Greener Solutions Case Study: Reducing/Eliminating PFAS Hazards from Moisture

Barriers in Product Packaging

What was the Challenge:

For this project, the Household Products Packaging (HPP) Team worked with the household

product manufacturer Method to design a safer alternative to using PFASs (Per- and Poly-

fluoroalkyl Substances) as moisture and grease barriers for a selection of the company’s product

packaging line. The objective of the project was to research and analyze alternatives to the

PFASs currently used as moisture barriers applied on paper packages. The team was also

charged to prioritize the use of environmentally sustainable resources and disposal methods for

the new product. Aligning their search with company needs, the team chose the three most

common Method products packaging types for: laundry powder (an example of dry powders),

laundry detergent (an example of high concentrated liquid solvent), and dish soap refill (an

example of high water content solutions) for their investigation.

The three success criteria for a moisture barrier material or treatment were as follows:

1. Improved moisture barrier (low water vapor permeability, and high contact angle).

2. Low environmental hazard (renewably sourced, biodegradable, low aquatic toxicity,

low persistence).

3. Reduced health impacts (non-irritating, non-carcinogenic or mutagenic, low

reproductive /developmental toxicity, no endocrine disruption).

A viable alternative would not need to match the same physical performance capabilities as the

current industry standards, but instead would simply need to function as a barrier through the

product’s expected shelf life. The solutions were evaluated by directly comparing the original

bad actors with the new alternatives in both technical and chemical hazard assessments;

summarized in the tables that follow. The three strategies were designed to build off one another,

starting with a biopolymer base and later blending physical and chemical additives to further

improve the barrier strength as needed.

This study drew a direct correlation between each strategy and its preferred product packaging.

This literature-exclusive study was limited in its capacity, however, and future teams would need

to test a combination of biopolymers and additives incorporated within films to develop a

package suitable for a diverse array of dry powders and high water content packaging solutions.

The HPP team devised a three prong strategy, developing product packaging structured

biopolymer bases which were modified by the infusion of chemical or physical additives to the

film.

The team categorized Method products by dilution and water content, which directly indicated

each product’s moisture barrier requirement, as shown in Figure 1.The categories of packages

were decided with the assistance of Kaj Johnson, Senior Director of Research and Development

at Method, who aided the team in dividing the Method products into three unique types of

formulations, as shown in Figure 1. The formulation with the lowest moisture barrier threshold

was dry powders, such as laundry detergent or other solid formulations. While these solid

powders are unlikely to leak out of a package in the same manner as a liquid formulation, they

still draw in moisture and cake- both ruining the product before its use as well as deteriorating

the packaging by making the film brittle. Following the category of dry powders was one

containing laundry detergents and other concentrated liquids. Here the primary objective for the

mid-class of formulated products was to keep liquids contained, requiring a medium level of

moisture barrier strength. The final product contained high water content soaps and other dilute

liquids. In this case, films should, once again, keep liquid contained and ideally not dissolve in

solution. Although each of the three strategies compiled by the HPP Team applies best to their

own specific product, the film protecting the highest liquid content would be suitable to all lower

moisture barrier threshold products.

Figure 1: Moisture Barrier Requirements for Three Product Types

Why this Project was Important:

The purpose of this exploration into alternative packaging sources was to reduce PFASs in

popular consumer products and the amount of single use plastic disposed of in the environment.

Containers and packaging remain the largest sources of plastic waste, prompting many

environmental activist groups to search for alternatives. Paper- cellulose-based packaging- has

been proposed for replacing petroleum-based plastic packaging.1 This paper packing has many

advantages: it requires minimal energy to recycle, maintains structural integrity, is low cost, and

is biodegradable. Paper’s fibrous and hydrophilic nature, however, makes it unable to

adequately address moisture barrier needs, especially in formulated solution product packaging.

The packaging industry, therefore, relies heavily on polyolefins -such as polyethylene and

polypropylene- along with per- and polyfluoroalkyl substances (PFASs) as treatments to paper

for strengthened moisture barriers.

Despite their high efficiency, both polyolefins and PFAS present environmental and health

concerns, including aquatic toxicity, carcinogenicity, mutagenicity, eye and respiratory irritation,

and environmental persistence. Polyolefins, although recyclable on their own, once added to a

separate packaging material, will render the entire packaging system non-biodegradable, non-

recyclable, and ultimately persistent in the environment. Many PFASs have been shown to be

toxic, carcinogenic, and environmentally persistent.2,3,4,5 The extreme health and environmental

risks outweigh the advantages of the material’s moisture barrier function. Safer and more

sustainable alternatives with comparable technical performance are needed.

