Regulatory and Safety Requirement for Use of Recycled Polyethylene in Food and Cosmetic Packaging

Abstract

Post-consumer resin, or PCR, is the technical term for recycled plastic. Plastic waste is collected, sorted, and re-purposed to make various types of new packaging. This includes ocean plastics, which are post-consumer resins made from plastics that are headed to oceans but picked up for recycling before they end up in oceans. Polyethylene terephthalate (PET) and high-density polyethylene (HDPE) are the most frequently recycled polymers where PET and HDPE bottles comprise 97.1% of the United States plastic bottle and packaging market. The greatest challenge to using PCR plastic is the potential chemical migration of contaminants from the plastic packaging into the package contents. This potential chemical contamination is often higher in PCR material as compared to virgin material due to the migration from and to the plastic during its lifetime. There are regulatory requirements to ensure safety of PCR in food packaging, but there are no clear guidelines for cosmetic industry to ensure their safe in cosmetic packaging. In this book chapter we will summarize the challenges for using recycled polyethylene, the global regulatory requirements for their use in food packaging and learning that can be applied for their safe use in cosmetic packaging.

1. Introduction

Plastic use is omnipresent in our society, where it’s used in durable consumer goods as well it’s use for packaging in cosmetics, food, and self-care products. The discarding of these plastics tends to be separated into three streams: solid waste for landfilling/disposal, recycling, and incineration use. Growing concern over the potential environmental impact of disposed plastic waste has led to the widespread use of post-consumer recycled (PCR) plastic. PCR is a type of recycled plastic material that is obtained by collecting, sorting, cleaning, and processing plastic waste that has been discarded by consumers after use [1]. This waste can come from a variety of sources, including plastic bottles, containers, bags, and other types of packaging. The collected plastic waste is then sorted based on its type, color, and quality. It is then cleaned and processed into small pellets or flakes that can be used to create new plastic products. The resulting PCR material can be used to make a wide range of plastic products, including new containers, bags, packaging materials, and other items for a variety of industries [2].

The use of PCR plastic is important for both sustainability and the circular economy. By using PCR plastic, companies can reduce their reliance on virgin plastic production, which conserves natural resources, reduces greenhouse gas emissions, and promotes resource efficiency [3]. In addition, the use of PCR plastic promotes a circular economy by creating a closed-loop system where materials are reused and repurposed, rather than discarded after a single use [1, 3]. The quantity and characteristics of the plastic used in PCR is variable and often depends on geographical location, but the most recycled plastics include polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS) [1]. These types of plastics are often found in products such as water bottles, grocery bags, food containers, and packaging materials [1, 4]. Of the four main types of polymers, PET and high-density PE are the most frequently recycled polymers, where HDPE and PET bottles compromise 97.1% of the United States plastic bottle and packaging market and both plastics are used in 98.6% of the recycled bottles [5].

While the use of PCR materials represents an important step towards more sustainable plastic manufacturing, there are several challenges associated with its use including maintaining the quality and consistency of the recycled material [1]. PCR plastics can vary in quality and consistency depending on the source material, the recycling process, and other factors. This can make it difficult to use PCR plastics in certain applications, such as high-performance products, where consistent material properties are critical [6]. The availability and supply of PCR plastics can also be a challenge. PCR plastics are typically more expensive to produce than virgin plastics, and there may be limited supplies of certain types of PCR plastics, depending on factors such as collection and recycling infrastructure, consumer behavior, and market demand [1, 6].

