3.1 General Characteristics
3.1.1 Distribution of Plastic Types
According to the data obtained, 50.2% (107 out of the 213) of the total samples of single-use food plastic packaging products tested at GSA within the 7-year period constituted recycled PE Carrier Bags, while HDPE and LDPE plastics represented 37.1% and 12.7%, respectively. From the data, recycled PE Carrier Bag products could represent the most widely used plastics for single-use food packaging in Ghana. This information is helpful to understand the market dynamics of food plastic packaging in Ghana and make informed decisions regarding regulations, waste management, and alternative materials for packaging.
In Ghana, recycled PE Carrier Bags are usually used by vendors to directly or indirectly package food for consumers. The LDPE products are usually used for direct packaging of foods such as Koko (porridge), soups and stews, bread, banku or kenkey, etc, while the HDPE film products are typically used for the production of sachet pure water.
3.1.2 Colour, Print Quality, and Odour
Black Carrier Bags constituted 96.3% of the recycled PE Carrier Bags tested at GSA, while the other colours recorded were White, Pink, Yellow, and Green. HDPE film products tested during the period were colourless (44.3%) and colourless with blue print markings (55.7%). The HDPE plastics (films) with print markings did not show the removal of print from the printed surface thus, conforming to the print requirement of GS 173: 2018. All the LDPE plastics tested were colourless.
Plastics offer the advantage of easy colour incorporation for various consumer applications, as compared to metals and ceramics that rely on external colouring methods, and popular pigments such as titanium dioxide, zinc oxides (white), carbon oxides (black), iron oxides, and chromium oxides, as well as insoluble pigments or soluble dyes made from organic compounds, are utilised for the pigmentation of plastics (Britannica, 2023). The requirements for the colour of polythene carrier bags can vary depending on the specific regulations and guidelines set by different countries or regions. In Ghana, the Ghana standard GS 173:2018 requires that the film used for plastic packaging shall be natural in colour unless otherwise agreed between the purchaser and supplier for the incorporation of pigments, carbon black (2.5% ± 0.5 by mass) or other approved materials (GSA, 2018).
From the analysis of the data, 99.1% of the plastic products tested at GSA within the period had no objectionable odour thus, passing the Odour tests. Analysing the data revealed that in 2019, two (2) black recycled PE Carrier Bag products failed to conform with the requirements for Odour of plastic packaging products used for food.
Like the European Regulation (EC) No 1935/2004 established by the European Parliament and the Council on 27 October 2004, which mandates the manufacture of materials and articles in adherence to good manufacturing practices to prevent the transfer of “constituents to food in quantities which could bring about a deterioration in the organoleptic characteristics thereof” (Consolidated TEXT, 2004), the Ghana standard GS 173:2018 also emphasizes the responsibility of users, particularly producers and manufacturers, to establish suitable safety and health protocols for the production of plastic packaging products intended for food applications (GSA, 2018). Nevertheless, the absence of explicit reference to defined threshold limits, application methods, or detection techniques leaves room for subjective assessments to determine whether the odour of the article is deemed objectionable. Relying on subjective assessments during testing raises the possibility of drawing inaccurate conclusions that could falsely suggest that, generally single-use food packaging plastic products in Ghana are safe from objectionable odour.
Consumers could negatively perceive the quality of food products by its odour (Torri et al., 2008). Food and beverage products stored in polyethylene plastic containers could become characterised by “plastic odours” due to the absorption of minor volatile compounds (Sanders et al., 2005). There could be a single compound or substance, or mixture of substances including volatile compounds of residual monomers and oligomers, residual solvents from printing inks, adhesives, coatings, and by-products of broken down polymers and additives, that could contribute to off odours of plastic packaging products, depending on their concentrations (Torri et al., 2008). Thermal oxidation that occurs during the heating of polymers during thermal processing or polymerisation, leads to the release of odourous volatile organic compounds (Hodgson et al., 2007; Sanders et al., 2005).
3.1.3 Dimensions of the plastic packaging products
The mean lengths of the HDPE, LDPE and recycled PE Carrier Bag products were 649.72 mm (SD = 426.2), 388.46mm (SD = 256.5), and 381.24mm (SD = 137.7), respectively, while mean widths were 340.49mm (SD = 65.4), 302.33mm (SD = 208.3), and 324.76mm (SD = 84.9), respectively. According to (Harper, 2006), extruders used to manufacture plastic films typically have diameters that vary from 20mm to 600mm.