Who was involved:

Course instructors for the UC Berkeley Public Health graduate course, Greener Solutions, (Dr.

Megan Schwarzman, Mr. Thomas McKeag, Dr. William Hart-Cooper, and Ms. Kimberly

Hazard), supported by the Berkeley Center for Green Chemistry as well as Kaj Johnson of

Method Products challenged the HPP team to find a safer alternative to PFAS packaging. The

HPP team comprised: Constancia Dominguez, Amanda Guan, Grayson Hamaker-Teals, and

Josue Ruiz. Constancia Dominguez was a first year M.S. student in Environmental Health

Science program with a concentration in Industrial Hygiene at UC Berkeley. Grayson Hamaker-

Teals studied Chemical Biology as a third year undergraduate student at UC Berkeley,

specializing in green chemistry and green education. Josue David Ruiz researched the

relationship between gentrification and cardiovascular disease in California; he studied as a

second year M.P.H. student in the Epidemiology & Biostatistics program at the UC Berkeley

School of Public Health. Amanda Guan, a fourth year undergraduate student majoring in

Materials Science and Engineering and minoring in Public Policy, emphasized her research on

polymer-induced nanocrystal crystallization mechanisms.

What was the Solution:

Alternative Recommendation 1: Biopolymer-based films

The team’s primary strategy was the use of biopolymer films due to the biodegradability and

inherent lack of dangerous derivatives. The team focused on biopolymers safe for human

consumption, such as: chitin (deacetylated to chitosan, derived from mushrooms or shellfish) and

pectin which functions as a food-grade gelling agent. Biopolymers presented the opportunity for

combining with other biopolymers, and, through additional additives, designing and producing

strengthened moisture barriers. This sets biopolymers as an attractive alternative to polyolefins

because of their ability to be cross-linked via chemical additives (alternative 2) and the

reinforcement of their barrier properties through physical additives (alternative 3). In this

research project, the team analyzed the technical performance and hazard assessment of three

biopolymers: chitin, pectin, and gelatin; these three candidates were chosen for their recyclability

and reusability, creating a more circular economic process where all non-film derivatives can be

recovered and repurposed. Combining the biopolymers created a foundation of sustainable film,

and created opportunities to further enhance the mechanical and barrier property discussed by the

HPP team in alternative recommendations 2 and 3.

The HPP Team divided their biopolymers into three potential alternative candidates:

chitin/chitosan, pectin, and gelatin, then measured their potential success by contrasting their

technical properties to the standard “bad actor” PFAS, polyethylene, and polypropylene as

retained from a variety of scientific databases. Among the alternatives presented, the team first

assessed chitosan, the deacetylated form of chitin. Chitosan has a Water Vapor Permeability

(WVP) several orders of magnitude higher than those of the leading industry coatings, and a

comparable high efficiency water contact angle.6,7 For the mechanical properties, chitosan

performed with a slightly lower tensile strength and elasticity.8,9 Pectin, the next biopolymer

alternative evaluated, demonstrated a WVP several orders of magnitude higher than the

industrial bad actors, similar to chitosan in its low efficiency.10 The final alternative, gelatin,

lacked specific quantitative data for its moisture barrier properties, but demonstrated at a

relatively high efficiency for tensile strength, exceeding even the current industry solutions;

conversely, gelatin has very poor elasticity compared to the bad actors, which may prove

troubling in product packaging.11 These summarized results can be found, along with more

specific quantitative data, within Table 1. In summary, the biopolymer alternatives

recommended maintained inferior barrier and mechanical properties to PFAS and polyolefins,

indicating a need for additives to improve their performance.

Table 1: Performance criteria for Bad Actors & Biopolymers1

1 References for Tables are in the final report, available at: https://bcgc.berkeley.edu/greener-solutions-2020/

PFASs are widely used throughout many industries, chosen for their highly effective water and

oil repellency. The HPP team chose one of the more common PFAS compounds, PFOA

(Perfluorooctanoic Acid), as well as the polyolefins, polyethylene and polypropylene, for the

baseline chemicals to evaluate each alternative’s health and technical performance (Table 2).

PFOA has been shown to have a multitude of health concerns due to its high resistance to

environmental degradation, high incidence of bioaccumulation, long-term toxic effects in aquatic

organisms and potential cancerous links for both humans and laboratory animals.11,12,13,14

Polyethylene and polypropylene, have excellent sealing properties for paper, and are the most

common form of synthetic polymers used for film coatings.15 Blending polyolefin with other

substances, however, causes the material to lose its biodegradability and value for composting

due to its high levels of persistence.