However, the greatest challenge to using PCR plastic is the potential chemical migration from the plastic packaging into the package contents [4]. This potential chemical contamination is often higher in PCR material as compared to virgin material due to the migration from and to the plastic during its lifetime [1, 4, 7]. To address this challenge, proper sorting, cleaning, and processing of PCR plastics is critical. However, absence of chemical decontamination included in a strict recycling process will result in post-consumer use plastic which may be contaminated with chemicals [4]. Contaminants can originate from the original products made from the plastic, such as food packaging, containers, or household items as well as external sources, such as additives used during the manufacturing process [1]. Potential residual chemicals that may be found in PCR materials includes traces of substances such as dyes, pigments, and food residue that leached into the recycled plastic during use and persisted in the material after recycling [7] as well as plastic additives such as flame retardants, plasticizers, UV stabilizers, antioxidants, and heavy metals [8]. The presence and concentration of these contaminants can vary depending on the specific recycling process, the type of plastic being recycled, and the level of quality control and sorting implemented during recycling operations [7]. Many of these contaminants have the potential to pose a risk to human health and therefore should be evaluated from a safety perspective prior to using PCR materials.

The use of recycled plastics for food contact is subject to various regulations. For example, in EU, the European Food Safety Authority (EFSA) assess the use of food contact materials containing recycled plastic and only those approved by the European Commission are permitted as outlined in various regulations including EC 1935/2004 [9], EU 10/2011 [10]. Other industries such as cosmetics are increasingly using PCR plastics to reduce the environmental footprint of their products [4]. However, there is no direction on the safety evaluation of PCR materials for use in cosmetic packaging. Therefore, in this chapter we will summarize the EU and US regulatory requirements for use of rPET in food packaging and learnings that can be applied to the safe use of rPET for cosmetics.

2. Classification of input steam and recycling process

The input materials for the recycling processes play an important role in the risk assessment of the recyclates and has an impact on the contamination levels [11]. The different approaches to the recycling of plastic packaging materials can be categorized into three distinct processes:

Primary recycling (input materials are referred to as class 1) is the recycling of industrial scrap produced during the manufacture of food contact plastic where the material has a low likelihood for contamination and provided that the material has been evaluated already by scientific groups, e.g., EFSA or FDA, it can be reused in cosmetic and food packaging materials like virgin materials [12]. Secondary recycling (input materials are referred to as class 2 or 3) are waste discarded by a given consumer or industry, after its use, is recovered and processed to manufacture new products, which do not necessarily have the same purpose as the original product [12]. The input materials under secondary recycling are divided up into two classes:

• Class 2: are post-consumer materials for well-known applications [11], which are recollected as pure grade by the recycler and the contamination levels are typically low and the variation in the contamination levels is small (e.g., milk bottles or pure collected shampoo bottles).

• Class 3: are post-consumer materials that typically have a wide range of contaminants at high levels as those are recollected from mixed plastics collections with unknown history of use with potential cross contamination from consumer misuse [11]. As a result, having good sorting efficiency is critical to establish homogenous fractions with a low potential for contamination [11].

Tertiary recycling where input materials are referred to as Class 4, use thermochemical methods to process the materials, organic or non-organic, which will be molecularly disintegrated and transformed into new products. The resulting materials are normally used as primary materials (oligomers and monomers), fuels or are co-processed with other materials. In the case of plastics, tertiary recycling allows the production of naphtha or monomers, which are further processed to produce new plastics [12].

In the case of class 2 and class 3 materials, contaminants might be present, and they require further control prior to using in recycled plastic. In general class 1 and class 4 materials are assumed to be safe and can be used with virgin polymers to remanufacture new packaging for food and cosmetic products.

The recycling process of polyethylene comprises the collection, sorting, cleaning, reprocessing by melting and then producing new products from the recycled polyethylene. It is critical for recycled plastics used in food or cosmetics to undergo a decontamination process in the recycling of plastics. Various contaminants can be present in recycled plastic including those introduced from consumer misuse (i.e., petrol or domestic-use pesticides) or unintentionally added during collection and recycling processes (e.g., detergents from the washing step), or newly formed during the recycling process (e.g., degradation products of plastic components). A so-called challenge test can be performed to assess the efficiency of the decontamination step during recycling where plastics are “spiked” (i.e., chemicals are added) with a set of representative surrogate contaminants at known concentrations [13]. Then, the intentionally contaminated plastics undergo a recycling process and analyzed afterwards to illustrate that the surrogate contaminants have been reduced to levels that do not pose any health concerns.