From the analysis of the data, a statistically significant difference (F = 5.731, p-value 0.004 < 0.05) with a small effect size (eta squared (η²) = 8.3%), was observed between the mean Lengths of HDPE, LDPE, and recycled PE Carrier Bag plastic products. However, there was no statistically significant difference (F = 1.472, p-value 0.232 > 0.05) between the mean Widths of these products.
3.1.4 Tensile Strength and Elongation at Break
Plastic films have high mechanical properties such as tensile strength, tear strength, and impact resistance, which usually depend on the molecular structure, molecular mass, and molar mass distribution of the plastics (Abdel-Bary, 2003). Based on the study, it was observed that the HDPE, LDPE, and recycled PE Carrier Bag plastic products demonstrated overall conformity to the Tensile Strength and Elongation at Break requirements specified in the standard GS 173:2018.
The average Tensile Strength (Machine) results of 44.3MPa (SD = 15.6), 41.6MPa (SD = 58.0), and 20.48MPa (SD = 11.7) for HDPE, LDPE, and recycled PE Carrier Bag plastic products, respectively, were recorded. All of these values met the requirement of Tensile Strength (Machine) being at least 11.70MPa. Similarly, the average Tensile Strength (Transverse) results obtained for the HDPE, LDPE, and recycled PE Carrier Bag plastic products were 34.21MPa (SD = 8.5), 31.88MPa (SD = 36.5), and 14.39MPa (SD = 7.8), respectively. These values met the specification of Tensile Strength (Transverse) not being less than 8.30MPa.
The average Elongation at Break (Machine/Longitudinal) values for HDPE, LDPE, and recycled PE Carrier Bag plastic products were 1069.58% (SD = 388.9), 1370.77% (SD = 1495.0), and 368.95% (SD = 325.4), respectively, all of which exceeded the minimum requirement of 225%. Furthermore, the average Elongation at Break (Transverse) results for HDPE, LDPE, and recycled PE Carrier Bag plastic products were 1271.15% (SD = 404.3), 1926.23% (SD = 2099.6), and 587.09% (SD = 299.6) respectively, all of which exceeded the minimum requirement of 350%.
The HDPE plastic products generally demonstrated overall conformity to the requirements for Machine Tensile Strength and Transverse Tensile Strength. However, approximately 12.1% of the recycled PE Carrier Bags and 8.3% of LDPE plastic products failed the Machine Tensile Strength test, while 14.3% of recycled PE Carrier Bag products and 4.3% of LDPE plastic products failed the Transverse Tensile Strength test, particularly in 2019 and 2022. Specifically, in 2019, two LDPE and six recycled PE Carrier Bag plastic products did not meet the requirements of the Machine Tensile Strength test, and in 2022, five recycled PE Carrier Bag plastic products failed the test. Additionally, in 2019, one LDPE plastic product and nine recycled PE Carrier Bag plastic products failed the Transverse Tensile Strength test, while four recycled PE Carrier Bag plastic products failed the test in 2022. Notably, no failures were observed in the Machine Tensile Strength and Transverse Tensile Strength tests for HDPE, LDPE, or recycled PE Carrier Bag plastics in both 2020 and 2021.
Regarding the Machine/Longitudinal Elongation at Break and Transverse Elongation at Break tests, HDPE plastics showed no failures, while recycled PE Carrier Bags and LDPE plastics recorded failure ranging from 8.7–30.8% in different years, with notable failures occurring in 2019, 2020, 2021, and 2022. From 2019 to 2022, the number of recycled PE Carrier Bag plastic products failing the Machine/Longitudinal Elongation at Break test varied, with 17 failures in 2019, 4 in 2020, 4 in 2021, and 3 in 2022. Additionally, two LDPE plastic products failed in 2019 and one LDPE plastic product in 2021. In 2020, 2021, and 2022, there were 9, 3, and 4 recycled PE Carrier Bag plastic products, respectively, that failed the Transverse Elongation at Break test, along with one LDPE plastic packaging product failing in 2019 and 2021. Notably, there were no failures in the Transverse Elongation at Break test for any plastic type in 2020. These findings highlight concerns about the tensile strength and elongation at break properties of LDPE and recycled PE Carrier Bag plastic packaging products, emphasizing the need for quality improvement and adherence to standards.
