2 JOURNAL OF COSMETIC SCIENCE
The need for green chemistry has been recognized as a fundamental part of cosmetic
sciences since the inception of the field.15 The International Fragrance Association has
recently adopted a “Green Chemistry Compass” to help.16 Because Green Chemistry has
been around since the early 1990s, we will not attempt to summarize its history and
fundamentals here. Instead, this manuscript will use various advances in cosmetics sciences
to illustrate each of the 12 Principles of Green Chemistry.
It is important to point out at the outset that no individual principle of green chemistry
should be considered in isolation. Dividing aspects of sustainability into 12 Principles
allows us to consider different types of molecular mechanisms at a level that is actionable.
Of course, a final product must combine each of these concepts in totality, but there is still
much work to be done. We have not yet invented most of the necessary new mechanisms. It
will take decades to make significant headway, and hopefully the examples illustrated here
will help give some direction and inspiration to future inventors to move the field forward.
It is well understood that many examples demonstrate more than one principle of Green
Chemistry, the choice of which principle to focus on is mostly for clarity.
Principle 1: It is better to prevent waste than to treat or clean up waste after it is formed.
Thie first principle acknowledges the US Pollution Prevention Act of 1990.17 This legislation
underscored the importance of source reduction as a fundamental part of pollution
prevention. Banjamin Franklin’s adage “an ounce of prevention is worth a pound of cure”
resonates as common sense.18 Illustrative of this principle is the issue of microplastics in
cosmetic formulations. There has been a great deal of information describing the hazards to
humans and the environment because of intentionally added microplastic beads.19 Efforts
to identify mineral and plant product alternatives are numerous.20 Specific examples using
chitosan21 and silk22 are promising.
Principle 2: Synthetic methods should be designed to maximize the incorporation of all
materials used in the process into the final product.
Atom Economy23 and its related concept environmental impact factor24 focus on
distinguishing between the yield of the product in a manufacturing process versus the
reactants that do not end up in the product. These are materials necessary to the reaction. For
example, in the reaction A plus B forms C and D, if one assumes compound C is the desired
product, D is a necessary coproduct. Even if one accomplishes the quantitative conversion of
the desired material C, by molecular definition, we MUST also form an equivalent amount
of the unnecessary coproduct D. An illustrative example of atom economy is the synthesis
of some biobased surfactants.25 Stubbs, Yousaf, and Khan describe the atom economy seen
in the synthesis of alkyl polyglucosides26 and sucrose esters27 surfactants.
Principle 3: Whenever practicable, synthetic methodologies should be designed to use and
generate substances that possess little or no toxicity to human health and the environment.
Principles 3 and 4 are closely related concepts. The third principle focuses on hazard during
the manufacturing forces and the fourth principle focuses on the toxicity of the product
itself. A good example of this principle is the use of ethylene oxide in the manufacture
of polyglycol ethers.28 Glycidyl methyl ether has been proposed as a safer alternative to
ethylene oxide for designing ethoxy free surfactants.29 Another route to avoid ethylene
oxide is to synthesize linear polyglycerols.30
Principle 4: Chemical products should be designed to preserve efficacy of the function
while reducing toxicity.

3 The 12 Principles of Green Chemistry
As mentioned above, this principle focuses on the health and environmental concerns of the
product itself. There are numerous examples available to mention. For illustration, sulfate-
based surfactants such as sodium lauryl sulfate and sodium laureth sulfate are typically
produced from petroleum and plant-derived palm oil. Advocates of sulfate-free formulation
typically cite dermal irritation31 and ecosystem damage (drinking water quality and
acidification of surface water and soil32). There are many biosurfactants alternatives from
microbial or plant origin that propose to be less toxic.33
Principle 5: The use of auxiliary substances (solvents, separation agents, etc.) should be
made unnecessary whenever possible and, when used, innocuous.
During the manufacture of cosmetic components, especially during extraction and chemical
synthesis, solvents are often the largest contributor to waste by both volume and waste. While
solid grinding techniques can trace their origin to antiquity, the field of mechanochemistry
has been vitalized recently as a new understanding at the molecular mechanistic level
has emerged. Mechanochemistry seeks to perform processes that typically use solvents
in the solid-state, using grinding and mixing equipment. Significant successes have been
accomplished in cosmetics.34 Essential oils have been extracted via mechanochemical
techniques from Citrus aurantium L. var. amara Engl.35 Another interesting example is
illustrated by the mechanochemical treatment of zinc oxide with phosphoric acid to make
white pigments.36
Principle 6: Energy requirements should be recognized for their environmental and
economic impacts, and should be minimized. Synthetic methods should be conducted at
ambient temperature and pressure.
The use of energy in manufacturing cosmetics is extensive. Heating and cooling chemical
reactions and evaporating water and other solvents are just a few examples where significant
energy is required to carry out processes.37 An extremely useful example of reducing this
energy use has been well documented for cosmetic emulsions.38 In this example, the carbon
footprint of several alternative oil and water emulsion processes were evaluated. The authors
demonstrated that both O/W and W/O (oil in water, water in oil, respectively) systems could be
created under colder conditions with reformulation work. Energy savings can also be achieved
by designing surface modified particles that offer better stability under various conditions.39
Examples exist for proteins (collagen, elastic, silk, and keratin) and Polysaccharides (chitosan,
hyaluronic acid, alginate, xanthan gum, and carrageenan) materials.
Principle 7: A raw material or feedstock should be renewable rather than depleting
whenever technically and economically practical.
This principle is often misunderstood to focus solely on biobased polymers, it is important
to point out that materials that are recyclable or fit within a circular economic model also
fit here. There are, however, many examples of biobased alternative materials for cosmetic
applications.40 As a specific example, various biopolymers have been used for hydrogels.41
Another important aspect has been the use of biopolymers from waste biomass.42
Principle 8: Unnecessary derivatization (blocking group, protection/deprotection, temporary
modification of physical/chemical processes) should be avoided whenever possible.
There are several aspects of this principle. One focus is avoiding the use of protecting
groups in organic synthesis. Another important aspect is what is called noncovalent
derivatization where the properties of an active molecule are controlled through specific
noncovalent interactions.43 While this technology has many examples in pharmaceuticals,44