Due to its biodegradability, lack of carcinogenicity, and more environmentally sustainable

nature, chitosan (the processed or de-acetylated form of chitin) makes a more green alternative

than PFAS, polyethylene, and polyproplylene.16,17 The Global Harmonized System of

Classification and Labeling of Chemicals (GHS) has classified chitosan as potentially hazardous

to aquatic environments due to toxicity studies in which oxygen interference and physiological

disorders in various aquatic animals were noted.18,19 Chitosan’s potential hazards increase when

in the powdered form, and can be mitigated during the manufacturing process if excess chitosan

is not discarded into any bodies of water; rather, any waste should be immediately transferred to

a separate designated container for approved waste disposal.

Pectin was the next alternative investigated; a natural polysaccharide recycled from an existing

industrial waste product, citrus peels and apple pomace: pectin is biodegradable and thus does

not persist in the environment. Studies from the European Food Safety Authority (EFSA) Panel

on Food Additives and Nutrient Sources reveal that the biopolymer pectin has no chronic toxicity

effects.20 The group chose the widely studied biopolymer gelatin as their final alternative.

Gelatin is likewise derived from organic material, it was not found to persist in the environment

nor bioaccumulate, and thus gelatin received a low concern to human health classification on a

variety of authoritative lists.21 The HPP team summarized the hazard assessment comparison

between the current industry substances and the recommended alternative biopolymers in Table

2. All three alternatives showed a dramatic reduction in health effects in comparison to the

current industry standards for polyolefins and PFAS while maintaining readily available sourcing

and simple biodegradability.

Table 2: Hazard Assessment for Bad Actors & Biopolymers

Biopolymers, while safer for human and environmental health, performed less well technically

than the baseline substances. Although the alternative biopolymer films pose minimal overall

hazards, these films lack the barrier and mechanical properties necessary to form a sufficient film

for more dilute products, such as the high water concentration or low water concentration soaps.

These films would still be suitable to prevent drawing in moisture for products like laundry

powders packaging, which would require a less demanding moisture barrier. The team

determined that the first strategy of incorporating biopolymer films would remain on the lower

end of the moisture barrier technical performance spectrum; best suited for non-moisture based

products.

Alternative Recommendation 2: The Addition of chemical cross-linking reagents

The team proposed using dry hydrogel (e.g. a packaging film) along with additional chemical

cross-linking reagents to strengthen the moisture barrier of the product packaging. The covalent

bonding of different biopolymer structures with the chemical cross-linking reagents strengthened

the dry hydrogels and created a polyion-complex due to the reagents’ charged interactions.22 The

team’s final structure of cross-linked polymers resulted in a stabilized network structure able to

prevent a significant degree of moisture from entering or leaving its barrier. Different

combinations of formulated biopolymers, as discovered in alternative 1, achieve limited

mechanical and/or barrier properties; therefore, to enhance the properties of the film,

crosslinking chemical reagents are typically added. The team assessed the following performance

measurements to quantify the stability of the moisture barriers: water vapor permeability (WVP),

water contact angle, tensile strength, and total elongation at break. Glutaraldehyde is considered

one of the more effective protein cross-linking reagents used in current industrial film

formulations; therefore the HPP team selected it for their industrial standard for assessing the

alternative chemical cross-linking reagents’ technical performances.

The first cross-linking alternative, genipin, was chosen for its success in the medical industry as

a tissue fixative, and according to more recent studies, for its application to moisture barrier

films. A 2011 study by Farris et al. investigated gelatin-pectin film properties and measured the

film’s performance when crosslinked with genipin.23 The film showed a significant decrease in

lower water sensibility when cross-linked with genipin.23 A different study investigating a

potential chitosan/polyethylene oxide film, revealed an increase in tensile strength and

elongation after adding genipin to the biopolymer films.24 Research has been limited for Genipin

as a crosslinking reagent; the overall consensus of the studies summarizes that genipin

outperforms the other biopolymers in moisture barrier mechanical metrics. Ferulic acid was

chosen as the second crosslinking reagent as it is naturally derived and has an ability to cross-

link in gelatin-based. According to a 2007, study by Cao et al., no recognizable WVP effects

were noted after the addition of a gelatin film, along with a marginal increase in tensile strength;

thus the packaging team suggested that this crosslinking pair would not be comparable in

performance to the current industrial solutions.25 In general, when ferulic acid was crosslinked

with chitosan there was a significantly lowered efficiency for barrier and mechanical properties

when compared to the current bad actors; such as a decrease in WVP as well as about a 2%

decrease in total elongation at break.26 A significant data gap for pectin crosslinked with ferulic

acid meant that no conclusive assessment could be reached. Table 3 offers specific comparisons

between the bad actor and its two alternatives.