3.2 Correlational Analysis of some critical parameters against the plastic types
Elongation at Break and Transverse Elongation at Break
For the HDPE, LDPE, and recycled PE Carrier Bags products, the study found statistically significant and strong correlations between Machine Elongation at Break and Transverse Elongation at Break (r = 0.584, 0.801, and 0.558, respectively, p-values < 0.05).
Table 3
Correlation between Machine and Transverse Elongation at Break of the HDPE, LDPE, and recycled PE Carrier Bag plastic products
EB Machine/Longitudinal | EB Transverse |
N | Correlation Coefficient | Sig. (2-tailed) |
HDPE | 52 | .584** | 0.000 |
Recycled PE Carrier Bag | 91 | .558** | 0.000 |
LDPE | 22 | .801** | 0.000 |
**. Correlation is significant at the 0.01 level (2-tailed). |
Additionally, there were statistically significant and strong correlations between Machine Tensile Strength and Transverse Tensile Strength for LDPE and recycled PE Carrier Bags products (r = 0.676 and 0.758, respectively, p-values < 0.05). However, there was no statistically significant correlation between Machine Tensile Strength and Transverse Tensile Strength for HDPE plastic products (r = 0.227, p-value > 0.05).
Table 4
Correlation between Machine and Transverse Tensile Strength of the HDPE, LDPE, and Recycled PE Carrier Bag plastic products
TS Machine | TS Transverse |
N | Correlation Coefficient | Sig. (2-tailed) |
HDPE | 52 | 0.227 | 0.105 |
Recycled PE Carrier Bag | 91 | .758** | 0.000 |
LDPE | 22 | .676** | 0.001 |
**. Correlation is significant at the 0.01 level (2-tailed). |
Regarding Acetic Acid and Ethanol Overall Migration, there were statistically significant and strong correlations for HDPE and LDPE products (r = 0.912 and 0.961, p-values < 0.05). Correlational analysis was not conducted for recycled PE Carrier Bag products with respect to Acetic Acid and Ethanol Overall Migration due to the limited sample size of only two bags, rendering statistical analysis unfeasible. The laboratory personnel disclosed that the exclusion of overall migration tests in the analysis of recycled PE Carrier Bags is predicated on the presumption that they are not intended for direct food contact.
Table 5
Correlation between OM Acetic Acid and OM Ethanol of the HDPE, LDPE, and recycled PE Carrier Bag plastic products
OM Acetic Acid | OM Ethanol |
N | Correlation Coefficient | Sig. (2-tailed) |
HDPE | 42 | .912** | 0.000 |
Recycled PE Carrier Bag | 2 | 1 | . |
LDPE | 17 | .961** | 0.000 |
**. Correlation is significant at the 0.01 level (2-tailed). |
3.3 Analysis of Variance of some critical parameters against the plastic types
An analysis of variance showed that there were statistically significant differences in the mean values of Machine Tensile Strength, Transverse Tensile Strength, Machine/Longitudinal Elongation at Break, and Transverse Elongation at Break between the HDPE, LDPE, and recycled PE Carrier Bag plastic product types. However, there were no statistically significant differences in the mean values of Acetic Acid Overall Migration (p-value 0.896 > 0.05), and Ethanol Overall Migration (p-value 0.647 > 0.05) between the HDPE, LDPE, and Recycled PE Carrier Bag plastic products.