Polyethylenes are common as food packaging components. In Europe, post-consumer recycling of PET into new PET bottles has been well established over past two decades and as a result, the procedures put forward for recycling of polyolefins are largely based on those developed for PET [14]. However, PET and polyolefin polymers have different material properties, which also includes the diffusion behavior of substances in the polymer where polyethylene has poorer functional barrier properties and a faster migration of absorbed contaminants within the polymeric material. This results in polyethylene being potentially highly contaminated due to fast sorption of contaminants, with higher molecular weight than those typical for PET [15]. As a result, polyethylene needs to be decontaminated to a high degree, since the migration of residual contaminants into food is likely to be fast and hence of higher concern [15]. Also, polyethylene has a reduced thermal stability which results in higher amounts of degradation products formed during the decontamination processes, especially the one based on thermal desorption, which is used most widely used [15]. Moreover, polyethylene has an application in a wide range of products, including fragranced cleaning agents as they often contain several different additives. Consequently, it becomes prone to contamination with a variety of substances to a more significant degree when compared to PET, which makes processing of polyolefins more challenging. This has major effects for proper decontamination procedures for polyolefins recycling, which should differ from those used for PET.

3. Potential contaminants in recycled polyethylene

Some data has been published on contamination levels of post-consumer recyclates. In one study, bottle samples from household waste were collected from five different sites where twenty-one rHDPE pellets samples of the bottle fraction were investigated towards post-consumer substances [16]. A total of seventy-four substances were identified at concentrations above 0.5 mg/kg which are not detected in virgin HDPE. Most of the substances are identified as constituents from consumer goods and cosmetic products including saturated fatty acids, phthalate esters, hydrocarbons, preservatives, monoterpenes and sesquiterpenes. The highest concentrations ranging from 50 to 200 mg/kg were found for limonene, diethylhexyl phthalate and the isopropyl esters of myristic and palmitic acid. In a follow-up study, seven rHDPE and eight rPP samples were analyzed [17] where limonene was detected as main substance in concentrations up to 100 mg/kg as well as phthalates esters, alkanes, 2,6-di-tert-butyl-4-hydroxytoluene and oligomers, but there was no indication of bottle misuse (e.g., for the storage of toxic chemicals).

Another study evaluated the contamination levels of rHDPE flakes from milk bottles recollected in the UK [18]. Unsaturated oligomers were the predominant contaminants in washed rHDPE flakes which were also found in virgin HDPE pellet samples. Like virgin HDPE, the concentrations of both decene and dodecene were around 20 mg/kg. Concentrations of the saturated oligomers were detected in slightly higher concentrations versus virgin HDPE. Both limonene and antioxidant additives di-tert-butylphenol were detected in the post-consumer rHDPE flakes. Unknown substances were found in one sample at 130 mg/kg and 40 mg/kg, respectively, which is an indication of consumer misuse.

A more recent analysis was conducted by Danish Environmental Protection Agency where they analyzed contaminants found in HDPE and PP [19]. The primary sources of waste incorporated samples from household polymer-sorted plastic, materials derived from fishing equipment, and collected plastic waste originating from oceans, rivers, and beaches within the Indian Ocean region. The utilization of GC/MS screening led to the identification of a considerable quantity of non-aromatic aliphatic compounds, with the majority being found in the saturated state. The non-aromatic, saturated aliphatic compounds may potentially stem from the degradation of polymer chains. This category of components is prevalent and stands as the most significant group detected. The presence of these components within the samples is semi-quantitatively estimated to range between 0.05% and 0.7%, respectively. One sample also contained several aromatic compounds of aliphatic functionality (MOAH, mineral oil aliphatic hydrocarbons), such as 5-phenyltridecane. These compounds do not originate from the degradation of the polymer chain, which does not have an aromatic functionality, but rather may be from components that migrated into the plastic throughout its lifetime while being used by the consumer. Also, different phthalates (DBP, DIBP, BBP and DEHP) were detected in several samples at relatively low levels (in all cases below 0.005%). The ICP/MS screening also revealed a small number of metals that have migrated into the product simulant including 0.5 mg/kg aluminum.

