken were estimated 1.19 particles/g with majority of fiber shapes⁵ which is higher than results of the current study. In Bahrani et al., study the MPs were 0.14 and 0.13 particles/g in edible tissues of cattle and sheep, respectively¹⁵ which is lower than results of the current study.

Bilal et al., identified MPs in chicken gizzards, predominantly in the 300 to 500 μm size range and exhibiting yellow and red colors. The detected polymer types were polyvinyl chloride (51.2%), low-density polyethylene (30.7%), polystyrene (13.6%), and polypropylene (4.5%), which was attributed to the chickens’ diet²⁴. In Habib et al., study the MPs in fish and chicken ranged from 0.03 ± 0.04 to 1.19 ± 0.72 particles/g in meat in chicken and 0.014 ± 0.024 to 2.6 ± 2.8 particles/g in fish. Also, the polyethylene-based plastic cutting board used for cutting food could be the source of MPs⁸. In Chen et al., study the polystyrene and polyamide particles were found in the chickens’ small intestine, liver, and skeletal muscles which was related to chicken manure²⁵. The polymers such as polypropylene, polyethylene, and polycarbonate were detected in animal feed (soybean, fish meal, corn meal)²⁶. Also, the food production chain is susceptible to MPs contamination from different sources including contamination of water containers, antibiotics used for medication and feed²⁷, as well as dust contamination of farms²⁸. In addition, food processing introduces additional MPs through abrasion of conveyor belts, machines, worker’s textile fabrics²⁹, and food preparation surfaces such as cutting boards⁸.

MPs in additives

According to the results, 6 transparent fibers with polymer type of polypropylene, ranged from 300 to 800 μm, were found in 5 g of additives (including salt and spices). In Sharma et al., study, 681 MPs particles/kg showed in 15 different brands of sea salt³⁰ which was lower than the results of the present study. In Binh et al., study, 320 to 1880 MPs were found in salt and spices which were fibers (99%) and fragments (1%) possessing different colors, predominantly red, blue, and black⁷. The number of MPs particles in salt and spices of Binh et al., research is relatively in the range of the current study. Spices could be contaminated during different drying process³¹, packaging (polyethylene bags)³², and irradiation (polyethylene terephthalate, polyethylene, ethyl vinyl alcohol copolymer-polyethylene release by multilayer packaging)³³.

MPs release in sausage during storage

After 180 days’ storage, the MPs were 15.44 ± 0.40, 33.66 ± 0.57, 52 ± 0.49 and 36.66 ± 0.5 MPs/5 g in 70 and 55% sausages stored at -18 and 4 °C, respectively (Tables 2 and 3). The MPs particles in the current study were evaluated higher than the results of Pirsaheb et al., (25.7 ± 21.68 particles/kg) in sausage¹⁸ and Akhbarizadeh et al., (tuna and mackere 0.05 ± 0.01 and 0.22 ± 0.02 particles/g, respectively) in canned fish¹. The presence of MPs in meat products could be related to release of MPs through packaging of bacon, mortadella, and salami³⁴. Also, the presence of MPs particles in salt-cooked fish was attributed to water and salt used for cooking, fish feeding conditions and the living environment³⁵. In the sausage production process, heat (75–80 °C for 2 h) is applied to packed sausages in polyamide coating which may results in the loosen of plastic coatings chains and release MPs particles into the food¹² which is in agreement with the results of the present study.

Table 2.

The MPs in sausage samples (55 and 70%) during 180 days storage at -18 and 4 °C.

Sausage (5 g)	Storage Temperature	Storage Time (Day)
		Before Packaging	1	7	14	21	28	180
70%	-18	10.45±0.31B, d	10.45±0.31B, d	11.61±0.51C, c	11.61±0.51C, c	11.66±0.51D, c	12.66±0.45D, b	15.44±0.4D, a
	4	10.45±0.31B, f	10.45±0.31B, f	12.66±0.3B, e	19.33±0.45B, d	26.51±0.4B, c	27.45±0.31B, b	33.66±0.57B, a
55%	-18	18.66±0.52A, e	18.66±0.52A, e	20.54±0.51A, d	21.66±0.51A, c	21.66±0.57C, c	25.54±0.51C, b	27.52±0.49C, a
	4	18.66±0.52A, d	18.66±0.52A, d	21.63±0.57A, c	21.66±0.53A, c	29.63±0.61A, b	30.66±0.57A, b	36.66±0.50A, a

Different Lowercase letters in each row means significant difference (p≤0.05).

Different capital letters in each column means significant difference (p≤0.05).

Table 3.

the number and polymer type of MPs in sausage samples (55 and 70%) during 180 days storage at -18 and 4 °C.