Table 3: Performance Criteria for Crosslinking Reagents

The HPP team established glutaraldehyde as their current industry baseline for the health and

environmental performance to properly compare their alternative chemical cross-linking reagents

demonstrated in Table 4. Multiple studies have identified glutaraldehyde as a neurotoxicant in

humans, as well as a chronic toxicant for aquatic organisms.22,27 The first alternative, genipin, is

a biopolymer naturally derived from the extraction of gardenia fruit. A 2004 study by Jin et al.

directly compared the cross-linking capabilities of genipin and glutaraldehyde for chitosan based

films, and concluded that genipin was approximately 10,000 times less cytotoxic than

glutaraldehyde.24 There is a general data gap for bioaccumulation, carcinogenicity/mutagenicity,

as well as its potential as an endocrine disruptor, however from the information available,

genipin proved to be significantly less hazardous than the current industrial model. A 2007 study

by Cao et al. had investigated plant phenolics, specifically ferulic acid, as natural cross-linking

reagent for gelatin gels.25 In the case of ferulic acid, the HPP team discovered no adverse effects

from toxicity studies performed on aquatic organisms or humans reported by authoritative

agencies, as well as low environmental and biological persistence, due to its biodegradabilitty.28

As a natural cross-linking alternative, ferulic acid was found to be less environmentally

persistent and, according to a multitude of governing agencies, ferulic acid had a minimal hazard

potential for: endocrine disruption, aquatic and developmental toxicity, and carcinogenicity /

mutagenicity. Overall, the HPP team decided that given the data available, both of the

alternatives demonstrated a lower environmental persistence and overall toxicity compared to the

industrial standard of glutaraldehyde.

Table 4: Hazard Assessment for Crosslinking Reagents

Before final assessments of the capabilities of ferulic acid and genipin as crosslinking reagent

alternatives for glutaraldehyde, the remaining data gaps for a few critical health hazard endpoints

and technical performances needed to be filled. The HPP team concluded that the presented

alternatives are indeed safer than glutaraldehyde. Genipin scored higher efficiency compared to

ferulic acid, but both of the alternatives performed less efficiently than glutaraldehyde, with the

lowest performing reagent being ferulic acid. The team proposed a combination of the first two

alternative recommendations by incorporating a biopolymer base as well as a chemical cross-

linking reagent to create a strengthened moisture barrier. Due to its enhanced ability for securing

concentrated liquid products, the team ranked this second alternative recommendation higher on

the moisture barrier spectrum for packaging capabilities.

Alternative Recommendation 3: Adding physical additives to biopolymer based films

The final alternative recommendation focused on the incorporation of nanofillers (both natural

clays and fibers) into a biopolymer matrix to form nanocomposites; this enhanced

nanocomposite matrix was found to strengthen water barrier properties and maintain its

environmental degradability.29 Figure 2 demonstrates that individual blends of silicate layers

with polymers create unique film properties; the exfoliated nanocomposite form films were

reported with the highest improvement in the barrier properties, as they maximize the contact

between the layered silicate and the polymers.30 The team researched the feasibility of the fiber

nanofiller Cellulose Nanocrystals (CNC). CNC is primarily sourced from biomaterial and has

many desirable biopolymer properties: nanoscale dimensions, unique morphology, high surface

area, low density, biodegradability, renewability, and high mechanical strength.31 The conversion

of cellulose fibers into nanocrystals through acid hydrolysis results in the formation of whiskers

with a large aspect ratio, mainly due to their nanoscale dimensions.31 Cellulose nanocrystals are

processed with acid treatment, to remove the para-crystalline domains regularly distributed along

the microfibers, then physically added into various polymer matrices to form polymer

nanocomposites.32

Figure 2: Scheme of Three Types of Composite Structures

Montmorillonite, a natural clay, was chosen as a more sustainable packaging alternative for its

extensive positive qualities, such as its ability to strengthen biopolymer films and reinforce

material in a: naturally abundant, nontoxic, inexpensive, chemically and thermally stable

manner.33 Table 5 shows a general trend of positive efficiency across the board for all

performance metrics, aside from total elongation at break, obtained from the literature relating to

montmorillonite infused biopolymer (pectin, gelatin, chitosan) films.34,35,36 Similarly, micro- and

nanofibrillated cellulose (NFC/MFC) or cellulose nanocrystals (CNC) provided high efficiency

for WVP and tensile strength.30,31 Biopolymer films combined with montmorillonite resulted in

similar improvements in barrier and mechanical properties to that of the cellulose nanocrystals

infused biopolymer films.