4. Food regulatory requirements for PCR

Food contact regulatory requirements for recycled plastics around the world are complex with regions like US and EU establishing the stringent requirements for authorization of recycled plastic, whereas regions like Australia, China, India do not have formalized regulations. However, it is essential to mitigate the risks associated with migration of chemical substances from recycled plastics into food, which could pose a health risk. The primary hindrance to the utilization and growth of recycled plastics in food contact applications stemmed from the absence of a regulatory framework that would permit and ensure the safe use of post-consumer materials for food purposes.

4.1 United States Food and Drug Administration (US FDA)

The US Food and Drug Administration (FDA) regulates the food contact materials including food packaging as per the Food, Drug, and Cosmetic (FD&C) Act. FD&C Act defines a food contact substance (FCS) as any substance that is intended for use as a component of materials used in manufacturing, packing, packaging, transporting, or holding food if such use of the substance is not intended to have any technical effect in such food [20].

FDA has adopted the Food Contact Notification (FCN) program as part of the Food and Drug Administration Modernization Act of 1997, where a manufacturer or supplier of a food contact material may, in most cases, submit a notification to FDA identifying the food contact substance and its intended conditions of use, and providing information to support the conclusion that the substance is safe for the intended use. If the FDA does not raise any objections within 120 days of receiving a notification, the manufacturer or supplier can proceed to market the product [20].

US FDA requires the prior approval of recycled plastic for food contact application via FCN before marketing by the manufacturer. FDA requires the manufacturer to submit the following information on post-consumer recycled resin. If all criteria were met, the FDA would issue a “Letter of No Objection” (LNO).

1. A comprehensive account of the entire recycling procedure, encompassing details on the origin of the PCR plastic as well as a description of any implemented processes used to guarantee that only plastic which originally adhered to relevant regulations is recycled. Additionally, an overview of the measures taken to prevent any contamination of recyclable plastic at any stage, whether prior to collection for recycling or during the actual recycling process [21].

2. The outcomes of any conducted tests aimed at illustrating the efficacy of the recycling procedure in eliminating potential incidental contaminants. When utilizing recycled material as a replacement for plastic produced from virgin sources, it’s critical to demonstrate that there is no possibility of contamination with substances other than food. This can be achieved through rigorous source control on the input material, or to showcase the efficacy of the recycling process in effectively removing contaminants via surrogate testing. If necessary, further migration testing or migration modeling may be carried out to demonstrate that the recycling process effectively eliminates potential incidental contaminants to a level that does not allow each contaminant to exceed 0.5 ppb, a threshold that the FDA deems as negligible exposure when employing recycled plastics for food packaging [21].

3. An explanation outlining the anticipated utilization scenarios for the plastic material. This entails providing details such as the intended usage temperature, the specific type of food that will have contact with the plastic, the duration of this contact, and whether the plastic designed for food contact is intended for single-use or repeated application [21].

4.2 European Union

The European Union (EU) has established comprehensive obligations and legislations that apply to a wide range of food contact materials and substances. All food contact materials fall within the scope of two European legislations: Regulation (EC) 1935/2004 (framework regulation) and Regulation (EC) 2023/2006 on good manufacturing practices. The framework regulation mandates the adoption of specific measures and guidelines for the groups of food contact materials including virgin plastics (Regulation (EC) 10/2011) and recycled plastics (Regulation (EC) No. 2022/1616) [22].