Sausage (5 g)	Storage Temperature	Storage Time (Day)
		Before Packaging	1	7	14	21	28	180
70%	-18	10 PP, 1 PC	10 PP, 1 PC	11 PP, 1 PC	11 PP, 1 PC	11 PP, 1 PC	12 PP, 1 PC	12 PP, 3 PC, 1 PA
	4			12 PP, 1 PC	19 PP, 1 PC	25 PP, 1 PC, 1 PA	25 PP, 2 PC, 1 PA	25 PP, 4 PC, 5 PA
55%	-18	18 PP, 1 PP	18 PP, 1 PP	19 PP, 2 PC	20 PP, 2 PC	20 PP, 2 PC	24 PP, 2 PC	24 PP, 4 PC
	4			21 PP, 1 PC	21 PP, 1 PC	29 PP, 1 PC	29 PP, 1 PC, 1 PA	29 PP, 6 PC, 2 PA

PP: Polypropylene, PC: Polycarbonate, PA: Polyamide.

According to the results, the release of MPs was significantly higher at 4 °C compared to -18 °C (P ≤ 0.05) which could be related to the structural and chemical changes occurred by storage temperature³⁶, which is in agreement with results of Hussain et al.,³⁶, and Hee et al.,¹¹. Also, long time storage can release millions to billions of MPs and nanoplastic (NPs) particles³⁷.

MPs characteristics (size, shape, color)

According to Fig. 1, the variation in MPs size was 50 to 200 μm (19.13%), 300 to 500 μm (48.70%), 500 to 800 μm (26.96%), and 900 to 1500 μm (5.22%). In the study of Akhbarizadeh et al., the size of the fibers (54%), fragments (38%) and films (8%) found in canned fish were in the range of 100 to 8000 μm, 10 to 1100, and 70 to 1000 μm, respectively¹. MPs particles are susceptible to breaking down into smaller fragments through processes including crushing, preparation, cooking, and frying. High temperatures, specifically at or above 65 °C, contribute to the destruction of the polymer⁸, the different extraction and analysis method³⁸, and variation of the shape and size. The limitation of the current study was that data does not capture the potential abundance of smaller particles (< 50 μm) and nanoplastics (< 1 μm).

In the present study, the colors of MPs particles were transparent (76.62%), black (14.78%), red/orange (3.48%), blue (3.48%), and brown (1.74%). In Pirsaheb et al., research, the colors of MPs particles in 7 brands of sausages were white, blue, green, and red¹⁸. Studies by Alak et al., on salmon fillets revealed that blue and black MPs were the most abundant². Similarly, Bilal et al., found yellow and red MPs to be most prevalent in chicken gizzards²⁴. The variation in MPs colors could be related to discoloration by absorbed pollutants³⁹ and different digestion methods⁴⁰.

MPs particles can be found in various forms such as pellets, fibers, films, and fragments⁴¹. According to the results, all MPs particles in sausage samples (70 and 55%) were in the form of fibers which is compatible with result of Pirsaheb et al., research in sausages. The presence of fiber forms may be attributed to textiles, plastic bags and food containers, as well as agricultural mulches and soil amendments¹⁸.

Polymer type of MPs

The Raman peaks in the regions of 850 –840 cm^-1 and 1375 cm^-1 indicate the CH₃ vibration groups and symmetric CH vibrations, respectively which belong to polypropylene (Figures A and B). Also, polycarbonate has distinct peaks in the regions of 830 –825 cm and 1600 cm^-1, which are associated with stretching vibrations of aromatic rings (Figures C and D). The Raman spectra at the 1650 cm^-1 (vibrations associated with the amide C = O stretching), 2900–2950 cm^-1 (vibrations associated with the CH₂ stretching), and the 1260 cm (C = N stretching) are associated with polyamide which is compatible with the coating of sausage. According to the results, polymers types of polypropylene (74%), polycarbonate (14%), and polyamide (12%) were identified in sausage that contained 70% meat. In other words, the transparent and brown fibers, black, red-orange and blue MPs were polypropylene, polycarbonate, and polyamide, respectively. In the 55% sausage samples, the polymer types were polycarbonate (81.54%), polycarbonate (15.38%), and polyamide (3.08%). According to Fig. 2, all transparent fibers, black fibers, red-orange and blue fibers were polypropylene, polycarbonate, and polyamide, respectively. The MPs particles identified within the sausage samples exhibited characteristics consistent with those detected in both the ingredients employed in sausage manufacturing and the outer coating. In the study conducted by Pirsaheb et al., the presence of polystyrene and polyethylene was confirmed in seven brands of commercially available sausages in Iran market¹⁸. The research by Akhbarizadeh et al., indicated polyethylene terephthalate as the predominant MPs in canned fish which was attributed to the fish type, the additives employed, and the production processes (cleaning and canning procedures)¹. The polymer types found in canned sardines were polypropylene polymer, which were related to factory production utilities²⁴.

Surface morphology and elemental composition of MPs by SEM-EDX

According to SEM results, some of the MPs have smooth surfaces and some have grooves (Fig. 3). The presence of fractures on the surfaces, indicating polymer erosion, and mechanical degradation⁴². In the MPs of sausage samples, the structure of MPs particles can be influenced by different stages of processing and preparation, and separation from the coating during storage and cutting¹⁸ which resulted in mechanical breakage of larger plastic particles⁴³.

Fig. 3.

Images of the surface morphology and elemental composition of MPs in sausage using SEM-EDX.