Table 6
ANOVA of critical parameters for HDPE, LDPE, and Recycled PE Carrier Bag plastic products
| Sum of Squares | df | Mean Square | F | Sig. |
TS Machine | 21977.87 | 2 | 10988.94 | 17.632 | 0.000 |
TS Transverse | 15090.63 | 2 | 7545.315 | 31.942 | 0.000 |
EB Machine/Longitudinal | 27713003.749 | 2 | 13856502 | 33.102 | 0.000 |
EB Transverse | 39041243.412 | 2 | 19520622 | 28.058 | 0.000 |
OM Acetic Acid | 0.123 | 2 | 0.062 | 0.11 | 0.896 |
OM Ethanol | 0.77 | 2 | 0.385 | 0.438 | 0.647 |
Tamhane’s post-hoc analysis showed that there were statistically significant differences between the mean values of Machine Tensile Strength (p-value 0.000 < 0.05), Transverse Tensile Strength (p-value 0.000 < 0.05), Machine Elongation at Break (p-value 0.000 < 0.05), and Transverse Elongation at Break (p-value 0.000 < 0.05) for HDPE and recycled PE Carrier Bags. Furthermore, there were statistically significant differences between the mean values of Machine Elongation at Break (p-value 0.010 < 0.05), and Transverse Elongation at Break (p-value 0.017 < 0.05) for LDPE and recycled PE Carrier Bags.
HDPE plastics recorded a mean machine tensile strength of 23.8MPa higher than recycled PE Carrier Bags, indicating that the TS Machine measurements were significantly higher for HDPE compared to recycled PE Carrier Bag. Similarly, HDPE plastics recorded a mean transverse tensile strength of 19.8MPa higher than recycled PE Carrier Bags, suggesting that the TS Transverse measurements were significantly higher for HDPE than recycled PE Carrier Bag. Furthermore, Machine/Longitudinal elongation at break measurements for HDPE and LDPE plastics were significantly greater (700.6% and 1001.8%, respectively) than those of recycled PE Carrier Bag. For Transverse elongation at break, HDPE and LDPE plastics both recorded mean differences of 684.1% and 1339.1%, respectively, significantly higher than recycled PE Carrier Bags.
No significant differences were observed between TS Machine (p-values 0.244 and 0.995 > 0.05) and TS Transverse (p-value 0.094 and 0.987 > 0.05) for LDPE and recycled PE Carrier Bag, and LDPE and HDPE plastics, respectively.
3.4 Regression Analysis
Regression analysis is one of the most powerful statistical techniques for making inferences about the relationship between two variables, and allows for direct prediction of parameters.
A simple linear regression was calculated to predict TS Machine, TS Transverse, EB Machine/Longitudinal, and EB Transverse using Length and/or Thickness.
Table 7
Regression Models to predict EB or TS
| Elongation at Break | Tensile Strength |
Model | 1. Machine/ Longitudinal (Coefficients) | 2. Transverse (Coefficients) | 3. Machine (Coefficients) | 4. Transverse (Coefficients) |
(Constant) | - | - | 29.44*** (4.7) | 15.066*** (2.9) |
Length (mm) | - | - | 0.022** (0.009) | 0.019** (0.006) |
Thickness (mm) | 16948.8*** (3838.3) | 18742.3*** (5080.8) | -567.79*** (134.3) | -242.523** (83.3) |
R Square | 0.19 | 0.133 | 0.162 | 0.135 |
Adjusted R Square | 0.175 | 0.117 | 0.146 | 0.119 |
Note: The values of standard errors are in parentheses. “***”, and “**” denote significance at the 1% and 5% levels, respectively. |
3.4.1 The effect of Thickness on Machine/Longitudinal Elongation at Break
For EB Machine/Longitudinal a significant regression equation was determined using Thickness (F (2, 107) = 12.554, p-value 0.000 < 0.05), with an R2 of 0.190. The R-value shows that there is a moderately strong correlation (0.436) between Machine/Longitudinal Elongation at Break and Thickness. Thickness can significantly (p-value 0.000 < 0.05) be used to predict the Machine/Longitudinal Elongation at Break using the equation; Machine/Longitudinal Elongation at Break = 16,948.804 (Thickness). Machine/Longitudinal Elongation at Break increases by 16,948.8 for each millimetre of Thickness.
3.4.2 The effect of Thickness on Transverse Elongation at Break
A significant regression equation was also determined for predicting EB Transverse values using Thickness (F (2, 106) = 8.141, p-value 0.001 < 0.05), with an R2 of 0.133. The R-value shows that there is a moderately weak correlation (0.365) between Transverse Elongation at Break and Thickness. Thickness can significantly (p-value 0.000 < 0.05) be used to predict the Transverse Elongation at Break using the equation; Transverse Elongation at Break = 18,742.256 (Thickness). Transverse Elongation at Break increases by 18,742.3 for each millimetre of Thickness.
