332 JOURNAL OF COSMETIC SCIENCE
removal of carbolic acid in response to warnings from health authorities.4 The innovation
and foresight of companies in the personal care industry played an instrumental role in
making hygiene accessible and appealing to the public.
The 20th century witnessed the continuation of this hygiene revolution, with companies
like Monsavon educating consumers on the importance of healthy skin as part of overall
well-being. Post-World War II economic reconstruction further advanced hygiene standards.
By the 1970s, modern amenities like indoor plumbing and private bathrooms became
widespread, transforming personal hygiene from a luxury into an essential component of
daily life.5
Sophistication in product development and marketing shifted public opinion, presenting
hygiene not just as a medical necessity but as a pleasurable, socio-economic marker. The
introduction of scientific authority into advertising—such as white-coated experts delivering
messages in the 1970s—reinforced this transformation, embedding hygiene practices into
everyday life and linking them to broader themes of sustainability and health.
In essence, the historical evolution of personal care products reflects the intersection of
public health, cultural norms, and individual practices. The journey toward sustainability
at the personal level highlights how innovative solutions and strategic messaging can
influence behavior and improve well-being across society, and it is a contemporary rather
than a purely historical venture.
HEALTHY AND SUSTAINABLE SKIN
The Aging Skin Barrier. In the ever-evolving landscape of skin biomechanics research, the
study of the aging skin barrier stands as a testament to the intricate interplay between time,
morphology, and physiology. As the population’s lifespan extends, the cosmetic industry
is presented with unique challenges and opportunities to innovate. In their review of the
aging skin barrier, Dr. Wickett and Dr. Tate shed light on the subtle yet significant ways
in which the aging process reshapes the stratum corneum’s structure and barrier function.
From the microscopic changes in the stratum granulosum that give rise to a corneocyte
structure comprising keratin microfibrils and release natural moisturizing factors, to
forms and function of the interstitial lipid layers, to surprising observations such as the
increase in corneocyte dimensions and the reduction in skin permeation and the decrease
of susceptibility to irritants as a person ages and progresses through the endocrine-induced
stages of life. They conclude with a detailed and fascinating discussion on the many efforts
to understand the yet-unsolved puzzle of why the elderly have “dry” skin.
Two articles discuss the topic of Sensitive Skin. Dr. Misery describes the clinical aspects of
this condition and considers the need to use “sensitive skin panels” to substantiate cosmetic
claims. Dr. Farage reveals that this condition can affect up to 70 percent of women and can
trigger other maladies.
The Definition and Clinical Study of Sensitive Skin. On the theme of sensitive skin, Dr. Misery
reports that sensitive skin is a complex and often misunderstood condition, characterized by
discomforting sensations such as stinging, burning, pain, itching, and tingling in response
to stimuli that would typically not provoke such reactions. Unlike other skin disorders,
these sensations cannot be linked to visible lesions or obvious skin diseases. The skin may
appear normal or show erythema (redness), making it difficult to diagnose based solely on

333 THE STATE OF SUSTAINABLE PRACTICES
appearance. As a result, sensitive skin is typically identified through questionnaires or self-
reports, with additional tests, like the stinging or capsaicin tests, sometimes used, though
they have limitations.
Sensitive skin is increasingly recognized as a multifactorial and neuropathic primary
disorder with a wide range of potential causes, rather than a secondary symptom of
other skin conditions, like atopic dermatitis. While a variety of environmental, physical,
chemical, and psychological factors have been identified as potential triggers, cosmetics
are the most significant contributor, far outweighing other factors such as temperature
fluctuations, pollution, or emotional stress. Despite this, sensitive skin is not considered
an immunological disorder rather, it is linked to disruptions in the skin’s nervous system,
with skin barrier abnormalities often present, though not directly related.
Recent studies suggest that sensitive skin may be a neuropathic disorder, further
highlighting the role of the nervous system in its pathophysiology. This has led to calls
for more sophisticated research models, such as co-cultures of skin and sensory neurons,
to better understand the underlying mechanisms. However, clinical evaluations remain
crucial, as one of the major challenges in studying and diagnosing sensitive skin is the
absence of objective, standardized tests to aid in the diagnosis of this condition. Most
evaluations rely on self-reported questionnaires, which assess the presence of sensory
symptoms without confirming their underlying cause. This makes it difficult to
distinguish between normal skin and sensitive skin, as there is no clear-cut boundary.
Some researchers propose setting cut-off points to help define sensitive skin, but these are
necessarily arbitrary, given the spectrum of sensations that can range from mildly sensitive
to highly reactive skin.
To substantiate cosmetic claims, sensitive skin panels are often used to assess whether
cosmetic products exacerbate or improve symptoms. However, the reliability of these panels
is frequently called into question, as many are inadequately defined. A well-constructed
sensitive skin panel must meet two critical criteria: 1) there must be no skin disease
present, and 2) the positive criteria for sensitive skin must be clearly outlined. Without
these foundations, it’s impossible to separate true cases of sensitive skin from other skin
conditions.
Despite the challenges, there is growing evidence supporting the idea that sensitive skin
is a distinct and significant dermatological issue, and research is progressing in ways that
may offer new insights. Future research will need to focus on refining diagnostic criteria
and developing better testing methodologies. Only then can the mechanisms at play be
understood to allow treatments, including cosmetic products, to be properly tailored to
alleviate the discomfort of those with sensitive skin.
Sensitive skin is a multifaceted syndrome that requires more than just symptom
management it demands a deeper understanding of its pathophysiology, precise diagnostic
criteria, and reliable testing methods. As research evolves, so too will the ability to define,
diagnose, and treat this increasingly prevalent condition.
Understanding the Vicious Cycle of Sensitive Skin Syndrome. Dr. Farage reports that Sensitive
Skin Syndrome is a major malady that affects a significant portion of the population, with
nearly 40% reporting moderate to severe sensitivity and another 30% experiencing mild
symptoms. This condition, marked by sensations like itching, burning, stinging, pain, and
tingling, can affect anyone and can manifest on any part of the body. Environmental and