4.2.1 Regulation (EC) No. 1935/2004

This regulation emphasizes that food contact materials must not pose any health risks or cause alterations in the smell, composition, color, or taste of the food. Furthermore, this regulation requires that food contact materials are manufactured in compliance with good manufacturing practice (GMP) as regulated by Regulation (EC) No. 2023/2006. It also specifies labelling and traceability (one step forward and one step back) requirements for food contact materials [9].

4.2.2 Regulation (EC) No. 2023/2006

Regulation 2023/2006 lays down the rules on good manufacturing practice (GMP) that apply to all group’s food contact materials. This regulation is applicable at all stages of the production and distribution process of food contact materials excluding the production of raw materials. This regulation outlines the requirements for quality assurance, quality control systems and documentation practices [23].

4.2.3 Regulation (EC) No. 10/2011

This regulation, also referred to as plastic implementation measures (PIM) is the most comprehensive legislation in the field of food contact materials. This regulation establishes specific requirements to ensure the safety and suitability of plastic materials used in food contact applications. This regulation applies to plastic materials and articles, whether composed exclusively of plastics (plastic monolayers or plastic multilayers) or plastic parts combined with other materials (multi-material multi-layer) [10].

The regulation covers various aspects such as permissible substances, migration limits, and testing methods to assess the compliance of plastic materials with food safety standards. It aims to safeguard consumer health by minimizing the migration of harmful substances from plastic packaging or utensils into food. Adherence to these regulations is essential for manufacturers, importers, and distributors involved in the production and distribution of food contact plastic materials within the EU market [10].

4.2.4 Regulation (EC) No. 2022/1616

This regulation governs the specific measures for recycled plastic materials and articles intended to come into contact with food. This regulation applies to post-consumer plastic waste, which refers to plastic waste generated by consumers rather than being a byproduct of another product’s production [24]. Recycled plastic must originate from an authorized recycling process that follows a Quality Assurance System (QAS) as defined in Regulation (EC) No. 2023/2006 [23]. The QAS is responsible for ensuring that the recycled plastic meets the specific requirements outlined in the authorization [25].

Furthermore, a recycling process must effectively monitor and evaluate both the initial plastic input and the resulting recycled plastic, adhering to predetermined criteria that guarantees compliance with the safety requirements outlined in the Framework Regulation for authorization i.e., plastic input complies with the Regulation (EC) No. 10/2011 for plastic materials and the GMP Regulation (EC) No. 2023/2006. The main principles mirror those captured in the US FDA criteria and include [25]:

• Comprehensive detailing of the procedure.

• Thorough characterization of the initial material.

• Evaluation of the process’s decontamination effectiveness using a surrogate challenge test after washing.

• In depth characterization of the recycled plastic.

• Explanation of the intended application.

• Demonstration of regulatory conformity.

• Identification of key process steps.

• An explanation of quality assurance mechanisms.

It aims to promote the circular economy by encouraging the safe and sustainable use of recycled plastics in food packaging applications.

4.3 Canada/Mexico

Canada has established guidelines for utilizing recycled plastics in food contact application and used the similar criteria outlined by the US FDA. Instead of implementing an official regulation, Canada opts for a case-by-case evaluation of technologies and issues a Letter of No Objection (LNO), similar to the United States [26].

Mexico does not have official regulations for recycled plastic. They have reviewed the concept and have adopted the US FDA guidance on use of recycled plastic in food packaging. In 2016, the National Standardization and Certification Organismo instituted a voluntary standard, NMX-E-263-CNCP, which addresses post-consumer recycled PET for food packaging. This aligns with guidance provided by the US FDA [26].

4.4 South America

In 2002, the Mercosur countries (Argentina, Brazil, Paraguay, Uruguay, and Venezuela) launched a collaborative initiative to comprehensively evaluate available data regarding recycling technologies for utilizing post-consumer plastics in food contact applications. In 2007, the Mercosur countries implemented legislation concerning post-consumer PET materials through resolution GMC 30/07 in 2007. This resolution incorporates a combination of guidelines from both the US FDA and EFSA [26].