Table 5: Performance Criteria for Nanofillers

While not as harmful as the current industrial films, the physical additives montmorillonite and

cellulose nanocrystals each demonstrated potential human and environmental concerns, as shown

in Table 6. When the team assessed the overall health impacts of the additives, they considered

which states of matter the chemicals would be utilized in as well as which demographics of

people will be most impacted by the hazard. The Association of Occupational and Environmental

Clinics (AOEC) found that cellulose nanocrystals pose a high respiratory sensitization hazard in

its powdered form, and for factory workers handling large amounts of cellulose nanocrystals,

facial protections would be a necessity to protect their lungs and respiratory systems.37,38 In

general, the HPP team found montmorillonite to be of low overall hazard, the Comparative

Toxicogenomics Database even cited montmorillonite as a possible therapeutic drug used in

medicine to assist in alleviating chemical and drug induced liver injuries.39,40 Cellulose

nanocrystals showed less of a health and environmental concern in comparison to the physical

additive montmorillonite, as CNC did not bioaccumulate nor persist.38 Overall, both

montmorillonite and cellulose nanocrystals both showed a decrease in hazard level compared to

the current industrial films, but comparatively, cellulose nanocrystals were seen to be safer for

the environment and consumers than montmorillonite.

Table 6: Health Assessment for Nanofillers

Nanotechnology integrated composites with biopolymer films to enhance water vapor and gas

permeability properties while preserving the biodegradability of the film. Both the physical

additives montmorillonite and cellulose nanocrystals were found to improve the barrier

properties of biopolymer films, specifically by reducing water permeability for high

concentration and diluted liquid packaging. The third and final alternative recommendation from

the team ranked highest on the moisture barrier spectrum, suggesting its priority packaging for

high water concentrated liquid solutions. For overall feasibility, the HPP team decided that

additional experimental research would be required to identify the potential moisture barrier of a

combination of natural clays and cross-linking reagents in biopolymer based films. While neither

individual additive matched up to the industrial standard, an alternative blending of clays and

crosslinking reagents could meet the industry standard performance criteria.

Figure 3: Chart of the Final Moisture Barrier Requirements Paired with their Product Types

What was Innovative about the Solution:

The widespread use of PFASs as the default moisture barrier has perhaps led to a slowing of

innovation across consumer product industries, carpets, product and food packaging among

them. In many applications select PFASs over perform as moisture barriers and risk the health of

workers, consumers, and the environment. The “one size fits all'' application of these substances

could be replaced with more selective formulations tuned to the specific technical requirements

of different types of packages, dry powders, highly concentrated liquids, and high water content

liquids.

This team presented a set of possible safer solutions to these three different types of packages, as

well as an approach to product packaging formulation that sector companies could use. This

approach gave equal weight to comparing EHS and technical performance, identified the

technical shortcomings of safer alternatives (biopolymers), and then mitigated the shortcomings

with a range of tactics, both chemical and physical. Finally, the team aligned the capabilities of

each material set with the appropriate technical job at hand for each of the product types by

building on the formulation enhancement as the technical demand increased. This approach

emulates a couple of strategies found in nature, namely the use of composites through a linear

hierarchy of scale, and designing to the adequate, rather than the optimum. In employing a

systems approach to problem solving the team also made recommendations for broader

interventions in the packaging sector, such as eliminating the liquid in many products and

shipping only the active ingredients to be diluted at the point of use.

What was the Impact:

Household product packaging comprises a wide range of types and materials, the three types of

fiber-based packaging studied here represent just a portion of the U.S. and world market for this

type of packaging which includes corrugated cardboard boxes as well as display materials and

containers for household goods. The total fiber based packaging market in the U.S. is estimated

at US$82.6 Billion in the year 2020. China, the world's second largest economy, is forecast to

reach a projected market size of US$71.8 Billion by the year 2027 trailing a CAGR of 4.6% over

the analysis period 2020 to 2027.2 The replacement of plastic packaging with natural and

renewable fibers, while a step toward the reduction of petroleum-based products, has been

complicated by the need for oleo and hydrophobicity in the typically absorbent fiber material.

This, in turn, has led to the widespread use of polyolefins, such as polyethylene and

polypropylene, along with per- and poly-fluoroalkyl substances (PFASs). While the fiber

feedstock may be more renewable, the film protections do not make them any more recyclable.

The Investigation of safer moisture barriers in this study could lead to the development of better

films to keep moisture and liquids in or out of these product packages as well as a change in how

companies like Method develop their formulations within this huge and growing market.

2 Source: Global Fiber Based Packaging Industry, 2021: https://www.reportlinker.com/p05960924/Global-Fiber-based-Packaging-Industry.html?utm_source=GNW

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