3.4.3 The effect of Length and Thickness on Machine Tensile Strength
Furthermore, a significant regression equation was determined for predicting TS Machine values using Length and Thickness (F (2, 107) = 10.309, p-value 0.000 < 0.05), with an R2 of 0.162. The R-value shows that there is a moderately strong correlation (0.402) between Machine Tensile Strength and Thickness, and Length. Length and Thickness can significantly (p-values 0.017 and 0.000, respectively < 0.05) be used to predict the Machine Tensile Strength using the equation, Machine Tensile Strength = 29.440–567.790 (Thickness) + 0.022 (Length). Machine Tensile Strength increases by 0.022 for each millimetre of Length and decreases by 567.790 for each millimetre of Thickness.
3.4.4 The effect of Length and Thickness on Transverse Tensile Strength
A significant regression equation was further determined for predicting TS Transverse values using Length and Thickness (F (2, 106) = 8.305, p-value 0.000 < 0.05), with an R2 of 0.135. The R-value shows that there is a weak correlation (0.368) between Transverse Tensile Strength and Thickness, and Length. Length and Thickness can significantly (p-values 0.001 and 0.004, respectively < 0.05) be used to predict the Transverse Tensile Strength using the equation, Transverse Tensile Strength = 15.066–242.523 (Thickness) + 0.019 (Length). Transverse Tensile Strength increases by 0.019 for each millimetre of Length and decreases by 242.523 for each millimetre of Thickness.
From the regression analysis, the R-values ranged from 0.365 to 0.436, suggesting moderate to weak correlations. The R2 values also ranged from 13.3–19.0%, indicating that the models can explain a modest portion of the variation in the mechanical properties. An R2 value of at least 10% (0.1) is considered acceptable when the explanatory variables demonstrate statistical significance (Ozili, 2023).
Polymers exhibit a wide range of mechanical properties and exist in many forms including soft plastics to rigid and durable ones (Deshmukh et al., 2020). Tensile Strength and Elongation at Break are some important critical parameters for the safety of plastic packaging products. Elongation at break is a property of plastics that signifies its resistance to change its shape without cracking, and serves as a measure of the polymer’s ductility by representing the extent to which the plastic material can be stretched until it breaks (Deshmukh et al., 2020). Elasticity measures the stiffness of the plastic while elongation at break measures the amount of total energy a plastic sample can take per unit volume until the point of breakage. Samples of identical dimensions should have similar elasticity measurements for quality control and reproducibility (ASTM D-882, 2017). Tensile strength on the other hand, signifies the stress or total force required to break the cross-sectional area of a plastic material (Deshmukh et al., 2020). The Tensile Strength properties help to characterise and identify the polymer material used for control and specification purposes (ASTM D-882, 2017). To ensure the accuracy of Tensile Strength analysis of plastic samples, the dimensions and thickness of the plastics are considered because tensile properties can differ with different thicknesses, preparation methods, duration of testing, and manner of measuring extensions (ASTM D-882, 2017).The Elongation at break compliments the Tensile strength by providing insights of the plastic material when subjected to stress or force during the breaking process (Polymer Science Learning Center, 2023).
The determined regression models predict the values of the mechanical properties based on Thickness and Length as explanatory variables. There have been some studies on the relationship between thickness and tensile strength or elongation at break of polymers.
The thickness of plastic has been found to affect the tensile strength properties of plastic. In a study by Tschegg et al. (1991), it was determined that an increase in thickness reduced the tensile strength of the plastic material. The regression models “Machine Tensile Strength = 29.440–567.790 (Thickness) + 0.022 (Length)” and “Transverse Tensile Strength = 15.066–242.523 (Thickness) + 0.019 (Length)” corroborate this assertion, that an increase in Thickness would result in reduced Tensile Strength. By knowing the thickness and length of the plastic product, one can use the regression equation to predict the force per unit area required for the plastic to break.
