Toxicology of the Skin PDF

Preface

Skin is one of the largest and most visible organs of the body and is the primary interface with the environment. It serves a unique purpose, both in protecting the organism from the harsh outside world and in providing the organism a unique identity and individuality. Because of these varied roles, skin comes in contact with numerous chemicals through environmental and occupational exposure as well as through contact with cosmetics designed to maintain or improve one's appearance or drugs to cure disease. Skin is also an interface with many of the body's biological systems, including the nervous system when sensation is involved, the cardiovascular system when changes in blood flow is used to modulate body temperature, the endocrine system through synthesis of vitamin D, and the immune system where foreign agents are first detected by the body. Skin is thus a complex organ that can interact with chemicals in a multitude of ways, their adverse effects being the subject of this book.

The underlying theme of this volume is the barrier function of mammalian skin. The most important role of skin in relation to protecting the body from chemical assault is its function as the primary barrier to the environment. The initial chapters of this text review the anatomy and physiology of the skin and provide details on how the outermost layer, the stratum corneum, is the primary barrier to foreign substances. The focus then shifts to how chemicals and drugs interact with and penetrate the skin, a prerequisite for producing an adverse effect. How can this process be predicted and quantitated based on chemical properties and how does transport through hair follicles or dermal metabolism alter these relations?

A major issue when studying chemical interactions with skin is when this barrier is perturbed, either through normal variations with age or race or through physical damage from the sun or disease. How a compromised barrier alters chemical or drug absorption is discussed in this context. If the barrier is intact, the critical problem is how to get drugs across this rate-limiting barrier after topical application, a continuing area of technological development as evidenced by the plethora of skin patches now appearing on the market. Modern approaches to drug delivery across the skin barrier are thoroughly presented. The final chapters provide examples and case studies of chemical toxicity after topical exposures ranging from arsenic to jet fuel exposures. The emerging area of nanomaterial interactions and penetration through skin is presented as a case study with chemical agents targeting the skin as tools of warfare.

The goal of this book is to present the field of dermal toxicology from the perspective of how chemicals and drugs interact with the barrier properties of skin. This unifying theme is key to an understanding of how central the skin barrier is to health and disease, for if the barrier is intact, chemical penetration cannot occur and dermal toxicity will not be expressed.