The Mercosur resolution incorporates the following essential components:

1. Processed postconsumer PET material must fulfill all regulatory requisites applicable for Virgin PET for food contact.

2. Authorized processes must undergo registration under the respective national governments.

3. Allocation of responsibilities includes:

   • Proposed recycling technologies must successfully complete surrogate challenge testing for validation.

   • Conducting tests to evaluate usage conditions.

   • Plants must be approved by the applicable sanitary authority.

   • Mandating package processors to be registered entities, maintain comprehensive documentation, and possess complete capabilities for package traceability.

   • The food processor is only permitted to utilize authorized material/packages and must be capable of demonstrating complete traceability.

4.5 Central America

Costa Rica: In 2017 Costa Rica implemented decree 40393/2017, which mandated the adaptation of the Costa Rican Standard RTCR 480-2016 for incorporating postconsumer PET in food contact. This standard drew its foundation from the guidelines set forth by the US FDA [26].

4.6 Asia-Pacific

4.6.1 Australia and New Zealand

Australia and New Zealand shares the food standards-setting procedures. The regulatory framework for food contact materials in Australia and New Zealand is comparatively less specific when compared to other jurisdictions like the European Union and the USA. In both countries, the emphasis is placed on the overarching legal obligation to ensure food safety. Currently, the Australian Packaging Covenant have indicated that the food standards code is currently under revision and more details will be included on use of recycled plastic [26].

4.6.2 China

Food contact materials (FCMs) are regulated by the general food safety law (FSL) adopted in 2009. The Chinese food packaging standards are primarily guided by the recently developed GB 4806.1-2016 (referred to as the “framework” standard) along with GMP standard GB 31603-2015. China does not have formalized recycled packaging regulations however, the Chinese government has directed the Chinese National Health and Family Planning Commission to initiate a re-evaluation of the current packaging regulations and other regulations pertaining to food additives [26, 27].

4.6.3 Japan

Japan’s National Institute of Health Sciences conducted a thorough review of scientific literature and the US FDA/EU guidelines, leading to the drafting of a proposed guidance document. Subsequently, on April 27, 2012, the Ministry of Health, Labor, and Welfare authorized the guidance document 0427 NO 2 [26].

4.6.4 India

Regulations regarding plastic, PET and recycled PET usage in India are issued by the Bureau of Indian Standards. The document IS 14534:1998 titled “Guidelines for Recycling of Plastics” indicates the step-by-step procedures for the recovery and recycling of plastic waste. It explains in detail the procedures to follow for the selection, segregation and processing of waste/scrap that are suitable for recycling [28].

5. Cosmetic use of PCR

There is a high uncertainty in the cosmetics market, both among manufacturers and recycling companies, about the use of PCR in cosmetics packaging. According to Regulation (EC) No. 1223/2009 on cosmetic products, manufacturers should only put on the market safe products. However, there are no guidelines on safety assessment of recycled material and conditions for which they may be used.

The major challenge for the recycling of plastic waste into new cosmetic packaging applications is that post-consumer substances or degradation products from the polymer or from polymer additives substances could migrate into the cosmetic product and result in adverse effects upon consumer use. The use of post-consumer recyclates in cosmetic packaging should not raise safety concerns for the consumer. Therefore, use of recycled plastic in cosmetic packaging requires assessment of potential contaminants and ensuring that levels would not pose a risk to consumer’s health [11].

Two recent studies have evaluated the use of recycled polyolefins (including HDPE) in cosmetic applications [11, 19]. The first step in the assessment was to identify substances found in the rHDPE and perform a quantitative risk assessment. The type of substances identified includes chemicals from the polymer, which were also found in the reference packaging made from virgin HDPE or chemicals from previous fillings or from cross-contamination during recollection or recycling. There were also unidentified or unknown chemicals found in rHDPE.