From the study, only Thickness emerged as the significant predictor in predicting Machine/Longitudinal Elongation at Break or Transverse Elongation at Break, whereas Length did not demonstrate significant predictive capability (p-values of 0.138 and 0.352, respectively > 0.05) which is intriguing, given that Elongation at Break is typically determined by calculating the percentage of the stretched or final length (L) relative to the original or initial length (L0) of the plastic material (Deshmukh et al., 2020).
The findings of the regression analysis highlights the importance of controlling Thickness in plastic manufacturing processes to ensure desired levels of Elongation at Break and Tensile Strength properties.
Furthermore, plastics with low molecular weights have been found to affect tensile strength and elongation at break as well, due to the stretching of the short molecular chains to their limit faster than the long molecular chain polymers (Stern et al., 2007). Deshmukh et al. (2020) asserts that the type of polymer, its molecular structure and molecular weight (MW), and degree of crystallinity, among other factors, determine the mechanical properties of polymers. This could possibly explain why the HDPE plastic products demonstrated superior performance in the Tensile strength and Elongation at Break tests as compared to the LDPE and Recycled PE Carrier Bag products.
The prediction models could be further improved by adding other prediction factors such as the molecular weight and structure of the plastic. Additional factors, such as the molecular weight and molecular structure of the plastic products, could be included to enhance the predictive capability of the models and increase the R2 values.
3.5 Handle Strength and Seal Creep Test of recycled PE Carrier Bags
The handle strength test and seal creep test were performed on recycled PE Carrier Bag products due to their primary function of securely containing and transporting items. Out of all the recycled PE Carrier Bag plastic products tested, only 2 black carrier bags failed the handle strength test as a result of their handles detaching within 10 minutes of hanging. Three (3) recycled PE Carrier Bag products submitted in 2022 also failed the Seal Creep test.
The handle strength test and seal creep test measure the extent to which seals or handles of carrier bag products can open or tear, or remain intact over time when made to carry weights under specified testing conditions. Franks (2002) asserts that the seal creep test is important to ensure that the sealed areas of the plastic packaging product do not break or open up, that could lead to the occurrence of leaks during processes such as sterilization, regular handling, transportation, and storage.
3.6 Overall Migration from the plastic products
Organisms would not usually be exposed to one migrant chemical at a particular time but may be exposed to the interactive effects of a combination of harmful chemicals (Bergmann et al., 2015), therefore, it is important to assess the overall migration of contaminants and migrant chemicals that may transfer from the plastic packaging products into food, to have a holistic idea of the potential of chemical migration from the products. Food simulants, not actual foodstuffs, are preferred due to the simplification of chemical analysis, to determine the extent of chemical transfer into food types including hydrophilic (water-based) food or drinks, lipophilic (fatty foods), or amphiphilic (foods with both watery and fatty properties) (Muncke, 2013). The Ghana standard GS EN 1189-1: 2002 Clause 6 specifies the selection of food simulants including distilled water as simulant A, 3% acetic acid (w/v) in aqueous solution as simulant B, 10% ethanol (v/v) in aqueous solutions as simulant C, and rectified olive oil as simulant D (GSA, 2012). Liquids and beverages with ethanol content greater than 10% (v/v) would require aqueous solutions of ethanol of similar strength (GSA, 2012). For the overall migration tests, 10% ethanol (Simulant C) and 3% acetic acid (Simulant B) were used to determine the gravimetric concentrations of non-volatile residues that could migrate out of plastic packaging products.
From the results, the mean Overall migration concentrations using 3% Acetic Acid for HDPE, LDPE and Recycled PE Carrier Bag products were 0.37mg/L (SD = 0.84), 0.29mg/L (SD = 0.46), and 0.48mg/L (SD = 0.59), respectively. Additionally, the mean Overall migration concentrations using 10% Ethanol for HDPE, LDPE and recycled PE Carrier Bag products were 0.49mg/L (SD = 1.08), 0.24mg/L (SD = 0.42), and 0.52mg/L (SD = 0.58), respectively.
The mean Overall migration concentrations are far below the limit of 5mg/l, indicating that the plastic products are safe from migration of non-volatile residues. According to GS 1186: 2018, the specified maximum limit for overall migration is 5mg/l.(GSA, 2012).