According to EDX results, elements such as carbon (C), oxygen (O), potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), silicon (Si), and aluminum (Al) were found in the MPs surface. The surface porosity of MPs enables adsorption of ambient heavy metals and organic pollutants⁴⁴. The presence of elements such as silicon, chlorine, and calcium could be related to plastic additives or environmental contamination¹⁵. Elements such as sodium, potassium, silicon, sulfur, calcium, magnesium, and aluminum originate from various sources including additives used in plastic structure or in sausage production. For instance, sodium and calcium serve as antioxidants in polypropylene and polyethylene⁴⁵. The detection of potassium was attributed to the chemicals used to sample digestion⁴⁶.

Estimated Daily Intake (EDI) of MPs

It should be mentioned that there is no definite information regarding to the MPs limits (maximum residue limits) or threshold in different foods. At the end of storage time, the Estimated Daily Intake (EDI) of MPs by consumption of 70% and 55% sausage samples at -18 °C and 4 °C in adults and children were 1.56, 1.43, 2.88, 6.28, 1.17, 1.56, 5.14 and 6.84 particles/kg BW/day (Table 4). In Pirsaheb et al., research the estimated yearly intake of MPs by sausage consumption was 804 and 3517 particles/kg BW/year in adults and children, respectively¹⁸. In Bahrani et al., study, the EDI of MPs by consumption of edible tissues of cattle and sheep ranged from 0.001 to 0.192 and 0.0007 to 0.096 particles/kg BW/day in children and adult, respectively¹⁵ which was much lower than the results of the current study. In a study of Makhdoumi et al., the EDI of MPs by fish fillet consumption was reported to range from 0.016 to 6.06 particles/kg BW/day⁴⁷. The variation between EDI of different studies could be related to sausage consumption rate, using plastic coating, quality of packaging materials, type of spices and its contamination rate, storage condition, MPs detection method⁴⁸.

Table 4.

Estimated Daily Intake (EDI) of MPs (particles/kg BW/day) by sausage consumption in adults and children.

Sausage (5 g)	Age group	Storage Temperature	Storage Time (Day)
			before packaging	1	7	14	21	28	180
70%	Adult	-18	0.44	0.48	0.50	0.51	0.50	0.57	0.65
		+4	0.44	0.48	0.54	0.88	1.13	1.24	1.43
	Child	-18	1.94	2.10	2.22	2.24	2.22	2.53	2.88
		+4	1.94	2.09	2.36	3.88	4.95	5.46	6.28
55%	Adult	-18	0.82	0.86	0.89	0.92	0.94	1.11	1.17
		+4	0.82	0.78	0.94	0.87	1.33	1.33	1.56
	Child	-18	3.61	3.77	3.9	4.04	4.12	4.85	5.14
		+4	3.61	3.42	4.11	3.83	5.85	5.83	6.84

Conclusion

The increasing consumption of sausages and other processed meat products has heightened concerns regarding MPs contamination during production and storage. The current study demonstrates that the raw materials used in sausage formulation including chicken meat, spices, and water contains MPs, primarily polycarbonate and polypropylene. Storage time was significantly associated with elevated MPs counts, indicating additional release from the packaging materials. Notably, sausages containing 55% meat and stored at 4 °C exhibited the highest MPs levels. The polymers identified in sausage samples were polypropylene, polycarbonate, and polyamide which correspond to raw ingredients and the multilayer plastic coatings, supporting the role of packaging as a secondary MPs source during storage. These findings highlight the necessity of routine MPs monitoring in processed foods and emphasize the need for further research into packaging-derived contamination pathways.

Abbreviations

MPs

Microplastics

KOH

Potassium hydroxide

INSO

Iran National Standards Organization

SEM-EDX

Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

PP

Polypropylene

PC

Polycarbonate

PA

Polyamide

EDI

Estimated daily intake

Author contributions

Conflict of Interest and Authorship Conformation FormPlease check the following as appropriate: Elham Khalili Sadrabad and Hossein Arfaeinia conceived of the presented idea. Zahra Asadi Qajarloo, Hossein Arfaeinia, Maliheh Jahanara, Amin Safaei, Marjan Jafari and Elham Khalili Sadrabad developed the theory and performed the experiments. Zahra Asadi Qajarloo and Arefeh Dehghani-tafti developed the theoretical formalism, performed the analytic calculations and performed the numerical simulation. All authors have participated in drafting the article or revising it critically for important intellectual content; and approval of the final version. o This manuscript has not been submitted to, nor is under review at, another journal or other publishing venue.o We also declare no conflict of interest.Author’s name Zahra Asadi Qajarloo Hossein ArfaeiniaMaliheh JahanaraAmin SafaeiMarjan JafariArefeh Dehghani-taftiElham Khalili SadrabadSincerely Yours, Elham khalili sadrabad.

Funding

The work was supported by Shahid Sadoughi University of medical sciences, Yazd, Iran.

Data availability

Data statementThe datasets used and analyzed during the current study available from the corresponding author on reasonable request.

Declarations

Competing interests

The authors declare no competing interests.