An exposure-based risk assessment was then performed to determine whether use of the rHDPE in cosmetic packaging would result in potentially any adverse systemic toxicity. For the identified substances a specific toxicological evaluation was done on each of the substances and determining the dose that is likely to be without any appreciable risk of deleterious effect during a lifetime and compared to the consumer exposure from daily use of cosmetic product (a rinse-off or a leave-on application). For the non-identified substances, a specific toxicological evaluation is not possible, and evaluation should be done using the principle of Threshold of Toxicological Concern Concept (TTC) [29]. The TTC is a pragmatic risk approach which is based establishing a threshold for human exposure below which there is an extremely low probability of any appreciable risk to human health from any chemical. A worst-case assumption was used that the unknown substance should be evaluated as a potentially genotoxic substance with a the relevant TTC value is 0.0025 μg/kg bw per day [29].

In both studies an exposure scenario was then carried out for rinse off products (e.g., shampoo) as well as leave on applications (e.g., body lotion). For rinse off products, it was assumed that 99% of the applied product is washed off and only 1% remaining has potential to be absorbed and become systemically available. For leave on products, one study used an adult body lotion [11] while other did an assessment for a baby lotion [19] where in both cases, it assumed that the cosmetic product remains on the skin and the resorption into the body will be assumed as 100%. Based on both assessments, it was demonstrated that rHDPE may be reusable as packaging for rinse off cosmetic products, but using genotoxicity TTC for unidentified substances, the rHDPE was not supported for use in leave on body lotions (including adult and baby).

In a more recent study [4] a safety assessment was conducted on rHDPE that was approved for food packaging to evaluate its use in cosmetic packaging using the guidelines published by EFSA on the use of recycled plastics. The highest concentration (Cmod) of representative chemical contaminants, that would not exceed the genotoxic TTC, when migrating from rHDPE packaging into the cosmetic formulation was predicted using a mathematical modeling software (MIGRATEST®EXP). A comparison was then made between the Cmod values of representative chemical contaminants to the EFSA-reported residual concentration (Cres) of each contaminant in the rHDPE. It was demonstrated that for each of the cosmetic product/packaging combinations evaluated, the modeled values were clearly lower for Cmod than Cres. This illustrates that the recycling process could effectively reduce potential contaminants of rHDPE to levels that would not pose systemic toxicity to consumers. In addition to systemic toxicity, the authors also investigated skin sensitization, where they assumed a worst-case scenario that 100% of each representative chemical contaminant migrates into the cosmetic formulation from rHDPE. The consumer exposure level for each contaminant was then calculated based on the dose per unit area. This was then compared with a value of 64 μg/cm² which is the acknowledged dermal sensitization threshold (DST) for reactive materials. In each case, it was demonstrated that there was no appreciable risk of skin sensitization as the migration of each representative chemical contaminant from rHDPE into each cosmetic formulation was significantly less than the DST. It was concluded that the rHDPE can be safely used in all cosmetic products (leave-on and rinse-off applications). This exposure-based approach can be used to assess additional polyethylene plastics to determine if they can be safely used for personal care products.

6. Conclusion

In recent years sustainability has become a key trend, with awareness on recycling everyday products and minimizing energy consumption becoming the norm in the average consumer’s household. The use of post-consumer recycled (PCR) plastic is important for both sustainability and the circular economy. By using PCR plastic, companies can reduce their reliance on virgin plastic production, which conserves natural resources, reduces greenhouse gas emissions, and promotes resource efficiency. The greatest challenge to using polyethylene plastic is the potential chemical migration of contaminants from the plastic packaging into the package contents. In the food industry there are regulatory requirements to ensure safety of use of recycled polyethylene in the intended food application. In addition to food, the cosmetic industry has a very heavy impact on packaging [30]. Cosmetic companies are setting ambitious sustainability goals which includes use of recycled PCR plastic [31] adding the need for regulatory requirements or industry guidance to ensure the safety of use of PCR in cosmetic products.