The highest concentrations recorded for HDPE plastics were 4.6mg/l and 6.1mg/l for overall migration using Acetic Acid and Ethanol, respectively. Also, the highest concentrations recorded for LDPE were 1.4mg/l and 1.6mg/l for overall migration using Acetic Acid and Ethanol, respectively.
From the analysis of the data, there was no statistically significant difference (p-value 0.896 > 0.05) observed between the means for Acetic Acid Overall migration of the HDPE, LDPE, and recycled PE Carrier Bag plastic products. Similarly, there was no statistically significant difference (p-value 0.647 > 0.05) observed between the means for Ethanol Overall migration of the plastic products.
3.7 Risk Assessment of Overall Migration – Hazards
The Mean Overall Migration using Acetic Acid, and using Ethanol for the HDPE plastics were 0.374mg/l and 0.490mg/l, respectively. Also, the Mean Overall Migration using Acetic Acid, and using Ethanol for the recycled PE Carrier Bag plastics were 0.475mg/l and 0.520mg/l, respectively. The Mean Overall Migration using Acetic Acid, and using Ethanol for the LDPE plastics were 0.286mg/l and 0.240mg/l, respectively.
A hazard quotient was calculated to determine the ratio of the potential exposure to non-volatile residues that could migrate out of the plastic packaging products and the level at which no adverse effects are expected, using the formula;
\(Hazard Quotient \left(HQ\right)= \frac{Exposure Concentration}{Effect Concentration or \text{R}\text{e}\text{f}\text{e}\text{r}\text{e}\text{n}\text{c}\text{e} \text{c}\text{o}\text{n}\text{c}\text{e}\text{n}\text{t}\text{r}\text{a}\text{t}\text{i}\text{o}\text{n} (\text{m}\text{g}/\text{m}3)}\) (USEPA, 2005)(1)
The results show that the Hazard Quotients for Overall Migration using Acetic Acid and Overall Migration using Ethanol were 0.0748 and 0.098, respectively, for HDPE plastic products. For recycled PE Carrier Bags, the Hazard Quotients were 0.095 and 0.104, respectively. Additionally, the Hazard Quotients for LDPE plastic products were 0.0572 and 0.048, respectively. In all cases, the Hazard Quotient values were less than one indicating that non-cancer hazard should not be an issue (ATSDR, 2022) and unlikely adverse effects from using the plastic products.
However, Overall migration only determines the gravimetric concentrations of non-volatile residues that can migrate out of the FPP product but does not indicate the concentrations of individual chemical contaminants that could potentially migrate into food.
Chemical additives including antioxidants, lubricants, nucleating agents, antistatic agents, antifogging agents, antimicrobials, blowing agents (García Ibarra et al., 2019), UV stabilisers, lead heat stabilizers, pigments, plasticisers, brominated flame-retardants, polyfluorinated compounds, and so on, are sometimes added to plastics during the production or manufacturing process, to improve certain desired properties of plastics such as durability, flame resistance, colour, and softness (Agency, 2019), flexibility, and tensile strength. Some chemicals that have been discovered to migrate out of plastics include Bisphenol A, plasticizers, and heavy metals such as Antimony (Sb), Titanium (Ti), Zinc (Zn), Iron (Fe), Cadmium (Cd), Lead (Pb), Arsenic (As), Chromium (Cr (VI)), Cobalt (Co), Mercury (Hg), and Tin (Sn) (Turner and Filella, 2021), phthalates, and some low levels of inorganic compounds and non-volatile oligomers from recycled PET (Dutra et al., 2014).
From Fig. 3–15, the Overall Migration using Ethanol recorded higher Hazard Quotient values than that of Overall Migration using Acetic Acid for recycled PE Carrier Bags and HDPE plastic products. On the other hand, the LDPE plastic products recorded higher Hazard Quotient values for Overall Migration using Acetic Acid than for Overall Migration using Ethanol.
Recycled PE Carrier Bags recorded the highest Hazard Quotient values, compared to LDPE and HDPE plastic products, while LDPE products recorded the lowest Hazard Quotient values. Based on the findings, it can be deduced that recycled PE Carrier Bags might pose a higher level of risk for food contact applications compared to HDPE and LDPE plastic product types by approximately 21.3% and 39.8%, respectively.